Small changes in water levels and groundwater nutrients alter nitrogen and carbon processing in dune slack soils

Rhymes, J.; Jones, L. ORCID: https://orcid.org/0000-0002-4379-9006; Wallace, H.; Jones, T.G.; Dunn, C.; Fenner, N.. 2016 Small changes in water levels and groundwater nutrients alter nitrogen and carbon processing in dune slack soils. Soil Biology and Biochemistry, 99. 28-35. https://doi.org/10.1016/j.soilbio.2016.04.018

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Abstract/Summary

Dune slacks are biodiverse seasonal wetlands which experience considerable fluctuation in water table depth. They are under threat from lowered water tables due to climate change and water abstraction and from eutrophication. The biological effects caused by the interactions of these pressures are poorly understood, particularly on soil processes. We used a mesocosm experiment and laboratory assays to study the impact of lowered water tables, groundwater nitrogen contamination, and their synergistic effects on soil microbial processes and greenhouse gas emissions. This study showed that just a 10 cm decrease in water table depth led to a reduction in denitrification and to a corresponding increase in soil nitrogen content. Meanwhile N2O emissions occurred for longer durations within dune slack soils subject to higher concentrations of groundwater nitrogen contamination. The results from extracellular enzyme assays suggest that decomposition rates increase within drier soils shown by the increase in β-glucosidase activity, with further sensitivity to groundwater nitrogen contamination shown by the increase in phenol oxidase activity. Dune slack soils with a 10 cm lower water table had significantly lower methane emissions, nearly 5 times lower in the drier soils. Our findings demonstrate that dune slacks are sensitive to both small changes in groundwater levels and to groundwater nitrogen contamination. The biological impacts from lowered water tables are likely to be intensified where there is also groundwater nitrogen contamination.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.soilbio.2016.04.018
UKCEH and CEH Sections/Science Areas:	Emmett
ISSN:	0038-0717
Additional Keywords:	wetland soils, dune slack, soil enzymes, greenhouse gases, climate change, groundwater contamination
NORA Subject Terms:	Ecology and Environment
Date made live:	05 Sep 2016 14:07 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/514381

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