Abstract

This study investigates the baseline environmental levels of arsenic (As) in two rivers; one of which traverses through Guguletu (R₁) and the other running by the peripheral of Langa (R₂) residential areas in Cape Town. The rivers were monitored for As in upstream, midstream and downstream stations for twelve months, during consecutive summer and winter seasons between 2011 and 2012. The collected water samples were treated with HCl and KI, and heated in a water bath at 80°C for 30 min, and As was measured using hydride generation atomic absorption spectrometer (HG-AAS). The data obtained were subjected to descriptive statistics, while the Duncan Multiple Range tests was used to compare the mean concentrations of As in the different sampling stations, and between the two rivers. The mean concentration levels of arsenic ranged R₁, 0.98±0.34 to 1.23±0.43 (0.62 – 2.03) µg/L and 0.43±0.02 to 0.44±0.03 (0.08 – 0.68) µg/â„“. The highest concentration of As (2.03 µg/â„“) was observed in R₁ river water during summer, and the least concentration 0.08 µg/â„“ in R₂ water during winter. There was significant difference (P≤0.05) in the mean concentrations of As in R₁ and R₂ rivers water, while the seasonal mean concentrations during winter and summer, was not significantly different (P≥0.05). The concentrations of As detected in both rivers were lower than the recommended guideline value for freshwater.

Key words: Arsenic, concentration levels, seasonal, Guguletu and Langa rivers, Cape Town.