Abstract
Poor groundwater quality in household wells is hypothesized as being a potential contributor to chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. However, the influencing factors of groundwater quality in Sri Lanka are rarely investigated at a national scale. Here, the spatial characteristics of groundwater geochemistry in Sri Lanka were described. The relationships of groundwater quality parameters with environmental factors, including lithology, land use, and climatic conditions, were further examined to identify the natural and anthropogenic controlling factors of groundwater quality in Sri Lanka. The results showed that groundwater geochemistry in Sri Lanka exhibited significant spatial heterogeneity. The high concentrations of NO3− were found in the districts that have a higher percentage of agricultural lands, especially in the regions in the coastal zone. Higher hardness and fluoride in groundwater were mainly observed in the dry zone. The concentrations of trace elements such as Cd, Pb, Cu, and Cr of all the samples were lower than the World Health Organization guideline values, while some the samples had higher As and Al concentrations above the guideline values. Principal component analysis identified four components that explained 73.2% of the total data variance, and the first component with high loadings of NO3−, hardness, As, and Cr suggested the effects of agricultural activities, while other components were primarily attributed to natural sources and processes. Further analyses found that water hardness, fluoride and As concentration had positive correlations with precipitation and negative correlations with air temperature. The concentration of NO3− and water hardness were positively correlated with agricultural lands, while As concentration was positively correlated with unconsolidated sediments. The environmental factors can account for 58% of the spatial variation in the overall groundwater geochemistry indicated by the results of redundancy analysis. The groundwater quality data in this study cannot identify whether groundwater quality is related to the occurrence of CKDu. However, these findings identify the coupled controls of lithology, land use, and climate on groundwater quality in Sri Lanka. Future research should be effectively designed to clarify the synergistic effect of different chemical constituents on CKDu.
Highlights
Chronic kidney disease (CKD) is a very common public health problem that can be observed in many parts of the world and a higher prevalence is reported from many countries including the USA, Australia, and Japan [1,2]
In the rural dry zone regions of Sri Lanka, groundwater is the primary source of water for both drinking and cooking, and CKD of unknown etiology (CKDu) is considered to be related to poor groundwater quality [10,11,12]
This study investigated the spatial characteristics of groundwater geochemistry in Sri Lanka
Summary
Chronic kidney disease (CKD) is a very common public health problem that can be observed in many parts of the world and a higher prevalence is reported from many countries including the USA, Australia, and Japan [1,2]. A CKD of unknown etiology (CKDu) has been reported in some countries in recent years in which the etiology is not recognizable [3] Such a disease with unknown etiology has been reported in certain parts of the world, especially in Africa, Central America, and Asia [4,5]. CKDu is found in the rural dry zone regions of Sri Lanka, in the North Central Province adjacent regions for more than two decades [6,7]. In the rural dry zone regions of Sri Lanka, groundwater is the primary source of water for both drinking and cooking, and CKDu is considered to be related to poor groundwater quality [10,11,12]
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