Eutrophication in the coastal waters of Alexandria following the increase in phosphorus load

Abstract

Samples from the coastal waters of Alexandria during 1991-1993 indicate a remarkable increase in the phosphorus load from 870 to 1140 kg y-1 compared to 567 kg y-1 in 1986 raising the average phosphorus from 1.01 to 1.47 μM compared to 0.44 μM during 1986. Consequently, average chlorophyll a levels raised from 9.5 μg l-1 in 1991 to 12.05 μg l-1 in 1993 with distinctive peaks during summer (maximum discharge period). The phosphorus residence time (183- 223 days) is sufficient for causing intermittent blooms and eutrophication. Anoxic conditions during 1991-1993 were accompanied by fish and benthos mortality.