Chemistry of Phosphate and Nitrogen Compounds in Sediments

This book deals with the processes constituting the cycles of the phosphate and nitrogen compounds in sediment and the phosphate equilibria between the sediment and the overlying water. Sediment, to a large extent, controls the P- and N concentrations and thus primary production. In most waters, too high concentrations of these compounds cause excessive growth of algae, causing so-called eutrophication. Abatement of this can only be achieved after a complete understanding of the quantitative role of sediment in the P- and N cycle. Thus, for the phosphate cycle the following processes are evaluated: -P-binding onto sediments, viz., onto iron hydroxide and calcium carbonate (limestone), -Fractionation of phosphate in relation to its bioavailability, -Release processes under anoxic and oxic conditions, and their dependence on pH changes, -Further items taken into account, including the influence of drying of sediment and its resuspension by wind.For the nitrogen cycle, the following are discussed: -Ammonification of organically bound nitrogen, -Nitrification and denitrification, including Dissimilatory Nitrate Reduction, -Links with other chemical elements are made.