The influence of water–rock interactions on household well water in an area of high prevalence chronic kidney disease of unknown aetiology (CKDu)

Abstract

Poor drinking water quality in household wells is hypothesised as being a potential contributor to the high prevalence of chronic kidney disease of uncertain aetiology (CKDu) among the farming communities of the Medawachchiya area, Anuradhapura, Sri Lanka. One of the natural processes that can affect water quality is the dissolution of minerals contained within an aquifer by water–rock interactions (WRIs). Here we present a comprehensive assessment of WRIs and their influence on the water chemistry in household wells and spring waters in the Medawachchiya area by combining measurements of environmental isotopes, such as strontium, lithium and stable carbon isotopes and inorganic chemistry parameters, and modelling geochemical mass balance reactions between rainfall and groundwater samples. Our results reveal the presence of strontium, dissolved from both silicate and carbonate minerals, with high isotopic (87Sr/86Sr) ratios of up to 0.7316. Geochemical mass balance modelling and prior 87Sr/86Sr studies on the Wanni Complex bedrock suggest these strontium values may be the result of biotite dissolution. We also identify lithium and uranium contributed from the dissolution of silicates, albeit at concentrations too low to constitute a known health risk. In contrast, the levels of magnesium and calcium in our samples are high and demonstrate that, despite the felsic bedrock, well water chemistry in the Medawachchiya area is dominated by carbonate dissolution.

Seasonal Variations in Groundwater Quality and Hydrogeochemistry in the Endemic Areas of Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka

“…The hard metamorphic terrain of the study areas is underlain by crystalline limestone and calc rocks which are considered to be prospective sources of Ca 2+ , Mg 2+ and HCO3 -in the groundwater [58,59]. Furthermore, a geochemical mass balance modelling study by [60] suggested that groundwater in the study areas is highly influenced by carbonate dissolution. However, geological evidence hardly suggested the presence of gypsum in these areas.…”

Hydrochemical and isotopic baselines for understanding hydrological processes across Macquarie Island

“…Future research will focus on long-term monitoring to understand seasonal, annual, and long-term variability to test fundamental hypotheses concerning ecosystem function and the consequences of environmental change on SOIs.The application of isotopic tracers in water is essential for understanding lake hydrology and the fundamental processes driving lake water chemistry 1,2 . These techniques give us information on how catchments respond to rainfall, evaporation, groundwater influx and carbon and nutrient cycling [3][4][5] . Lake water can be used to provide a deeper understanding of past environment and ecosystem information contained within lake sediments to understand long-term environmental change for a region [6][7][8] .…”