# Seasonal Pollution Levels and Heavy Metal Contamination in the Jukskei River, South Africa
## 3 Results and Discussion
### Dry and Wet Season Concentrations of the Heavy Metals
These rivers drain artisanal gold mining sites in a manner similar to the Jukskei River, which drains the site that is infamous for its mine dumps and illicit mining activities like in the Tambopata and Malinowski Rivers, Peru [44; 45; 46]. The abundance of radionuclides and heavy metals in river systems are diverse, encompassing both natural and anthropogenic origins. The detected levels of Th, U, and Cd showed no significance differences in both the dry and wet seasons. As was at the highest (8.14 mg/kg) at point Juks-P2 and lowest (3.55 mg/kg) at Juks-DS-8 in the dry season whereas the concentration levels of 8.6 mg/kg and 1.3 mg/kg at Juks-P2 and Juks-DS-9 were determined during the wet season. The potential sources contributing to the presence of Th and U in the river sediment and waters may affect the ecological and radiological characteristics of these environments [47]. The toxicity and bioaccumulation nature of As is influenced by biotic factors, such as biofilms and aquatic organisms, and abiotic factors, including sediment composition and water chemistry, which may result in significant ecological and health implications [11]. During dry seasons, finer sediment particles settle out, concentrating the heavy metals in a smaller area, while during wet seasons, increased water flow can suspend the sediment, distributing the metals more widely throughout the river system, but still largely contained within the sediment matrix [48]. This is because most heavy metals bind to sediment particles and are primarily transported and deposited with the sediment itself [49; 50]. Depending on the predominant sediment type, the composition of the sediment can affect how metals bind and are released, perhaps causing minor seasonal fluctuations [51; 52; 53]. The accumulation of anthropogenic-induced heavy metals dispersed throughout the water requires a feasible safety precaution and management strategies for river water systems [54]. The As, Cd, and Pb determinations in water samples were undetected in both wet and dry seasons, as presented in Table 3. The concentrations of Hg were notable, ranging from 0.01 to 0.07 \(\mathrm{\SIUnitSymbolMicro\SIUnitSymbolMicro\SIUnitSymbolMicro\SIUnitSymbolMicro \SIUnitSymbolMicro\SIUnitSymbolMicro\SIUnit  
of 0.34 and 0.95 \(\upmu\)g/L were detected at Juks-P5 in both wet and dry seasons whereas a Th concentration of 62 \(\upmu\)g/L at Juks-P1 was notable in the dry season. The variation of Hg, Th, and U in both sampling seasons indicated continuous introduction of these pollutants through either anthropogenic or natural input in the river water system. The presence of these elements in river water can lead to various health risks and ecological disturbances. For instance, heavy metals can bioaccumulate in aquatic organisms, such as fish, which are then consumed by humans, leading to potential health risks. This bioaccumulation is particularly concerning for elements like Pb and Cd [55]. South Africa has established water quality regulations to ensure the protection of aquatic ecosystems and human health by setting permissible limits for various contaminants in water. The assessment of Jukskei River water quality is crucial for ensuring compliance with national water quality regulations and safeguarding public health. For instance, the high concentration level of Th in the dry sampling season highlights that contamination levels of heavy metals in South African rivers often exceeds permissible limits set by local and international guidelines [28; 56]. With regards to ecological impacts, heavy metals can adversely affect the physiological health of fish, leading to changes in oxidative stress markers and energy reserves. This can result in reduced fish populations and biodiversity in affected rivers. These findings underscore the need for stringent monitoring and management practices to protect water resources and public health.