SULFATE-MEDIATED IRON LIMITATION AND EUTROPHICATION IN AQUATIC ECOSYSTEMS

In large parts of the peaty lowlands of The Netherlands, alkaline, sulphate-enriched river water poor in iron is let in to compensate for decreased ground water levels. As a result, iron input rates decrease while sulphate reduction rates in the anaerobic sediment increase. Iron sulphide precipitation and decreased iron input result in iron exhaustion, sulphide accumulation and increased phosphate mobilization in the anaerobic sediments. Futhermore, iron shortage and sulphide toxicity can occur in aquatic species while disturbance of the iron cycle results in increased phosphate levels in the water layer.