Environmental Science And Technology - Research Publications

Permanent URI for this collectionhttps://kr.cup.edu.in/handle/32116/88

Browse

Subject: search.filters.subject.Salinity

Search Results

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Meta-analysis of uranium contamination in groundwater of the alluvial plains of Punjab, northwest India: Status, health risk, and hydrogeochemical processes
    (Elsevier B.V., 2021-11-23T00:00:00) Sahoo, Prafulla Kumar; Virk, Hardev Singh; Powell, Mike A.; Kumar, Ravishankar; Pattanaik, Jitendra Kumar; Salom�o, Gabriel Negreiros; Mittal, Sunil; Chouhan, Lokesh; Nandabalan, Yogalakshmi Kadapakkam; Tiwari, Raghavendra Prasad
    Despite numerous studies, there are many knowledge gaps in our understanding of uranium (U) contamination in the alluvial aquifers of Punjab, India. In this study, a large hydrogeochemical dataset was compiled to better understand the major factors controlling the mobility and enrichment of uranium (U) in this groundwater system. The results showed that shallow groundwaters (<60 m) are more contaminated with U than from deeper depths (>60 m). This effect was predominant in the Southwest districts of the Malwa, facing significant risk due to chemical toxicity of U. Groundwaters are mostly oxidizing and alkaline (median pH: 7.25 to 7.33) in nature. Spearman correlation analysis showed that U concentrations are more closely related to total dissolved solids (TDS), salinity, Na, K, HCO3?, NO3? Cl?, and F? in shallow water than deep water, but TDS and salinity remained highly correlated (U-TDS: ? = 0.5 to 0.6; U-salinity: ? = 0.5). This correlation suggests that the salt effect due to high competition between ions is the principal cause of U mobilization. This effect is evident when the U level increased with increasing mixed water species (Na-Cl, Mg-Cl, and Na-HCO3). Speciation data showed that the most dominant U species are Ca2UO2(CO3)2? and CaUO2(CO3)3?, which are responsible for the U mobility. Based on the field parameters, TDS along with pH and oxidation-reduction potential (ORP) were better fitted to U concentration above the WHO guideline value (30 ?g.L?1), thus this combination could be used as a quick indicator of U contamination. The strong positive correlation of U with F? (? = 0.5) in shallow waters indicates that their primary source is geogenic, while anthropogenic factors such as canal irrigation, groundwater table decline, and use of agrochemicals (mainly nitrate fertilizers) as well as climate-related factors i.e., high evaporation under arid/semi-arid climatic conditions, which result in higher redox and TDS/salinity levels, may greatly affect enrichment of U. The geochemical rationale of this study will provide Science-based-policy implications for U health risk assessment in this region and further extrapolate these findings to other arid/semi-arid areas worldwide. � 2021 Elsevier B.V.
  • No Thumbnail Available
    Item
    Green fabrication of ZnO nanoparticles using Eucalyptus spp. leaves extract and their application in wastewater remediation
    (Elsevier Ltd, 2020) Chauhan A.K.; Kataria N.; Garg V.K.
    The present study explored removal of carcinogenic cationic and anionic dyes from aqueous medium using green fabricated zinc oxide nanoparticles (ZnO-NPs). The ZnO-NPs were synthesized employing biogenic green reduction and precipitation approach. The characterization of ZnO NPs was done using various techniques such as FESEM, XRD, BET, TGA, HRTEM, EDX, and FTIR. All experiments were conducted in batch mode. Maximum removal was achieved at pH 6.0 and pH 8.0 for Congo Red (CR) and Malachite Green (MG) dyes respectively. Dye adsorption process showed better fit with Langmuir and Temkin isotherm models for CR dye and MG dye respectively. Maximum adsorption capacity of ZnO NPs was 48.3 mg/g for CR dye and 169.5 mg/g for MG dye. The dye adsorption followed pseudo-second order model and values of thermodynamic parameters confirmed that the adsorption process was spontaneous and favourable. Reusability efficiency of the nanoparticle was explored using ethanol and water and based on results it was inferred that ZnO-NPs can be reused for dye removal. Effect of salinity on the removal of CR and MG dyes was also explored and found that presence of salinity in aqueous medium have adverse impact on the dye removal efficiency of ZnO-NPs.