View source for London Atlas: Materials and methods I: data acquisition

{{LondonAtlas}}
__TOC__
The London Region Atlas of Topsoil Geochemistry (LRA) covers a rectangular area of 80&nbsp;x&nbsp;62&nbsp;km (4960&nbsp;km<sup>2</sup>), from British National Grid coordinates X, Y: 490000, 153000 to 570000, 215000.  The LRA was produced using the London Region Topsoil Dataset ('''LRD''', N=8400), which was created from two BGS geochemical surveys (LOND and SEEN) carried out under the Geochemical Baseline Survey of the Environment (G-BASE<ref name="Geochemical Baseline Survey of the Environment (G-BASE)">Geochemical Baseline Survey of the Environment (G-BASE) http://www.bgs.ac.uk/gbase/home.html</ref>) project between 2005 and 2009. LOND is an '''urban''' soil survey based on 6801 sampling sites at a sampling density of 1 per 0.25 km<sup>2</sup>; 6494 (95.5%) of the LOND samples are part of the London Earth<ref name="London Earth">London Earth http://www.bgs.ac.uk/gbase/londonearth.html</ref> project as they are located within the GLA.  SEEN is a south-east England '''rural''' soil survey carried out at a sampling density of 1 per 2&nbsp;km<sup>2</sup>; 1599 (out of the 4089) SEEN sample sites are included in the LRA rectangle area; however, 95% are outwith the GLA limit as these are rural samples ([[Media:P929858.jpg |'''Figure 2''']]).

Field procedures and laboratory methods were undertaken in a standardised way to ensure consistency and enable quality assessment of the analytical results (Johnson et al., 2005<ref name="Johnson et al., 2005">Johnson, C C, Breward, N, Ander, E L, and Ault, L. 2005.  GBASE: baseline geochemical mapping of Great Britain and Northern Ireland. Geochemistry: Exploration, Environment, Analysis, Vol. 5 (4), 347–357.</ref>).  This allowed adequate levelling of geochemical datasets from contiguous areas, sampled and analysed at different times or under different projects.  Methods are described in the following sections.  Descriptions of the interpolation method (parent material mapping method, Appleton and Adlam, 2012<ref>Appleton, J D, and Adlam, K A M. 2012. Geogenic control on soil chemistry in urban areas: a novel method for urban geochemical mapping using parent material classified data. Applied Geochemistry, Vol. 27, 161–170. 10.1016/j.apgeochem.2011.10.001</ref>) used to generate maps of the soil geochemical properties and of the exploratory data analysis techniques deployed are outlined in the last section.

Throughout this atlas the '''LRD''' dataset, and <span style="color:#006401">'''SEEN'''</span> and <span style="color:#8b0003">'''LOND'''</span> subsets are generally represented by the colours '''black/white''', <span style="color:#006401">'''dark green'''</span> and <span style="color:#8b0003">'''dark red'''</span> respectively, while Quaternary, Palaeogene and Cretaceous geological time periods are represented by soft yellow, orange and lime green colours respectively.

==Sampling==
Sampling strategies for geochemical mapping using soil samples in rural (regional) and urban areas are described by Johnson et al. (2005)<ref name="Johnson et al., 2005"></ref> and Fordyce et al. (2005)<ref>Fordyce, F M, Brown, S E, Ander, E L, Rawlins, B G, O'Donnell, K E, Lister, T R, Breward, N, and Johnson, C C. 2005. GSUE: urban geochemical mapping in Great Britain. Geochemistry: Exploration, Environment, Analysis, Vol. 5 (4), 325–336. [http://nora.nerc.ac.uk/883/ Download from NORA].</ref>, respectively.  The only major difference between the two is the sampling density.  In rural areas soil samples are collected from alternate British National Grid (BNG) kilometre squares, corresponding to a sampling density of 1 sample/2&nbsp;km<sup>2</sup> (or 0.5 samples/km<sup>2</sup>); sites are ideally located at least 100&nbsp;m from roads, buildings, railways, electricity pylons etc., on open unforested, and undisturbed ground whenever possible; the site should be generally representative of the land use within the selected kilometre square.  In urban areas, the sample density is 1 sample/0.25&nbsp;km<sup>2</sup> (or 4 samples/km<sup>2</sup>); samples are collected from open ground (preferably gardens, parks, sports fields, road verges, allotments, open spaces, schoolyards, and waste ground) as close as possible to the centre of each 500&nbsp;m cell (subdivisions of the BNG 1&nbsp;km cell) ([[Media:P929861.jpg |'''Figure 5''']]).  The greater density in urban areas allows the capture of more local-scale element concentration variability caused by human activity.  The way of defining an urban area for sample collection purposes is described by Johnson and Ander (2008)<ref>Johnson, C C, and Ander, E L. 2008. Urban geochemical mapping studies: how and why we do them. Environmental Geochemistry and Health, Vol. 30, 511–530.</ref>.

Soil sampling was carried out according to the procedures detailed in the G-BASE<ref name="Geochemical Baseline Survey of the Environment (G-BASE)">Geochemical Baseline Survey of the Environment (G-BASE) http://www.bgs.ac.uk/gbase/home.html</ref> field procedures manual (Johnson, 2005<ref name="Johnson 2005">Johnson, C C. 2005. [http://nora.nerc.ac.uk/5190/ 2005 G-BASE Field Procedures Manual.] British Geological Survey Internal Report, IR/05/097. [http://nora.nerc.ac.uk/5190/ Download from NORA].</ref>).  All soil samples were collected and transported in 5”x10” Kraft™ paper bags.  Each sample consisted of approximately 250&nbsp;g of unsieved material and was a composite of five subsamples from auger holes distributed within an area of approximately 20 x 20&nbsp;m whenever possible.  Auger holes were located at the corners and centre of a square ([[Media:P929862.jpg |'''Figure 6''']]).  A 1&nbsp;m stainless steel Dutch auger with a 15&nbsp;cm auger flight was used to collect soil samples from a fixed depth.

Topsoil samples (sample type code ‘A’) were collected to a depth of 20&nbsp;cm, after removal of surface vegetation, surface litter and root zone.  The bottom depth of the sample was recorded on the field card and the depth of any rootlet zone and surface litter was also noted.  The deep soil sample (sample type code ‘S’) was targeted to collect to a depth of 35-50&nbsp;cm (in rural areas this had the objective of sampling below any ploughed horizon), the actual sampling depth was recorded on the field card.  Over terrains where only thin soils were developed e.g. over chalk, then a topsoil sample was collected from the normal surface depth, i.e. 5 to 20&nbsp;cm and the S sample from as deep as possible down to bedrock.  In such instances there may be little difference in the sampling depths between the A and S samples.

An extra surface sample (0–2&nbsp;cm) was collected in the London Earth<ref name="London Earth">London Earth http://www.bgs.ac.uk/gbase/londonearth.html</ref> GLA area, designated as sample type code ‘X’.  The X samples often demanded material from additional auger holes within the 20&nbsp;m square in order to reach the required sample weight of ca. 250&nbsp;g. If a root layer was present this was collected as part of the surface sample (Knights and Scheib, 2010<ref>Knights, K V, and Scheib, A J. 2010. London Earth: details of field campaigns across the Greater London area, 2005 to 2009. British Geological Survey Open Report, OR/09/056. [http://nora.nerc.ac.uk/9421/ Download from NORA]. </ref>).

Field duplicate samples were collected at a rate of 1 duplicate per 100 sampling sites in rural surveys.  This rate was doubled (2 per 100 sampling sites) in urban surveys following the higher sampling density implemented in these areas.  For quality control purposes, the field duplicates were collected with exactly the same procedure as a regular sample, but in an adjacent auger square ([[Media:P929862.jpg |'''Figure 6''']]).

At each sampling site, information about date of sampling, local details (location, geology, visible contamination, land use, etc.) and observations of the sample, such as soil colour, depth, clast lithology and apparent abundance, and textural classification, were recorded on a field card.

The geochemical results for the topsoil samples type ‘A’ (5-20&nbsp;cm depth) only are presented in this atlas.



[[Image:P929861.jpg|thumb|center|500px|'''Figure 5'''  The G-BASE strategy for urban (red X) and rural (green X) soil sampling sites. The grid represents 1&nbsp;km squares and the urban region is shaded (adapted from Johnson, 2005<ref name="Johnson 2005"></ref>). ([[Media:P929861.jpg |P929861]]).]]



[[Image:P929862.jpg|thumb|center|500px|'''Figure 6'''  Plan of composite auger holes for collecting a soil sample (dashed square represents adjacent duplicate sample) (from Johnson, 2005<ref name="Johnson 2005"></ref>). ([[Media:P929862.jpg |P929862]]).]]


==Sample preparation and analysis==
Soil samples were prepared and analysed at the BGS laboratories in Keyworth.  All samples were dried and sieved but only the topsoils were routinely analysed by XRFS.  After air-drying at <35°C (to prevent volatilisation of Se and Hg), each sample was sieved through a nylon sieve to give the <2&nbsp;mm fraction.  The sample was then homogenised, coned and quartered before a 50&nbsp;g subsample was pulverised in an agate planetary ball mill to create a homogeneous sample (95% under 53&nbsp;mm), from which a portion (12&nbsp;g) was taken to prepare a pressed powder pellet for XRFS analysis.

Samples were analysed for total element concentration by XRFS in the BGS laboratories<ref name="Laboratory services">Laboratory services http://www.bgs.ac.uk/sciencefacilities/laboratories/geochemistry/igf/Services/home.html</ref> in Keyworth.  Analysis is accredited to ISO 17025 and to the Environment Agency's Monitoring Certification Scheme (''M''CERTS) standard for soils.  Several different XRFS instruments were used, namely a PANalytical Axios advanced and a Philips MagiX PRO wavelength dispersive XRF spectrometer (WD-XRFS); and a PANalytical Epsilon-5 polarised energy dispersive XRF spectrometer (ED(P)XRFS), to determine 53 chemical elements.  Forty-four of these elements are listed together with their lower limit of detection (LLD<ref>Young, M E, and Donald, A W(eds). 2013. A guide to the Tellus data. Geological Survey of Northern Ireland, Belfast, UK. 233 pp.</ref>) and the number of samples below LLD in [[London Atlas: Materials and methods I: data acquisition #Table 3 |'''Table 3''']]. The remaining nine elements ([[London Atlas: Materials and methods I: data acquisition #Table 4 |'''Table 4''']]) were excluded as six of them (Cl, In, S, Te, Hg and Ta) showed more than 90% of the results below the LLD in at least one of the '''LRD''' subsets (<span style="color:#006401">'''SEEN'''</span>, <span style="color:#8b0003">'''LOND'''</span>) and five of them (Sm, Tl, Yb, Hg and Ta) showed a very small between-site variability (less than 35%), due to high within-sample and/or within-site variability mostly as a results of data close to the LLD ([[London Atlas: Materials and methods I: data acquisition #Table 5 |'''Table 5''']]).  Of the 44 elements shown in the London Region Atlas of Topsoil Geochemistry,  the 10 most abundant elements ([[Aluminium: LRA |Al<sub>2</sub>O<sub>3</sub>]], [[Calcium: LRA |CaO]], [[Iron: LRA |Fe<sub>2</sub>O<sub>3</sub>]], [[Potassium: LRA |K<sub>2</sub>O]], [[Magnesium: LRA |MgO]], [[Manganese: LRA |MnO]], [[Sodium: LRA |Na<sub>2</sub>O]], [[Phosphorus: LRA |P<sub>2</sub>O<sub>5</sub>]], [[Silicon: LRA |SiO<sub>2</sub>]], [[Titanium: LRA |TiO<sub>2</sub>]]) are expressed in terms of weight percent oxide (wt%) as concentration units, while the remaining 34 ([[Silver: LRA |Ag]], [[Arsenic: LRA |As]], [[Barium: LRA |Ba]], [[Bismuth: LRA |Bi]], [[Bromine: LRA |Br]], [[Cadmium: LRA |Cd]], [[Cerium: LRA |Ce]], [[Cobalt: LRA |Co]], [[Chromium: LRA |Cr]], [[Caesium: LRA |Cs]], [[Copper: LRA |Cu]], [[Gallium: LRA |Ga]], [[Germanium: LRA |Ge]], [[Hafnium: LRA |Hf]], [[Iodine: LRA |I]], [[Lanthanum: LRA |La]], [[Molybdenum: LRA |Mo]], [[Niobium: LRA |Nb]], [[Neodymium: LRA |Nd]], [[Nickel: LRA |Ni]], [[Lead: LRA |Pb]], [[Rubidium: LRA |Rb]], [[Antimony: LRA |Sb]], [[Scandium: LRA |Sc]], [[Selenium: LRA |Se]], [[Tin: LRA |Sn]], [[Strontium: LRA |Sr]], [[Thorium: LRA |Th]], [[Uranium: LRA |U]], [[Vanadium: LRA |V]], [[Tungsten: LRA |W]], [[Yttrium: LRA |Y]], [[Zinc: LRA |Zn]] and [[Zirconium: LRA |Zr]]) are shown in mg/kg (equivalent to the non-SI old notation ppm - parts per million).

Two extra parameters, loss on ignition ([[Loss on ignition: LRA |LOI]]) and [[Acidity/Basicity: LRA |pH]] were also determined on the topsoil samples from the <span style="color:#8b0003">'''LOND'''</span> subset (except one for [[Loss on ignition: LRA |LOI]]) and about two thirds (1128 out of 1599) of the <span style="color:#006401">'''SEEN'''</span> subset, resulting in a total of 7928 (for [[Loss on ignition: LRA |LOI]]) and 7929 (for [[Acidity/Basicity: LRA |pH]]) measurements.  The loss on ignition, a proxy for the soil’s organic matter content (but can be affected by the loss of structural water in clay soils (Rowell, 1994<ref>Rowell, D L. 1994. Soil science: methods and applications. UK: Longman Scientific and Technical</ref>), was determined on 2&nbsp;g of <2&nbsp;mm size material by weighing the sample before and after heating in a furnace at 450°C for 24 hrs.  The soil [[Acidity/Basicity: LRA |pH]] was determined with a pH electrode after mixing 10&nbsp;g of <2&nbsp;mm size material in 25&nbsp;ml of 0.01&nbsp;M CaCl<sub>2</sub>.2H<sub>2</sub>O and shaking until a slurry was formed.



<span id="Table 3"></span>
 <div align="center">
{| Class="wikitable"
|+ Table 3 List of elements determined by XRFS reported in the London Region Atlas of Topsoil Geochemistry. The lower limit of detection (LLD), the number of samples below the LLD (n<LLD) and the n<LLD in percent (%<LLD) are shown for the London Region Dataset (LRD), and the two subsets (<span style="color:#006401">SEEN</span> and <span style="color:#8b0003">LOND</span>). Number of samples (N) is as follow: LRD = 8400, <span style="color:#006401">SEEN</span> = 1599 and <span style="color:#8b0003">LOND</span> = 6801.
| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>
|-
| rowspan="3" style="height: 30pt; background-color:#ffffff" | <p align="center">'''Aluminium oxide'''<br>'''[[Aluminium: LRA |Al<sub>2</sub>O<sub>3</sub>]]'''<br>'''%'''</p>
| style="height: 10pt" | <p align="center">'''LRD'''</p>
| <p align="center">0.2</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" style="height: 30pt; background-color:#ffffff" | <p align="center">'''Cadmium'''<br>'''[[Cadmium: LRA |Cd]]'''<br>'''mg/kg'''</p>
| style="height: 10pt" | <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">2317</p>
| <p align="center">27.6</p>
| rowspan="3" style="height: 30pt; background-color:#ffffff" | <p align="center">'''Lead'''<br>'''[[Lead:_LRA |Pb]]'''<br>'''mg/kg'''</p>
| style="height: 10pt" | <p align="center">'''LRD'''</p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| style="height: 10pt" | <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.2</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| style="height: 10pt" | <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">787</p>
| <p align="center">49.2</p>
| style="height: 10pt" | <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| style="height: 10pt" | <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.2</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| style="height: 10pt" | <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1530</p>
| <p align="center">22.5</p>
| style="height: 10pt" | <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" style="background-color:#ffffff" | <p align="center">'''Calcium oxide'''<br>'''[[Calcium: LRA |CaO]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.05</p>
| <p align="center">14</p>
| <p align="center">0.2</p>
| rowspan="3" style="background-color:#ffffff" | <p align="center">'''Cerium'''<br>'''[[Cerium: LRA |Ce]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" style="background-color:#ffffff" | <p align="center">'''Rubidium'''<br>'''[[Rubidium: LRA |Rb]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.05</p>
| <p align="center">14</p>
| <p align="center">0.9</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.05</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Iron (III) oxide'''<br>'''[[Iron: LRA |Fe<sub>2</sub>O<sub>3</sub>]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Cobalt'''<br>'''[[Cobalt: LRA |Co]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.5</p>
| <p align="center">27</p>
| <p align="center">0.3</p>
| rowspan="3" | <p align="center">'''Antimony'''<br>'''[[Antimony: LRA |Sb]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">84</p>
| <p align="center">1.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.5</p>
| <p align="center">19</p>
| <p align="center">1.2</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">68</p>
| <p align="center">4.3</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.5</p>
| <p align="center">8</p>
| <p align="center">0.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">16</p>
| <p align="center">0.2</p>
|-
| rowspan="3" | <p align="center">'''Potassium oxide'''<br>'''[[Potassium: LRA |K<sub>2</sub>O]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Chromium'''<br>'''[[Chromium: LRA |Cr]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Scandium'''<br>'''[[Scandium: LRA |Sc]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">3</p>
| <p align="center">374</p>
| <p align="center">4.5</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">3</p>
| <p align="center">198</p>
| <p align="center">12.4</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">3</p>
| <p align="center">176</p>
| <p align="center">2.6</p>
|-
| rowspan="3" | <p align="center">'''Magnesium oxide'''<br>'''[[Magnesium: LRA |MgO]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.3</p>
| <p align="center">376</p>
| <p align="center">4.5</p>
| rowspan="3" | <p align="center">'''Caesium'''<br>'''[[Caesium: LRA |Cs]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Selenium'''<br>'''[[Selenium: LRA |Se]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.2</p>
| <p align="center">140</p>
| <p align="center">1.7</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.3</p>
| <p align="center">83</p>
| <p align="center">5.2</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.2</p>
| <p align="center">51</p>
| <p align="center">3.2</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.3</p>
| <p align="center">293</p>
| <p align="center">4.3</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.2</p>
| <p align="center">89</p>
| <p align="center">1.3</p>
|-
| colspan="17" style="color:white" |
|-
| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>
|-
| rowspan="3" | <p align="center">'''Manganese oxide'''<br>'''[[Manganese: LRA |MnO]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.005</p>
| <p align="center">20</p>
| <p align="center">0.2</p>
| rowspan="3" | <p align="center">'''Copper'''<br>'''[[Copper: LRA |Cu]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Tin'''<br>'''[[Tin: LRA |Sn]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.005</p>
| <p align="center">12</p>
| <p align="center">0.8</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.005</p>
| <p align="center">8</p>
| <p align="center">0.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Sodium oxide'''<br>'''[[Sodium: LRA |Na<sub>2</sub>O]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.3</p>
| <p align="center">447</p>
| <p align="center">5.3</p>
| rowspan="3" | <p align="center">'''Gallium'''<br>'''[[Gallium: LRA |Ga]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Strontium'''<br>'''[[Strontium: LRA |Sr]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.3</p>
| <p align="center">167</p>
| <p align="center">10.4</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.3</p>
| <p align="center">280</p>
| <p align="center">4.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Phosphorous<br>pentoxide'''<br>'''[[Phosphorus: LRA |P<sub>2</sub>O<sub>5</sub>]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.05</p>
| <p align="center">16</p>
| <p align="center">0.2</p>
| rowspan="3" | <p align="center">'''Germanium'''<br>'''[[Germanium: LRA |Ge]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">384</p>
| <p align="center">4.6</p>
| rowspan="3" | <p align="center">'''Thorium'''<br>'''[[Thorium: LRA |Th]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.7</p>
| <p align="center">3</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.05</p>
| <p align="center">15</p>
| <p align="center">0.9</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">109</p>
| <p align="center">6.8</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.7</p>
| <p align="center">1</p>
| <p align="center">0.1</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.05</p>
| <p align="center">1</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">275</p>
| <p align="center">4.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.7</p>
| <p align="center">2</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Silica'''<br>'''[[Silicon: LRA |SiO<sub>2</sub>]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Hafnium'''<br>'''[[Hafnium: LRA |Hf]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Uranium'''<br>'''[[Uranium: LRA |U]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">43</p>
| <p align="center">0.5</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1</p>
| <p align="center">0.1</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">42</p>
| <p align="center">0.6</p>
|-
| rowspan="3" | <p align="center">'''Titanium dioxide'''<br>'''[[Titanium: LRA |TiO<sub>2</sub>]]'''<br>'''%'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Iodine'''<br>'''[[Iodine: LRA |I]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">15</p>
| <p align="center">0.2</p>
| rowspan="3" | <p align="center">'''Vanadium'''<br>'''[[Vanadium: LRA |V]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">3</p>
| <p align="center">0.2</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.01</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">12</p>
| <p align="center">0.2</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| colspan="17" style="color:white" |
|-
| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>

| rowspan=16 style="color:white" | <p align="center">.</p>

| style="background-color:#dbd7d2" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''Data'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''n<LLD'''<span style="color:#dbd7d2">-</span></p>
| style="background-color:#dbd7d2" | <p align="center"><span style="color:#dbd7d2">-</span>'''%<LLD'''<span style="color:#dbd7d2">-</span></p>
|-
| rowspan="3" | <p align="center">'''Silver'''<br>'''[[Silver: LRA |Ag]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">1232</p>
| <p align="center">14.7</p>
| rowspan="3" | <p align="center">'''Lanthanum'''<br>'''[[Lanthanum: LRA |La]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Tungsten'''<br>'''[[Tungsten: LRA |W]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.6</p>
| <p align="center">219</p>
| <p align="center">2.6</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">175</p>
| <p align="center">10.9</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.6</p>
| <p align="center">81</p>
| <p align="center">5.1</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1057</p>
| <p align="center">15.5</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.6</p>
| <p align="center">138</p>
| <p align="center">2.0</p>
|-
| rowspan="3" | <p align="center">'''Arsenic'''<br>'''[[Arsenic: LRA |As]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">2.4</p>
| <p align="center">9</p>
| <p align="center">0.1</p>
| rowspan="3" | <p align="center">'''Molybdenum'''<br>'''[[Molybdenum: LRA |Mo]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.2</p>
| <p align="center">18</p>
| <p align="center">0.2</p>
| rowspan="3" | <p align="center">'''Yttrium'''<br>'''[[Yttrium: LRA |Y]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">2.4</p>
| <p align="center">5</p>
| <p align="center">0.3</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.2</p>
| <p align="center">11</p>
| <p align="center">0.7</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">2.4</p>
| <p align="center">4</p>
| <p align="center">0.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.2</p>
| <p align="center">7</p>
| <p align="center">0.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Barium'''<br>'''[[Barium: LRA |Ba]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Niobium'''<br>'''[[Niobium: LRA |Nb]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Zinc'''<br>'''[[Zinc: LRA |Zn]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.3</p>
| <p align="center">3</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.3</p>
| <p align="center">1</p>
| <p align="center">0.1</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.3</p>
| <p align="center">2</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Bismuth'''<br>'''[[Bismuth: LRA |Bi]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.3</p>
| <p align="center">4490</p>
| <p align="center">53.5</p>
| rowspan="3" | <p align="center">'''Neodymium'''<br>'''[[Neodymium: LRA |Nd]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">4</p>
| <p align="center">19</p>
| <p align="center">0.2</p>
| rowspan="3" | <p align="center">'''Zirconium'''<br>'''[[Zirconium: LRA |Zr]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.3</p>
| <p align="center">918</p>
| <p align="center">57.4</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">4</p>
| <p align="center">14</p>
| <p align="center">0.9</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.3</p>
| <p align="center">3572</p>
| <p align="center">52.5</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">4</p>
| <p align="center">5</p>
| <p align="center">0.1</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|-
| rowspan="3" | <p align="center">'''Bromine'''<br>'''[[Bromine: LRA |Br]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.8</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| rowspan="3" | <p align="center">'''Nickel'''<br>'''[[Nickel: LRA |Ni]]'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.3</p>
| <p align="center">3</p>
| <p align="center">0.0</p>
| rowspan="3" colspan="5" | <p align="center">.</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.8</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.3</p>
| <p align="center">3</p>
| <p align="center">0.2</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.8</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.3</p>
| <p align="center">0</p>
| <p align="center">0.0</p>
|}
</div>



<span id="Table 4"></span>
<div align="center">
{| class="wikitable"
|+ Table 4 List of elements determined by XRFS not reported in the London Region Atlas of Topsoil Geochemistry. The lower limit of detection (LLD), the number of samples below the LLD (n<LLD) and the n<LLD in percent (%<LLD) are shown for the London Region Dataset (LRD), and the two subsets (<span style="color:#006401">SEEN</span> and <span style="color:#8b0003">LOND</span>). Number of samples (N) is as follow: LRD = 8400, <span style="color:#006401">SEEN</span> = 1599 and <span style="color:#8b0003">LOND</span> = 6801.
| style="width: 70pt; background-color:#dbd7d2;" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="width: 50pt; background-color:#dbd7d2;" | <p align="center">'''Data'''</p>
| style="width: 25pt; background-color:#dbd7d2;" | <p align="center">'''LLD'''</p>
| style="width: 30pt; background-color:#dbd7d2;" | <p align="center">'''n<LLD'''</p>
| style="width: 35pt; background-color:#dbd7d2;" | <p align="center">'''%<LLD'''</p>
| rowspan=10 style="color:white" | <p align="center">.</p>
| style="width: 70pt; background-color:#dbd7d2;" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="width: 50pt; background-color:#dbd7d2;" | <p align="center">'''Data'''</p>
| style="width: 25pt; background-color:#dbd7d2;" | <p align="center">'''LLD'''</p>
| style="width: 30pt; background-color:#dbd7d2;" | <p align="center">'''n<LLD'''</p>
| style="width: 35pt; background-color:#dbd7d2;" | <p align="center">'''%<LLD'''</p>
| rowspan=10 style="color:white" | <p align="center">.</p>
| style="width: 70pt; background-color:#dbd7d2;" | <p align="center">'''Element<br>Symbol<br>Units'''</p>
| style="width: 50pt; background-color:#dbd7d2;" | <p align="center">'''Data'''</p>
| style="width: 25pt; background-color:#dbd7d2;" | <p align="center">'''LLD'''</p>
| style="width: 30pt; background-color:#dbd7d2;" | <p align="center">'''n<LLD'''</p>
| style="width: 35pt; background-color:#dbd7d2;" | <p align="center">'''%<LLD'''</p>
|-
| rowspan="3" | <p align="center">'''Chlorine'''<br>'''Cl'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">200</p>
| <p align="center">8378</p>
| <p align="center">99.7</p>
| rowspan="3" | <p align="center">'''Tellurium'''<br>'''Te'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">8347</p>
| <p align="center">99.4</p>
| rowspan="3" | <p align="center">'''Samarium'''<br>'''Sm'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">3.0</p>
| <p align="center">3217</p>
| <p align="center">38.3</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">200</p>
| <p align="center">1596</p>
| <p align="center">99.8</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1583</p>
| <p align="center">99.0</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">3.0</p>
| <p align="center">533</p>
| <p align="center">33.3</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">200</p>
| <p align="center">6782</p>
| <p align="center">99.7</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">6764</p>
| <p align="center">99.5</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">3.0</p>
| <p align="center">2684</p>
| <p align="center">41.9</p>
|-
| rowspan="3" | <p align="center">'''Indium'''<br>'''In'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">8348</p>
| <p align="center">99.4</p>
| rowspan="3" | <p align="center">'''Mercury'''<br>'''Hg'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">6921</p>
| <p align="center">82.4</p>
| rowspan="3" | <p align="center">'''Thallium'''<br>'''Tl'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">0.5</p>
| <p align="center">6054</p>
| <p align="center">72.1</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1586</p>
| <p align="center">99.2</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1513</p>
| <p align="center">94.6</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">0.5</p>
| <p align="center">1049</p>
| <p align="center">65.6</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">6762</p>
| <p align="center">99.4</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">5408</p>
| <p align="center">79.5</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">0.5</p>
| <p align="center">5005</p>
| <p align="center">78.2</p>
|-
| rowspan="3" | <p align="center">'''Sulphur'''<br>'''S'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">2000</p>
| <p align="center">8243</p>
| <p align="center">98.1</p>
| rowspan="3" | <p align="center">'''Tantalum'''<br>'''Ta'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.0</p>
| <p align="center">7741</p>
| <p align="center">92.9</p>
| rowspan="3" | <p align="center">'''Ytterbium'''<br>'''Yb'''<br>'''mg/kg'''</p>
| <p align="center">'''LRD'''</p>
| <p align="center">1.5</p>
| <p align="center">2520</p>
| <p align="center">30.0</p>
|-
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">2000</p>
| <p align="center">1586</p>
| <p align="center">99.2</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.0</p>
| <p align="center">1368</p>
| <p align="center">85.6</p>
| <p align="center"><span style="color:#006401">'''SEEN'''</span></p>
| <p align="center">1.5</p>
| <p align="center">371</p>
| <p align="center">23.2</p>
|-
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">2000</p>
| <p align="center">6657</p>
| <p align="center">97.9</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.0</p>
| <p align="center">6373</p>
| <p align="center">93.7</p>
| <p align="center"><span style="color:#8b0003">'''LOND'''</span></p>
| <p align="center">1.5</p>
| <p align="center">2149</p>
| <p align="center">33.6</p>
|}
</div>



<span id="Table 5"></span>
<div align="center">
{| class="wikitable"
|+ Table 5 Nested ANOVA results for the London Region Data topsoil duplicate and replicate sets. The number of sites indicate the number of locations with duplicate and replicate samples. Results below the lower limit of detection are excluded from the ANOVA analysis (Johnson et al., 2010<ref>Johnson, C C, Scheib, A, and Lister, T R. 2010 London Earth topsoil chemical results : user guide. British Geological Survey Open Report, OR/11/035.</ref>). Elements are ordered according to their performance in the nested ANOVA test. Shaded elements were excluded from the atlas after this test.
| style="background-color:#dbd7d2" | <p align="center">'''Element'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Between-site %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Within-site %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Within-sample %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Number of sites'''</p>
| rowspan=26 style="color:white" | <p align="center">.</p>
| style="background-color:#dbd7d2" | <p align="center">'''Element'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Between-site %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Within-site %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Within-sample %'''</p>
| style="background-color:#dbd7d2" | <p align="center">'''Number of sites'''</p>
|-
| <p align="center">'''[[Niobium: LRA |Nb]]'''</p>
| <p align="center">94.5</p>
| <p align="center">4.2</p>
| <p align="center">1.3</p>
| <p align="center">171</p>
| <p align="center">'''[[Manganese: LRA |MnO]]'''</p>
| <p align="center">84.2</p>
| <p align="center">13.1</p>
| <p align="center">2.7</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Potassium: LRA |K<sub>2</sub>O]]'''</p>
| <p align="center">93.3</p>
| <p align="center">6.4</p>
| <p align="center">0.3</p>
| <p align="center">171</p>
| <p align="center">'''[[Arsenic: LRA |As]]'''</p>
| <p align="center">83.8</p>
| <p align="center">13.4</p>
| <p align="center">2.8</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Rubidium: LRA |Rb]]'''</p>
| <p align="center">93.1</p>
| <p align="center">6.6</p>
| <p align="center">0.3</p>
| <p align="center">171</p>
| <p align="center">'''[[Phosphorus: LRA |P<sub>2</sub>O<sub>5</sub>]]'''</p>
| <p align="center">82.5</p>
| <p align="center">16.6</p>
| <p align="center">0.9</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Lanthanum: LRA |La]]'''</p>
| <p align="center">92.0</p>
| <p align="center">6.0</p>
| <p align="center">2.0</p>
| <p align="center">171</p>
| <p align="center">'''[[Barium: LRA |Ba]]'''</p>
| <p align="center">82.3</p>
| <p align="center">15.3</p>
| <p align="center">2.4</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Titanium: LRA |TiO<sub>2</sub>]]'''</p>
| <p align="center">91.6</p>
| <p align="center">7.1</p>
| <p align="center">1.3</p>
| <p align="center">171</p>
| <p align="center">'''[[Sodium: LRA |Na<sub>2</sub>O]]'''</p>
| <p align="center">82.3</p>
| <p align="center">10.2</p>
| <p align="center">7.5</p>
| <p align="center">124</p>
|-
| <p align="center">'''[[Cerium: LRA |Ce]]'''</p>
| <p align="center">91.0</p>
| <p align="center">7.4</p>
| <p align="center">1.6</p>
| <p align="center">171</p>
| <p align="center">'''[[Cobalt: LRA |Co]]'''</p>
| <p align="center">82.1</p>
| <p align="center">10.6</p>
| <p align="center">7.3</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Gallium: LRA |Ga]]'''</p>
| <p align="center">90.7</p>
| <p align="center">6.3</p>
| <p align="center">2.9</p>
| <p align="center">171</p>
| <p align="center">'''[[Caesium: LRA |Cs]]'''</p>
| <p align="center">81.7</p>
| <p align="center">4.5</p>
| <p align="center">13.7</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Magnesium: LRA |MgO]]'''</p>
| <p align="center">90.7</p>
| <p align="center">8.4</p>
| <p align="center">0.9</p>
| <p align="center">168</p>
| <p align="center">'''[[Tungsten: LRA |W]]'''</p>
| <p align="center">80.1</p>
| <p align="center">5.5</p>
| <p align="center">14.4</p>
| <p align="center">166</p>
|-
| <p align="center">'''[[Yttrium: LRA |Y]]'''</p>
| <p align="center">90.6</p>
| <p align="center">7.0</p>
| <p align="center">2.4</p>
| <p align="center">171</p>
| <p align="center">'''[[Nickel: LRA |Ni]]'''</p>
| <p align="center">79.9</p>
| <p align="center">16.2</p>
| <p align="center">3.9</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Aluminium: LRA |Al<sub>2</sub>O<sub>3</sub>]]'''</p>
| <p align="center">90.5</p>
| <p align="center">8.7</p>
| <p align="center">0.7</p>
| <p align="center">171</p>
| <p align="center">'''[[Copper: LRA |Cu]]'''</p>
| <p align="center">79.6</p>
| <p align="center">17.8</p>
| <p align="center">2.6</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Vanadium: LRA |V]]'''</p>
| <p align="center">90.5</p>
| <p align="center">8.3</p>
| <p align="center">1.2</p>
| <p align="center">171</p>
| <p align="center">'''[[Zinc: LRA |Zn]]'''</p>
| <p align="center">77.0</p>
| <p align="center">20.9</p>
| <p align="center">2.0</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Thorium: LRA |Th]]'''</p>
| <p align="center">89.4</p>
| <p align="center">6.2</p>
| <p align="center">4.4</p>
| <p align="center">171</p>
| <p align="center">'''[[Scandium: LRA |Sc]]'''</p>
| <p align="center">76.4</p>
| <p align="center">9.3</p>
| <p align="center">14.2</p>
| <p align="center">165</p>
|-
| <p align="center">'''[[Zirconium: LRA |Zr]]'''</p>
| <p align="center">88.9</p>
| <p align="center">9.4</p>
| <p align="center">1.7</p>
| <p align="center">171</p>
| <p align="center">'''[[Antimony: LRA |Sb]]'''</p>
| <p align="center">75.9</p>
| <p align="center">14.9</p>
| <p align="center">9.2</p>
| <p align="center">170</p>
|-
| <p align="center">'''[[Calcium: LRA |CaO]]'''</p>
| <p align="center">88.3</p>
| <p align="center">10.3</p>
| <p align="center">1.3</p>
| <p align="center">171</p>
| <p align="center">'''[[Tin: LRA |Sn]]'''</p>
| <p align="center">75.0</p>
| <p align="center">16.4</p>
| <p align="center">8.5</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Iron: LRA |Fe<sub>2</sub>O<sub>3</sub>]]'''</p>
| <p align="center">88.1</p>
| <p align="center">8.8</p>
| <p align="center">3.1</p>
| <p align="center">171</p>
| <p align="center">'''[[Uranium: LRA |U]]'''</p>
| <p align="center">72.1</p>
| <p align="center">5.5</p>
| <p align="center">22.3</p>
| <p align="center">165</p>
|-
| <p align="center">'''[[Molybdenum: LRA |Mo]]'''</p>
| <p align="center">88.1</p>
| <p align="center">8.9</p>
| <p align="center">3.0</p>
| <p align="center">151</p>
| <p align="center">'''[[Selenium: LRA |Se]]'''</p>
| <p align="center">66.7</p>
| <p align="center">14.9</p>
| <p align="center">18.4</p>
| <p align="center">171</p>
|-
| <p align="center">'''[[Strontium: LRA |Sr]]'''</p>
| <p align="center">88.0</p>
| <p align="center">10.5</p>
| <p align="center">1.5</p>
| <p align="center">171</p>
| <p align="center">'''[[Cadmium: LRA |Cd]]'''</p>
| <p align="center">62.9</p>
| <p align="center">24.7</p>
| <p align="center">12.4</p>
| <p align="center">108</p>
|-
| <p align="center">'''[[Neodymium: LRA |Nd]]'''</p>
| <p align="center">86.6</p>
| <p align="center">7.5</p>
| <p align="center">5.9</p>
| <p align="center">170</p>
| <p align="center">'''[[Germanium: LRA |Ge]]'''</p>
| <p align="center">62.3</p>
| <p align="center">17.8</p>
| <p align="center">20.0</p>
| <p align="center">168</p>
|-
| <p align="center">'''[[Bromine: LRA |Br]]'''</p>
| <p align="center">86.4</p>
| <p align="center">11.4</p>
| <p align="center">2.2</p>
| <p align="center">171</p>
| <p align="center">'''[[Silver: LRA |Ag]]'''</p>
| <p align="center">58.9</p>
| <p align="center">30.9</p>
| <p align="center">10.2</p>
| <p align="center">26</p>
|-
| <p align="center">'''[[Hafnium: LRA |Hf]]'''</p>
| <p align="center">86.0</p>
| <p align="center">7.1</p>
| <p align="center">6.9</p>
| <p align="center">171</p>
| <p align="center">'''[[Bismuth: LRA |Bi]]'''</p>
| <p align="center">52.2</p>
| <p align="center">28.1</p>
| <p align="center">19.7</p>
| <p align="center">55</p>
|-
| <p align="center">'''[[Lead:_LRA |Pb]]'''</p>
| <p align="center">85.3</p>
| <p align="center">10.7</p>
| <p align="center">4.0</p>
| <p align="center">171</p>
| style="background-color:#dcdcdc" | <p align="center">'''Yb'''</p>
| style="background-color:#dcdcdc" | <p align="center">34.8</p>
| style="background-color:#dcdcdc" | <p align="center">5.3</p>
| style="background-color:#dcdcdc" | <p align="center">59.8</p>
| style="background-color:#dcdcdc" | <p align="center">99</p>
|-
| <p align="center">'''[[Iodine: LRA |I]]'''</p>
| <p align="center">85.2</p>
| <p align="center">8.8</p>
| <p align="center">6.0</p>
| <p align="center">171</p>
| style="background-color:#dbd7d2" | <p align="center">'''Hg'''</p>
| style="background-color:#dbd7d2" | <p align="center">29.7</p>
| style="background-color:#dbd7d2" | <p align="center">55.2</p>
| style="background-color:#dbd7d2" | <p align="center">15.1</p>
| style="background-color:#dbd7d2" | <p align="center">39</p>
|-
| <p align="center">'''[[Silicon: LRA |SiO<sub>2</sub>]]'''</p>
| <p align="center">85.0</p>
| <p align="center">12.5</p>
| <p align="center">2.5</p>
| <p align="center">171</p>
| style="background-color:#dcdcdc" | <p align="center">'''Sm'''</p>
| style="background-color:#dcdcdc" | <p align="center">25.7</p>
| style="background-color:#dcdcdc" | <p align="center">4.5</p>
| style="background-color:#dcdcdc" | <p align="center">69.8</p>
| style="background-color:#dcdcdc" | <p align="center">166</p>
|-
| <p align="center">'''[[Chromium: LRA |Cr]]'''</p>
| <p align="center">85.0</p>
| <p align="center">13.9</p>
| <p align="center">1.2</p>
| <p align="center">171</p>
| style="background-color:#dcdcdc" | <p align="center">'''Tl'''</p>
| style="background-color:#dcdcdc" | <p align="center">16.6</p>
| style="background-color:#dcdcdc" | <p align="center">-8.6</p>
| style="background-color:#dcdcdc" | <p align="center">91.9</p>
| style="background-color:#dcdcdc" | <p align="center">65</p>
|-
| colspan="5" |
| style="background-color:#dbd7d2" | <p align="center">'''Ta'''</p>
| style="background-color:#dbd7d2" | <p align="center">15.3</p>
| style="background-color:#dbd7d2" | <p align="center">3.0</p>
| style="background-color:#dbd7d2" | <p align="center">81.7</p>
| style="background-color:#dbd7d2" | <p align="center">54</p>
|}
</div>



==Quality control==
G-BASE<ref name="Geochemical Baseline Survey of the Environment (G-BASE)">Geochemical Baseline Survey of the Environment (G-BASE) http://www.bgs.ac.uk/gbase/home.html</ref> analytical results are subjected to rigorous quality control procedures described in detail elsewhere (Lister and Johnson, 2005<ref>Lister, T R, and Johnson, C C. 2005. G-BASE data conditioning procedures for stream sediment and soil chemical analyses. British Geological Survey Internal Report, IR/05/150. [http://nora.nerc.ac.uk/11170/ Download from NORA].</ref>; Johnson, 2011<ref name="Johnson, C C. 2011">Johnson, C C. 2011 [http://nora.nerc.ac.uk/16218/ Understanding the quality of chemical data from the urban environment. Part 1, quality control procedures.] 61–76 ''In'' Johnson, C C et al., (eds.) Mapping the chemical environment of urban areas. Wiley. </ref>).  The entire process, from field procedures to sample preparation and analysis in the laboratory is designed to minimise errors.  Systematic errors are able to be checked because a randomised number is assigned to samples on collection.

Accuracy, precision and long-term analytical drift is assessed by including BGS XRF laboratory primary and secondary certified reference materials (CRMs) along with every batch of 500 samples in the analytical runs.  Secondary CRMs allow any between batch bias to be identified and corrected.  Primary CRMs ensure that bias from the 'true' result is minimized.  Primary and secondary reference materials have been used routinely to assess the quality of regional geochemical data since the UK national mapping programme commenced in the 1960s (Lister and Johnson, 2005<ref>Lister, T R, and Johnson, C C. 2005. G-BASE data conditioning procedures for stream sediment and soil chemical analyses. British Geological Survey Internal Report, IR/05/150. [http://nora.nerc.ac.uk/11170/ Download from NORA].</ref>; Johnson et al., 2008<ref>Johnson, C C, Ander, E L, Lister, T R, and Flight, D M A. 2008. Data conditioning of environmental geochemical data: quality control procedures used in the British Geological Survey's Regional Geochemical Mapping Project. 93–118 ''in'' Environmental geochemistry: site characterisation, data analysis and case histories. De Vivo, B, Belkin, H E, and Lima, A (editors). Oxford: Elsevier.</ref>).  This ensures a ‘seamless’ continuation of geochemical data across large regions for samples collected over many field campaigns and analysed by different analytical instruments.  All data in this London Region Geochemical Dataset are levelled using four accredited reference materials (GSD-7, GSS-1, LKSD-1, LKSD-4).  Certified values (in red) together with the values reported by the BGS XRF laboratory are shown in [[London Atlas: Materials and methods I: data acquisition #Table 6 |'''Table 6''']].

A previously unrecognised analytical interference between high topsoil Pb concentration and U measurement in the London Earth<ref name="London Earth">London Earth http://www.bgs.ac.uk/gbase/londonearth.html</ref> results, where high Pb was suppressing the U results, has been corrected in this London Region dataset.

The G-BASE<ref name="Geochemical Baseline Survey of the Environment (G-BASE)">Geochemical Baseline Survey of the Environment (G-BASE) http://www.bgs.ac.uk/gbase/home.html</ref> project also inserts field ''duplicate'' and laboratory ''replicate'' samples in every batch of fifty (urban) or one hundred (rural) samples.  The laboratory ''replicate'' is a sub-sample of the ''same sample'' taken before analysis, whilst a field ''duplicate'' is a ''second'' ''sample'' collected in the field at the same location as a regular sample.  These two control samples allow assessment of the analytical and sampling variability respectively and comparison to the total variability. This provides a check that the local (within-site) ‘noise’ is low enough so that the regional patterns (between sites) are distinguishable and reliable.  This was achieved by performing a nested unbalanced analysis of variance (ANOVA) using these duplicate and replicate samples (Johnson, 2002<ref>Johnson, C C. 2002. Within-site and between-site nested analysis of variance (ANOVA) for geochemical surveys using MS EXCEL. British Geological Survey Internal Report, IR/02/043.  [http://nora.nerc.ac.uk/5190/ Download from NORA].</ref>).  The validity of the nested ANOVA depends on the representativeness of the duplicates and replicates, and it may not be valid if a large number of samples have element concentrations that are near or below the LLD.  Nevertheless, results give an indication of the elements for which the natural geochemical variability is significantly higher than the variability related to the sampling and analytical procedures. The higher the percentage of total variability attributed between sites, the higher the confidence in the results ([[London Atlas: Materials and methods I: data acquisition #Table 5 |'''Table 5''']]).  For elements with a value above 80% the sampling and analytical methodology is considered suitable, as it does not introduce too much 'background noise'.  As between-site variability decreases from 80% down to about 50%, increasing caution must be taken during statistical analysis and/or interpretation.  Elements showing a between-site variability below 50% (Yb, Hg, Sm, Tl and Ta) are not considered further in the LRA, as already explained under the [[London Atlas: Materials and methods I: data acquisition #Sample preparation and analysis | Sample preparation and analysis]] section of this atlas.



<span id="Table 6"></span>
 <div align="center">
{| class="wikitable"
|+ Table 6 Summary of primary reference material results for soil samples XRFS analyses in the London Region Atlas of Topsoil Geochemistry. Units for elements shown as oxides are wt% and mg/kg otherwise.
| valign="bottom" colspan="31" | <p align="center">'''Elements by XRF-ED'''</p>
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Silver: LRA |Ag]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ag'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Cadmium: LRA |Cd]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Cd'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''In'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert In'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Tin: LRA |Sn]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Sn'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Antimony: LRA |Sb]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Sb'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Iodine: LRA |I]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert I'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Caesium: LRA |Cs]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Cs'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Barium: LRA |Ba]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ba'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Lanthanum: LRA |La]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert La'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Cerium: LRA |Ce]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ce'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">1.4</p>
| valign="bottom" style="color:red;" | <p align="center">1.1</p>
| valign="bottom" | <p align="center">0.9</p>
| valign="bottom" style="color:red;" | <p align="center">1.1</p>
| valign="bottom" | <p align="center">not detected</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">4.8</p>
| valign="bottom" style="color:red;" | <p align="center">5.4</p>
| valign="bottom" | <p align="center">2.8</p>
| valign="bottom" style="color:red;" | <p align="center">2.6</p>
| valign="bottom" | <p align="center">0.9</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">5</p>
| valign="bottom" style="color:red;" | <p align="center">6</p>
| valign="bottom" | <p align="center">740</p>
| valign="bottom" style="color:red;" | <p align="center">720</p>
| valign="bottom" | <p align="center">45</p>
| valign="bottom" style="color:red;" | <p align="center">45</p>
| valign="bottom" | <p align="center">82</p>
| valign="bottom" style="color:red;" | <p align="center">78.0</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">0.4</p>
| valign="bottom" style="color:red;" | <p align="center">0.4</p>
| valign="bottom" | <p align="center">4.4</p>
| valign="bottom" style="color:red;" | <p align="center">4.3</p>
| valign="bottom" | <p align="center">not detected</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">5.9</p>
| valign="bottom" style="color:red;" | <p align="center">6.1</p>
| valign="bottom" | <p align="center">1.0</p>
| valign="bottom" style="color:red;" | <p align="center">0.9</p>
| valign="bottom" | <p align="center">1.9</p>
| valign="bottom" style="color:red;" | <p align="center">1.9</p>
| valign="bottom" | <p align="center">9</p>
| valign="bottom" style="color:red;" | <p align="center">9</p>
| valign="bottom" | <p align="center">587</p>
| valign="bottom" style="color:red;" | <p align="center">590</p>
| valign="bottom" | <p align="center">34</p>
| valign="bottom" style="color:red;" | <p align="center">34</p>
| valign="bottom" | <p align="center">68</p>
| valign="bottom" style="color:red;" | <p align="center">70.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">0.5</p>
| valign="bottom" style="color:red;" | <p align="center">0.6</p>
| valign="bottom" | <p align="center">1.1</p>
| valign="bottom" style="color:red;" | <p align="center">1.2</p>
| valign="bottom" | <p align="center">0.5</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">15.2</p>
| valign="bottom" style="color:red;" | <p align="center">16.0</p>
| valign="bottom" | <p align="center">0.9</p>
| valign="bottom" style="color:red;" | <p align="center">1.2</p>
| valign="bottom" | <p align="center">1.7</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">1</p>
| valign="bottom" style="color:red;" | <p align="center">2</p>
| valign="bottom" | <p align="center">396</p>
| valign="bottom" style="color:red;" | <p align="center">430</p>
| valign="bottom" | <p align="center">14</p>
| valign="bottom" style="color:red;" | <p align="center">16</p>
| valign="bottom" | <p align="center">25</p>
| valign="bottom" style="color:red;" | <p align="center">27.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">0.1</p>
| valign="bottom" style="color:red;" | <p align="center">0.2</p>
| valign="bottom" | <p align="center">1.9</p>
| valign="bottom" style="color:red;" | <p align="center">1.9</p>
| valign="bottom" | <p align="center">not detected</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">4.6</p>
| valign="bottom" style="color:red;" | <p align="center">5.0</p>
| valign="bottom" | <p align="center">1.3</p>
| valign="bottom" style="color:red;" | <p align="center">1.7</p>
| valign="bottom" | <p align="center">9.5</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">2</p>
| valign="bottom" style="color:red;" | <p align="center">2</p>
| valign="bottom" | <p align="center">262</p>
| valign="bottom" style="color:red;" | <p align="center">330</p>
| valign="bottom" | <p align="center">21</p>
| valign="bottom" style="color:red;" | <p align="center">26</p>
| valign="bottom" | <p align="center">38</p>
| valign="bottom" style="color:red;" | <p align="center">48.0</p>
|}
</div> 
<div align="center">
{| class="wikitable"
| valign="bottom" colspan="25" | <p align="center">'''Elements by XRF-WDT'''</p>
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Potassium: LRA |K<sub>2</sub>O]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert K<sub>2</sub>O'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Calcium: LRA |CaO]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert CaO'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Titanium: LRA |TiO<sub>2</sub>]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert TiO<sub>2</sub>'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Manganese: LRA |MnO]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert MnO'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Iron: LRA |Fe<sub>2</sub>O<sub>3</sub>]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Fe<sub>2</sub>O<sub>3</sub>'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''S'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert S'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Cl'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Cl'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Scandium: LRA |Sc]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Sc'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">3.64</p>
| valign="bottom" style="color:red;" | <p align="center">3.54</p>
| valign="bottom" | <p align="center">1.65</p>
| valign="bottom" style="color:red;" | <p align="center">1.67</p>
| valign="bottom" | <p align="center">0.707</p>
| valign="bottom" style="color:red;" | <p align="center">0.747</p>
| valign="bottom" | <p align="center">0.093</p>
| valign="bottom" style="color:red;" | <p align="center">0.089</p>
| valign="bottom" | <p align="center">6.50</p>
| valign="bottom" style="color:red;" | <p align="center">6.51</p>
| valign="bottom" | <p align="center">646</p>
| valign="bottom" style="color:red;" | <p align="center">190</p>
| valign="bottom" | <p align="center">83</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">13.7</p>
| valign="bottom" style="color:red;" | <p align="center">14.6</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">2.53</p>
| valign="bottom" style="color:red;" | <p align="center">2.59</p>
| valign="bottom" | <p align="center">1.75</p>
| valign="bottom" style="color:red;" | <p align="center">1.72</p>
| valign="bottom" | <p align="center">0.766</p>
| valign="bottom" style="color:red;" | <p align="center">0.805</p>
| valign="bottom" | <p align="center">0.238</p>
| valign="bottom" style="color:red;" | <p align="center">0.227</p>
| valign="bottom" | <p align="center">5.18</p>
| valign="bottom" style="color:red;" | <p align="center">5.19</p>
| valign="bottom" | <p align="center">847</p>
| valign="bottom" style="color:red;" | <p align="center">310</p>
| valign="bottom" | <p align="center">114</p>
| valign="bottom" style="color:red;" | <p align="center">78</p>
| valign="bottom" | <p align="center">10.4</p>
| valign="bottom" style="color:red;" | <p align="center">11.2</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">1.06</p>
| valign="bottom" style="color:red;" | <p align="center">1.10</p>
| valign="bottom" | <p align="center">12.14</p>
| valign="bottom" style="color:red;" | <p align="center">10.80</p>
| valign="bottom" | <p align="center">0.448</p>
| valign="bottom" style="color:red;" | <p align="center">0.500</p>
| valign="bottom" | <p align="center">0.093</p>
| valign="bottom" style="color:red;" | <p align="center">0.100</p>
| valign="bottom" | <p align="center">4.03</p>
| valign="bottom" style="color:red;" | <p align="center">4.10</p>
| valign="bottom" | <p align="center">9306</p>
| valign="bottom" style="color:red;" | <p align="center">1570</p>
| valign="bottom" | <p align="center">430</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">6.5</p>
| valign="bottom" style="color:red;" | <p align="center">9.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">0.76</p>
| valign="bottom" style="color:red;" | <p align="center">0.80</p>
| valign="bottom" | <p align="center">1.85</p>
| valign="bottom" style="color:red;" | <p align="center">1.80</p>
| valign="bottom" | <p align="center">0.299</p>
| valign="bottom" style="color:red;" | <p align="center">0.400</p>
| valign="bottom" | <p align="center">0.068</p>
| valign="bottom" style="color:red;" | <p align="center">0.100</p>
| valign="bottom" | <p align="center">4.20</p>
| valign="bottom" style="color:red;" | <p align="center">4.10</p>
| valign="bottom" | <p align="center">5952</p>
| valign="bottom" style="color:red;" | <p align="center">999</p>
| valign="bottom" | <p align="center">215</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">7.1</p>
| valign="bottom" style="color:red;" | <p align="center">7.0</p>
|-
| valign="bottom" colspan="25" |
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Vanadium: LRA |V]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert V'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Chromium: LRA |Cr]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Cr'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Cobalt: LRA |Co]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Co'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Nickel: LRA |Ni]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ni'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Copper: LRA |Cu]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Cu'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Zinc: LRA |Zn]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Zn'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Gallium: LRA |Ga]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ga'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Germanium: LRA |Ge]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ge'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">93.4</p>
| valign="bottom" style="color:red;" | <p align="center">96.0</p>
| valign="bottom" | <p align="center">119.3</p>
| valign="bottom" style="color:red;" | <p align="center">122.0</p>
| valign="bottom" | <p align="center">20.6</p>
| valign="bottom" style="color:red;" | <p align="center">21.0</p>
| valign="bottom" | <p align="center">55.6</p>
| valign="bottom" style="color:red;" | <p align="center">53.0</p>
| valign="bottom" | <p align="center">36.1</p>
| valign="bottom" style="color:red;" | <p align="center">38.0</p>
| valign="bottom" | <p align="center">246.2</p>
| valign="bottom" style="color:red;" | <p align="center">238.0</p>
| valign="bottom" | <p align="center">16.7</p>
| valign="bottom" style="color:red;" | <p align="center">17.7</p>
| valign="bottom" | <p align="center">0.9</p>
| valign="bottom" style="color:red;" | <p align="center">1.4</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">80.7</p>
| valign="bottom" style="color:red;" | <p align="center">86.0</p>
| valign="bottom" | <p align="center">60.0</p>
| valign="bottom" style="color:red;" | <p align="center">62.0</p>
| valign="bottom" | <p align="center">13.9</p>
| valign="bottom" style="color:red;" | <p align="center">14.2</p>
| valign="bottom" | <p align="center">20.7</p>
| valign="bottom" style="color:red;" | <p align="center">20.4</p>
| valign="bottom" | <p align="center">19.7</p>
| valign="bottom" style="color:red;" | <p align="center">21.0</p>
| valign="bottom" | <p align="center">671.6</p>
| valign="bottom" style="color:red;" | <p align="center">680.0</p>
| valign="bottom" | <p align="center">17.6</p>
| valign="bottom" style="color:red;" | <p align="center">19.3</p>
| valign="bottom" | <p align="center">0.6</p>
| valign="bottom" style="color:red;" | <p align="center">1.3</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">47.8</p>
| valign="bottom" style="color:red;" | <p align="center">50.0</p>
| valign="bottom" | <p align="center">27.0</p>
| valign="bottom" style="color:red;" | <p align="center">31.0</p>
| valign="bottom" | <p align="center">11.0</p>
| valign="bottom" style="color:red;" | <p align="center">11.0</p>
| valign="bottom" | <p align="center">16.0</p>
| valign="bottom" style="color:red;" | <p align="center">16.0</p>
| valign="bottom" | <p align="center">40.6</p>
| valign="bottom" style="color:red;" | <p align="center">44.0</p>
| valign="bottom" | <p align="center">322.4</p>
| valign="bottom" style="color:red;" | <p align="center">331.0</p>
| valign="bottom" | <p align="center">9.0</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">0.1</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">45.5</p>
| valign="bottom" style="color:red;" | <p align="center">49.0</p>
| valign="bottom" | <p align="center">30.1</p>
| valign="bottom" style="color:red;" | <p align="center">33.0</p>
| valign="bottom" | <p align="center">11.7</p>
| valign="bottom" style="color:red;" | <p align="center">11.0</p>
| valign="bottom" | <p align="center">34.1</p>
| valign="bottom" style="color:red;" | <p align="center">31.0</p>
| valign="bottom" | <p align="center">30.1</p>
| valign="bottom" style="color:red;" | <p align="center">31.0</p>
| valign="bottom" | <p align="center">194.3</p>
| valign="bottom" style="color:red;" | <p align="center">194.0</p>
| valign="bottom" | <p align="center">7.9</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">0.5</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|-
| valign="bottom" colspan="25" |
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Arsenic: LRA |As]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert As'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Selenium: LRA |Se]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Se'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Bromine: LRA |Br]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Br'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Rubidium: LRA |Rb]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Rb'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Strontium: LRA |Sr]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Sr'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Yttrium: LRA |Y]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Y'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Zirconium: LRA |Zr]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Zr'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Niobium: LRA |Nb]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Nb'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">83.7</p>
| valign="bottom" style="color:red;" | <p align="center">84.0</p>
| valign="bottom" | <p align="center">0.2</p>
| valign="bottom" style="color:red;" | <p align="center">0.3</p>
| valign="bottom" | <p align="center">0.6</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">146.4</p>
| valign="bottom" style="color:red;" | <p align="center">147.0</p>
| valign="bottom" | <p align="center">222.4</p>
| valign="bottom" style="color:red;" | <p align="center">220.0</p>
| valign="bottom" | <p align="center">24.9</p>
| valign="bottom" style="color:red;" | <p align="center">24.0</p>
| valign="bottom" | <p align="center">156.9</p>
| valign="bottom" style="color:red;" | <p align="center">162.0</p>
| valign="bottom" | <p align="center">15.1</p>
| valign="bottom" style="color:red;" | <p align="center">17.0</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">35.8</p>
| valign="bottom" style="color:red;" | <p align="center">33.5</p>
| valign="bottom" | <p align="center">0.1</p>
| valign="bottom" style="color:red;" | <p align="center">0.1</p>
| valign="bottom" | <p align="center">2.5</p>
| valign="bottom" style="color:red;" | <p align="center">2.9</p>
| valign="bottom" | <p align="center">137.9</p>
| valign="bottom" style="color:red;" | <p align="center">140.0</p>
| valign="bottom" | <p align="center">156.6</p>
| valign="bottom" style="color:red;" | <p align="center">155.0</p>
| valign="bottom" | <p align="center">24.9</p>
| valign="bottom" style="color:red;" | <p align="center">25.0</p>
| valign="bottom" | <p align="center">250.1</p>
| valign="bottom" style="color:red;" | <p align="center">245.0</p>
| valign="bottom" | <p align="center">14.7</p>
| valign="bottom" style="color:red;" | <p align="center">16.6</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">34.9</p>
| valign="bottom" style="color:red;" | <p align="center">40.0</p>
| valign="bottom" | <p align="center">1.0</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">10.3</p>
| valign="bottom" style="color:red;" | <p align="center">11.0</p>
| valign="bottom" | <p align="center">22.7</p>
| valign="bottom" style="color:red;" | <p align="center">24.0</p>
| valign="bottom" | <p align="center">259.4</p>
| valign="bottom" style="color:red;" | <p align="center">250.0</p>
| valign="bottom" | <p align="center">20.9</p>
| valign="bottom" style="color:red;" | <p align="center">19.0</p>
| valign="bottom" | <p align="center">132.8</p>
| valign="bottom" style="color:red;" | <p align="center">134.0</p>
| valign="bottom" | <p align="center">4.0</p>
| valign="bottom" style="color:red;" | <p align="center">7.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">16.6</p>
| valign="bottom" style="color:red;" | <p align="center">16.0</p>
| valign="bottom" | <p align="center">2.3</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">50.6</p>
| valign="bottom" style="color:red;" | <p align="center">49.0</p>
| valign="bottom" | <p align="center">25.0</p>
| valign="bottom" style="color:red;" | <p align="center">28.0</p>
| valign="bottom" | <p align="center">121.0</p>
| valign="bottom" style="color:red;" | <p align="center">110.0</p>
| valign="bottom" | <p align="center">22.2</p>
| valign="bottom" style="color:red;" | <p align="center">23.0</p>
| valign="bottom" | <p align="center">101.3</p>
| valign="bottom" style="color:red;" | <p align="center">105.0</p>
| valign="bottom" | <p align="center">4.3</p>
| valign="bottom" style="color:red;" | <p align="center">9.0</p>
|-
| valign="bottom" colspan="25" |
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Molybdenum: LRA |Mo]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Mo'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Neodymium: LRA |Nd]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Nd'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Sm'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Sm'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Yb'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Yb'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Hafnium: LRA |Hf]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Hf'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Ta'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Ta'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Tungsten: LRA |W]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert W'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Hg'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Hg'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">1.3</p>
| valign="bottom" style="color:red;" | <p align="center">1.4</p>
| valign="bottom" | <p align="center">34.1</p>
| valign="bottom" style="color:red;" | <p align="center">37.0</p>
| valign="bottom" | <p align="center">4.4</p>
| valign="bottom" style="color:red;" | <p align="center">6.1</p>
| valign="bottom" | <p align="center">2.2</p>
| valign="bottom" style="color:red;" | <p align="center">2.6</p>
| valign="bottom" | <p align="center">5.0</p>
| valign="bottom" style="color:red;" | <p align="center">4.9</p>
| valign="bottom" | <p align="center">0.8</p>
| valign="bottom" style="color:red;" | <p align="center">1.4</p>
| valign="bottom" | <p align="center">6.5</p>
| valign="bottom" style="color:red;" | <p align="center">5.5</p>
| valign="bottom" | <p align="center">-0.3</p>
| valign="bottom" style="color:red;" | <p align="center">0.1</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">1.1</p>
| valign="bottom" style="color:red;" | <p align="center">1.4</p>
| valign="bottom" | <p align="center">26.3</p>
| valign="bottom" style="color:red;" | <p align="center">28.0</p>
| valign="bottom" | <p align="center">3.9</p>
| valign="bottom" style="color:red;" | <p align="center">5.2</p>
| valign="bottom" | <p align="center">2.1</p>
| valign="bottom" style="color:red;" | <p align="center">2.7</p>
| valign="bottom" | <p align="center">7.7</p>
| valign="bottom" style="color:red;" | <p align="center">6.8</p>
| valign="bottom" | <p align="center">0.5</p>
| valign="bottom" style="color:red;" | <p align="center">1.4</p>
| valign="bottom" | <p align="center">4.6</p>
| valign="bottom" style="color:red;" | <p align="center">3.1</p>
| valign="bottom" | <p align="center">-0.8</p>
| valign="bottom" style="color:red;" | <p align="center">0.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">9.4</p>
| valign="bottom" style="color:red;" | <p align="center">10.0</p>
| valign="bottom" | <p align="center">19.4</p>
| valign="bottom" style="color:red;" | <p align="center">16.0</p>
| valign="bottom" | <p align="center">2.9</p>
| valign="bottom" style="color:red;" | <p align="center">4.0</p>
| valign="bottom" | <p align="center">1.7</p>
| valign="bottom" style="color:red;" | <p align="center">2.0</p>
| valign="bottom" | <p align="center">4.1</p>
| valign="bottom" style="color:red;" | <p align="center">3.6</p>
| valign="bottom" | <p align="center">-0.2</p>
| valign="bottom" style="color:red;" | <p align="center">0.3</p>
| valign="bottom" | <p align="center">1.7</p>
| valign="bottom" style="color:red;" | <p align="center"><4</p>
| valign="bottom" | <p align="center">-0.6</p>
| valign="bottom" style="color:red;" | <p align="center">0.0</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">1.3</p>
| valign="bottom" style="color:red;" | <p align="center"><5</p>
| valign="bottom" | <p align="center">27.1</p>
| valign="bottom" style="color:red;" | <p align="center">25.0</p>
| valign="bottom" | <p align="center">4.3</p>
| valign="bottom" style="color:red;" | <p align="center">5.0</p>
| valign="bottom" | <p align="center">2.1</p>
| valign="bottom" style="color:red;" | <p align="center">2.0</p>
| valign="bottom" | <p align="center">3.1</p>
| valign="bottom" style="color:red;" | <p align="center">2.8</p>
| valign="bottom" | <p align="center">-0.1</p>
| valign="bottom" style="color:red;" | <p align="center">0.4</p>
| valign="bottom" | <p align="center">1.8</p>
| valign="bottom" style="color:red;" | <p align="center"><4</p>
| valign="bottom" | <p align="center">-0.5</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''Tl'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Tl'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Lead:_LRA |Pb]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Pb'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Bismuth: LRA |Bi]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Bi'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Thorium: LRA |Th]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Th'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Uranium: LRA |U]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert U'''</p>
| valign="bottom" rowspan="5" colspan="22" |
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">0.7</p>
| valign="bottom" style="color:red;" | <p align="center">0.9</p>
| valign="bottom" | <p align="center">361.1</p>
| valign="bottom" style="color:red;" | <p align="center">350.0</p>
| valign="bottom" | <p align="center">0.6</p>
| valign="bottom" style="color:red;" | <p align="center">0.7</p>
| valign="bottom" | <p align="center">12.6</p>
| valign="bottom" style="color:red;" | <p align="center">12.6</p>
| valign="bottom" | <p align="center">3.4</p>
| valign="bottom" style="color:red;" | <p align="center">3.5</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">0.7</p>
| valign="bottom" style="color:red;" | <p align="center">1.0</p>
| valign="bottom" | <p align="center">98.2</p>
| valign="bottom" style="color:red;" | <p align="center">98.0</p>
| valign="bottom" | <p align="center">0.7</p>
| valign="bottom" style="color:red;" | <p align="center">1.2</p>
| valign="bottom" | <p align="center">11.4</p>
| valign="bottom" style="color:red;" | <p align="center">11.6</p>
| valign="bottom" | <p align="center">3.7</p>
| valign="bottom" style="color:red;" | <p align="center">3.3</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">0.1</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">83.7</p>
| valign="bottom" style="color:red;" | <p align="center">82.0</p>
| valign="bottom" | <p align="center">0.6</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">2.1</p>
| valign="bottom" style="color:red;" | <p align="center">2.2</p>
| valign="bottom" | <p align="center">9.7</p>
| valign="bottom" style="color:red;" | <p align="center">9.7</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">0.8</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">97.3</p>
| valign="bottom" style="color:red;" | <p align="center">91.0</p>
| valign="bottom" | <p align="center">0.0</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
| valign="bottom" | <p align="center">5.1</p>
| valign="bottom" style="color:red;" | <p align="center">5.1</p>
| valign="bottom" | <p align="center">31.4</p>
| valign="bottom" style="color:red;" | <p align="center">31</p>
|}
</div>

 <div align="center">
{| class="wikitable"
| valign="bottom" colspan="19" | <p align="center">'''Elements by XRF-WDM'''</p>
|-
| valign="bottom" | <p align="center">'''CRM ID'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Sodium: LRA |Na<sub>2</sub>O]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Na<sub>2</sub>O'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Magnesium: LRA |MgO]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert MgO'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Aluminium: LRA |Al<sub>2</sub>O<sub>3</sub>]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert Al<sub>2</sub>O<sub>3</sub>'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Silicon: LRA |SiO<sub>2</sub>]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert SiO<sub>2</sub>'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''[[Phosphorus: LRA |P<sub>2</sub>O<sub>5</sub>]]'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert P<sub>2</sub>O<sub>5</sub>'''</p>
| rowspan=5 style="color:white" | <p align="center">.</p>
| valign="bottom" | <p align="center">'''SO<sub>3</sub>'''</p>
| valign="bottom" style="color:red;" | <p align="center">'''Cert SO<sub>3</sub>'''</p>
|-
| valign="bottom" | <p align="center">'''''GSD-7'''''</p>
| valign="bottom" | <p align="center">1.2</p>
| valign="bottom" style="color:red;" | <p align="center">1.2</p>
| valign="bottom" | <p align="center">4.3</p>
| valign="bottom" style="color:red;" | <p align="center">3.1</p>
| valign="bottom" | <p align="center">14.6</p>
| valign="bottom" style="color:red;" | <p align="center">13.4</p>
| valign="bottom" | <p align="center">67.3</p>
| valign="bottom" style="color:red;" | <p align="center">64.7</p>
| valign="bottom" | <p align="center">0.21</p>
| valign="bottom" style="color:red;" | <p align="center">0.19</p>
| valign="bottom" | <p align="center">not detected</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|-
| valign="bottom" | <p align="center">'''''GSS-1'''''</p>
| valign="bottom" | <p align="center">1.4</p>
| valign="bottom" style="color:red;" | <p align="center">1.7</p>
| valign="bottom" | <p align="center">2.1</p>
| valign="bottom" style="color:red;" | <p align="center">1.8</p>
| valign="bottom" | <p align="center">14.1</p>
| valign="bottom" style="color:red;" | <p align="center">14.2</p>
| valign="bottom" | <p align="center">57.4</p>
| valign="bottom" style="color:red;" | <p align="center">62.6</p>
| valign="bottom" | <p align="center">0.18</p>
| valign="bottom" style="color:red;" | <p align="center">0.17</p>
| valign="bottom" | <p align="center">0.1</p>
| valign="bottom" style="color:red;" | <p align="center">0.08</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-1'''''</p>
| valign="bottom" | <p align="center">1.6</p>
| valign="bottom" style="color:red;" | <p align="center">2.0</p>
| valign="bottom" | <p align="center">1.8</p>
| valign="bottom" style="color:red;" | <p align="center">1.7</p>
| valign="bottom" | <p align="center">5.6</p>
| valign="bottom" style="color:red;" | <p align="center">7.8</p>
| valign="bottom" | <p align="center">31.5</p>
| valign="bottom" style="color:red;" | <p align="center">40.1</p>
| valign="bottom" | <p align="center">0.16</p>
| valign="bottom" style="color:red;" | <p align="center">0.20</p>
| valign="bottom" | <p align="center">2.6</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|-
| valign="bottom" | <p align="center">'''''LKSD-4'''''</p>
| valign="bottom" | <p align="center">0.5</p>
| valign="bottom" style="color:red;" | <p align="center">0.7</p>
| valign="bottom" | <p align="center">1.0</p>
| valign="bottom" style="color:red;" | <p align="center">0.9</p>
| valign="bottom" | <p align="center">5.2</p>
| valign="bottom" style="color:red;" | <p align="center">5.9</p>
| valign="bottom" | <p align="center">45.2</p>
| valign="bottom" style="color:red;" | <p align="center">41.6</p>
| valign="bottom" | <p align="center">0.36</p>
| valign="bottom" style="color:red;" | <p align="center">0.30</p>
| valign="bottom" | <p align="center">2.1</p>
| valign="bottom" style="color:red;" | <p align="center">no data</p>
|}
</div>

==References==
<References/>
[[Category:London Region Atlas of Topsoil Geochemistry | 04]]