South African Water Quality Guidelines Research Articles

The Impact of Sewage Water Overflow (SWO): An Analysis of Zandspruit River in Cosmo City, Johannesburg, South Africa

Cosmo City, situated in Johannesburg, Gauteng, has been experiencing sewage water overflows (SWO) for several years, and this raises concerns about the water quality of Zandspruit River. The study aimed to investigate the impacts of SWO on the Zandspruit River, and the perceptions of the community towards SWO. Water samples were collected from three sampling sites of Zandspruit River. Some water quality parameters were measured in the field using a multi-parameter water quality meter while other parameters were analyzed at a SANAS accredited laboratory. Results were compared with South African water quality guidelines and most water quality parameters were within permissible set standards. However, COD, E. coli and turbidity were above permissible set standards which indicates a highly polluted river. Furthermore, we assessed perceptions of the Cosmo City community towards SWO through questionnaires. The community ascribed the main causes of SWOs to population growth, blocked, and broken sewers. This study revealed that SWO around Cosmo City has a negative impact on the quality of river water and poses health risks. The combined evidence from both the experimental analysis and the community perception survey underscores the urgent need for effective management strategies to address the negative environmental and human health implications of SWO in the Zandspruit River. By integrating these findings and considering the broader implications of pollution on both the ecosystem and community well-being, policymakers and stakeholders can work towards implementing sustainable solutions to mitigate the risks associated with sewage water overflows.

Evaluation of River and Groundwater Quality in the Mzimvubu to Tsitsikamma Water Management Area (WMA7)

This paper assessed and evaluated the river and groundwater quality of five major catchments in the Mzimvubu to Tsitsikamma Water Management Area (WMA7). The river assessment and evaluation considered the present state maximum, minimum and mean seasonal values of physiochemical parameters (EC, NO3 + NO2, Cl, pH, NH4-N, PO4-P and Mg). The study was able to successfully make use of statistical analysis and a water quality index in order to explain seven-year trends and the present state of all five catchments within the study area. The statistical analysis results showed that water quality parameters such as PO4, NH4 and NO3 + NO2 were not complying with the South African Water Quality Guidelines (SAWQG) limits, suggesting that the study area was impacted by anthropogenic activities such as agriculture, sewage works, etc. The application of WQI showed that the Gamtoos catchment was in a good water quality state (49.71) while the other four catchments were in a poor to very poor state, according to the WQI classification. Based on the groundwater quality assessment, the physicochemical parameters (NH4, EC, Ca, NO3 + NO2, pH, Na, Cl, Mg, F, K, SO4 and CaCO3) were selected and the main parameters of concern were EC (salinity), NO3 + NO2 and SO4. However, groundwater assessment revealed that groundwater quality was chemically suitable for drinking purposes in most parts of the study area. Therefore, the study recommended resource-directed measures to improve surface and groundwater resource protection, especially in areas where surface and groundwater quality for other uses remains a challenge. Further, strong water resource compliance monitoring and enforcement to control water resource pollution sources is critical.

The drivers of benthic macroinvertebrates communities along a subtropical river system: Sediments chemistry or water quality?

AbstractImpacts of metal pollution, either on water or in sediments within aquatic systems have been a serious challenge globally. Little is known about the ecological impacts of metal pollution on benthic macroinvertebrates species in sub–tropical river systems. The aim of this study was to examine benthic macroinvertebrates community composition in relation to sediment metal concentrations and other physicochemical variables in the Mutshundudi River system. Benthic macroinvertebrates sampling and community composition analysis, sediment collection, processing, metal analysis and assessment of water variables in the river system were done across two seasons at 12 sampling sites. The river was categorized into three segments: upstream, midstream and downstream. The results from geo‐accumulation (Igeo) values showed that sediments were loaded with Na, Zn, and B in all river segments. In comparison with South African water quality guidelines for aquatic ecosystems, water quality ranged from good at upstream sites because of low anthropogenic activities to very poor in downstream sites because of high anthropogenic activities. Sediments from the Mutshundudi River showed significant differences on high concentrations of metals (i.e., Mg, K, Na, and Cu) and seasonal variations. Both water quality and sediment chemistry were considered the driving factors of benthic macroinvertebrates, since species densities and composition reduced with a decline in water and sediment quality during both cool–dry and hot–wet seasons. Continuous build‐up of the metal contaminants, such as Mg, K, Na, and Cu in river sediments may pose adverse impacts on macroinvertebrate community structure.

Evaluation of the impact of coal mining on surface water in the Boesmanspruit, Mpumalanga, South Africa

Surface water quality has major environmental and socioeconomic consequences, notably in terms of the country’s long-term fresh water supply. This study aimed at assessing the current state of water quality and status of the Boesmanspruit in a coal mining environment. The study used historical water quality data for a period of five years from 2017 to 2021. Aluminum, calcium, iron, manganese, magnesium, sodium, sulfate, electrical conductivity, pH, and total dissolved solids were the water quality variables selected for the study; the chosen variables were chosen based on the available secondary data. The water quality was evaluated against South African resource quality objectives, the South African water quality guidelines, and the Canadian Council of Ministers of the Environment water quality index (CCME-WQI). The data were analyzed using such as the CCME-WQI, the comprehensive pollution index (CPI), and multivariate statistics. The following parameters were above the prescribed thresholds: pH, total dissolved solids, electrical conductivity, sulfate, manganese, and iron. The CCME-WQI results showed that monitoring locations GR S26 and GR S21 near mining activities had poor water quality (40–44), whereas comprehensive pollution index (CPI) also had similar category results for the monitoring points, indicating that they were heavily polluted (2.4–4.8). The WQI showed that if certain variables, such as aluminum, iron, magnesium, sulfate, electrical conductivity, and total dissolved solids, exceed the permissible range, the water quality would deteriorate in accordance with the CPI classification. Therefore, the CPI was the best way to categorize the water quality. The principal component analysis and cluster analysis identified two primary sources of pollution which are anthropogenic and natural. The utilization of statistical analysis proved to be effective in determining the ideal quantity of significant variables within the study area. The study recommends low-cost options for reducing the effects of acid mine drainage, which includes passive mine water treatment methods using artificial wetlands.

Water quality modelling and quantitative microbial risk assessment for uMsunduzi River in South Africa.

South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R2 of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organization (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.

The impact of informal settlement on water quality of Diep River in Dunoon

Water quality is declining due to the rise of urbanization, overpopulation, industrial production, climate change, non-compliance of wastewater treatment plants, and agricultural waste. The mushrooming of informal settlements along the bank of the Diep River due to population growth in Dunoon compromises the quality of water. Inadequate sanitation and waste disposal practices in the Dunoon informal settlement are a major problem, leading to the contamination of water resources. This research aimed to investigate the impact of Dunoon informal settlement on the Diep River water quality. Water samples were collected for 4 months from four sites of the river to cover the spatial distribution. The laboratory determined the concentrations of nitrates, phosphates, dissolved oxygen, chemical oxygen demand, total suspended solids, and E. coli, while the field study used a multiparameter reader to determine turbidity, temperature, electrical conductivity, pH, salinity, and dissolved oxygen. The results were compared with the South African water quality guidelines for irrigation, recreation, and aquatic ecosystems, and South African National Standards. The study revealed that the average concentrations of E. coli, dissolved oxygen, electrical conductivity, salinity, turbidity, chemical oxygen demand, and ammonia exceeded the recommended limits in both the wet and dry seasons. Based on the findings, the water quality in Diep River is poor and the Dunoon informal settlement has contributed to this to some extent. The pollution of the river may be linked to health problems and environmental degradation. Considering this, the waste discharged into the neighbouring aquatic environments needs to be monitored and managed frequently.

Soul of the Jukskei River: The Extent of Bacterial Contamination in the Jukskei River in Gauteng Province, South Africa.

River water quality is an important health issue as the water is utilised for drinking, domestic and agricultural use in developing countries. This study aimed to investigate the effect water from a major city has on the water quality of the Jukskei River that daylights in Johannesburg, South Africa. The river water samples were analysed for physio-chemical properties, microbiology, antibiotic resistance of bacterial isolates, genetic markers, and potentially toxic metals. Data analysis revealed increased electrical conductivity, total dissolved solids, and turbidity since 2010. Total Coliform and Escherichia coli detected were above the South African water quality guidelines for domestic, recreational, and irrigation purposes. Additionally, sodium, zinc, nickel, lithium, and lead exceeded the guidelines in domestic, recreational, and irrigation water. Pathogenic strains of E. coli (aEPEC, EHEC, EIEC, and EAEC) were isolated from the water. Various other potentially pathogenic organisms that have been implicated as causes of gastro-intestinal, and a wide range of other diseases, were also detected and demonstrated multiple levels of resistance to antibiotics tested. The results show that the river water is a potential health threat to downstream users. These results will feed into the environmental management action plan for Water for the Future (NGO group).

Green roofs and stormwater runoff quality in the urban landscape in South Africa

A number of sustainable urban drainage systems (SuDS), such as green roofs, are being developed and implemented in cities around the world to help reduce stormwater runoff and improve stormwater runoff quality. This study compares the water quality of green roofs with that of conventional roofs in the eThekwini region, South Africa. Samples of stormwater runoff from the different green roof systems on the eThekwini Green Roof Pilot Project were collected to test their level of contaminants and pollutants. The tests focused on all physical, aesthetic, chemical, and microbiological determinants pertaining to stormwater runoff. For all tests, the level of contaminants and pollutants were measured against the South African Water Quality Guidelines Volume 7 for Aquatic Ecosystems. The data revealed significant variations in pollutant concentrations between the green roofs and the conventional roof. Moreover, runoff water quality varied across the various roof types, which may indicate that the substrate composition has the greatest impact on green roof performance regarding rainwater quality. Overall, the results suggest that these green roof systems do not have the ability to filter pollutants out of stormwater runoff, but rather increase their levels of concentration.

Metal pollution source apportionment in two important Rivers of Eastern Cape Province, South Africa: a case study of Bizana and Mthatha Rivers

Regular monitoring of the chemical status of water bodies remains crucial in countries where data on chemical fingerprints that can assist in environmental policy is still limited. The current study focused on the concentrations of 14 metals and their sources in two important South African rivers that pass through various rural areas and two semi-urban towns in the province of the Eastern Cape. Most of the essential metals were within the South African guidelines for domestic water use except for selenium and iron which reached the concentrations of 131 and 712 µg L−1 that exceed the guideline values of 20 and 200 µg L−1, respectively. Cadmium and lead were above the South African Water Quality Guidelines and World Health Organization limits of 3 and 10 µg L−1, attaining the highest concentrations of 35 and 34 µg L−1, respectively. The impact of the wastewater treatment plant effluent and the municipal dumpsite leachates on metal ion concentrations in the rivers was observed for some metals. The metals source was related to deterioration of galvanized corrugated steel sheets from scrap yards and dwellings made-out of galvanized corrugated sheets, as well as agricultural activities and natural geological processes. An overview of the current water quality status of the two rivers may serve as a basis for sink-oriented pollutant fingerprinting toward sustainable water sources for communities.

Using groundwater quality index and concentration duration curves for classification and protection of groundwater resources: relevance of groundwater quality of reserve determination, South Africa

Water quality assessment for water resource protection and management is key towards sustainable provision of potable water supply and in meeting sustainable development goals (SDGs) linked to clean water and sanitation. The spatial and temporal aspects of groundwater quality in the Nseleni catchment, South Africa (SA) was investigated, its suitability for domestic use was considered, and required protection measures were established. Using a hybrid approach methodology based on multiple water quality resource assessment techniques such as groundwater quality index (GQI) and concentration duration curves (CDCs), 72 groundwater samples collected from 1994 to 2017 were analysed for physico-chemical (Na+, Ca2+, Mg2+, Cl−, SO42−, NO3−, F−, EC, pH) parameters. Approximately, 33.3% of groundwater samples in the Nseleni catchment were found suitable for drinking when compared to South African water quality guidelines. The use of a hybrid approach method showed that overall groundwater quality in the study catchment was classified as excellent for domestic water use when the groundwater quality index was calculated to be 39.11. Groundwater quality reserve limits for groundwater resources protection were determined for the nine water quality parameters using CDCs. The study concluded that using groundwater quality index and concentration duration curves, it was feasible to classify groundwater resources for improved groundwater quality of reserve determination in the South African context. The study recommends the application of the hybrid method in various catchments of similar characteristics to the studied catchment for setting groundwater quality limits that would contribute towards achieving the goal of groundwater resources protection in other catchments.

The deteriorating nutrient status of the Berg River, South Africa

The upper catchment area of the Berg River in the Western Cape, South Africa, supplies most of Cape Town and its suburbs with freshwater, in addition to providing water for irrigation purposes along the middle and lower reaches of the river. This study investigates the nutrient status of the Berg River and long-term trends therein. It is shown that inorganic nitrogen and phosphorus levels increase downstream by a factor of more than 10, in response to anthropogenic inputs. Similarly, nutrient levels fluctuate seasonally by more than an order of magnitude, in response to input from diffuse and point sources of pollution. These changes of more than 1 000% far exceed the 15% maximum change stipulated by the South African water quality guidelines for aquatic ecosystems. Total phosphorus levels indicate that hypertrophic conditions prevail at least episodically at all of the Berg River monitoring stations and most of the time at some of them. Additionally, river water phosphate levels show a dramatic increase over the past 20 years. There is also strong evidence that the trophic status of the Berg River is very sensitive to reduced river runoff. The implication is that the construction of the new Berg River Dam in the upper catchment area of the Berg River will exacerbate the existing situation, threatening ecosystem services, human health and lucrative agricultural activities.Keywords: Berg River, eutrophication, nutrients, nitrate, phosphate

Variation in levels and removal efficiency of heavy and trace metals from wastewater treatment plant effluents in Cape Town and Stellenbosch, South Africa.

This study focused on one year monitoring campaign to monitor the occurrence and removal of Endocrine Disruptive Metals (EDMs) and trace metals from selected wastewater treatment plants (WWTPs) in Stellenbosch and Cape Town. Composite water samples were collected from the WWTPs from January 2010 to December 2010 on a quarterly basis and concentrations determined using inductively coupled plasma-mass spectrometry (ICP-MS) after open beaker digestion. A total of 432 water samples consisting of raw, primary effluent, secondary effluent and final effluents were collected and analyzed. The general abundance distribution pattern for metals was Zn > Cu > Pb > Cr > Ni > As > Co > Cd > Hg. The removal efficiency ranged from 1.5% for Hg at Zandvliet WWTP plant during winter to 98.27% for Cu at Athlone WWTP treatment plant during summer. The final effluent concentration for most of the metals were within South African water quality guidelines while As, Hg, Cd and Pb concentration were higher than maximum limits set by the Canadian Council of Ministers of the Environment. Potsdam WWTP showed to be the most effective at heavy metals removal as compared with the other five treatment plants investigated in this study. The effluent metal concentration over time could pose health risk if used for agricultural irrigation. Key words: Seasonal variation, endocrine disrupting metals, wastewater treatment plants, effluents, coupled plasma-mass spectrometry (ICP-MS), Cape Town.

Spatiotemporal characterization of water chemistry and pollution sources of the Umhlatuzana, Umbilo and Amanzimnyama River catchments of Durban, KwaZulu-Natal, South Africa

The physical, chemical and microbiological properties of three freshwater systems contributing inflows to the Bayhead Canal of the Durban Harbour: the Umhlatuzana and Umbilo Rivers, and the Amanzimnyama Canal of KwaZulu-Natal, South Africa are presented. Parameters targeted for analysis collectively included pH, total dissolved solids, dissolved oxygen, biological oxygen demand, chemical oxygen demand, conductivity, ammonium ions, phosphorous, sodium ions, sulphur, copper, calcium, magnesium, chromium, aluminium, nickel, lead, vanadium, mercury, potassium ions, Escherichiacoli and total coliforms. These parameters were analyzed seasonally during the wet and dry seasons in relation to land use change for spatial characterization. Comparisons with relevant South African Water Quality Guidelines for freshwater systems showed that pollution associated with catchment activities was the main factor governing water quality, with nutrient concentrations that frequently exceeded prescribed standards and often rendered the system hypertrophic. In addition, the sanitary state of the rivers across all land use types was shown to be contaminated and polluted. This study also attempted to determine spatiotemporal (dis)similarity in the water quality of sample sites through Principal Components Analysis (PCA) with varimax rotation. Results show that although these systems were separated on the basis of water quality (both spatially and temporally), there were generally no apparent trends in water quality based on specific land use patterns which linked sites across different catchments. In the wet season, a few exceptions were noted for residential sites across the Umbilo and Umhlatuzana catchments and industrial sites across the Amanzimnyama catchment which showed spatial similarity. Finally, the study examined the impacts of the three freshwater systems on the water quality of the Bayhead Canal of the Durban Harbour, and identified the Amanzimnyama Canal as the most influential on heavy metal and microbiological contamination near the confluence.

Analysis of grey-water used for irrigating vegetables and possible effects on soils in the vicinity of Umtata Dam, Eastern Cape

In the search for alternative and reliable water sources to irrigate vegetables for backyard gardens, an experimental field was set up in the vicinity of the Umtata Dam, north-west of the town of Umtata, to test grey-water quality and its effects on soil nutrient content following 4 successive growing seasons. Samples of grey-water that were generated from informal housing adjacent to the Umtata Dam were collected from kitchen and bath tubs/washing basins. These samples were analysed before being used for irrigating vegetable crops. The results showed that grey-water quality was efit for purposef for irrigating edible vegetable plants. Although the average Na+ (16 mg/.) and Cl- (15 mg/.) ions were significantly higher (p = 0.05) for grey-water than other treatments, both were below the limit of 100 mg/. set in the South African Water Quality Guidelines. The concentrations of nutrients and heavy metals found in the grey-water samples were significantly lower compared to the World Health Organization guidelines for the safe use of grey-water and within the target water quality range (TWQR) prescribed by South African guidelines for irrigation water. However, the study strongly recommends that grey-water be diluted in order to lower the salt content and to improve the irrigation water quality. Results from an analysis of soil samples showed no significant differences in pH as a result of applying grey-water throughout the soil profile of up to 90 cm depth. Na content of the soil irrigated with grey-water was not significantly different than that of plots where diluted grey-water and potable water were used. Therefore, the grey-water used in this study does not appear to cause an accumulation of salts and heavy metals in soil, in the short term. Keywords : grey-water, vegetables, soil, heavy metals, pH

Derivation of South African water quality guidelines for Roundup® using species sensitivity distribution

Glyphosate-based herbicides are among the leading products used in South Africa to control weeds and invading alien plant species. Although these herbicides ultimately find their way into aquatic ecosystems, South Africa has no water quality guideline based on indigenous species to protect the country's aquatic biota against these biocides. In this study, South African water quality guidelines (SAWQGs) for Roundup® based on species sensitivity distribution (SSD) using indigenous aquatic biota were developed. Short-term and long-term toxicity tests were conducted with eight different aquatic species belonging to five different taxonomic groups. Static non-renewal experimental methods were employed for short-term lethal tests (≤4 days), and static renewal for long-term sublethal tests (≥4 days ≤21 days). LC50 values for animal exposure and EC50 values for algae were calculated using probit analysis and linear regression of transformed herbicide concentration as natural logarithm data against percentage growth inhibition, respectively. No effect concentration (NEC) was determined based on the dynamic energy budget model, using survival data. The LC50, EC50 and NEC values were used to develop species sensitivity distribution (SSD) concentrations for Roundup®. Based on the SSD concentrations, the short-term and long-term SAWQGs for Roundup® were derived as 0.250 (0.106–0.589) mg/L, and 0.002 (0.000–0.021) mg/L, respectively. These WQGs may be useful in protecting South African aquatic life against transient or long-term exposure to glyphosate-based chemicals as part of integrated water resources management.

An Evaluation of the Cumulative Surface Water Pollution on Selected Areas within the Consolidated Main Reef Area, Roodepoort, South Africa

Mining has long been at the center of the South African economy and has contributed to significant developments within the country. However, despite the large economic impact, surface water pollution due to mining is prevalent in most of the country's water catchments. Surface water in many areas of the central Roodepoort area in Johannesburg, South Africa, has also been impacted primarily by mining activities. The surface water quality for the Bosmontspruit, Russell's Stream, and the New Canada Dam was assessed in this study from October 2010 to March 2011. Physicochemical and biological characteristics of the water were determined for eight monitoring points, and the results obtained were compared with the in-stream water quality guidelines for the Klip River catchment and the South African Water Quality Guidelines. A trend noticed throughout the sampling period was the noncompliance to the set target water quality ranges (TWQRs) in the levels of total dissolved solids (TDS) and dissolved oxygen (DO). The results indicate that concentrations of iron, aluminum, nickel, manganese, and potassium were above the permissible limits across the Bosmontspruit and Russell's Stream. Excessive fecal coliforms and ammonium pollution were also detected in the Bosmontspruit. Additionally, during the monitoring period, it was noted that the water was being utilized for domestic purposes, and may pose health hazards due to poor water quality.

Comparison of biofilm formation and water quality when water from different sources was stored in large commercial water storage tanks

Rain-, ground- and municipal potable water were stored in low density polyethylene storage tanks for a period of 90 days to determine the effects of long-term storage on the deterioration in the microbial quality of the water. Total viable bacteria present in the stored water and the resultant biofilms were enumerated using heterotrophic plate counts. Polymerase chain reaction (PCR) and Colilert-18(®) tests were performed to determine if the faecal indicator bacteria Escherichia coli was present in the water and in the biofilm samples collected throughout the study. The municipal potable water at the start of the study was the only water source that conformed to the South African Water Quality Guidelines for Domestic Use. After 15 days of storage, this water source had deteriorated microbiologically to levels considered unfit for human consumption. E. coli was detected in the ground- and potable water and ground- and potable biofilms periodically, whereas it was detected in the rainwater and associated biofilms at every sampling point. Imperfections in the UV resistant inner lining of the tanks were shown to be ecological niches for microbial colonisation and biofilm development. The results from the current study confirmed that long-term storage can influence water quality and increase the number of microbial cells associated with biofilms on the interior surfaces of water storage tanks.

Cadmium in False Bay: Monitoring potential of the marine snail, Oxystele tigrina (Mollusca)

Cadmium contamination levels in the False Bay intertidal zone in South Africa were assessed in the water and sediments over a period of one year. Samples were collected seasonally from six sites within the bay, and from a reference site situated just outside the eastern arm of False Bay in order to obtain a general overview of contamination levels to which invertebrates in the coastal areas are exposed. The results from the chemical analyses of water and sediment samples revealed that most contamination was associated with the northern shore of the bay between Strand and Muizenberg, where the most populated and industrialised catchments occur. The high contamination factors calculated for Cd for sediments from some sites suggested a strong input of industrial and other discharges containing this heavy metal. There were signifi cant seasonal and spatial differences in the cadmium concentrations, with spatial variations indicating localised contamination, while seasonal variations were assumed to be predominantly related to changes in precipitation and runoff at different times of the year. The mean cadmium concentrations in the water and sediments were occasionally higher than the levels recommended by the South African Water Quality Guidelines, and indicated an increase in the levels compared to the previous water quality surveys. Laboratory experiments were conducted to examine the uptake, accumulation and loss of cadmium by the different organs of the periwinkle, Oxystele tigrina, from the False Bay intertidal zone. Tissue-specific cadmium accumulation in the control and exposed individuals were compared over a 14-day exposure period to sub-lethal concentrations (0.2 and 0.4 µg/ml) of water-borne cadmium in the form of CdCl2. The animals were sampled at regular intervals and the cadmium concentrations in the different organs measured by atomic absorption spectrophotometry. The results showed a general pattern of cadmium increase in the exposed individuals over a relatively short period. Cadmium was detected in all the tissues, with varying degrees of bioaccumulation. A more or less linear pattern of cadmium accumulation indicated that the metal was not regulated by O. tigrina. The metal was partitioned differently into the soft tissues and shells, with the soft tissues generally displaying a higher rate of cadmium uptake. There was a loss of the accumulated cadmium from the organs of the contaminated individuals upon transfer to clean seawater, with variations in the percentage of cadmium loss probably indicating that only part of the accumulated cadmium was firmly bound to the different tissues. The cadmium loss in the group that was exposed to 0.40µg/ml was not significant, indicating that the cadmium may have been more tightly bound in the tissues of this group compared to the group exposed to 0.20 µg/L. The amounts of cadmium in sediments and animal bodies in some parts of False Bay were such that cadmium could at current relatively low levels be expected to accumulate over time in these animals. Under changed physical conditions that may increase bioavailability, body levels could be reached that could affect the long term survival of this species and possibly its predators.

The development of water quality methods within ecological Reserve assessments, and links to environmental flows

In the South African National Water Act (NWA, No 36 of 1998), the ecological Reserve is defined as the quality and quantity of water required to ensure appropriate protection of water resources, so as to secure ecologically sustainable development and use. Aquatic ecosystems are recognised as the core location of water resources, and although considerable progress has been made in developing methods for quantifying environmental flow requirements, this paper describes and discusses the first agreed method for quantifying environmental water quality requirements in an ecological Reserve assessment. Integration of flow and water quality is emphasised, and is based on the philosophy that environmental flows should be motivated to provide ecologically important flow-related habitat, or geomorphological function, but should not be motivated to solve water quality problems by dilution. Water quality is multivariate, and not all variables can be considered in an ecological Reserve assessment, but core water quality variables include: system variables (salts, dissolved oxygen, turbidity, temperature), nutrients (phosphate, nitrite, nitrate) and toxic substances (those listed in the South African Water Quality Guidelines for Aquatic Ecosystems, including toxic metal ions, toxic organic substances, and/or substances from a chemical inventory of an effluent or discharge). In addition, biological indicator data (e.g. SASS data), chlorophyll-a (e.g. phytoplankton and periphyton data) and toxicity test data may be used. For each variable, a concentration range or response is linked to a class within a water resource classification system, where classes range from minimally to severely modified. There are five main stages in the environmental water quality method: • Initiate study and determine scope of assessment. • Delineate water quality sub-units. • Select sites and collect data and information. • Determine benchmarks, including generic boundary values (literature-based concentrations related to classes); the unimpacted, natural or reference condition; the present ecological state; and the contribution of water quality to the overall ecosystem importance and sensitivity. • Provide quantified and qualitative water quality objectives for each ecosystem health class, and each variable in each resource unit. These steps are integrated with environmental flow assessment procedures. After environmental flows have been recommended to achieve a selected level of protection (class), flow-concentration relationships are modelled, and the likely water quality consequences of modified flows are provided to resource managers, who then decide on whether to allocate water for dilution and/or to address the pollution problem directly using source controls. Water SA Vol. 31 (2) 2005: pp.161-170

Cadmium in the Umtata River and the associated health impact of on rural communities who are primary users of water from the river

Trace levels of Cd were determined in Umtata River which may affect human health. The levels of Zn were also determined since Zn can provide partial protection against the toxic effect of Cd in humans. The levels of Cd varied between trace and 0.007 mg/ℓ while that of Zn ranged from trace to 0.019 mg/ℓ. Generally the levels of Cd and Zn found in the river were below the South African water quality guidelines for Cd and Zn, respectively. The hazard quotients for Cd in the river were calculated in order to show the potential health risks of cadmium to local primary users of water from river and the values were within acceptable limits. Keywords: Cadmium, River water, Health risk WaterSA Vol.30(4) 2004: 507-513