Search

Geogenic contamination of Arsenic (As) poses major health threat to people living in Indus Plain of Pakistan particularly in Punjab. In this paper, we described in detail the hydrogeochemistry of As contaminated groundwaters in selected sites from Lahore, Kasur and Okara districts and its associated potential health risks. Sampling was done in 2019 and 141 groundwater samples were collected. High variability in As concentrations was observed varying between below detection level (3− and Fe-reduction in groundwaters was also seen. Furthermore, higher potential health risks were found to be associated with elevated As levels in terms of estimated average daily dosage (EDI), hazard quotient (HQ) and carcinogenic risk assessment (CR). The average values for HQ for adults, teenagers and children were found to be 9.06, 13.6 and 13.07, respectively. Meanwhile average CR values were found to be 0.004, 0.01, 0.006 mg/Kg/day in adults, teenagers and children respectively. These results suggest an increased risk of adverse health impacts in current study sites and require effective remedial measures at urgent basis.

Irrigating rice with groundwater can lead to As accumulation in soil and rice grains. Matched sets of irrigation water, paddy soil, and rice grains were collected to assess the scale of the problem in the Punjab plains of Pakistan. From a total of 60 sites, irrigation water and rice grains as well as 103 soil samples were collected and analyzed in the laboratory. Irrigation water and 660 soil samples were also analyzed in the field using a field kit. Concentrations of As in irrigation water (65 + 32 μg/L) are higher in the floodplain of the Ravi River compared to the Chenab (13 + 9 μg/L) and Jhelum (4 + 5 μg/L) rivers, as well as the intervening Rechna (6 + 6 μg/L) and Chaj doabs (0.8 + 0.2 μg/L). Area-weighted mean soil As concentrations are 12 + 3 mg/kg along the Ravi, 8.9 + 2 and 8.1 + 2 mg/kg along the Chenab and Jhelum, respectively, and 6.2 + 0.2 mg/kg and 6.1 + 0.1 mg/kg, respectively, within the Rechana and Chaj doabs. The As content of polished grains export-quality basmati rice of 0.09 + 0.05 mg/kg, however, is low across the entire area. Groundwater irrigation leads to elevated As concentrations in paddy soil of some rice-growing regions of Punjab but does not result in increased uptake of As in basmati rice grains.

Arsenic (As), and fluoride (F−) are potent contaminants with established carcinogenic and non-carcinogenic impacts on the exposed populations globally. Despite elevated groundwater As and F− levels being reported from various regions of Pakistan no biomonitoring study has been reported yet to address the co-exposure impact of As and F− among school children. We aimed to investigate the effects of these two contaminants on dental fluorosis and intelligence quotient (IQ) along with the induction of oxidative stress in rural children under co-exposed conditions. A total of 148 children (5 to 16 years old) from the exposed and control group were recruited in the current study from endemic rural areas of Lahore and Kasur districts, Pakistan having elevated As and F− levels in drinking water than permissible limits. We monitored malondialdehyde and its probable association with antioxidants activity (SOD, CAT, and GR) as a biomarker of oxidative stress. GSTM1/T1 polymorphisms were measured to find the impact of As on health parameters. Mean urinary concentrations of As (2.70 vs. 0.016 µg/L, P

The present study aimed at exploring the sources of salinity and the link it shares with the enrichment of As (arsenic) and F- (fluoride) in the groundwater of Rachna Doab. Total Dissolved Solids (TDS) were used as the measure of salinity to classify samples into three groups: TDS1000 mg/L (freshwater), 1000-3000 mg/L (slightly saline) and 3000-10,000 mg/L (moderately saline). The stable isotope analysis (δ

In this study, we tested 123 groundwater wells from five different areas of Punjab, Pakistan for arsenic (As) contamination level and species, as well as delineated hydrogeochemical behaviour of As in aquifers. Results revealed that 75% and 41% of the groundwater wells exceeded the safe As limit of World Health Organisation (WHO, 10 μg L−1) and Pakistan-EPA (50 μg L−1), respectively. Arsenite (As(III)) and arsenate (As(V)) spanned 0–80% and 20–100% of total As (1.2–206 μg L−1), respectively. The mean As content (5.2 μg L−1) of shallow wells at 9–40 m depth did not exceed the WHO safe limit, representing a safe aquifer zone for pumping of groundwater compared to deeper wells at 41–90 m (51 μg L−1) and >90 m (23 μg L−1) depths. Piper-plot elucidated that the aqueous chemistry was dominated with Na-SO4, Na-Ca-SO4, Na-Mg-SO4 type saline water. Principal component analysis grouped As concentration with well depth, pH, salinity, Fe and CO3, exhibiting that these hydrogeochemical factors could have potential role in controlling As release/sequestration into the aquifers of study area. Geochemical modeling showed positive saturation indices only for iron (Fe) oxide-phases, indicating Fe oxides as the major carriers of As. Overall, this study provides insights to tackle emerging As threat to the communities in Punjab, Pakistan, as well as help develop suitable management/mitigation strategies – based on the baseline knowledge of As levels/species and factors governing As contamination in the study area.

Release of arsenic (As) and fluoride (F−) species into groundwater is a serious health concern around the world. The present study was the first systematic baseline study conducted in Rahim Yar Khan district, Punjab, focusing on As and F− contamination in groundwater. A total of 51 representative groundwater samples comprising of 44 samples from agricultural suburbs and 7 from an industrial base were analysed. Statistical parameters, principal component analysis-multiple linear regression (PCA-MLR) and health risk assessment model were used to investigate the hydro geochemistry, spatial patterns, interrelation, source contribution and associated health risks of high As and F− in groundwater of the study area. Results showed high risk of F− exposure to people of the study area, with all samples exceeding the WHO standard of 1.5 mg/L, and for As, 32.5% of the studied groundwater samples exceeded the WHO standard (10 µg/L). The maximum As (107.23 µg/L) and F− (26.4 mg/L) levels were observed in samples close to the agricultural and smelting areas, implicating the frequent use of fertilizers and influence of industrial effluents in the study area. The PCA-MLR receptor model quantitatively illustrates that the majority of As and F− comes from natural sources, while, among anthropogenic sources, industrial and agricultural activities contributed the most. Health risk assessment revealed a high risk of As and F− contamination to the exposed population; therefore, detailed control strategies and policies are required in order to mitigate the health risks.

Biogeochemical mobilization of arsenic in groundwater depends on the presence of dissolved organic matter (DOM) that likely promotes the As release, i.e., reductive dissolution, complexation, competition, and electron shuttling. We investigated the role of DOM in As release, along with its complete characterization, in the Indus plain of Pakistan, one of the worst arsenic impacted zones in the South Asian region. In total, 60 groundwater and 15 soil samples, collected at six sites from north to south within the flood plain of the Ravi River, Lahore, Pakistan were investigated. Arsenic concentration ranged from 9.61 μg/L to 386 μg/L in the groundwater samples (high As observed in areas close to the river). Dissolved organic carbon (DOC) in 29 groundwater samples ranged between 0 and 10.1 mg-C/L. A moderately positive correlation of As with DOC and Fe in the northern part of the study area suggest the reductive dissolution of FeOOH associated with dissolved organic matter (DOM). The reductive dissolution plays an essential role for As enrichment in the area evidenced by the lower concentrations of SO42−, NO3−, and PO34−and a non-correlative pattern with As. In contrast, a positive correlation of As with PO34−, DOC, and HCO3− in the southern part indicate competitive desorption behind the As release. Fluorescence excitation-emission matrix intensity data of DOM indicate the maximum presence of humic-like substances in the northern part that gradually shifts to aromatic, fulvic and protein type towards the southern part. Specific ultraviolet absorbance and fluorescence index display aromatic and terrestrial (allochthonous) sources of DOM near the riverbank and mixed (both allochthonous and autochthonous) source away from the river. The positive correlations of As with DOC and fluorescence intensity also attest that DOM played a vital role in the As mobilization in groundwater of the study area.

This article has been withdrawn at the request of the editor. The Publisher apologizes for any inconvenience this may cause.

Groundwater contamination with arsenic and fluoride has affected over 300 million people worldwide. Ingestion of arsenic and fluoride for extended period of time or at high concentration causes severe health effects. Arsenic can cause thickening and discoloration of the skin, cardiovascular disorders, cancer and skin lesions. Excessive intake of fluoride leads to dental and skeletal fluorosis and bone deformities. This report reviews the distribution of arsenic and fluoride contamination, their sources, mobilization and associated health risks. Remediation technologies to remove arsenic and fluoride are presented.

Trace metal contamination in drinking water poses severe threat to human health through long-term exposure. The present study highlighted the elevated arsenic (As) and trace metal concentrations in drinking water and associated potential health risk to local residents of Tehsil Mailsi (Punjab), Pakistan. Our results showed that concentrations of As, Cd, Fe, Cr and Pb exceeded the WHO limits in drinking water, whereas Cu, Mn, Co, Ni and Zn concentrations were below the safe limits. The calculated estimated daily intake (EDI) of metals from local drinking water had the order of Zn > As > Cu > Pb > Cd > Ni > Mn > Cr, and the consequent target hazard quotient (THQ) above 1 was observed for As and Cd, which employed high potential health risk to local residents. Spatial distribution of As and trace metals in drinking water were related to the local anthropogenic sources, due to intensive application of agrochemicals. The study area presents high potential health risk associated with As and trace metals pollution in drinking water. The local wells have never been tested for metal concentrations prior to use, and necessary processes should be taken to test the wells with respect to As and trace metals contamination.

The present study for the first time highlighted the arsenic and heavy metals (HM) concentrations as well as their source of contamination in tube-well water and associated potential health risk to local residents of Tehsil Mailsi (Punjab), Pakistan. 44 samples were collected from Jala Jeem and Dunia Pur. Results revealed average concentrations of anion and heavy metals such as Iron (Fe), (Cadmium) Cd, (Lead) Pb, (Sodium) Na+, (Bicarbonate) HCO3−, (Sulfate) SO42− and Arsenic (As) exceeded the WHO limits in the tube well water. The calculated target hazard quotient (THQ) of metals from local tube well water above 1 was observed for As (36.5) and Cd (6.2), which employed highly potential health risk to local residents. The suitability of water for irrigation is evaluated based on residual sodium carbonate (RSC), sodium adsorption ratio (SAR), Kelly’s index (KI), Sodium percent (%Na) and Magnesium absorption ratio (MAR). Dominant ions in the study area are HCO3−, Ca2+ and Mg2+ and water chemistry of the area is Ca2+-Mg2+-HCO3− type. However, different statistical tools, including principal component analysis (PCA), hierarchical cluster analysis (CA) and correlation matrices revealed the contribution of both natural as well as anthropogenic activities towards the high level of arsenic and heavy metals contamination in the local tube well water. The results show that consumption of heavy metals contaminated groundwater poses an emerging health threat to the populations in the study area, and hence needs urgent remedial and management measures. Continued monitoring of heavy metals levels is recommended for future management strategies.

In the present study, the tube well water quality and the associated health risks, emphasizing on arsenic contamination, were investigated in rural and urban samples from Tehsil Mailsi located in Punjab, Pakistan. Arsenic concentrations (μg/L) were ranged from 12 to 448.5 and which exceeded the WHO recommended limit (10 μg/L) in all cases. The calculated average daily dose (3.3 × 10−0.4 to 1.2 × 10−0.2 mg/kg day) and hazard quotient (1.1–40) reflected the potential health risk to local population due to tube well water consumption as drinking purpose. Sodium percent (Na%), sodium absorption ratio, residual sodium carbonate, Kelly’s index and magnesium absorption ratio were also determined to assess the suitability of tube well water for irrigation purpose. The resulting piper plot revealed the Na–Ca–HCO3 type water chemistry of the area and generally alkaline environment. The spatial distribution of arsenic in the tube well waters pinpoints the significant contribution of anthropogenic activities to arsenic pollution. Nevertheless, different statistical tools, including principal component analysis, hierarchical cluster analysis and correlation matrices, revealed the contribution of both natural and anthropogenic activities and alkaline type of aquifers toward the high level of arsenic contamination.

The present study aimed at exploring the sources of salinity and the link it shares with the enrichment of As (arsenic) and F- (fluoride) in the groundwater of Rachna Doab. Total Dissolved Solids (TDS) were used as the measure of salinity to classify samples into three groups: TDS

Present study aimed to provide a baseline data on arsenic (As) and other potentially toxic element (PTEs; Cd, Cr, Cu, Ni, and Pb) contamination in groundwater and soils (surface and sub-surface) from an industrial area of district Gujrat, Pakistan. Statistical parameters, principal component analysis-multiple linear regression (PCA-MLR), and health risk assessment model were used to elaborate the interrelations, source contributor, and associated health risks. This study revealed that the concentrations of Cd, Cr, Cu, and Pb in drinking water were within the permissible limits of the World Health Organization (WHO). However, As and Ni concentrations exceeded the WHO limits of 10 μg/L for As and 0.07 mg/L for Ni. In soils, the concentration of Cr was within permissible limits, whereas As, Cd, Cu, Ni, and Pb exceeded the prescribed values. Solid waste and industrial effluents from the area also contained high levels of As, Cd, Cr, Cu, Ni, and Pb. Calculated health index of As and other PTEs for industrial site and control area was less than 1 which indicated that the groundwater was assumed to be safe for drinking. High contamination of As (15 mg/kg) and other PTEs (Pb was 978, Cr 51, Cu 111, Cd 68, and Ni was 90 mg/kg, respectively) in upper soil could be due to the discharge of industrial effluent prior to the treatment, which signifies the industrial contribution towards As and heavy metal contamination. It can be concluded that critical examination of soil profile affinity to the respective, industrial waste pollutants can reduce the health risks to the local community. This trend not only reveals the geochemistry of the area but also useful for developing a link to access health risk and associated remediation processes.

Most of the rural population of 90 million in Punjab province in Pakistan and Punjab state in India drinks, and cooks with, untreated water drawn from shallow wells. Limited laboratory testing has shown that groundwater in the region can contain toxic levels of arsenic. To refine this assessment, a total of 30,567 wells from 383 villages were tested with a field kit in northern Punjab province of Pakistan and western Punjab state of India. A subset of 431 samples also tested in the laboratory show that 85% of wells were correctly classified by the kit relative to the World Health Organization guideline of 10 μg/L for arsenic in drinking water. The kit data show that 23% of the tested wells did not meet the WHO guideline for arsenic but also that 87% of households with a well high in arsenic live within 100 m of a well that meets the WHO guideline. The implication is that many households could rapidly lower their exposure if the subset of safe wells could be shared. In a follow-up conducted one year later in five villages where 59% of wells were elevated in arsenic, two-thirds of households indicated that they had switched to a neighboring well in response to the testing. The blanket testing of millions of wells for arsenic in the region should therefore be prioritized over much costlier water treatment and piped water supply projects that will take much longer to have a comparable impact.

Stable isotopes ratios (‰) of Hydrogen (δ2H) and Oxygen (δ1⁸O) were used to trace the groundwater recharge mechanism and geochemistry of arsenic (As) contamination in groundwater from four selected sites (Larkana, Naudero, Ghari Khuda Buksh and Dokri) of Larkana district. The stable isotope values of δ2H and δ1⁸O range from 70.78‰ to −56.01‰ and from −10.92‰ to −7.35‰, relative to Vienna Standard for Mean Ocean Water (VSMOW) respectively, in all groundwater samples, thus indicating the recharge source of groundwater from high-salinity older water. The concentrations of As in all groundwater samples were ranged from 2 μg/L to 318 μg/L, with 67% of samples exhibited As levels exceeding than that of World Health Organization (WHO) permissible limit 10 μg/L and 42% of samples expressed the As level exceeding than that of the National Environmental Quality Standard (NEQS) 50 μg/L. The leaching and vertical mixing with return irrigation water are probably the main processes controlling the enrichment of As in groundwater of Larkana, Naudero, Ghari Khuda Buksh and Dokri. The weathering of minerals mostly controlled the overall groundwater chemistry; rock-water interactions and silicate weathering generated yielded solutions that were saturated in calcite and dolomite in two areas while halite dissolution is prominent with high As area.

The study was done to assess the effect of the river Sutlej on arsenic (As) contamination. Sampling was done from the alluvial plain with increasing distance from the river Sutlej in district Vehari and compared with the study done in the proximity of River Sutlej. Sixty (60) groundwater samples mostly from shallow depths were collected and analyzed for As concentrations. Multivariate statistical tools (PCA and CA), saturation index, piper plots and Gibbs diagrams were used to detect evidence about the interrelationship and sources of As and other water quality variables responsible for groundwater contamination. Results revealed that As concentration ranged from below detection limit to 156 µg/L indicating that 50% samples exceeding the WHO guidelines (10 µg/L) and 17% exceeding the Pakistan National Environmental Quality Standards (NEQS) limits (50 µg/L) Sutlej. The piper plot revealed that water chemistry of the study area was Ca–HCO3−, Ca–Mg–Cl, type. Correlations between As and HCO3− (r2 = 0.433) was positive, while negative correlations were observed between As–Mn2+ and As–Fe2+ (r2 = − 0.102), (r2 = 0.107) respectively. Geochemical signatures of the groundwater in the study area showed that the As could be released by oxidative dissolution to some extent and elevated evaporation in the arid environment of the study area under the stimulus of alkaline water and high pH (range 7.1–8.4). Although the concentrations are exceeding the WHO limit in 50% of the water samples but, are less than the previous study done in Mailsi near River Sutlej. Further, the concentrations decreased as the distance from the River increased which shows the probable role of sediments deposited by the River Sutlej.

Biosorption efficiency of natural orange peel (NOP) and charred orange peel (COP) was examined for the immobilization of arsenate (As(V)) in aqueous environments using batch sorption experiments. Sorption experiments were carried out as a function of pH, time, initial As(V) concentration and biosorbent dose, using NOP and COP (pretreated with sulfuric acid). Arsenate sorption was found to be maximum at pH 6.5, with higher As(V) removal percentage (98%) by COP than NOP (68%) at 4 g L−1 optimum biosorbent dose. Sorption isotherm data exhibited a higher As(V) sorption (60.9 mg g−1) for COP than NOP (32.7 mg g−1). Langmuir model provided the best fit to describe As(V) sorption. Fourier transform infrared spectroscopy and scanning electron microscopy combined with energy dispersive X-ray spectroscopy analyses revealed that the –OH, –COOH, and –N-H surface functional groups were involved in As(V) biosorption and the meso- to micro-porous structure of COP sequestered significantly (2-times) higher As(V) than NOP, respectively. Arsenate desorption from COP was found to be lower (10%) than NOP (26%) up to the third regeneration cycle. The results highlight that this method has a great potential to produce unique ‘charred’ materials from the widely available biowastes, with enhanced As(V) sorption properties.

Geochemical investigation was carried out for delineating factors responsible for the mobilization of arsenic (As) from aquifer material into the groundwater. Four sites along Ravi River, (Samada, Sarai Chimba, Kot Maiga and Chah Fatehwala), were selected based on the blanket survey. Groundwater-rock interaction and evaporation were the key phenomena controlling groundwater chemistry, as shown by the hydrogeochemical data. Groundwater was predominantly Na-Cl type, with other principle facies being Na-HCO3, Na-Ca-HCO3 and Ca-Mg-Cl. The groundwater As concentration ranged between below detection level (2 mu g/L) to 548 mu g/L with 59% samples exceeding the World Health Organization (WHO) guidelines for As in drinking water (10 mu g/L) and 31% having higher concentrations than the National Environmental Quality Standard (NEQS, 50 mu g/L). Moderate to high concentrations of SO4-2 averaged at 244 mg/L and moderate NO3- concentrations averaged at 8 mg/L, together with alkaline pH (73-8.8) and high Eh values (113-402 mV) suggest partial oxidizing nature of the aquifers. The values for delta O-18 and delta H-2 in groundwater varied between -9.14 and -5.51 parts per thousand, and -56.57 to -39.5%o respectively, and suggests meteoric origin of the groundwater with some evaporative loss. This effect could be partly responsible for elevated levels of pH and salinity in groundwater. Based on geochemical and isotopic composition of groundwater, desorption of As from metal surfaces under alkaline environment might be the factor causing As enrichment in study area. (C) 2018 Elsevier Ltd. All rights reserved.

This chapter deals with the arsenic sources, its contamination in paddy soils, and its toxic effects to human health when it becomes the part of the food chain. Arsenic, the 20th abundant metalloid, exists naturally and has potential to become part of different matrices like air, soil, and water. In groundwater its contamination is recognized worldwide. Similarly, several studies indicate its contamination in paddy soils. Specially, arsenic has become a threat to sustainable rice cultivation in South and Southeast Asia. Rice has a special ability to uptake the arsenic, and it is a staple food in different countries of this region like Bangladesh, India, and Pakistan. In this region, people are at high risk of arsenic contamination through the ingestion of arsenic-contaminated rice. Thousands of people are suffering from the toxic effects of arsenic and its compounds all over the world. Arsenic in the human body is transported through the blood to the different organs of the body, in the form of MMA after ingestion. Its acute and chronic exposures cause several adverse health effects like dermal changes and respiratory, pulmonary, cardiovascular, gastrointestinal, hematological, hepatic, renal, neurological, developmental, reproductive, immunologic, genotoxic, mutagenetic, and carcinogenic effects. So, to overcome this issue, there is a need of modification in agricultural practices, genetic modifications, and public awareness regarding this menace.

Evaluating the ability of industrial based adsorbents to remove arsenic and fluoride from drinking water has global significance due to their easy and widespread availability. Present study aimed to assess selected industrial waste materials for simultaneous removal of arsenic and fluoride from drinking water in order to find cost effective adsorbent. Commercially available Hydrated Cement, Marble Powder (waste) and Brick Powder (waste) were used. Adsorbents were characterized by using X-Ray Diffractrometry techniques. The surface morphology of adsorbents was studied by Scanning Electron Microscopy (SEM). Batch adsorption tests were employed to evaluate the percent removal and adsorption capacity of adsorbents, under optimum conditions of adsorption time, dose, pH and adsorbate concentration. Removal percentage of studied adsorbents followed the decreasing trend: Hydrated Cement > Bricks Powder > Marble Powder. Hydrated Cement showed highest percentage removal, 97% and 80% for arsenic and fluoride respectively and was selected as the best media at neutral pH compared to other four adsorbents substantiating its potential for the drinking water treatment process. The applicability of the adsorbents for As was assessed under natural conditions with As contaminated groundwater samples collected from Tehsil Mailsi. In order to determine maximum adsorption capacity of adsorbents and to understand the nature of reaction on their surfaces, Langmuir and Freundlich isotherm were calculated. This study revealed that this new adsorbent (Hydrate Cement) is indigenous, easily available and could be easily applied in order to diminish the arsenic and fluoride pollution from drinking water.

Finding appropriate adsorbent may improve the quality of drinking water in those regions where arsenic (As) and fluoride (F−) are present in geological formations. In this study, we evaluated the efficiency of potato peel and rice husk ash (PPRH-ash)-derived adsorbent for the removal of As and F from contaminated water. Evaluation was done in batch adsorption experiments, and the effect of pH, initial adsorbate concentration, contact time, and adsorbent dose were studied. Characteristics of adsorbents were analyzed using scanning electron micropcope (SEM) and Fourier transform infrared (FTIR) spectroscopy. Both the Langmuir and Freundlich isotherm models fitted well for F− and As sorption process. The maximum adsorption capacity of adsorbent for As and F− was 2.17 μg g−1 and 2.91 mg g−1, respectively. The As and Fi removal was observed between pH 7 and 9. The sorption process was well explained with pseudo-second order kinetic model. Arsenic adsorption was not decreased in the presence of carbonate and sulfate. Results from this study demonstrated potential utility of this agricultural biowaste, which could be developed into a viable filtration technology for As and F− removal in As- and F-contaminated water streams.

91% exceeded the WHO standard (10 µg/L) for As and 75% exceeded the WHO standard (1.5 mg/L) for F ‐ . The highly contaminated As (max. 2400 µg/L) and F ‐ (max. 22.8 mg/L) groundwaters were found from shallow depths down to 30 m from the surface. The contaminated groundwaters are characterized by high pH (max. 8.8), alkalinity (HCO3 ‐ up to 1281 mg/L), SO4 2‐ (max. 960 mg/L), Na + (max. 1058 mg/L) and maximum electric conductivity >4.6 mS/cm. Fluoride concentrations showed positive correlations with those of Na + and HCO 3 ‐ and negative ones with Ca 2+ and Mg 2+ . The alkaline waters were saturated with calcite in spite of the low Ca 2+ concentrations. Fluoride concentration is governed by fluorite solubility. Speciation analysis showed As is mostly in the form of As V . There was a positive correlation between As and pH, while there is no relationship between As vs. Fe and F ‐ . Thus, the fluoride and As contamination occurred in the oxidizing and alkaline conditions of the groundwater. However, F ‐ and As are derived from two or more sources. Suspected contaminant sources in the study area contained considerable amounts of F ‐ and As; fertilizers (DAP, n = 5) contained leachable F ‐ ranging from 53‐255 mg/kg, and As 5‐10 mg/kg, and coals (n = 8) contained F ‐ ranging from 5‐20 mg/kg. Sulfur isotopic ratios indicated that the high SO 4 2‐ in groundwater (3.2‐7.0‰, CDT) is mainly derived from coal combusted atmospheric pollutants, fertilizers and household wastes. Nitrogen isotope data (8‐30‰, Air) showed that NO3 ‐ ‐N is attributed to animal waste distributed in the study area. The major chemical characteristics of the groundwaters are related with anthropogenic activities on the ground surface. The resultant major chemistry, especially highly alkaline and low Ca 2+ and Mg 2+ concentrations, must promote the high concentrations of F ‐ and As in the studied groundwaters.

Worldwide huge number of technologies are available for arsenic removal from arsenic-contaminated water. Some of these technologies include pre-oxidation of arsenic(III) to arsenic(V) by the use of different oxidants, as As(V) has high adsorbance capacity and reacts more strongly than As(III) (Ahmed et al. 2001).

A health risk assessment model derived from the USEPA (Integrated Risk Information System (IRIS): arsenic CASRN 7440-38-2, 1998) was applied to compute the non-carcinogenic and carcinogenic effects to individuals who consume groundwater as their drinking water source.

Arsenic and F− testing of groundwater is considered as an important activity because As and F− are now recognized as the most serious inorganic contaminants in drinking water on a worldwide basis and due to its serious effects on human health (Smedley et al. 2002).

This paper reports high levels and variability in arsenic (As) levels at locations identified as one of the highest As-contaminated locations in Pakistan. Groundwater pollution related to arsenic has been reported since many years in the areas lying in outskirts of District Lahore, Pakistan. A comparative study is done to determine temporal variations of As from three villages, i.e., Kalalanwala (KLW), Manga Mandi (MM), and Shamki Bhattian (SKB). Seventy-three percent of the 30 investigated samples ranging in depth from 20 to 200 m, show an increasing trend in variations of As concentration over a time span of 4 years and 87 % of samples exceeded the WHO standard of 10 μg/L for As while 77 % of samples have As concentration >50 μg/L (national standard). Further results indicate that high levels of As is accompanied with increase pH (r = 0.8) favoring desorption of As from minerals at higher pH under oxidizing conditions. For health risk assessment of arsenic, the average daily dose, hazard quotient (HQ), and cancer risk were calculated. The residents of the studied areas had toxic risk index in the order of SKB>KLW>MM, with 87 % of samples exceeding the typical toxic risk index 1.00 (ranging from 2.3–48.6) which was 83 % (ranging from 0.3–41) 4 years before. The results of the present study therefore indicate that arsenic concentrations are increasing in the area, which needs an immediate attention to provide alternate sources of water to save people at risk.