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Total photosynthetic pigments (TPP) or chlorophyll-a analysis can be useful in selecting coagulant treatments that will improve phytoplankton removal and reduce treatment costs. The objectives of this study were to compare the efficacy of phytoplankton and turbidity removal when using TPP and turbidity as indicator parameters of appropriate coagulant treatments as well as to evaluate the cost impacts thereof. During seven different sampling occasions, source water samples with substantially different TPP and turbidity contents were collected from two South African freshwater sources (Benoni Lake and Vaal Dam) to conduct jar stirring tests. After sedimentation, TPP and turbidity analyses were performed to assess the efficacy of coagulant treatments (Ca(OH)2-SiO2, Ca(OH)2-organic polymer and organic polymer). Results showed that TPP analysis is indeed a useful indicator parameter to consider purifying source water enriched with phytoplankton. Ca(OH)2-organic polymer treatment was more costly than Ca(OH)2-SiO2 and organic polymer, but the only coagulant treatment that met the removal criteria after sedimentation. Benoni Lake source water (TPP: 34.29 µg/l; 4.29 NTU) was more costly to treat than Vaal Dam source water (TPP: 2.29 µg/l; 80.29 NTU). Findings made from this study confirm that high phytoplankton concentrations in source water due for treatment will increase the treatment costs. [ABSTRACT FROM AUTHOR]

The implication of invertebrates found in drinking water distribution networks to public health is of concern to water utilities. Previous studies have shown that the bacteria associated with the invertebrates could be potentially pathogenic to humans. This study investigated the level and identity of bacteria commonly associated with invertebrates collected from the drinking water treatment systems as well as from the main pipelines leaving the treatment works. On all sampling occasions bacteria were isolated from the invertebrate samples collected. The highest bacterial counts were observed for the samples taken before filtration as was expected. There were, however, indications that optimal removal of invertebrates from water did not always occur. During the investigation, 116 colonies were sampled for further identification. The isolates represent several bacterial genera and species that are pathogenic or opportunistic pathogens of humans. Diarrhoea, meningitis, septicaemia and skin infections are among the diseases associated with these organisms. The estimated number of bacteria that could be associated with a single invertebrate (as based on average invertebrate numbers) could range from 10 to 4000 bacteria per organism. It can, therefore, be concluded that bacteria associated with invertebrates might under the worst case scenario pose a potential health risk to water users. In the light of the above findings it is clear that invertebrates in drinking water should be controlled at levels as low as technically and economically feasible. [ABSTRACT FROM AUTHOR]

Water quality is of prime importance to Rand Water's core business of ensuring a reliable supply of good quality drinking water to more than 10 million people. Rand Water has, therefore, implemented a water quality monitoring programme of the source water as well as the drinking water produced. The establishment of the Lesotho Highlands Water Transfer scheme necessitated the expansion of the monitoring programme. In 1996, Rand Water and Lesotho Highlands Development Authority (LHDA) signed an agreement to jointly develop an extensive water quality monitoring programme for the Lesotho Highlands Water Project (LHWP). Prior to this agreement, monitoring was mainly undertaken by consultants on behalf of LHDA in the main feeder rivers within the Katse Dam catchment (donor system). On the recipient system (Ash/Liebenbergsvlei), extensive physical and chemical monitoring was undertaken by Rand Water and Department of Water Affairs and Forestry (DWAF). Biological monitoring was however only carried out superficially prior to the release of water. Information gained from carrying out biological and chemical assessments clearly indicates that the water from LHWP has negatively impacted on the biological communities in the recipient system. The importance of detailed before and after biological and physiochemical monitoring of both donor and recipient systems is emphasized. [ABSTRACT FROM AUTHOR]

Despite the health risks associated with exposure to Cryptosporidium and Giardia, there is no uniform approach to monitoring these protozoan parasites across the world. In the present study, a strategy for monitoring Cryptosporidium and Giardia in drinking water was developed in an effort to ensure that the risk of exposure to these organisms and the risks of non-compliance to guidelines are reduced. The methodology developed will be applicable to all water supply systems irrespective of size and complexity of the purification works. It is based on monitoring procedures proposed by the US Environmental Protection Agency, the Drinking Water Inspectorate, Australia and New Zealand, as well as the risk-based procedure followed by Northern Ireland. The monitoring strategy developed represents a preventative approach for proactively monitoring Cryptosporidium and Giardia species in drinking water. The strategy consists of 10 steps: (i) assessment of the monitoring requirements, (ii) description and characterisation of the source water types, (iii) abstraction of source water, (iv) assessment of the water purification plant, (v) water quality monitoring, (vi) cryptosporidiosis and giardiasis outbreak, (vii) risk assessment, (viii) sample collection and laboratory processing, (ix) data evaluation, interpretation and storage, (x) process evaluation and review. Proper implementation of this protocol can contribute to the protection of drinking water consumers by identifying high-risk source water, identifying areas of improvement within the water treatment system, and also preventing further faecal pollution in the catchments. The protocol can also be integrated into the Water Safety Plans to optimise compliance. Furthermore, this methodology has a potential to contribute to Blue Drop certification as it should form part of the incident management protocols which are a requirement of Water Safety Plan implementation. [ABSTRACT FROM AUTHOR]

Tilapia rendalli was exposed to various silt concentrations for different exposure periods to determine LC50 and sublethal concentration ranges. The extent of damaging effects, if any, of suspended silt on the exposed fish, were investigated by means of scanning electron microscopy. The LC50 values ranged between 21 to 24 g l-1 and 42--48 g l-1 for juveniles and adults respectively. The silt concentrations tolerated by the test fisheswere above those found in most natural waters. The results thereforesupport the hypothesis that suspended silt is lethal to fish at concentrations higher than those naturally observed in surface water. Theobserved mortalities can be attributed to the combined physical effects of high silt concentrations and associated reduction in dissolvedoxygen levels. To prevent fish mortalities and other impacts on biota, anthropogenic activities that affect the natural variation in suspended silt concentrations in surface water should be carefully monitored and, where possible, be restricted. [ABSTRACT FROM AUTHOR]

Eighty largemouth yellowfish, Labeobarhus kimherleyensis, were collected between April 2005 and February 2006 with gill nets close to the island (26° 52, 249‱ S, 28° 10, 249‱ E) in the Vaal Dam. The fish were killed, weighed and their length determined. Muscle, liver and spinal cord tissues were collected from each fish and the intestines removed and opened to expose Bothriocephalus acheilognathi. The tapeworms were collected in glass bottles and frozen. Water and sediment, as well as liver, muscle and tapeworm samples were digested and thereafter metal concentrations of 23 elements (lithium, beryllium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, arsenic, selenium, molybdenum, cadmium, tin, antimony, tellurium, barium, mercury, thallium, lead and uranium) were determined with an ICP-MS. Bioconcentration of metals (selenium, mercury, and lead during autumn; copper, zinc, selenium, cadmium, antimony, thallium and mercury during winter; lithium, zinc, selenium, cadmium and antimony during spring; and zinc during summer) occurred in tapeworms. The highest mean value was recorded in sediment, followed by water, tapeworms and host tissue. A seasonal trend showed that a higher concentration of the metals had accumulated in tapeworms during winter when water levels were at their lowest. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the potential use of the freshwater river crab, Potamonautes warreni, as a bioaccumulative indicator of iron and manganese pollution in aquatic ecosystems. Water and sediment analysis of the two study sites (Germiston Lake and Potchefstroom Dam) revealed that while levels of manganese were higher in Germiston Lake, iron concentrations were higher in Potchefstroom Dam. Metal analysis of P. warreni revealed that while the crabs from Potchefstroom Dam contained slightly higher iron levels than those from Germiston Lake, manganese concentrations in P. warreni from the latter site were significantly higher than those in the crabs from the former site. Iron and manganese levels in these organisms were influenced by the size, mass, and sex of the crabs on occasion, but these relationships were not always consistent at both of the sites. The results of this study clearly indicate that the ultimate levels of iron and manganese attained in P. warreni do vary depending on the site from which animals are collected. From this, it is suggested that these crustaceans be incorporated into biomonitoring protocols, particularly in areas that are subjected to elevated metal levels in the environment, (Copyright 1998 Academic Press.)

The effect of copper on the blood coagulation in freshwater fish, Oreochromis mossambicus was investigated. These fish were exposed to sublethal copper concentrations over short-term (96 hr) and long-term (4 wk) periods, at 29 +/- 1 degree C (summer) and 19 +/- 1 degree C (winter), in experimental flow-through systems. Copper concentrations applied during short-term exposures were 0.16 mg/l and 0.40 mg/l, respectively, while 0.40 mg/l copper was applied during the long-term exposures. After a photocymographic observation of blood, during all the phases of coagulation was made, it was evident that there were delays in the blood coagulation times, as well as decreases in the shear modulus (elasticity) of the clots formed, after the exposure of the fish to copper concentrations at both temperatures. Copper was found to induce haemophilia at 29 +/- 1 degree C and 19 +/- 1 degree C, while at the latter it also induced thrombocytopenia. Thus exposure to copper lead to coagulation defects, which caused haemorrhage in the body tissue, which can eventually cause the death of those fish.

Environmental stressors, both natural and humanly induced, could cause changes in cellular function which alter the physiology of organ systems in fish. The need to comprehend and predict the condition which stress metals will pose on fish, and extrapolate the effect of pollutants from laboratory to population levels, have forced scientists to search for physiological and biochemical indicators of health and sublethal toxicant effects. Hematological evaluation of fish blood provides valuable facts concerning the physiological response of fish to changes in the external environment. Furthermore, hematological variables are well known for their clinical value in prognosis and diagnosis. Sublethal responses after exposure to toxicants can be determined by commonly applied techniques. Measurements for a number of hematological and carbohydrate metabolic variables were recorded at winter and summer temperatures after fish, acclimated for 3 months to experimental conditions, were exposed to sublethal concentrations of copper for 96 hr in a continuous-flow experimental system. Controls were run at the same time to establish essential baseline hematological values. Fish were exposed to the mean copper concentration as was found in the Olifants River, Kruger National Park, during summer (0.05 +/- 0.032 mg liter-1) and winter (0.085 +/- 0.032 mg liter-1) to establish the effect thereof on the variables mentioned. The results proved that the concentration of copper in the river exerts a physiological effect on Clarias gariepinus at 21 +/- 1 and 28 +/- 1 degrees C which manifests in changed blood chemistry. Pathological conditions, such as erythrocytopenia, leucocytosis, hyperglycemia, and hyperprotonemia, are evident. The fish physiologically adapted to the environmental change, which does not necessarily reflect a state of normality.

1. The bioconcentration of atrazine was determined in the liver, muscle, heart, gonads and brain of Tilapia sparrmanii exposed to high concentrations of atrazine. 2. The highest concentrations were recorded in the ovaries (50.6 micrograms/g) and in the liver (40.1 +/- 5.5 micrograms/g). This may be attributed to the higher lipid content of these organs, while the liver also accumulates atrazine as a result of its detoxification function. 3. The bioaccumulation factors for atrazine in the liver, muscle, heart, gonads and brain ranged from 0.9 to 20.0. Bioconcentration of atrazine in banded tilapia was found to be low, even after exposure to external atrazine concentration much higher than detected in natural surface water.

1. Tilapia sparrmanii was exposed to 0.098 mg/l potassium dichromate. 2. The effect of chromium on blood coagulation was measured with a thrombelastograph at a pH of 5, 7.4 and 9 over 96 hr, as well as an uncontrolled pH after 2 weeks of exposure. 3. The prolonged kinetic times and reduced maximal amplitudes at a pH of 7, 4 and 9, differed significantly from the control values. 4. Thrombelastograms reflected a decrease in the clotting ability of fish blood, with an increase in pH, which is typical of thrombocytopenia. 5. It was evident that the exposure of fish to chromium led to clotting defects that caused internal bleeding.