Abstract

This study investigated the levels and distribution of phosphorus in sediments along the Swart River, Cape Town, and identified the pollution trends along the river. The harmonised protocol developed by the Standards Measurements and Testing Program of the European Commission was used to extract the different fractions of phosphorus in the sediments. The phosphorus levels in the extracts were measured with a spectrophotometer operated at 880 nm. The total phosphorus levels ranged from 797.7 – 6877.1 ug/g with the inorganic phosphorus being the principal constituent of the total extractable phosphorus in most of the sampling sites surveyed. The speciation results showed that HCl-P was the dominant form of inorganic phosphorus, while NaOH-P was the minor non-apatitic constituent in the sediments. Most of the inorganic phosphorus was fixed in the apatitic form. The total phosphorus levels in the sediments are indicative of high pollution along the Swart River, with the deposition majorly from anthropogenic sources (industrial activities, sewage/effluent discharges, and agricultural run-off). Eutrophication problems could arise at some of the sampling points in the future if the prevailing conditions are not mitigated.

Keywords: Phosphorus, Sediments, Speciation, Swart River, Cape Town