Atmospheric deposition at groundwater dependent wetlands: implications for effective catchment management and Water Framework Directive groundwater classification in England and Wales

摘要

This report is the product of an Environment Agency (EA) contract co-funded by the British Geological Survey (NERC) to review and collate information regarding atmospheric and terrestrial nutrient loading at groundwater dependent terrestrial ecosystems (GWDTEs) in both England and Wales (the inclusion of Welsh sites are covered by the co-funding from BGS and not from EA funding. Many GWDTEs are low nutrient systems therefore any increase in loading can have a detrimental effect upon the ecology. In order to better protect GWDTEs in England and Wales it has become increasingly important to understand the sources of nutrients so that effective regulation and management can be applied to return the GWDTEs into favourable condition. This report highlights many knowledge gaps and also provides the first comparison of two national assessments, Critical Load (assessment of atmospheric deposition) and Threshold Value (assessment of groundwater nitrate levels). It shows that nearly 90% of the GWDTEs in England and Wales exceed their Critical Load for atmospheric deposition. Implications for future Water Framework Directive classification cycles are highlighted. Suggestions are made for suitable GWDTEs to be included in a future research project. The project will aim to provide a methodology to define source attribution from both atmospheric and terrestrial nutrients, enabling environment managers to make effective decisions to project GWDTEs.