Fluctuations of indicator and index microbes as indication of pollution over three years in the Plankenburg and Eerste Rivers, Western Cape, South Africa

Abstract

The Plankenburg and Eerste Rivers (Western Cape) have been reported to be contaminated with faecal coliforms. Water is drawn from both rivers for irrigation of fresh produce. The potential risk in the use of these rivers as irrigation sources was assessed by determining the fluctuations of ‘indicator’ and ‘index’ microbes over 3 years. Selected physico-chemical (water temperature, pH, COD, conductivity and alkalinity) and microbiological parameters, including coliforms, faecal coliforms, Escherichia coli and enterococci, as ‘indicators’ of faecal pollution, and Salmonella , Listeria and Staphylococcus , as ‘index’ of the presence of potential pathogens, were monitored. No correlation was found between water temperature and COD ( r2 = 0.0003), whereas for temperature and pH a significant trend ( p = 0.0004), but low correlation ( r2 = 0.108), was observed. With the exception of the faecal coliforms ( E. coli), no significant trends and no correlations between temperature and the dependent variables were found.

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