|Farr, G, and Hall J. 2014. Atmospheric deposition and groundwater dependent wetlands: implications for effective catchment management and future Water Framework Directive groundwater classification in England and Wales. British Geological Survey Internal Report, OR/14/047.|
The Environment Agency, Natural England and Natural Resources Wales are responsible for the management of water and the environment in England and Wales. These responsibilities include the protection of Groundwater Dependent Terrestrial Ecosystems (GWDTEs). GWDTEs are wetlands that critically depend on groundwater flows and or chemistries (Schutten et al. 2011) and include statutory (e.g. SSSI/SAC/NNR) and non statutory sites (e.g local nature reserves). Examples of sites classified as GWDTEs include; fens, bogs, humid dunes and wet heath.
The regulatory bodies are charged with the successful implementation of both the Habitats Directive (92/43/EEC) and the Water Framework Directive (2000/60/EC). The Habitats Directive (HD) requires that member states should maintain or restore Annex 1 habitats to ‘favourable conservation status’, whilst the Water Framework Directive (WFD) requires groundwater to be in ‘good chemical and quantitative status’.
As part of the WFD classification a series of tests are carried out on each ‘groundwater body’. The results are used to assign either ‘good’ or ‘poor’ status to a groundwater body. One of these tests considers the impact of groundwater quality and availability on the condition of GWDTEs that are located within each groundwater body. In simple terms if a groundwater pressure such as over abstraction or elevated nutrients results in significant damage (see Whiteman et al. 2010) to a GWDTE then it is likely to fail both targets for the HD (remaining in ‘unfavourable’ condition) and the WFD (resulting in ‘poor’ status for the surrounding groundwater body). This report focuses on the GWDTE test that is part of the chemical classification process for the WFD (UKTAG, 2012b).
Two ‘cycles’ of groundwater characterisation have been undertaken in England and Wales (2008 & 2013). During each cycle GWDTEs in unfavourable status due to chemical (and quantitative) pressures have resulted in the failure of associated groundwater bodies. When a groundwater body fails the WFD classification the process requires an investigation to be undertaken, the identification of the source/s and reversal of the trends that lead to both unfavourable condition and poor groundwater status. These actions are known as WFD program of measures.
During WFD investigations at various wetlands (e.g. Environment Agency, 2011 and SWS, 2010a/b) it became clear that elevated nutrients were a key pressure resulting in unfavourable condition and poor status. To date WFD investigations have primarily been focused upon groundwater and surface water (i.e terrestrial) nutrient pathways.
GWDTEs can be ecologically and hydrologically complex, and when they are in unfavorable condition it can be easy to ‘point the finger’ at groundwater or surface waters as the pathway for nutrient enrichment. However there are other sources and pathways for nutrients, and atmospheric deposition is recognised as a serious threat to many UK habitats (e.g. Emmett et al. 2011). There is also ample evidence (e.g. Stevens et al. 2011 and RoTAP, 2012) that exists to show that atmospheric nitrogen pollution is having adverse impacts on UK habitats, causing the loss of sensitive species and an overall decline in habitat quality (Emmett et al. 2011). Being able to discriminate between atmospheric and terrestrial nutrient sources and pathways is vital for undertaking successful WFD classification and for implementing targeted and successful WFD program of measures to reduce sources and break pathways of nutrients to GWDTEs.
It is for these reasons that the Wetlands Task Team of the WFD UKTAG (UK Technical Advisory Group) highlighted the need to better understand the fate and impact of aerial nutrient deposition on wetlands. The conclusions of the RoTAP (2012) report also state ‘further research to determine the ecological impacts of nitrogen on sensitive ecosystems ‘is required. At the time of writing a DEFRA project titled ‘Identification of potential remedies for air pollution (nitrogen) impacts on statutory sites (RAPIDS) AQ0834’ is underway and due for completion in late 2014 however the results of this work will not be available in time to include within this report.
The drivers for this work include:
- effectiveness of WFD measures: Understanding the mechanisms for nutrient inputs to wetlands will help to ensure WFD measures are, defensible, cost-effective and targeted on the correct sources of nitrogen
- identifying priority regulatory actions: The provision of evidence will allow the identification of various sources of atmospheric deposition (e.g. power stations, poultry, other agriculture)
When a source has successfully been identified it will become easier to implement actions aimed at reducing the sources of nutrients that contribute to unfavourable condition at many GWDTEs.
The key objectives of this project are to provide:
- critical review of literature focusing on the fate, impact and influence of atmospheric nutrient deposition at GWDTEs and the result of these impacts on WFD groundwater status in England and Wales
- desk based assessment of statutory sites, nutrient deposition and WFD status across England and Wales.
- and to identify GWDTEs that are suitable for source apportionment studies
This report aims to provide the regulatory bodies in England and Wales with better information, allowing evidence based decisions to be made when implementing measures to address poor status at groundwater bodies and unfavorable condition at designated GWDTEs.
- SCHUTTEN, J, VERWEIJ, W, HALL, A, and SCHEIDLEDER, A. 2011. Common Implementation strategy for the Water Framework Directive (2000/60/EC). Technical report No. 6. Technical report on Groundwater Dependent terrestrial Ecosystems. ISBN: 978-92-79-21692-3
- WHITEMAN, M, BROOKS, A, SKINNER, A, and HULME, P. 2010. Determining significant damage to groundwater dependant terrestrial ecosystems in England and Wales for use in implementation of the Water Framework Directive. Ecological Engineering, 36, p1118–1125.
- UKTAG, 2012b. Paper 11b(i) Groundwater Chemical Classification for the purpose of the Water Framework Directive and the Groundwater Directive. Version Feb 2012. http://www.wfduk.org/sites/default/files/MediaAssessing%20the%20status%20of%20the%20water%20environment/GWChemical%20Classification_FINAL_2802121.pdf
- ENVIRONMENT AGENCY, 2011. Refining River Basin Planning through targeted investigations on GWDTE: Wynbunbury Moss.
- SWS (2010a). River basin planning through targeted investigations on selected Welsh Groundwater Dependent Terrestrial Ecosystems — Cors Bodeilio and Merthyr Mawr. Schlumburger Water Services Report 1–274/R3 for Environment Agency.
- SWS (2010b). Desk study Cors Erddreiniog Investigations on selected Welsh Groundwater Dependent Terrestrial Ecosystems (GWDTEs). Schlumberger Water Services. Report 1–274/R3 for Environment Agency.
- EMMET, B A, ROWE, E C, STEVENS, C J, GOWING, D J, HENRYS, P A, MASKELL, L C, and SMART, S M. 2011. Interpretation of evidence of nitrogen impacts on vitiation in relation to UK biodiversity objectives. JNCC Report No. 449.
- STEVENS, C J, SMART, S M, HENRYS, P, MASKELL, L C, WALKER, K J, PRESTON, C D, CROWE, A, ROWE, E, GOWING, D J, and EMMETT, B A. 2011. Collation of evidence of nitrogen impacts on vegetation in relation to UK biodiversity objectives. JNCC Report, No. 447. http://jncc.defra.gov.uk/pdf/jncc447_web.pdf
- RoTAP, 2012. Review of transboundary Air Pollution : Acidification, Eutrophication, Ground Level Ozone and Heavy Metals in the UK. Contract Report to the Department for Environment, Food and Rural Affairs. Center for Ecology & Hydrology.