Bioavailability of particle‐associated nutrients as affected by internal regeneration processes in the <scp>N</scp>yanza <scp>G</scp>ulf region of <scp>L</scp>ake <scp>V</scp>ictoria

Abstract

Abstract Land‐use changes have been implicated a lot in the eutrophication of many lakes while forgetting the role of internal loading as influenced by the hydrological regimes of a given lake. The phosphorus loading of N yanza G ulf is influenced both by internal and external loading with the internal loading playing a greater role in its eutrophication. The shear on the A patite P hosphorus ( AP ) rich residual rock in the western end of the gulf through strong currents across the R usinga C hannel erodes the rock into non‐apatite inorganic phosphorus ( NAIP ) which is readily available for primary productivity. The current suspends the phosphorus rich apatite sediment together with the reserved phosphorus within sediments to the water column. The NAIP concentration on the western end of the gulf is exceptionally high, &gt;1500 mg kg −1 , and together with the hydrological forcing; is believed to be the driving force of N yanza G ulf eutrophication. External loading through rivers and municipal discharges exacerbates the problem. The external loading mainly influences the inner gulf on the eastern shore while the internal loading affects mainly the western end of the gulf. Nyanza G ulf eutrophication can be managed by adopting the following measures: (i) the M bita Causeway needs to be opened and a bridge erected in its place in order to reduce the strong current through the R usinga C hannel and the residence time within the gulf, by increasing the flushing rates; (ii) the farming communities within the basin need to be sensitized on the controlled use of fertilizers; (iii) the municipal wastes should be treated to tertiary level before discharge into the lake; and (iv) reduce erosion within the basin through re/afforestation.