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Litho-geochemical characteristics of low and high fluoride (F−) groundwater along with hydrological processes were investigated to delineate its genesis and enrichment mechanism in a watershed sedimentary basin. In this study, groundwater F− concentration ranged from 0 to 20 mg/L with a mean and standard deviation of 2.8 and ± 3.7 mg/L, respectively. Out of N = 87, 63% of samples exceeded the World Health Organization (WHO) limit of 1.5 mg/L. The order of cationic and anionic dominance in groundwater samples with mean was found in decreasing order as Na+ > Mg2+ > Ca2+ > K+ and HCO3− > SO42− > Cl− > PO43− > NO3− measured in milligrams per liter. Groundwater chemistry changed from Ca-HCO3 to Na-HCO3 type and low to high fluoride as we moved from mountain foot towards the synclinal basin. Low fluoride groundwater reflected weathering, recharge, and reverse ion exchange processes with Ca–HCO3– and Ca–Mg–Cl–type water while high fluoride groundwater revealed base ion exchange, mixing, and desorption as dominant hydrological processes with Na-HCO3 and Na-Cl types of water. Gibb’s diagram showed rock weathering and mineral dissolution as the major geochemical processes controlling water chemistry with an insignificant role of evaporation in the semi-arid area. Fluoride was undersaturated with mineral fluorite, indicating fluoride in groundwater is released by secondary minerals. However, due to complex geological features, groundwater fluoride enrichment was affected by a broad-scale process across a wide area such as depth, residence time, and most important geomorphological units hosting the aquifer.

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.

To assess the trace metal pollution in the Siran River, sediments were collected from 12 sites, from the left and right banks of the river in 2013. The concentrations, accumulation, distribution pattern, and pollution status of heavy metals in sediments were investigated using geoaccumulation index (I geo) and enrichment factor (EF). The toxic risk of heavy metals was assessed using interim sediment quality guidelines (ISQGs), portable effect level (PEL), threshold effect level (TEL), and toxic effect threshold (TET). I geo and EF values showed that sediments were loaded with Ni, Cd, Pb, and Co and no obvious variations were found among the left and right banks of the river. The EF and I geo values were found in order of Co > Pb > Ni > As > Cd > Cu > Zn > Fe and Cd > Co > Pb > Ni > As > Fe > Zn > Cu > Mn, respectively. Furthermore, multivariate statistical analysis like inter-metal correlation, cluster analysis (CA), and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of sediment contamination in the study area. These results indicated that more attention should be paid to the inner loads of sediment in order to achieve improvements in reservoir water quality after the control of external pollution.

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.