Exploring the Impact of Climate Change on Metals in Water: A Case Study of Artisanal Gold Mines in Kenya's Lake Victoria Basin

Abstract

emissions from fossil fuels, power plants, vehicles, and mining activities have contributed to increased atmospheric carbon levels associated with climate change threat. Carbon enrichment in aquatic habitats impacts pH, salinity, and the mobility of toxic metals like Cu, Cd, Zn, and As. Climate change poses significant challenges for hydrologists, as water resource management systems historically focused on climatic stability. Maintaining the quality of river water, which constitutes a major source of drinking water, is vital for environmental health as well as for the well-being of humans and animals. Consequently, a study was undertaken to examine the presence of potentially harmful metals in water prior to and following the El Nino event of 2020. A total of forty-eight samples of drinking water were collected in triplicate using Van Dorn water bottles from twenty randomly selected sites. The sampling sites, all located in Migori County, included River Kucha and River Migori, both of which discharge into Lake Victoria and pass through the Migori artisanal mining sites. The samples were processed, packed, and sent to Bureau Veritas, Vancouver, Canada, for heavy metal analysis using inductively coupled plasma-mass spectrometry (ICP-MS). The analysed heavy metals included mercury (Hg), chromium (Cr), copper (Cu), cadmium (Cd), zinc (Zn), lead (Pb), and arsenic (As). Water mercury levels were found to be elevated both before October, 2016 and after El Nino in October, 2021. The study indicated that mean metal concentrations in water samples decreased in the following order: Zn >Pb >Cu >Cr >As >Cd >Hg. The analysed metals exhibited concentrations higher than the permissible limits by WHO for drinking water. The results of the ecological risk assessment indicated that there is an urgent need to prioritize the control and management of heavy metal contamination and the associated risks in the studied rivers and water sources. Additionally, it is crucial to maintain ongoing monitoring of potentially harmful metal levels in order to mitigate the unnecessary risks associated with their toxic effects. Importantly, the analysis revealed that the levels of heavy metals, in general, were elevated after the El Nino event compared to the period prior to it.