Impacts of pollutant loading, climate variability and site management on the surface water quality of a lowland raised bog, Thorne Moors, E. England, UK

Variations in surface water S chemistry were investigated at a waterlogged raised peatland in the NE of England from 1994 to 2000. While S inputs were important, below-ground cycling of S, dependent upon water table height, played a dominant role in affecting SO4 concentration of the surface waters. Evaporative concentration of SO4 during drought played only a subordinate role in increasing SO4 concentrations. At Thorne Moors SO4 in surface water shows a clear and statistically significant trend:(i)high concentrations (relative to pristine bogs) (mean 18 mg L−1) under high pollutant loadings before drought;(ii)extremely elevated concentrations (mean 52 mg L−1) under declining pollutant loadings during drought in 1996 and lowered water tables;(iii)recovery to significantly lower concentrations (mean 4.3 mg L−1) as water tables recovered (due to increased rain and site management) whilst pollutant loadings continued to fall.The increase in surface water SO4 in 1996 was accompanied by a significant rise in the S content of Sphagnum moss growing on the surface of the pools. As such the S content of Sphagnum may act as a proxy for variations in surface water S chemistry and thus environmental change.