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Hydro-geochemistry of drinking water was characterized in chronic kidney disease of unknown etiology (CKDu) endemic areas in Girandurukotte (GK) and Dehiattakandiya (DH) and non-endemic areas in GK, DH, and Sewanagala (SW) in Sri Lanka to comprehend any potential risk factors for CKDu. Groundwater (n = 142) and surface water (n = 08) were sampled during wet and dry seasons and analyzed for major anions, cations and stable isotopes of hydrogen and oxygen (δ 2 H and δ 18 O). Besides the typical water quality analysis, the water quality status was determined using the weighted arithmetic water quality index (WQI) and Hofmeister ion exposure levels. The measured average groundwater F - level was higher than the permissible level assigned by regulatory agencies for tropical countries at CKDu locations in GK, DH and non-CKDu locations in DH and SW. Significant differences in the content of total hardness (p = 0.017) and total dissolved solids (p = 0.003) were observed between CKDu and non-CKDu locations whereas the differences were insignificant for F - (p = 0.985) and alkalinity (p = 0.203). Weathering of silicate and carbonate minerals was found to be the main governing factor of groundwater compositions in both CKDu and non-CKDu areas, while recharging of groundwater is mainly determined by the rainfall than the surface water inputs. Higher ionic strength of groundwater in non-CKDu areas suggested that the potential environmental CKDu risk factors might be suppressed from dissolution into groundwater. The WQI calculations revealed that the both CKDu and non-CKDu locations were frequently presented with poor water quality. This study highlights the water quality status of the CKDu and non-CKDu locations and signifies the potential health risks that could arise even in non-CKDu areas due to the consumption of poor quality water. Accordingly, regular monitoring of water quality and assessment of Hofmeister ions exposure from food and beverages are highly warranted., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Meththika Vithanage reports financial support was provided by National Science Foundation, Sri Lanka and the Natural Science Foundation of China., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Environmental exposure to trace elements has been widely suspected as an etiological factor for the emergence of chronic kidney disease of undetermined origin (CKDu) that prevails in certain districts of the dry zone areas of Sri Lanka. Contaminated rice can be act as a host for potentially toxic trace elements that ultimately led to health hazards; thus, rice soils were investigated in detail, giving particular attentions to identified CKDu hotspots. A total of 102 rice soil samples were collected from main climatic zones viz. wet and dry zones including CKDu hotspots. In addition to pH, electrical conductivity and cation exchange capacity, acid extracted major and trace element contents in rice soils were determined by using ICP-MS. Significant differences were observed for Mn, Ni, Cu, Zn, and Pb contents between climatic zones. Arsenic and Pb contents in soils were lower than the levels reported in soils from other regions of the world, though significantly higher contents were observed in CKDu regions compared to non-endemic wet zone regions. Calculation of enrichment factor revealed that soils in both dry and wet zones were moderately enriched with As, Cd, and Pb, suggesting an influence of anthropogenic processes. Twenty percent of the wet zone samples showed significant enrichment of Ni, Cu, and Zn. Geo-accumulation index assorted that the studied soil samples were uncontaminated to moderately contaminated, implying that rice soils in both climatic zones are not alarmingly contaminated with toxic trace elements. However, regular and continuous monitoring of rice soil quality is extremely important., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Fluoride is a beneficial trace element for human health as its deficiency and excess levels can cause detrimental health effects. In Sri Lanka, dry zone regions can have excessive levels of fluoride in drinking water and can cause dental and skeletal fluorosis. In addition to drinking water, traditional habits of tea consumption can cause an additional intake of fluoride in the population. A total number of 39 locally blended black tea samples were collected from a village where chronic kidney disease with undetermined origin (CKDu) is prevalent. In addition, unblended tea samples were obtained from tea-producing factories. The fluoride contents in infusions of 2% weight per volume (w/v) were measured using calibrated ion-selective fluoride electrodes. The mean fluoride content was 2.68±1.03 mg/L in loose tea, 1.87±0.57mg/L in packed tea samples, and 1.14±0.55 mg/L in unblended tea. Repeated brewing of the same tea leaves showed that over 50% of fluoride leached into the solution in the first infusion. An estimate of the daily total average fluoride intake via tea consumption per person is 2.68 mg per day. With groundwater in many dry zone regions in Sri Lanka showing high fluoride levels that exceed 0.5 mg/L, the additional daily intake can rapidly exceed recommended thresholds of 2 mg/day. This can add to adverse health impacts that might also relate to CKDu., (© 2021. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Information on the geographic origin of milk is important in determining quality attributes and for economic gain through building brand value associated with origin. Stable isotope signatures and trace element concentrations have been increasingly used in authentication of milk, though information on the power of such technology in verifying agroclimatic origin in small continents with diverse climatic, environmental conditions, and animal management practice is scarce. Therefore, the main objective of this study was to investigate the possibility of using a stable isotope composition of C, N, O, and H and element fingerprints to determine the agroclimatic origin of milk produced in different agroclimatic zones of Sri Lanka. Stable isotopes ratios of C, N, H, and O, and elemental fingerprints of milk samples were determined by IRMS and ICP-MS, respectively. Significant variations were observed in stable isotope ratios, especially δ 18 O and the mean content of Li, Al, Cr, Mn, and Sr in the bulk milk samples obtained from different agroclimatic zones. A linear discriminant analysis differentiated cow milk produced from four agroclimatic zones based on stable isotope ratios, and the inclusion of elemental ratios enhanced the discriminating ability.

The epidemic of chronic kidney disease of unknown etiology (CKDu) that contributes significantly to morbidity and mortality rates among dry-zonal farming communities has become a public health priority in Sri Lanka. Though a large number of hypotheses were introduced as causative factors, none of them have been confirmed so far. As drinking water quality is among the most suspected causative factors for the emergence of CKDu, a detailed hydro-geochemical investigation was carried out concurrently with the population screening in the Monaragala district of Sri Lanka where high incidences of CKDu are reported. A population screening was performed selecting 46,754 people using both dipstick proteinuria test and Albumin-Creatinine Ratio (ACR). The results revealed that the disease prevalence is about 6.7 % in the district. A total of 60 groundwater samples, 30 each, were collected from CKDu-prevalent locations and control locations where there are no CKDu cases reported. The samples were analyzed to identify any possible linkage between water quality and disease prevalence. Concentrations of hardness, F - , Na +, and Mg 2+ in groundwater revealed a statistically significant difference between CKDu and control wells at a confident level of p = 0.05. The study revealed that alkali (Na + +K + ) and alkaline earth cations (Mg 2+ , Ca 2+ , Sr 2+ , Ba 2+ ) were relatively higher in drinking water sources used by CKDu patients, compared to the well waters used by healthy individuals. Nearly 87 % of the wells used by CKDu cases showed higher fluoride levels that exceed the threshold level (1.0 mg L -1 ). Contents of nephrotoxic trace elements such as As, Cd, and Pb were found to be comparable in both types of wells and were well below the WHO permissible levels, thus negating their prime influence on the CKDu prevalence. It is obtrusive that the elevated fluoride levels together with water hardness associated with higher Mg 2+ levels have a possible relation with CKDu and may influence the disease progression., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Antimony (Sb) is introduced into soils, sediments, and aquatic environments from various sources such as weathering of sulfide ores, leaching of mining wastes, and anthropogenic activities. High Sb concentrations are toxic to ecosystems and potentially to public health via the accumulation in food chain. Although Sb is poisonous and carcinogenic to humans, the exact mechanisms causing toxicity still remain unclear. Most studies concerning the remediation of soils and aquatic environments contaminated with Sb have evaluated various amendments that reduce Sb bioavailability and toxicity. However, there is no comprehensive review on the biogeochemistry and transformation of Sb related to its remediation. Therefore, the present review summarizes: (1) the sources of Sb and its geochemical distribution and speciation in soils and aquatic environments, (2) the biogeochemical processes that govern Sb mobilization, bioavailability, toxicity in soils and aquatic environments, and possible threats to human and ecosystem health, and (3) the approaches used to remediate Sb-contaminated soils and water and mitigate potential environmental and health risks. Knowledge gaps and future research needs also are discussed. The review presents up-to-date knowledge about the fate of Sb in soils and aquatic environments and contributes to an important insight into the environmental hazards of Sb. The findings from the review should help to develop innovative and appropriate technologies for controlling Sb bioavailability and toxicity and sustainably managing Sb-polluted soils and water, subsequently minimizing its environmental and human health risks., (Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Fresh milk is an important source of essential mineral supplement for humans. However, the levels of trace elements in milk are an important component of its safety and quality. Trace elements also act as a bio-indicator of agricultural pollution. Samples of raw cow milk (n = 68), animal feed [forage (n = 36) and concentrates (n = 14)], and water (n = 35) were collected from different agro-climatic regions of Sri Lanka. The concentrations of 15 trace elements including toxic heavy metals such as Cd, Pb, and As were quantified using inductively coupled plasma mass spectrometry after microwave-assisted digestion. Among the studied trace elements, the mean elemental concentrations of Se, Cd, As, and Cu in cow milk were 18.1, 1.45, 7.35, and 71.7 μg L -1 , respectively. The mean concentrations of these elements in forage were 0.216, 0.066, 0.046, and 9.21 mg kg -1 , and in concentrate feed were 0.329, 0.202, 0.229, and 2.28 mg kg -1 , respectively. The As content of the studied milk was well below the maximum permissible level while 15% of the samples had Pb exceeding the permissible limit of 20 μg L -1 . However, As, Cd, and Pb levels in drinking water provided to animals were well below the WHO permissible limits. The results of this study revealed that the trace elements in cow milk depend mainly on the feed, and hence, levels of these contaminants in feed materials should be monitored. Although due to the consumption of milk, the populations have a minor exposure to trace elements and also minimum health risks, a detailed study with a large number of samples is highly recommended.

Fluoride is a common anion present in natural waters. Among many analytical methods used for the quantification of fluoride in natural waters, potentiometric analysis is one of the most widely used methods because of minimum interferences from other ions commonly present in natural waters. The potentiometric analysis requires the use of ionic strength adjusting buffer abbreviated as TISAB to obtain accurate and reproducible data. In most of the reported literature, higher concentrations of strong metal chelating ligands are used as masking agents generally in the concentration range of 1.0 to 0.01 M. In the present study, effectiveness of the masking agents, phosphate, citrate, CDTA ((1,2-cyclohexylenedinitrilo)tetraacetic acid), EDTA (ethylenediaminetetraacetic acid) HE-EDTA ((hydroxyethyl)ethylenediaminetriacetic acid)), triethanolamine, and tartaric acid at 1.0 mM in TISAB solutions was investigated. The experimental data were compared with a commercially available WTW 140100 TISAB solution as the reference buffer. According to the experimental data, the reference buffer always produced the highest fluoride concentrations and the measured fluoride concentrations were in the range of 0.611 to 1.956 mg/L. Out of all the masking agents investigated, only CDTA performed marginally well and approximately a quarter of the samples produced statistically comparable data to the reference buffer. All the other masking agents produced significantly low concentrations compared to the reference buffer. The most probable reasons for the underestimation of fluoride concentrations could be shorter decomplexing time and lower masking agent concentrations., Competing Interests: The authors declare that they have no conflicts of interest., (Copyright © 2020 Sakuni M. De Silva et al.)

Water supplies in coastal aquifers throughout the world are often threatened by salinization due to seawater intrusion and anthropogenic activities. In the Kalpitiya Peninsula in Sri Lanka, agricultural and domestic water supplies entirely depend on groundwater resources extracted from unconfined Holocene sandy aquifers. To differentiate the effects of seawater intrusion and agriculture on the coastal aquifers of this 160 km 2 peninsula, 43 groundwater samples were collected. These samples were analyzed for major ions, trace elements, and stable isotopes of water (δ 18 O and δ 2 H). The solute compositions were dominated by Cl - , [Formula: see text], and [Formula: see text], which were mostly balanced by Ca 2+ , Na + , and Mg 2+ . Among the four main water types, Na + -Cl - and Ca 2+ -[Formula: see text] classifications were predominant in the investigated aquifers. Modifications of the groundwater due to evaporation during irrigation activities, but also due to seawater intrusion seem most plausible as indicated by the correlation of δ 18 O with δ 2 H (δ 2 H = 5.51 * δ 18 O-3.08, r = 0.93) deviating from the local meteoric water line. Particularly in the southern part of the peninsula, Mg 2+ /Ca 2+ ratios and stable isotopes of water attributed salinization of groundwater to agricultural activities. However, especially in the north, seawater intrusions were also evident. Established mass balance calculations revealed that local groundwater had seawater admixtures of up to 12%. Our results indicate that integrated water management is essential and water resources should critically monitor in the Kalpitiya Peninsula in order to avoid over-exploitation and further seawater inflows.

Glutathione Peroxidase activity in whole blood is well correlated with the Selenium (Se) levels in cattle hence can be used effectively to assess the supply of Se to farm animals. In this study, Se status of cattle from five different geographic regions of Sri Lanka were assessed based on glutathione peroxidase (GSH-Px) activity. The GSH-Px activity was determined in whole blood samples collected from 80 cattle from 31 different farms in five districts viz. Kandy, Anuradhapura, Batticoloa, Trincomalee and Jaffna using photometric method. Mean GSH-Px activity was found to be 825, 1239, 1039, 849 and 1307 μkat L -1 in above districts, respectively while the reference value was considered as 665.4 μkat L -1 . Among the studied animals, insufficient Se levels were detected in 50%, 17%, 9%, 27% and 5%, respectively, from above districts. Kruskal Wallis test indicated a significant variation among the sampled locations with respect to the GSH-Px activity (p = 0.001). Selenium content in pasture and water collected from studied locations varied from 6.0 to 554 μg kg -1 and < 0.03-1.14 μg L -1 , respectively. The lower Se levels in feeds recorded from Kandy region infer the lower GSH-Px activity in the animals from the same region. This variability may be due to differences in nutrient supply, age and species of cattle, and lactation stage. Although the assessing method has some limitations, the activity of GSH-Px of the samples indirectly confirms that considerable numbers of cattle from Sri Lanka are with insufficient selenium levels.

Major ion, trace elements, and stable isotope analyses were performed on groundwater samples collected from Mannar Island in the northern Indian Ocean. Arsenic concentrations up to 34μg/L have been observed in groundwater samples from the island. In addition, 23% of extensively used shallow drinking water wells showed higher arsenic contents than the recommended value by the World Health Organization (10μg/L). Groundwater in the island showed pH values between 6.9 and 8.9 and was dominated by Na + , K + , Ca 2+ , Mg 2+ , HCO 3 - , Cl - and SO 4 2- . The δ 18 O H2O and δ 2 H H2O composition of most groundwater plotted very close to the local meteoric waterline, however, some wells showed enriched isotope compositions that are most likely due to evaporation. Sea water intrusion in this island was likely of minor importance as indicated by the major ion composition. An approximated mass balance calculation using chloride concentrations indicated that out of the 35 investigated wells only 6 near-shore wells were influenced by sea water intrusion up to about 15%. Even though this is a sandy aquifer, groundwaters were characterized with higher contents of dissolved inorganic carbon (DIC) (2.11-10.9mmol/L). The corresponding δ 13 C DIC values varied from -19.4‰ to -6.5‰. Except for a few samples with values approaching -20‰, these isotope values are more typical for carbonate dissolution and equilibration of CO 2 in the aquifer. This study shows that the underlying carbonate system may buffer the aqueous geochemistry of the groundwater on the island. The high arsenic content in groundwater may have been mobilized through reductive dissolution of Fe-Mn oxides and oxy-hydroxides that are coated on sandy aquifer materials. The lower content of DOC (0.2-1.5mmol/L) provides evidence for the restricted formation of pyrite in the aquifer., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Chronic kidney disease of unknown aetiologies (CKDu) is increasingly recognized in tropical regions and is now considered a global health problem. A detailed hydrogeochemical investigation has been performed in three CKDu hotspots in Sri Lanka to assess the geo-environmental aetiological factors influencing this disease. A total of 71 ground- and 26 surface water samples were collected from Girandurukotte, Wilgamuwa and Nikawewa regions and analysed for major constituents and trace elements. The affected regions are dominated by Ca-Mg-HCO 3 facies groundwater that is mainly controlled by silicate weathering. Higher levels of fluoride associated with higher hardness is the main feature of groundwater from CKDu regions compared to non-CKDu regions. Results showed that 65% of the wells in the affected regions exceeded the fluoride concentration of 0.5mg/L. Environmental isotopes of groundwater in the CKDu regions are represented by the regression line of δ 2 H=5.42δ 18 O-3.59 (r 2 =0.916) with a clear isotopic differentiation between local precipitation and groundwater. None of the trace elements exceeded the recommended scales and in most cases levels are negligible in both surface and groundwater in study areas. Therefore, the involvement of trace elements such as Cd, As and Pb can be ignored as causative factors for CKDu. This study highlights the synergistic influence of fluoride and hardness that could enhance the disease, and thereby refute earlier theories that attribute trace elements as causative factors for CKDu. Higher hardness in drinking water also restricts sufficient water uptake, particularly by farmers and which affects the physiological, biochemical and nutritional requirements., (Copyright © 2017 Elsevier GmbH. All rights reserved.)

An alarming increase in chronic kidney disease with unknown etiology (CKDu) has recently been reported in several provinces in Sri Lanka and chronic exposures to toxic trace elements were blamed for the etiology of this disease. Keratinized matrices such as hair and nails were investigated to determine the possible link between CKDu and toxic element exposures. Elements Li, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba, Hg and Pb of hair and nails of patients and age that matched healthy controls were determined with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that trace element contents in the hair of patients varies in the order of Zn>Fe>Al>Mn>Cu>Ba>Sr>Ni>Pb>Cr>B>Hg>Se>Mo>Co>As>Li>Cd while Fe>Al>Zn>Ni>Cu>Mn>Cr>Ba>Sr>B>Pb>Se>Mo>Co>Hg>Li>As>Cd in nail samples. The hair As levels of 0.007-0.165μgg -1 were found in CKDu subjects. However, no significant difference was observed between cases and controls. The total Se content in hair of CKDu subjects ranged from 0.043 to 0.513μgg -1 while it was varied from 0.031 to 1.15μgg -1 in controls. Selenium in nail samples varied from 0.037μgg -1 to 4.10μgg -1 in CKDu subjects and from 0.042μgg -1 to 2.19μgg -1 in controls. This study implies that substantial proportions of Sri Lankan population are Se deficient irrespective of gender, age and occupational exposure. Although some cutaneous manifestations were observed in patient subjects, chemical analyses of hair and nails indicated that patients were not exposed to toxic levels of arsenic or the other studied toxic elements. Therefore the early suggested causative factors such as exposure to environmental As and Cd, can be ruled out., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Background: Samples of 226 new improved and 21 indigenous rice ( Oryza sativa L.) varieties were collected from the rice fields in three climatic zones of Sri Lanka and concentrations of 18 trace elements (Li, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba, Pb and Bi) were measured giving particular emphasis on Se, Cd and As using ICP-MS. The two way multivariate analysis of variance (MANOVA) method was employed to identify the differences in composition among rice from different climatic zones., Results: The mean values obtained for both white and red rice were Se (36; 25 µg/kg), As (42; 45 µg/kg) and Cd (70; 123 µg/kg) on dry weight basis. However mean content of Se, As and Cd of native rice varieties were 69, 74 and 33 µg/kg, respectively. Statistical interpretations showed that in the majority of cases, there was a significant difference in Cd content among climatic zones whereas Se and Pb show differences between white and red rice varieties. Arsenic did not indicate any significant difference either between rice types or among climatic regions. Notably Se and As contents in indigenous rice were higher than that of improved rice types. To assess the safety of dietary of intake, daily intake of Se, Cd and As by rice were calculated. Non-gender specific Estimated Daily Intake (EDI) of Se, Cd and As consuming improved rice are 9.31, 24.1 and 12.2 µg day -1 , respectively., Conclusions: Since over 50 % of daily meals of people contain rice or rice based products, Se intake is expected to be deficient among the Sri Lankan population.

The Mahaweli is the largest river basin in Sri Lanka that provides water to the dry zone region through multipurpose irrigation schemes . Selenium, arsenic, cadmium, and other bioimportant trace elements in surface waters of the upper Mahaweli River were measured using ICP-MS. Trace element levels were then compared with water from two other rivers (Maha Oya, Kalu Ganga) and from six dry zone irrigation reservoirs. Results showed that the trace metal concentrations in the Mahaweli upper catchment were detected in the order of Fe > Cu > Zn > Se > Cr > Mn > As > Ni > Co > Mo. Remarkably high levels of Ca, Cr, Co, Ni, Cu, As, and Se were observed in the Mahaweli Basin compared to other study rivers. Considerably high levels of Cr, Mn, Fe, Co, Ni, Cu, Zn, As, and Se were found in upstream tributaries of the Mahaweli River. Such metals possibly originated from phosphate and organic fertilizers that are heavily applied for tea and vegetable cultivations within the drainage basin. Cadmium that is often attributed to the etiology of unknown chronic kidney diseases in certain parts of the dry zone is much lower than previously reported levels. Decrease in these metals in the lower part of the Mahaweli River could be due to adsorption of trace metals onto sediment and consequent deposition in reservoirs.

Groundwater in Miocene karstic aquifers in the Jaffna Peninsula of Sri Lanka is an important resource since no other fresh water sources are available in the region. The subsurface is characterized by highly productive limestone aquifers that are used for drinking and agriculture purposes. A comprehensive hydrogeochemical study was carried out to reveal the processes affecting the groundwater quality in this region. Major and trace element composition and environmental isotope ratios of oxygen and hydrogen (δ(18)OH2O and δ(2)HH2O) were determined in 35 groundwater samples for this investigation. The ion abundance of groundwater in the region was characterized by an anion sequence order with HCO3->Cl->SO4->NO3-. For cations, average Na(+)+K(+) contents in groundwater exceeded those of Ca(2+)+Mg(2+) in most cases. Ionic relationships of major solutes indicated open system calcite dissolution while seawater intrusions are also evident but only close to the coast. The solute contents are enriched by agricultural irrigation returns and associated evaporation. This was confirmed by the stable isotope composition of groundwater that deviated from the local meteoric water line (LMWL) and formed its own regression line denoted as the local evaporation line (LEL). The latter can be described by δ(2)HH2O=5.8×δ(18)OH2O -- 2.9. Increased contents of nitrate-N (up to 5mg/L), sulfate (up to 430mg/L) and fluoride (up to 1.5mg/L) provided evidences for anthropogenic inputs of solutes, most likely from agriculture activities. Among trace elements Ba, Sr, As and Se levels in the Jaffna groundwater were higher compared to that of the dry zone metamorphic aquifers in Sri Lanka. Solute geochemistry and stable isotope evidences from the region indicates that groundwater in the area is mainly derived from local modern precipitation but modified heavily by progressive evaporative concentration rather than seawater intrusion., (Copyright © 2016 Elsevier B.V. All rights reserved.)