London Atlas: Introduction

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Ferreira, A, Johnson, C C, Appleton, J D, Flight, D M A, Lister, T R, Knights, K V, Ander, L, Scheib, C, Scheib, A, Cave, M, Wragg, J, Fordyce, F and Lawley, R. 2017. London Region Atlas of Topsoil Geochemistry. British Geological Survey.

The British Geological Survey’s Geochemical Baseline Survey of the Environment (G-BASE[1]) project systematically maps the distribution of inorganic chemical elements in the surface environment of Great Britain (Johnson et al., 2005[2]) to help characterise land quality. This systematic and high-resolution geochemical baseline mapping, completed in 2015, was initially based on drainage samples collected from low order streams (Plant, 1971[3]) but has since been expanded to include soils. The work started in the late 1960s in northern Britain and was primarily concerned with mineral exploration. Since commencement, the geochemical mapping has progressed southwards. It is now principally focused on underpinning research projects, supporting stakeholders, and work on maintaining sustainable and healthy environments, particularly since the project’s remit was expanded to include the mapping of urban areas in the 1990s (Fordyce et al., 2005[4]; Johnson and Ander, 2008[5]; Flight and Scheib, 2011[6]). The systematically collected rural and urban G-BASE[1] soil database available for England is summarised in Figure 1 and the area covered by this atlas is indicated on this figure. Separate to the G-BASE[1] survey, the National Soil Inventory (NSI[7]) samples were collected by the Soil Survey of England and Wales. These were re-analysed by X-ray fluorescence spectrometry (XRFS) in the BGS laboratories to be compatible with the G-BASE[1] dataset and reported by Rawlins et al. (2012)[8]. The NSI[7] samples were collected at a low density (1 site every 25 km2) and not from urban areas. With the high density G-BASE[1] samples available for the London region there was no need to include the low density NSI[7] samples in this atlas. For the last G-BASE rural survey (SSEEN) carried out in 2014/2015 (Figure 1, sample sites in blue), a lower sampling density was used. These samples were not used for this atlas, as the dataset here was compiled before the SSEEN results were available.


Figure 1 Map showing the distribution of systematically collected topsoil samples from England (until 2015) with the area covered by this atlas shown by the red rectangle around London. NSI (XRFS) covers the whole of England at a sample density of 1:25 km2. G-BASE sampling densities for rural and urban are 1:2 km2 and 4:1 km2, respectively, except for the 2014 survey (in blue). Only G-BASE samples collected previous to 2014 are used in this atlas. (P929857).


By 2005 the geochemical survey had reached the outskirts of northern London and sampling in urban areas of London commenced with priority given to the area proposed for the main Olympic site at Stratford. After sampling in some south Essex urban centres (Scheib and Brown, 2005[9]; Scheib et al., 2006[10]), a project sampling soils of the Greater London Autority area (GLA), known as the London Earth[11] project, commenced in 2008 and was completed in 2009 (Johnson et al., 2010[12]). Soils were collected from over 6000 sites across London at a density of four sites for every British National Grid (BNG) kilometre square (Knights and Scheib, 2010[13] and Table 1). The GLA has an area of 1579 km2 (607 sq mi) and in 2011, was reported to contain a population of 8.2 million (ONS, 2012[14]). The London Earth[11] project represents the world’s largest systematic geochemical survey of an urban area.


Table 1 Details of the number of soil samples collected from each London local government district and urban centres in south Essex, 2005–2009 (after Knights and Scheib, 2010[15])

London local government districts

Sample sites

Date of sampling

21

London local government districts

Sample sites

Date of sampling

Barking and Dagenham

140

2005, 2006 & 2008

Lambeth

113

2009

Barnet

354

2008

Lewisham

143

2009

Bexley

269

2009

Merton

155

2009

Brent

176

2008

Newham

164

2006 & 2008

Bromley

610

2009

Redbridge

233

2008

Camden

92

2008

Richmond upon Thames

247

2009

City of London

16

2008

Royal Borough of Kensington and Chelsea

57

2008

City of Westminster

87

2008

Royal Borough of Kingston upon Thames

149

2009

Croydon

353

2009

Southwark

126

2009

Ealing

227

2008

Sutton

181

2009

Enfield

325

2008

Tower Hamlets

87

2006 & 2008

Greenwich

191

2009

Waltham Forest

153

2006 & 2008

Hackney

75

2006 & 2008

Wandsworth

146

2009

Hammersmith and Fulham

69

2008

Haringey

118

2008

South Essex urban centres
Harrow

206

2008

Basildon

115

2005

Havering

453

2005, 2006 & 2008

Brentwood

66

2005, 2006 & 2008

Hillingdon

423

2008 & 2009

Grays and Tilbury

180

2005 & 2006

Hounslow

234

2008 & 2009

Southend-on-Sea

271

2006

Islington

63

2008

Stanford-le-Hope and Shell Haven

51

2006


A selection of geochemical maps showing element concentrations in topsoil for the GLA area were published online in 2011 as part of the London Earth[11] project and the database of soil results made publicly available (Johnson et al., 2011[16]). In addition to sampling urban areas, the G-BASE[1] project has continued to collect soils from rural areas at a density of 1 site every 2 km2 using the same sampling and analytical methods as used in the urban area. The region around the GLA has, therefore, been sampled also (Figure 2). As a result, in this atlas it is possible to study the London soils in the context of surrounding rural areas, so that the impact of urbanisation on the geochemical baseline can be determined. The atlas provides details of the sampling and analytical methodology along with initial data exploration to accompany a set of extrapolated grid geochemical maps for each soil element created using the parent-material polygon-mapping method described by Appleton and Adlam (2012)[17]. The data exploration is reported here and is seen as a resource and catalyst for further research on the surface chemical environment of London.


Figure 2 Map showing the topsoil sample locations in the London Region. (P929858).


References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 Geochemical Baseline Survey of the Environment (G-BASE) http://www.bgs.ac.uk/gbase/home.html
  2. 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.
  3. Plant, J A. 1971. Orientation studies on stream sediment sampling for a regional geochemical survey in northern Scotland. Transactions of the Institute Mining & Metallurgy, Vol. 80, 323–346.
  4. 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. Download from NORA.
  5. 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.
  6. Flight, D M A, and Scheib, A J. 2011. Soil geochemical baselines in UK urban centres: the G-BASE project. Chapter 13, 186–206. In: Mapping the chemical environment of urban areas. Johnson C C, Demetriades, A, Locutura, J, and Ottesen, R T (eds.). John Wiley & Sons, Ltd., Chichester, UK.
  7. 7.0 7.1 7.2 NSI | Soils Summary Information http://www.bgs.ac.uk/gbase/sampleindexmaps/soilnsi.html
  8. Rawlins, B G, McGrath, S P, Scheib, A J, Cave, M R, Breward, N, Lister, T R, Ingham, M, Gowing, C J B, and Carter, S. 2012. The advanced soil geochemical atlas of England and Wales. British Geological Survey, Keyworth, Nottingham. Published as an electronic book. at: www.bgs.ac.uk/gbase/advsoilatlasEW.html (last accessed 14th February 2013).
  9. Scheib, A J, and Brown, S E. 2005. A report on the G-BASE summer field campaign of 2005: Essex and urban areas of north-east London. British Geological Survey Internal Report, IR/05/142.
  10. Scheib, A J, Brown, S E, and Knights, K V. 2006. A report on the G-BASE summer field campaign of 2006: Bedfordshire, Hertfordshire and Buckinghamshire and urban areas of north-east London and Southend. British Geological Survey Internal Report, IR/06/122.
  11. 11.0 11.1 11.2 London Earth http://www.bgs.ac.uk/gbase/londonearth.html
  12. 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. Download from NORA.
  13. 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. Download from NORA.
  14. ONS. 2012. 2011 Census – population and household estimates for England and Wales, March 2011. Office for National Statistics. 20 July 2012. 36 pp. Available online from http://www.ons.gov.uk/ons/dcp171778_270487.pdf.
  15. 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. Download from NORA.
  16. Johnson, C C. 2011 Understanding the quality of chemical data from the urban environment. Part 1, quality control procedures. In: Johnson, C C. et al., (eds.) Mapping the chemical environment of urban areas. Wiley, 61–76.
  17. 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