Use of multiple indicators to assess the pollution condition of urban streams: a case study of Bloemspruit, Free State Province, South Africa

摘要

The Bloemspruit in the Free State, South Africa, is being polluted by increasing anthropogenic activities alongside the stream. Water quality, macro-invertebrate diversity and macro-invertebrate habitats were studied to determine the extent of pollution. Pollution condition was quantified by calculating several indicators. The study revealed that Bloemspruit is highly polluted for the majority of the sampling sites. Two sites had fair water quality, while the water quality at the other sites was either marginal or poor. SASS 5 scores revealed that most macro-invertebrate families present were pollution tolerant, indicating the poor state of the water. According to the modified IHAS (mIHAS) scores, macro-invertebrate habitats at two sites were fair, seven adequate/fair and two poor. The relatively low values of the IHI scores confirm that the majority of the sites were affected by human activities. One site was classified as being largely modified because of the degrading effect of a wastewater treatment plant (WWTP) nearby.