Despite the fact that several cases of unsafe pesticide use among farmers in different parts of Africa have been documented, there is limited evidence regarding which specific interventions are effective in reducing pesticide exposure and associated risks to human health and ecology. The overall goal of the African Pesticide Intervention Project (APsent) study is to better understand ongoing research and public health activities related to interventions in Africa through the implementation of suitable target-specific situations or use contexts. A systematic review of the scientific literature on pesticide intervention studies with a focus on Africa was conducted. This was followed by a qualitative survey among stakeholders involved in pesticide research or management in the African region to learn about barriers to and promoters of successful interventions. The project was concluded with an international workshop in November 2021, where a broad range of topics relevant to occupational and environmental health risks were discussed such as acute poisoning, street pesticides, switching to alternatives, or disposal of empty pesticide containers. Key areas of improvement identified were training on pesticide usage techniques, research on the effectiveness of interventions targeted at exposure reduction and/or behavioral changes, awareness raising, implementation of adequate policies, and enforcement of regulations and processes.

Fresh water quality is threatened by increasing pesticide concentrations due to the heavy reliance of our food production systems on agrochemicals. This study reports on atrazine leaching dynamics from a range of low-carbon topsoils, including a sandy loam under conventional tillage (CT) and no-till (NT) practices, as well as a high clay, highly structured, and very sandy soil. Undisturbed soil leaching column data were used to calibrate and test the Pesticide in Water Calculator (PWC) model for additional verification of results and assess potential for future use. Atrazine leaching concentrations were highest just after application and ranged from 2.75 mg L -1 (sand) to 0.52 mg L -1 (structured soil) for the first leaching event. Slightly higher, but not statistically significant, cumulative atrazine leaching occurred for the CT than NT soils. This indicates that the increased hydraulic conductivity of recently tilled soils may match the greater porosity of the NT soil in promoting leaching. Based on the relatively high leaching load for the clay soil, it is recommended that label recommendation rates be re-assessed for these soils. The PWC model performed well in simulating leaching dynamics and is recommended for further application for similar soils, including in decision making by authorities on whether to register new agrochemicals for commercial use. Growers are encouraged to minimize over-irrigation following atrazine application, and to consider rainfall forecasts prior to application to avoid periods where high deep drainage coincide with recent applications.

Thyroid function and nutritional indicators were measured in obese, steatitis-affected Mozambique tilapia Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. Plasma thyroid hormones (especially T3) and thyroid follicle histomorphology revealed high levels of activity in every aspect of the thyroid cascade measured in fish from LR compared to a reference population of steatitis-free fish. Concurrent measurements of nutritional state including plasma lipids, liver lipid content and hepatocyte size showed that fish from LR had significant energy stores indicative of abundant nutritional intake. There were distinct sex and seasonal differences, with the highest plasma lipids and T3 levels observed in steatitis-affected females during spring and summer. Positive correlations were observed between plasma lipids (especially cholesterol) and T3 concentrations in fish from both populations, indicating a link between lipid metabolism and thyroid function. There was no direct evidence of thyroid disruption, but this cannot be ruled out until further research determines the factors that underlie the homeostatic shift leading to elevated plasma and liver lipids and T3 levels in steatitis-affected tilapia.

South Africa is prone to droughts and is heavily dependent on stored water resources. Few studies in South Africa have investigated the impact of drought on water quality when rainfall resumes and reservoir sediments are rewet. Other research has shown that several negative impacts may occur with rewetting, including eutrophication, and acidification with increased metal solubility. In this study, the impact of drying and rewetting sediments on the mobility of nutrients and metals is explored using sediments from Loskop Reservoir. Rarely exposed sediments were collected from three sites, dried at 35°C for 36 days, and then rewet under aerobic conditions. Filtered water samples were collected on Days 1, 2 ,4, 7, 11 and 16 following rewetting, and analysed for NH 4 + , NO 3 - , NO 2 - , total N, total P, PO 4 3- , dissolved Al, Fe, Mn, and SO 4 2- . Results were expressed as mass/m 2 , and were compared to reference (non-drought) treatments that were maintained under saturated conditions. Acute toxicity tests were performed using Daphnia magna to establish if toxic effects were associated with changes in water quality following sediment rewetting. Following rewetting, elevated SO 4 2- indicated the mobilisation of acid from sulfide oxidation, with an associated reduction in pH. Nitrification was evident as high quantities of organic N and NH 4 + were initially released, followed by increases in NO 2 - + NO 3 - . Total P increased, but PO 4 3- reduced. This was attributed to complexes formed between PO 4 3- and Fe (FePO 4 ) and Al (AlPO 4 ). Amounts of Fe and Al released were lower following rewetting due to the formation of relatively immobile (hydr)oxides. In contrast, Mn increased substantially reaching maximum values > 2 300 mg/m 2 (14 000 μg/L). There were no acute toxic effects observed to D. magna. This study highlights the potential for acidification, mobilisation of nutrients, SO 4 2- , and Mn following rewetting of reservoir sediments under aerobic conditions. This information may be incorporated into reservoir and catchment management plans in the form of revised water quality guidelines and a better ability to predict how drought impacts water quality in our stored water resources. Keywords : sediment, drought, drying, rewetting, nutrient and metal release, Loskop Reservoir

Emerging chemical pollutants (ECPs) are defined as new chemicals which do not have a regulatory status, but which may have an adverse effect on human health and the environment. The occurrence and concentrations of ECPs in South African water bodies are largely unknown, so monitoring is required in order to determine the potential threat that these ECPs may pose. Relevant surface water sampling sites in the Gauteng Province of South Africa were identified utilising a geographic information system (GIS). The sites were identified by identifying potential sources of ECPs, including hospitals and clinics, sewage treatment plants, and areas with high population densities or areas that were vulnerable from an environmental point of view. Buffers were drawn around these areas to identify the water sources which have the highest probability of containing ECPs. Areas along the Klip River were identified as having a high likelihood of containing both anthropogenic ECPs and agricultural ECPs. Additionally, sections of the Hennops River were likely to contain anthropogenic ECPs, while the Blesbokspruit area had a high likelihood of containing agricultural ECPs.

The alien invasive silver carp Hypophthalmichthys molitrix established a self-sustaining feral population in an oligotrophic impoundment, Flag Boshielo Dam, in South Africa. The ability of this population to persist in a dam with low algal biomass (median annual suspended chlorophyll a = 0.08 µg l−1), and limited access to rivers considered large enough for successful spawning, has implications for their invasive potential in other systems. Stomach content and stable isotope analysis were used to assess the trophic ecology of H. molitrix, which was then compared with indigenous Mozambique tilapia Oreochromis mossambicus, on a seasonal basis during 2011. Hypophthalmichthys molitrix are generalist filter feeders, with a diet consisting primarily of sediment, vegetative detritus, dinoflagellates and diatoms. The dominance of sediments in their stomachs suggests occasional benthic scavenging. However, H. molitrix occupied a higher trophic level (TL = 2.8) than expected, suggesting that this population subsidised their diet with an unidentified dietary constituent, characterised by enriched nitrogen values. Although the stomach contents indicated dietary overlap between H. molitrix and O. mossambicus, stable isotopes revealed fine-scale resource partitioning, despite both species occupying the same trophic level. Nonetheless, the persistence of this feral H. molitrix population in an oligotrophic impoundment highlights their phenotypic plasticity.

Regulatory risk assessment considers vegetated buffer strips as effective risk mitigation measures for the reduction of runoff-related pesticide exposure of surface waters. However, apart from buffer strip widths, further characteristics such as vegetation density or the presence of erosion rills are generally neglected in the determination of buffer strip mitigation efficacies. This study conducted a field survey of fruit orchards (average slope 3.1-12.2%) of the Lourens River catchment, South Africa, which specifically focused on the characteristics and attributes of buffer strips separating orchard areas from tributary streams. In addition, in-stream and erosion rill water samples were collected during three runoff events and GIS-based modeling was employed to predict losses of pesticides associated with runoff. The results show that erosion rills are common in buffer strips (on average 13 to 24 m wide) of the tributaries (up to 6.5 erosion rills per km flow length) and that erosion rills represent concentrated entry pathways of pesticide runoff into the tributaries during rainfall events. Exposure modeling shows that measured pesticide surface water concentrations correlated significantly (R(2)=0.626; p<0.001) with runoff losses predicted by the modeling approach in which buffer strip width was set to zero at sites with erosion rills; in contrast, no relationship between predicted runoff losses and in-stream pesticide concentrations were detected in the modeling approach that neglected erosion rills and thus assumed efficient buffer strips. Overall, the results of our study show that erosion rills may substantially reduce buffer strip pesticide retention efficacies during runoff events and suggest that the capability of buffer strips as a risk mitigation tool for runoff is largely overestimated in current regulatory risk assessment procedures conducted for pesticide authorization.

Over 3000 pesticides are registered for use in South Africa. Many studies have highlighted the movement of pesticides to agricultural crops from the point of application into non-target environments, particularly surface and groundwater resources. Exposure to pesticides can lead to serious human health and environmental effects. It is therefore important to identify critical areas where specific pesticides may result in a high risk of exposure to humans or the environment. Crop specific pesticide use data were obtained from a market research company and integrated into a geographical information system detailing the distribution of agricultural crops in South Africa as determined by an agricultural census performed in 2002. By estimating the total application of a specific pesticide to all crops produced in a magisterial district, it was possible to generate maps which provide an estimate of the application rate of over 200 pesticides per magisterial district. These maps were intersected with an agricultural land-cover map to provide a refined map giving details of the spatial distribution of pesticide use across the country. These maps are the first of their kind in South Africa and provide a spatial overview of the likely distribution of specific active ingredients based on the distribution of crops throughout the country. While there are a number of limitations and uncertainties associated with the data used to produce these maps, these are not unique to South Africa, and similar methodologies have been applied in more developed countries.

Air dispersion software models for evaluating pesticide spray drift during application have been developed that can potentially serve as a cheaper convenient alternative to field monitoring campaigns. Such models require validation against field monitoring data in order for them to be employed with confidence, especially when they are used to implement regulatory measures or to evaluate potential human exposure levels. In this case study, off-target pesticide drift was monitored during ground application of a pesticide mixture to a sorghum field in South Africa. Atrazine was used as a drift tracer. High volume air sampling onto polyurethane foam (PUF) was conducted at six downwind locations and at four heights at each sampling point. Additional data, including meteorological information, required to simulate the spray drift with the AGDISP® air dispersion model was collected. The PUF plugs were extracted by a plunger method utilizing a hexane:acetone mixture with analysis by GC-NPD (94.5% recovery, 3.3% RSD, and LOD 8.7 pg). Atrazine concentrations ranged from 4.55 ng L(-1) adjacent to the field to 186 pg L(-1) at 400 m downwind. These results compared favourably with modeled output data, resulting in the validation of the model up to 400 m from the application site for the first time. Sensitivity studies showed the importance of droplet size distribution on spray drift, which highlighted the need for good nozzle maintenance. Results of this case study indicate that the model may provide meaningful input into environmental and human health risk assessment studies in South Africa and other developing countries.

Increasing demands for water, discharge of effluents, and variable rainfall have a negative impact on water quality in the Olifants River. Crocodile and fish mortalities attributed to pansteatitis, in Loskop Dam and downstream in the Kruger National Park (KNP), have highlighted the serious effects these impacts are having on aquatic ecosystems. Flag Boshielo Dam is a reservoir on the Olifants River, located between Loskop Dam and the KNP. It has the largest crocodile population outside of the KNP, and pansteatitis has not been reported in fish or crocodiles to date. This study evaluated comparative water quality parameters concurrent to a similar study undertaken at Loskop Dam to establish possible environmental drivers of pansteatitis. Long-term monitoring data collected by the Department of Water Affairs were analysed for trends using a Seasonal-Kendall trend test. Short-term monitoring showed that water quality in Flag Boshielo Dam was of a good standard for ecosystem health. Concentrations of dissolved Cu, Se, V and Zn were always below instrument detection limits, and Al, Fe and Mn were mostly within guideline levels for ecosystem health. A severe drought occurred between November 2002 and December 2005. Long-term monitoring showed that water quality during the drought deteriorated, with high levels of dissolved salts, especially K, Na, Cl, F, and total alkalinity. Following the drought, dissolved salt concentrations dropped, and there was a brief flush of inorganic N and P. However, between 1998 and 2011, inorganic N showed a significant decreasing trend into the oligotrophic range, while inorganic P remained in the oligo-to mesotrophic range. The inorganic N to inorganic P ratio of 5.4 after the drought was indicative of N limitation, and the phytoplankton assemblage was dominated by nitrogen-fixing species, especially Cylindrospermopsis sp. In contrast, further upstream, Loskop Dam has undergone increasing eutrophication, has frequent blooms of Microcystis aeruginosa and Ceratium hirundinella, and concentrations of Al, Fe and Mn periodically exceed guideline levels. The difference in trophic state, phytoplankton assemblage and levels of productivity between these two reservoirs may provide insights into the aetiology of pansteatitis, which is frequently associated with dietary causes.

Predicting the potential geographical distribution and spread of non-native species is of major concern to ecologists. Silver carp Hypophthalmichthys molitrix, ranked as one of the world's 100 worst invasive species, were introduced into South Africa in 1975, but the potential spread of this invader has not yet been addressed, despite recent studies indicating its potential ecological impacts in South Africa. The potential range of silver carp in South Africa was identified based on ecological niche modelling (ENM) using the maximum entropy method. Models were constructed using occurrence records and a defined background, and calibrated using a k-fold method. The area under the receiver operating characteristics curve (AUC) was used to evaluate model performance. Both the native and introduced range model accurately predicted species occurrences (AUC 0.98 and 0.94, respectively). Most of the north-eastern part of South Africa, including the Limpopo River Basin, where the presence of silver carp has been recorded, was correctly predicted as climatically suitable for silver carp. Other areas with suitable climatic conditions for silver carp but with no known introductions were also identified. The model demonstrated the potential use of ENM to predict the potential range of silver carp in South Africa.

Summary Pansteatitis (yellow fat disease) is ubiquitous in the free‐ranging population of Oreochromis mossambicus from Loskop Reservoir (LR), South Africa. The disease is nutritionally mediated and associated with a diet high in polyunsaturated or rancid fats, frequently of fish origin. While piscivory has never been reported in dietary studies of O. mossambicus in their native range, their opportunistic and omnivorous feeding habits mean that piscivory cannot be ruled out as a cause of the disease. The diet of O. mossambicus from LR (n = 91) was compared with a population from Flag Boshielo Reservoir (FBR; n = 81) located <100 km downstream, where no pansteatitis occurs. The stomach contents and stable isotope signatures (δ15N and δ13C) of fish and food sources were evaluated across four seasons. Isotope signatures were also compared over various time scales from historic samples and mortalities collected from LR. There was no evidence of piscivorous feeding behaviour in fish from either location or from historic LR samples. The results of the stable isotope analysis in R mixing model and stomach contents analysis showed that the dinoflagellate, Ceratium hirundinella, was the dominant food source followed by zooplankton, detritus and Microcystis aeruginosa in LR. The diet of fish from FBR was less diverse than fish from LR and was dominated by sediment and detritus. The distinguishing feature of the dietary comparison between reservoirs was the abundance of planktonic food items dominated by C. hirundinella in the diet of fish from LR. The lack of evidence for piscivory among O. mossambicus from LR suggests that the classic aetiology of pansteatitis does not apply. This highlights the need to further explore direct (environmental exposure to pollutants) and indirect (dietary exposure) links to pansteatitis. This study identified the major dietary constituents for O. mossambicus, which enables future research to focus on their nutritional and chemical composition.

Concentrations of pollutants were measured in water, sediment and algal samples collected along a longitudinal gradient from a stretch of the Olifants River, South Africa, that receives acid mine drainage (AMD) from the Klipspruit River. The effects of AMD were determined through macroinvertebrate biotic indices (SASS5) and multivariate analysis of macroinvertebrate communities. The acidic Klipspruit River caused increased concentrations of total Al, Fe and Mn in the Olifants River. Upon mixing of the Klipspruit with that from the alkaline Olifants River, Al and Fe precipitate rapidly, leading to lower concentrations in the dissolved phase and higher concentrations in the suspended phase and in sediment at sites in close proximity to the confluence. Similarly, filamentous algae accumulated high concentrations of Al, Fe and Zn immediately after the confluence. Mn remains in the dissolved phase, and sediment and algal concentrations increase with increasing distance downstream. Metal speciation analysis indicate that Al is rapidly converted from more toxic forms (e.g. Al3+ and Al(OH)2+) to less toxic forms (e.g. Al(OH)3(aq) and Al(OH)4−). In contrast, Mn remains in the soluble Mn2+ form. Macroinvertebrate metrics and community structure showed clear signs of deterioration in water quality in the Olifants River downstream of the point of AMD input. While total TDS concentrations at all sites fall within ranges likely to affect macroinvertebrates, the relative composition of major ions changes as a result of AMD input, which may also account for the observed changes in macroinvertebrate communities. Further downstream, the Wilge River discharges into the Olifants River and significantly improves water quality downstream of the confluence. Future mining and development activities in the Wilge catchment should be carefully managed and monitored so as to ensure sufficient flows of acceptable quality to prevent further deterioration of water quality in the Olifants River and downstream reservoirs. Copyright © 2014 John Wiley & Sons, Ltd.

Excessive phosphate loading in the upper Olifants River, South Africa has resulted in widespread eutrophication and associated ecosystem health impacts. The majority of sewage treatment works (STWs) are operating poorly and are likely an important source of bioavailable orthophosphate (OP) in the catchment. The Soil Water Assessment Tool (SWAT) was used to identify important sources of OP loading in the catchment and to predict changes in the trophic status of four reservoirs associated with three STW effluent OP standards (the current average of 4 mg L-1 and standards of 1 and 0.1 mg L-1). Nash-Sutcliffe and PBIAS statistics showed good model performance for simulations of flow and OP loading using a multi-site calibration and validation approach. Key sub-catchments responsible for high OP loading were identified. Three of the four reservoirs are heavily impacted by OP loading originating from STWs. Two reservoirs show mean annual OP concentrations indicative of eutrophic conditions and a 1 mg L-1 effluent standard would reduce concentrations to well within the mesotrophic range. There was little difference in OP loads and concentrations associated with the 1 and 0.1 mg L-1 effluent standards, indicating that attention to nonpoint sources would be required to realise any benefit associated with the strictest effluent standard. Regression analyses and associated 95% prediction limits between simulated OP loads and concentrations for all effluent treatment scenarios from 2002 to 2010 allowed for the quantification of OP loading that would ensure a specific trophic status in each reservoir. This study is one of the first to apply SWAT in simulating OP loading and concentrations in large reservoirs, and its application in South Africa provides further support for its utility throughout a wide geographical area.

A GIS based pesticide risk indicator that integrates exposure variables (i.e. pesticide application, geographic, physicochemical and crop data) and toxicity endpoints (using species sensitivity distributions) was developed to estimate the Predicted Relative Exposure (PREX) and Predicted Relative Risk (PRRI) of applied pesticides to aquatic ecosystem health in the Lourens River catchment, Western Cape, South Africa. Samples were collected weekly at five sites from the beginning of the spraying season (October) till the beginning of the rainy season (April) and were semi quantitatively analysed for relevant pesticides applied according to the local farmers spraying programme. Monitoring data indicate that physicochemical data obtained from international databases are reliable indicators of pesticide behaviour in the Western Cape of South Africa. Sensitivity analysis identified KOC as the most important parameter influencing predictions of pesticide loading derived from runoff. A comparison to monitoring data showed that the PREX successfully identified hotspot sites, gave a reasonable estimation of the relative contamination potential of different pesticides at a site and identified important routes of exposure (i.e. runoff or spray drift) of different pesticides at different sites. All pesticides detected during a monitored runoff event, were indicated as being more associated with runoff than spray drift by the PREX. The PRRI identified azinphos-methyl and chlorpyrifos as high risk pesticides towards the aquatic ecosystem. These results contribute to providing increased confidence in the use of risk indicator applications and, in particular, could lead to improved utilisation of limited resources for monitoring and management in resource constrained countries.

South Africa is the largest user of pesticides in sub-Saharan Africa and many studies have highlighted the occurrence of pesticides in water resources. Poor management of water treatment facilities in combination with a relatively high dependency on untreated water from boreholes and rivers creates the potential for exposure of human communities to pesticides and their associated health effects. Pesticide use, physicochemical and toxicity data was therefore used to prioritize pesticides in terms of their potential risk to human health. After eliminating pesticides used in very low quantities, four indices were used to prioritize active ingredients applied in excess of 1000 kg per annum; the quantity index (QI) which ranked pesticides in terms of the quantity of their use; the toxicity potential index (TP) which ranked pesticides according to scores derived for their potential to cause five health effects (endocrine disruption, carcinogenicity, teratogenicity, mutagenicity and neurotoxicity); hazard potential index (HP) which multiplied the TP by an exposure potential score determined by the GUS index for each pesticide (to provide an indication of environmental hazard); and weighted hazard potential (WHP), which multiplied the HP for a pesticide by the ratio of its use to the total use of all pesticides in the country. The top 25 pesticides occurring in each of these indices were identified as priority pesticides, resulting in a combined total of 69 priority pesticides. A principal component analysis identified the indices that were most important in determining why a specific pesticide was included in the final priority list. As crop specific application pesticide use data was available it was possible to identify crops to which priority pesticides were applied to. Furthermore it was possible to prioritize crops in terms of the specific pesticide applied to the crop (by expressing the WHP as a ratio of the total amount of pesticide applied to the crop to the total use of all pesticides applied in the country). This allows for an improved spatial assessment of the use of priority pesticides. The methodology applied here provides a first level of basic, important information that can be used to develop monitoring programmes, identify priority areas for management interventions and to investigate optimal mitigation strategies.

A declining crocodile population and fish mortalities attributed to pansteatitis, along with increasing blooms of Microcystis aeruginosa and Ceratium hirundinella, have led to serious concerns about water quality in Loskop Dam, on the Olifants River, South Africa. Major impacts include acid mine drainage and eutrophication associated with sewage effluent. However, the specific causes of pansteatitis remain elusive. In 2011 the water chemistry and limnology of Loskop Dam were studied to determine factors that may be influencing aquatic ecosystem health. Long-term monitoring data collected by the Department of Water Affairs were analysed for trends using a seasonal Mann-Kendall trend test, and were used to determine the trophic state of Loskop Dam using the Carlson index. Multiple sites were sampled which showed the reservoir was heterogeneous with regard to nutrient concentrations, algal biomass and dissolved metals. Specifically, the transitional zone was characterised by frequent algal blooms, resulting in fluctuating dissolved oxygen (range = 2.1-14.5 mg/ l) and pH (range = 7.35-10.59) levels. Using total phosphorus, Secchi depth, and chlorophyll-a concentrations, the trophic state of Loskop Dam was classified as meso-to eutrophic. Significant positive trends were observed in total (Tau = 0.422) and dissolved inorganic (Tau = 0.193) phosphorus. The reservoir showed a monomictic pattern of summer stratification (October to April) and holomictic winter circulation (June to July), with an increase in the depth and extent of anoxia in the hypolimnion when compared to previous research. Simultaneous elevated concentrations of manganese (> 370 mu g/ l) and iron in nearbottom water samples coincided with hypolimnetic anoxia. Aluminium concentrations exceeded the target water quality range (> 10 mu g/ l) during summer (December) in both surface and near-bottom water samples. We conclude that fish in Loskop Dam are periodically exposed to several physiological stressors including elevated ammonia, aluminium, iron and manganese and possibly hydrogen sulphide, as well as low dissolved oxygen. While these factors have never individually been linked to pansteatitis, their combined impacts have not been studied. To ensure the sustainability of Loskop Dam, catchment management plans must focus on reducing phosphorus inputs, and continue seeking treatment solutions for mine-water associated with abandoned and working coal mines.

Routine sampling of water quality was conducted at sites along a longitudinal gradient from upstream to downstream in the Olifants River to determine spatial trends in nutrient and metal concentrations and to relate these trends to changes in land use activities in the catchment. In addition, once-off sampling was conducted at a number of sites located downstream of current mining, abandoned mining, agriculture, wastewater treatment works (WWTWs) and industry. Nutrient concentrations were relatively high and a number of sites within the catchment had average N:P ratios that were indicative of eutrophic to hypertrophic conditions. Routine and once-off sampling indicated that wastewater treatment works contribute high nutrient loads to the system. Trend analysis of Department of Water Affairs (DWA) data indicated significant positive trends in ortho-phosphate at 12 of 14 stations in the catchment. An increase in sulphate concentrations from upstream to downstream indicates that mining activities have a progressively greater impact on water quality with increasing distance downstream. While dissolved metal concentrations frequently exceeded chronic and acute effect aquatic ecosystem health guidelines (particularly aluminium, copper and zinc), there was no observable trend from upstream to downstream. Once-off sampling showed high variability in water quality parameters downstream of current mining activities, and some sites showed higher metal concentrations in comparison to other land use activities. However, the contribution of current mining activities to metals is low in comparison to the contribution from abandoned mines. Hydrological data showed that acidic rivers contribute proportionally higher flow volumes in comparison to neutral rivers during the drier winter months, which may significantly impact on the lower stretches of the upper Olifants River and into Loskop Dam. A prolonged drought period will most likely result in severe impacts to the lower reaches of the Olifants River and to Loskop Dam. Improved management and maintenance of wastewater treatment works and rehabilitation and/or treatment of abandoned mines and associated acid mine drainage are crucial. Proper rehabilitation of current mining activities is essential to avoid or minimise acid mine drainage related impacts in the future.

Recent studies suggest an increase in mercury (Hg) emissions to the global environment, particularly as a result of anthropogenic activities. This has prompted many countries to complete Hg emission inventories, based on country-specific Hg sources. In this study, information on annual coal consumption and Hg-containing commodities produced in South Africa, was used to estimate Hg emissions during 2000-2006. Based on the information, the UNEP toolkit was used to estimate the amount of Hg released to air and general waste from each activity; using South Africa specific and toolkit based emission factors. In both atmospheric and solid waste releases, coal-fired power plants were estimated to be the largest contributors of Hg emissions, viz. 27.1 to 38.9 tonnes y(-1) in air, and 5.8 to 7.4 tonnes y(-1) in waste. Cement production was estimated to be the second largest atmospheric Hg emission contributor (2.2-3.9 tonnes y(-1)), while coal gasification was estimated to be the second largest Hg contributor in terms of general waste releases (2.9-4.2 tonnes y(-1)). Overall, there was an increase in total atmospheric Hg emissions from all activities, estimated at ca. 34 tonnes in 2000, to 50 tonnes in 2006, with some fluctuations between the years. Similarly, the total Hg emissions released to general waste was estimated to be 9 tonnes in 2000, with an increase to 12 tonnes in 2006. (C) 2010 Elsevier Ltd. All rights reserved.

As a first step towards assessing Hg levels in a systematic approach in South Africa, representatives from the South African government, academia, research councils and key industries recently initiated a South African Mercury Assessment (SAMA) Programme (Leaner et al., 2006). The SAMA Programme has undertaken some limited Hg inventory development and monitoring studies in South Africa. The preliminary results of those studies and that of Hg monitoring Undertaken at Cape Point's Global Atmospheric Watch Station (Baker et al., 2002), are discussed in this paper.