Geostatistical appraisal of water quality, contamination, source distribution of potentially toxic elements (PTEs) in the lower stretches of Subarnarekha River (Odisha), India, and health risk assessment by Monte Carlo simulation approach.

In the present study, the status of water quality, environmental contamination in the lower stretch of Subarnarekha River with respect to potentially toxic elements (PTEs), its seasonal distribution, and ecotoxicological health impacts were investigated. For this purpose, a combination of indexing approaches and geospatial methods was used. The estimated water quality index (WQI) has shown that the river water falls under "moderate to very poor" category during the pre-monsoon and "moderate to poor" category in the post-monsoon season. The abundance of PTEs (Pb, Cu, Ni, Cd, Fe, and Cr) was on the higher side during the pre-monsoon in comparison with the post-monsoon season. The results of contamination index (Cd) and heavy metal evaluation index (HEI) explain that Subarnarekha River has low-to-moderate levels of contamination with PTEs in the majority of sampling sites. However, HPI indicated that the river water is moderate-to-highly contaminated with PTEs in both seasons. Principal component analysis (PCA) and cluster analysis (CA) reveal that anthropogenic sources are prime contributors to PTEs contamination in Subarnarekha River. The potential non-cancerous health concerns for child and adults due to Cr and Pb in some sampling stations along the river stretch have been observed. The carcinogenic risk (CR) has been established for Cr, Pb, and Cd in Subarnarekha River with Cr (> 10-4) as the most unsafe element. Monte Carlo simulation (MCS) indicates a high risk of cancer hazards due to Cr (values > 1E-04) in present as well as future for both child and adults.

PSS functionalized and stabilized carbon nanodots for specific sensing of iron in biological medium.

Carbon Quantum Dots (CQDs) are already emerged as an excellent sensing element for its exceptional behavior in fluorescence, biocompatibility, and water dispersibility. However, its poor stability, selectivity and reproducibility in complex medium still be a big problem for its practical application. To overcome this, in the work, we have developed a new type of carbon quantum dot-PSS fluorescent nanocomposites which has been used for specific Fe3+ detection. The polystyrene sulfonate (PSS) polymer not only stabilize the QDs but also produces specific sites for Fe3+ to make a co-ordinate complex via Fe3+-SO3. The detection limit is calculated as low as 1 ppm which is adequate for measuring Fe3+ in blood or water samples. The mechanism of the quenching is very specific towards the Fe3+ ion due to the presence of PSS which makes the sensor selective among other metal ions and possible interferences. The rapid process of sensing, simple instrumentation, and excellent performances in presence of 1 % BSA and serum samples indicates the possible application for diagnostic usage in near future.

Contamination level, source identification and health risk evaluation of potentially toxic elements (PTEs) in groundwater of an industrial city in eastern India.

The present investigation explores the spatial and seasonal variations in potentially toxic element (PTEs) concentrations and contamination level assessment of groundwater samples in and around the Asansol industrial city, eastern India. The representative samples of groundwater from 24 different locations were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH) and PTEs, e.g., Pb, Cu, Cd, Zn, Fe and Cr for pre-monsoon and post-monsoon. The pH level of examined groundwater samples is under the desirable limit with few exceptions (S5, S11 and S16 in pre-monsoon and S12 in post-monsoon). The recorded values for Pb, Cd, Fe and Cr in many sampling stations found higher than the prescribed limits of Indian standards (IS 10500: 2012) in both the seasons. The mean contamination factor (Cf) for PTEs in the groundwater is in the order of Cr > Fe > Cd > Pb > Cu > Zn and Fe > Cr > Cd > Pb > Cu > Zn, with mean contamination index (Cd) value of 2.83 and 2.72 in pre-monsoon and post-monsoon season, respectively, indicating moderate level of contamination in the examined area. Geospatial depiction of HPI values shows high level of contamination during pre-monsoon (58.3% sampling sites) and post-monsoon (45.8% sampling sites) in majority of sampling sites. Further, application of multivariate statistical analysis ascertains that the PTEs in groundwater are majorly derived from anthropogenic activities such as opencast mining, thermal power plants, iron and steel industries, sponge iron and other metallurgical industries, and leachate from urban and industrial wastes along with limited contribution from geogenic and lithogenic sources. The health risk assessment demonstrates that the non-carcinogenic risk (due to PTEs) in adults is in the sequence of Cr > Cd > Pb > Fe > Cu > Zn, while for children the order is Cr > Pb > Cd > Fe > Cu > Zn for both the seasons. The results also reveal higher chance of occurrence of carcinogenic risk due to Cr (ILCR > 1.0E-04) for children and adults in both the seasons.

Sources evaluation, ecological and health risk assessment of potential toxic metals (PTMs) in surface soils of an industrial area, India.

The present study aims to appraise the spatial distribution of potential toxic metals by using geostatistical technique and find their associated ecological and human health risks from surface soils of Durgapur industrial area, India. The results show that the mean metal concentrations are 116.03, 32.96, 154.37, 321.20, 50.08, 29.54 and 2.97 mg/kg for Pb, Cd, Cr, Fe, Cu, Ni and Hg, respectively, and majority of them is found higher than their background and world natural soil concentrations. The GIS contour map of pollution load index values clearly distinguished the studied sampling area is highly to very highly polluted by the toxic metals. Contamination factor (Cf) and geo-accumulation index (Igeo) values of studied metals show a similar sequence of Hg > Cd > Pb > Fe > Cr > Ni > Cu. Calculated enrichment factor (EF) value for Hg (13.29), Cd (5.26) and Pb (1.11) in studied soils was found significantly higher, which suggests that their primary sources are higher industrial activities in the studied area. Computation of potential ecological risk index reveals that the entire study area is under high risk level (1941.60-3367.23), in which Cd (588.52) and Hg (1979.26) possess the maximum ecological risk factor in all the sampling sites. The results of correlation analysis, principle component analysis and cluster analysis explore that industrial discharges, atmospheric disposition and waste disposal are the major sources of soil metal pollution in the studied region. Human health hazard indices are lower than 1 for all metals, indicating low non-carcinogenic risks to children and adults. Carcinogenic risk assessment reveals the existence of cancer risk of Cd (5.5E-03), Cr (8.6E-04) and Ni (3.0E-04) to child and Cd (8.2E-04) and Cr (1.3E-04) to adults in Durgapur.

Efficient removal of Hg2+, Cd2+ and Pb2+ from aqueous solution and mixed industrial wastewater using a designed chelating ligand, 2-pyridyl-N-(2'-methylthiophenyl) methyleneimine (PMTPM).

The present study is focused on the removal of Hg2+, Cd2+ and Pb2+ ions from aqueous solution using a tridentate chelating agent, 2-pyridyl-N-(2'-methylthiophenyl) methyleneimine (PMTPM); and applicability of such removal from industrial wastewater using PMTPM is also investigated. The results showed that the metal ions removal efficiency using PMTPM was in the order of Hg2+(99.46%) > Cd2+(95.42%) > Pb2+(94.54%) under optimum reaction conditions (L:M2+ = 3:1, pH = 9, time = 24 h, temp. = 30 °C). Formed chelated complexes such as [Hg(PMTPM)Cl2] (1), [Cd(PMTPM)Cl2] (2) and [Pb(PMTPM)Cl2] (3) were characterized by numerous spectroscopic tools and X-ray structure determination of a representative complex of Hg2+. In the X-ray structure of [Hg(PMTPM)Cl2], 1, the Hg2+ adopted a distorted tetrahedral coordination geometry surrounding two N donors of PMTPM and two chloride ions. A similar coordination geometry surrounding the respective metal centres in 2 and 3 was established. The thermogravimetric analysis (TGA) revealed a stability order of [Cd(PMTPM)Cl2] > [Hg(PMTPM)Cl2] > [Pb(PMTPM)Cl2]. Further the comparative metal leaching behaviour of these chelate complexes exhibited higher stability in alkaline solution than in acidic. Moreover, PMTPM was applied in real mixed industrial wastewater with alkaline pH, and adequate removals of toxic metals were achieved.