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This study investigated spatial patterns of chronic kidney disease of unknown aetiology (CKDu) patients in Badulupura village. The analysis utilized published locational data for all households, including households affected by CKDu, and all wells used by CKDu-affected patients (CPA wells). The study employed Average Nearest Neighbour (ANN) and Hot Spot Analysis (Getis-Ord Gi*) tools to assess the spatial clustering of CKDu households and CPA wells. The study also explored the impact of topographical factors such as elevation, slope, and distance to watershed boundaries on the spatial distribution of CKDu patients. The ANN analysis revealed a dispersed pattern for all wells, and a random distribution for all households. However, both CKDu households and CPI wells exhibited a clustered pattern, suggesting a location-specific cause for the spatial distribution of the disease. Additionally, overlaying CKDuaffected households on the digital elevation model revealed a concentration of CKDu hot spots in high-elevation areas, while cold spots were observed in low-elevation regions. Furthermore, the t-test was employed to investigate the significance of elevation, slope, and distance to the watershed boundaries in relation to CKDu distribution. The results indicated a significant (p<0.05) prevalence of CKDu in high-elevation areas, while no significant association was found with slope or distance to watershed boundaries. The study revealed the presence of localized CKDu hot spots and cold spots within a small geographical area, highlighting the importance of considering topographical factors and conducting comprehensive hydrogeological and geological studies to gain valuable insights into the spatial distribution of CKDu. [ABSTRACT FROM AUTHOR]

The Eppawala area in Sri Lanka has an agriculturalbased economy. As a result, the recent agricultural intensification could increase the risk of heavy metal contamination in lakes in the area as the main water canal in the area, i.e., Jaya Ganga, flows across these lakes. Therefore, this study focuses on the risk assessment of heavy metals in the freshwater lake sediments in the Eppawala area and the identification of potential sources for heavy metal contamination in the lakes. Nine heavy metals (Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) were investigated in surface sediments (n = 22) of the upstream and downstream lakes of the Eppawala Phosphate Deposit (EPD). The average heavy metal concentrations in the upstream lake sediments were higher than those downstream. Eppawala lake sediments were heavily polluted by As along with moderate to high Cr pollution. However, only As and Cd indicated considerable to moderate ecological risk levels to the local environment. The downstream lake sediments showed lower heavy metal contents compared to those upstream and had negative correlations between heavy metals and P2O5 contents. This reveals that the EPD does not contribute to the heavy metal contamination in the Eppawala lake sediments. However, the statistical analysis showed that heavy metals were mostly derived from similar pollution sources. Agrochemicals used in paddy cultivation in the vicinity might be a potential source of heavy metals. This study highlights the importance of implementing remediation to control the heavy metal pollution prevailing in the Eppawala lakes. [ABSTRACT FROM AUTHOR]

Freshwater salinisation is a growing problem worldwide, affecting surface and groundwater resources. Compared with other global environmental issues, freshwater salinisation has been studied extensively in North America, Australia, and Europe but less so in South America, Asia, and Africa. Both the natural and anthropogenic sources can contribute for freshwater salinisation, through the concentration of dissolved salts in water rising above its normal levels. This review provides a comprehensive assessment of the causes of freshwater salinisation, the impacts on freshwater communities and ecosystem functions, the adaptive mechanisms for survival in an increasingly saline environment, and the management strategies available to control freshwater salinisation. Many human activities contribute to freshwater salinisation, including road salt use, agricultural practices, resource extraction, reservoir construction, and climate change. Aquatic organisms have evolved mechanisms to survive in increasingly saline environments, but excessive salinity can lead to mortality and non-lethal effects. Such effects can have cascading impacts on the structure and function of aquatic communities and ecosystem services. Therefore, monitoring programmes and chemical fingerprinting are needed to identify highly salinised areas, determine how various human activities contribute to freshwater salinisation, and implement management strategies. Furthermore, current research on freshwater salinisation has been limited to a few regions of the world. It is essential to expand the research further into exploring the impacts of salinisation on freshwater resources in unexplored geographic areas of the world that are mainly impacted by climate change scenarios., Competing Interests: Declarations Ethical approval All authors have read, understood, and have complied as applicable with the statement on “Ethical responsibilities of Authors” as found in the Instructions for Authors. Consent to participate and publish All authors who contributed to the manuscript read and approved the final version of the manuscript. Competing interests The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Chronic kidney disease of unknown origin (CKDu) has emerged as a serious health risk for farming communities in remote semi-arid lowland regions of Sri Lanka, with geoenvironmental factors widely believed to be associated with the etiology. Although numerous case-control studies have been carried out to determine the causes of CKDu, none have been conducted in at-risk communities. The main objective of this study is to identify the potential geo-environmental risk factors associated with the at-risk community in the Wilgamuwa region, a CKDu endemic area in Sri Lanka. The study collected and analyzed 92 water sources currently or previously used in the study area for major cations, anions, and trace elements, mainly As, Cd, Pd, Mn, Zn, Ba and Sr. The major cations and anions in CKDu-susceptible groundwater varied Si 4+  > Ca 2+  > Na +  > Mg 2+  > K + and HCO 3 -  > Cl -  > SO 4 2-  > NO 3 -  > F -  > PO 4 3-  > Br - . The higher average values of Si 4+ , F - and total hardness (TH) were reported in groundwater consumed by communities at risk of CKDu, with average values (in mg/L) of Si 4+ -46, F - -0.62, and TH-178. Considering the Water Quality Index (WQI) values, 73% of groundwater sources are classified as poor water quality, and the groundwater quality mainly depends on the fluoride distribution in the region. According to the Hazard Quotient (HQ), the risk of adverse health effects from exposure to F - and SiO 2 increased in magnitude in the order of male < female < children. Health hazards due to As, Cd and Pb exposure fell between the 'no-risk' and 'low-risk' categories. As outlined in this study, continuous monitoring of vulnerable communities for environmental exposures to key groundwater constituents is important in the dry zone of Sri Lanka., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

The understanding of global carbon has rarely extended to small-scale tropical river basins. To address these uncertainties, this study aims to investigate the importance of rock weathering and organic matter turnover in the carbon cycle in a terrain dominated by crystalline silicate rocks. The geochemical composition of the dissolved and particulate carbon phases (DIC, DOC and POC) and their stable carbon isotopes were studied in the Deduru Oya River in Sri Lanka. Dissolved inorganic carbon (DIC) was the most dominant carbon phase and its contribution to the total carbon pool varied between 67 and 89 %. Furthermore, the δ 13 C DIC values in the river varied between -1.1 and -16.5 ‰. The lithological characteristics and molar ratios between Ca 2+ , Mg 2+ and HCO 3 - indicated rock weathering mainly by CO 2 and carbonic acid. The δ 13 C DIC values for groundwater input were -15.9 ‰, while for carbonate weathering, mainly due to fertiliser input, they reached a value of -12.7 ‰. This input was fed into an isotope mass balance to determine the relative contributions. However, the isotope mass balance was only plausible after correcting for the effects on δ 13 C DIC caused by degassing and photosynthesis. Our study demonstrated that carbonate weathering and organic matter turnover are essential components of the river carbon cycle even in a silicate dominated catchment. They can represent up to 60 % of the DIC pool. Combined with the higher organic matter turnover and high pCO 2 in the river water, it can be suggested that the Deduru Oya River acts as a net source of CO 2 in the atmosphere. Our study shows that CO 2 degassing and in-stream photosynthesis in tropical river systems need to be considered along with chemical weathering to account for carbon transport and turnover in tropical rivers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)