Phosphorus cycling and phosphorus sources in Lake Kinneret: tracing by oxygen isotopes in phosphate

The isotope composition of oxygen in phosphate in sediments and suspended matter of Lake Kinneret (L.K.) serves as a tracer of phosphorus sources and sinks. The major fraction of phosphorus in L.K. sediments is linked to calcium, either as apatite or as a surface complex on calcite crystals. A minor fraction is adsorbed on clays and iron hydroxides. A phosphate surface complex on calcite crystals is precipitated in the L.K. catchment basin and contributes one quarter of the particulate phosphate entering the lake from the Jordan. A large part of this complex is removed at the Jordan River delta at relatively high pH, but it is re-precipitated on calcite surfaces in the deep part of the lake. -from Authors