Sulfate loads may induce internal eutrophication and accumulation of dissolved phytotoxic sulfide. We show that upwelling sulfate rich groundwater may also benefit the conservation of rare and threatened alkaline fens, since excessive fertilisation and pyrite oxidation also produces acidity.
Acidity invokes calcite dissolution, increased alkalinity and hardness (Ca2+ + Mg2+) of groundwater. Our observations in a very species-rich wetland nature reserve show that sulfate is reduced and precipitated as iron sulfides in the organic soil of the nature reserve, produces alkalinity and calcite precipitation in the soil. Seepage dependent alkaline fen ecosystems can therefore be remarkably resilient to groundwater affected by fertilisation and pyrite oxidation.
Cirkel, D.G.; Beek, C.G.E.M. van; Witte, J.P.M.; Zee, S.E.A.T.M. van der (2013)
Sulphate reduction and calcite precipitation in relation to internal eutrophication of groundwater fed alkaline fens
Biogeochemistry, DOI 10.1007/s10533-013-9879-4