RESUMO
The presence of antibiotics in the environmental matrix has raised concerns regarding their risk to the aquatic ecosystem and human health. Surface water, such as rivers, plays a pivotal role in the dispersion and transport of antibiotic residues. The effective monitoring of these contaminants requires investigating their sources and distribution. While numerous studies have been conducted globally to comprehend the emergence, prevalence, and management of these substances, the investigation of therapeutic antibiotics in Africa remains notably underrepresented. Consequently, data regarding these emerging contaminants in the African aquatic environments are scarce, warranting further exploration. This study aims to investigate the occurrence of four specific therapeutic antibiotics-tetracycline, sulfathiazole, penicillin g, and erythromycin-across different seasons in the Msunduzi River, Eastern South Africa. Three sampling campaigns were conducted during spring, autumn, and winter to assess the presence of these antibiotics in the river. Analyte extraction from water samples was achieved through solid-phase extraction, and quantification was performed using liquid chromatography-mass spectrometry. The findings reveal notable concentrations of these antibiotics in the river at locations closest to a wastewater treatment discharge point. Among the antibiotics studied, tetracycline (158.42-1290.43 ng/L) and sulfathiazole (112.68-1151.25 ng/L) were the most frequently detected compounds across the majority of the sampling sites and tributaries of the river. Erythromycin was less frequently detected in the surface water and wastewater effluent but was found to be a risk to algal species within the river. While wastewater effluents represent a significant source of antibiotic contamination in the river, tributaries from industrial areas and informal settlements were identified as continuous sources of antibiotic pollution. Thus, it is imperative to implement appropriate monitoring protocols to mitigate antibiotic pollution in the aquatic environment.
RESUMO
Naturally occurring radionuclides and metals have adverse human health impacts when they occur at higher activity and concentration above the threshold value, respectively, in the water supply system. This study aimed to establish the baseline radionuclide and metal content in rocks, soils, and water in the Thyspunt area of the Eastern Cape Province, South Africa, which is selected as a potential site for the development of a nuclear power plant. Extensive sampling of rocks, soils, groundwater, and surface water was conducted in the area. The employed methods of sample analyses include ICP-MS, gamma-ray spectrometery (RS 230), and accelerator mass spectrometry. The results indicate that the Ceres Subgroup shale and the Skurwerburg formation quartzite of the Table Mountain Group (TMG) contain the highest activity of most radionuclides, including 238U, 235U, 234U, 226Ra, 232Th, and 210Pb; these are linked to the natural geochemistry of the rocks that have been facilitated by the low-grade metamorphism to which the local geology was subjected. The metamorphism-related radionuclide enrichment is also apparent in the soils and groundwater associated with these rocks. The activity of the radiotoxic and carcinogenic uranium (238U and 235U) and radium (226Ra and 224Ra) isotopes in water was found to be well above the WHO guideline of 0.03 and 1 Bq/L, respectively. The exposure dose rate was the highest in the Ceres Subgroup shales (185.7 nS/h), and this is linked to the elevated natural radioactivity in the rocks. The estimate of the ingestion-related effective dose indicates high doses associated with the uranium and radium isotopes, thus signifying the potential adverse impact on human health associated with the ingestion of the widely used groundwater in the area.
