Abstract
M.A.
The increased demand on resources and particular on water in South Africa is, inter alia, owing to the high population growth, urbanisation and concomitant industrial development. A decrease in water quality impairs the sustainable use of water, economic development and environmental health. Although water quality monitoring in the past focused mainly on the determination of the chemical and physical variables it is currently accepted as inadequate to determine the “health” of an aquatic ecosystem. This study does not concentrate on the impact of the chemical and physical variables on the ecosystem but rather determines the biological affect of treated underground mine water pumped into an aquatic ecosystem. The causes of water pollution can be point source in origin, for example, from water purification works and mines or it could also be from a diverse source such as stormwater, agricultural activities, seepage from various sources such as dumpsites, slimes dams and even from some geological formations. Mining, as one of the major job creators in South Africa, is also one of the major sources of pollution of aquatic systems. This is, in particular, relevant to worked out mines, older mines and marginal mines. The area of investigation is a portion of the Blesbokspruit Ramsar Site on the East Rand and, with its large bird specie diversity, appears to be a healthy system. This study shows that there is extensive debilitation of water quality in this portion of the Blesbokspruit which is further being impaired by the treated underground water pumped into the Blesbokspruit by the Grootvlei Mine. The purpose of this study was to determine the probable hazard of the polluted water of the Blesbokspruit for biota by making use of benthic faunal studies. Previous studies (Adendorff, 1997; Chutter, 1998 and Davies & Day, 1998) proved that the benthic fauna decrease with an increase in water pollution. The water quality of the Blesbokspruit in the test area was compared with the water quality standards for natural water set by the National Department of Water Affairs and Forestry as well as the water quality targets as set by Rand Water. The water quality of the test area was below standard when compared with both sets of standards. Biomonitoring also indicated that, because of the low counts of invertebrates, compared to the high counts of invertebrates in pristine aquatic systems, that this system is under pressure. This study indicates that the water quality of the Blesbokspruit Ramsar Site seriously impacts upon the benthic fauna and that the treated mine water from Grootvlei Mine, which is being pumped into the system, leaves this system stripped of all benthic fauna over an undetermined area. From this study it is also clear that managerial standards are urgently needed for water quality control and that water quality management should not only take the data of chemical water analysis into account but biological compounds should also be considered.