Evaluation of Metal Pollution in Groundwater in the Industrialized Environs in and Around Dindigul, Tamilnadu, India

Characteristics of Water Pollution and Evaluation of Water Quality in Subsidence Water Bodies in Huainan Coal Mining Areas, China

The subsidence water bodies in coal mining areas are vulnerable to being polluted by the surrounding mining production wastewater, domestic sewage, and agricultural return flow. Therefore, it is important to grasp the water quality condition of the above water bodies. A total of 16 surface water samples from 7 different subsidence water bodies in the Huainan mining area were collected and focused on the selection of 22 water quality indicators for water pollution characteristics analysis. The result of correlation analysis showed that Cr and Zn came from the same source of pollution. Three principal factors were selected by factor analysis, which could explain 82.294% of the total variance. Principal factor 1 indicated a mixture of pollution related to nitrogen and phosphorus nutrients, organic pollutants, and heavy metals; principal factor 2 showed heavy metal pollution; and principal factor 3 presented the pollution from heavy metals and cations. Results of cluster analysis showed that the water quality status of 16 sampling points could be divided into 4 clusters. The results of the heavy metal pollution index method showed that the heavy metal pollution was most serious in sample 9 (S9), S15, and S16, and the main elements of pollution were Ni, Fe, and Mn. Single-factor evaluation, comprehensive pollution index, the universal exponential formula of logarithmic power function, and membership degree method were used to evaluate the five important water quality indicators, namely total nitrogen, ammonia nitrogen, total phosphorus, dissolved oxygen, and chemical oxygen demand. The results showed that the total nitrogen pollution in the study area was more serious, most of the sites exceed class V standards of the surface water, S14 and S16 were heavily polluted. Based on the comparison of the different methods, the surface water quality in the study area can be reflected more comprehensively.

Occurrence of Heavy Metals in Groundwater Along the Lithological Interface of K/T Boundary, Peninsular India: A Special Focus on Source, Geochemical Mobility and Health Risk

Evaluation of the hydrogeochemical processes governing the heavy metal distribution and the associated health risk is important in managing and protecting the health of freshwater resources. This study mainly focused on the health impacts due to the heavy metals pollution in a known Cretaceous-Tertiary (K/T) contact region (Tiruchinopoly, Tamilnadu) of peninsular India, using various pollution indices, statistical, and geochemical analyses. A total of 63 samples were collected from the hard rock aquifers and sedimentary formations during southwest monsoon and analysed for heavy metals, such as Li, Be, Al, Rb, Sr, Cs, Ba, pb, Mn, Fe, Cr, Zn, Ga, Cu, As, Ni, and Co. Ba was the dominant element that ranged from 441 to 42,638 μg/l in hard rock aquifers, whereas Zn was the major element in sedimentary formations, with concentrations that ranged from 44 to 118,281 μg/l. The concentrations of Fe, Ni, Cr, Al, Cr, and Ni fell above the permissible limit in both of the formations. However, the calculated heavy metal evaluation index (HEI), heavy metal pollution index (HPI), and the degree of contamination (C_d) parameters were higher in the sedimentary formation along the contact zone of the K/T boundary. Excessive health risks from consumption of contaminated groundwater were mostly confined to populations in the northern and southwestern regions of the study area. Carcinogenic risk assessment suggests that there are elevated risks of cancer due to prolonged consumption of untreated groundwater. Ba, Sr, and Zn were found to be geochemically highly mobile due to the partitioning between the rock matrix and groundwater, aided by the formation of soluble carbonato-complexes. Factor analysis indicates that the metals are mainly derived from the host rocks and anthropogenic inputs are relatively insignificant. Overall, this study indicated that groundwater in K/T contact zones is vulnerable to contamination because of the favorable geochemical factors. Long-term monitoring of such contact zones is required to avert the potential health hazards associated with consumption of the contaminated groundwater.

Spatial variations of heavy metal contamination and associated risks around an unplanned landfill site in India

The study highlights the impact of unplanned landfill site on quality of groundwater, soil, and plants. The site selected is the Bhalaswa landfill site located in the urbanized region of Delhi, India. The associated potential ecological and human health risks to the population residing within the catchment area of the landfill site were evaluated. The order of abundance of heavy metals (measured using atomic absorption spectrometer) in the soil was found to be Fe > Cu > Cd > Ag, with Cu and Cd exceeding the WHO (World Health Organization)-recommended limits. Translocation factor (Root_metal/Shoot_metal) for Cd in P. juliflora plant (most dominant species in the region) at the landfill site was found to be the highest. The groundwater at the landfill site, 500 m, and 1000 m distance were found to exceed the WHO recommendation limits for Cd by 14.2%, 7.1%, and 1.4%, respectively. The estimated ecological risk index (E_r) indicated a high level of contamination particularly by Cu (E_r = 90.63) and Cd (E_r = 180). Children were found to be at higher risk by ingestion of Cd contaminated water (target hazard quotient = 5.1 > 1, indicating highest risk due to noncarcinogenic effects) followed by Ag (1.5) and Cu (1.4). The strong positive correlation of Cd between various ecological compartments with distance (Spearman rho's correlation > 0.75, 99% confidence level test) implied its high mobility and easy dispersion capacity towards the residential colony around the landfill, thereby indicating high associated ecological and human health risks. To conclude, there is a need to maintain a setback distance greater than 500 m from the landfill site in order to reduce the ecological as well as health risks associated with the landfill. The findings of this study provides a brief glimpse of the scenario of heavy metal pollution around such unplanned landfill sites and aids in taking remedial steps.

Evaluation of groundwater contamination in Chandigarh: Source identification and health risk assessment

The major objective of the current study is to estimate the groundwater quality and identify the likely sources of contamination in Chandigarh, India. Total 80 groundwater samples were collected from different locations and at various depths. Further, physcio-chemical analysis was done to estimate pH, electrical conductivity (EC), total dissolved solids, total hardness (TH), total alkalinity (TA), Na⁺, K⁺, Cl^-, SO₄^2-, PO₄^3- and NO₃^-. The groundwater samples collected from shallow water sources contain higher concentration of total dissolved salts. EC, TA, Cl^-, TH, Na⁺, and K⁺ were found relatively higher in the shallow aquifer (<150 ft). Based on the location of pollution sources at the surface and consecutive geo-statistical distribution of physicochemical characteristics, this study suggests that non-scientific disposal of municipal solid waste, dumping of industrial waste and agricultural activities, in the nearby areas lead to the deterioration of groundwater of shallow aquifer. These observations were also confirmed using various water quality indices and outcomes of multivariate modeling, including principal component analysis. Health risk assessment for nitrates indicated that 29 groundwater samples pose non-carcinogenic health risk for children due to dermal and oral exposure. Hence, there is a need to establish a system for regularly assessing the groundwater quality to minimize public health risks.

Assessment of Heavy Metals Pollution and Stable Isotopic Signatures in Hard Rock Aquifers of Krishnagiri District, South India

The area chosen for study, Krishnagiri district, has a hard rock terrain and the aquifers located there are sparsely recharged by limited rainfall. The study area has a complex geology with hard rock aquifers. To have an overall view of the trace metals concentration in the groundwater of the study area, 39 groundwater samples were collected during Post Monsoon (POM) representing various lithologies. pH, EC, TDS, major ions and 22 heavy metals were analyzed for all the samples. Ca-Cl is the dominant water facies in the groundwater, which indicates the dissolution of ions by local precipitation. The analysis shows the dominance of trace metal levels in groundwater as follows: Zn > Ba > Sr > Fe > Al > B > Mn > Cu > Pb > Ni > V > Li > Rb > Cr > Mo > Se > As > Co > Cd > Ag > Sb > Be. The pollution indices, namely the heavy metal pollution index (HPI) and degree of contamination (Cd) were calculated to assess the drinking and agriculture water usage. The pollution indices show that 2% of samples are polluted with respect to HPI and 3% with respect to the degree of contamination. The heavy metals (Al-Cr-Mn-Fe-Ni-Co-Zn-Ba-Pb) in groundwater show significant correlations with these indices, suggesting that they are affected by weathering of rock matrix with less anthropogenic impact. Stable isotopes (Oxygen and Hydrogen) were analyzed to identify the possible recharge mechanisms in the groundwater. It has been identified that recharge is mainly due to the local precipitation, which is the result of release metals in the groundwater through weathering.