Dhanwinder Singh

The Journal retracts the article titled, “Synthesis of CaFe₂O₄-NGO Nanocomposite for Effective Removal of Heavy Metal Ion and Photocatalytic Degradation of Organic Pollutants”

In the original publication [...].

Groundwater contamination is a significant threat to human health and hygiene, particularly when high levels of nitrate and fluoride are present. Punjab is currently experiencing a crisis of groundwater depletion and contamination, particularly severe in the southwestern region due to the limited availability of surface water. So, the present study was planned in the Mansa district of Punjab to know the status of groundwater with special reference to nitrate and fluoride and its associated health risks. The study found that all drinking water parameters in the district exceeded the desirable limits. The order of cations found was Na⁺ > Mg²⁺ > Ca²⁺ > K⁺, and the anions were ordered as HCO₃⁻ > SO₄²⁻ > Cl⁻ > NO₃⁻ > F⁻. The variation in Na⁺, K⁺, Mg²⁺, and HCO₃⁻ levels is attributed to processes such as silicate weathering, evaporation, and direct ion exchange. The dominant types of groundwater in the area are mixed type and Na-Cl type. The concentration of NO₃⁻ varied from 13.3 to 56.9 mg L⁻¹ with mean 33.3 mg L⁻¹, while F⁻ ranged from 0.09 to 1.81 mg L⁻¹ with mean 1.07 mg L⁻¹. The study revealed that 23.2% and 12.6% of water samples in the district exceeded the acceptable limits for nitrate and fluoride, respectively. According to the water quality index (WQI), the majority of groundwater in the study area is categorized as very poor (36.6%) for drinking, with the largest contribution from the Budhlada (43.9%) and Sardoolgarh (41.1%) blocks. The hazard quotient (HQ) for NO₃⁻ was below 1 for adults. However, HQ was greater than 1 for children in all blocks except for the Bhikhi. Similarly, for fluoride, HQ was less than 1 in all blocks for both children and adults, except for children in Sardoolgarh block. The cancer risk due to nitrate exceeded acceptable limits in all blocks. Conclusively, the study results indicate that the Mansa district of Punjab is facing severe groundwater contamination due to nitrate and fluoride, with the highest contamination levels in Jhunir (47.4% of samples exceeded the acceptable limit of NO₃⁻) and Sardoolgarh (87.18% samples exceeded the desirable limit of F⁻) blocks of the district. The study recommends implementing strict policies to regulate the use of agrochemicals in fields to mitigate nitrate pollution in groundwater and reduce associated risks.

Prevention and control of water pollution for maintaining and restoring the wholesomeness of rivers are unavoidable. The current water quality approach of designated best use has some limitations such as it is non-integrative and inflexible with regard to the consideration of variables and does not provide a separate rating scale for a given designated use. We thus used water quality index approach proposed by the Canadian Council of Ministers of the Environment (CCME WQI) to evaluate and develop a separate rating system for drinking and irrigation purposes of rivers Beas, Satluj and their confluence water of the Indian Punjab using information collected over 4 years (2016 to 2019). River Beas exhibited better water quality compared to river Satluj for irrigation as well as for drinking. The overall drinking water quality index (DWQI) for Beas was marginal (45.5), whereas it was poor for Satluj (37.7) and confluence waters (40.1). The spatial variation in DWQI was greater for Satluj compared to Beas and confluence waters reflecting the effect of dumping of untreated industrial and domestic waste waters. Variables such as Total coliform (T. coli), dissolved oxygen (DO), turbidity and biological oxygen demand (BOD) contributed to the deterioration of DWQI. The irrigation water quality index (IWQI) was good for Beas (86), marginal for Satluj (60.1) and fair for confluence waters (71.2). Faecal coliform (F. coli), Kelly ratio (KR) and %Na contributed to the deterioration of IWQI. Calcium-magnesium-bicarbonate (Ca-Mg-HCO₃) was the dominant water type in Beas and confluence waters, whereas for Satluj, in addition to Ca-Mg-HCO₃, sodium-potassium-chloride-sulphate and mixed water types were also prevalent. The river waters witnessed salinity hazard but did not pose sodicity hazard except at a few locations of Satluj. The study indicates the need to take location specific measures for improving river water quality for drinking as well as irrigation purposes. The current status of water quality calls for an urgent need to formulate stringent policy regulations to maintain the surface water quality.

Rice straw burning causes very serious and widespread air pollution in the north-west Indo-Gangetic Plains of India. Therefore, management of rice straw to avoid burning is a major challenge in agriculture. Use of rice straw as compost can be a viable option to manage rice straw. A three-year field experiment was conducted to evaluate the rice straw compost (RSC) prepared under aerobic and anaerobic conditions in maize (Zea mays L.) at PAU, Ludhiana, India. Three doses of the RSC were compared with farm yard manure (FYM) and recommended doses of fertilizers (RDF). Application of FYM, and aerobic and anaerobic RSC increased maize grain yield (mean of three years) by 19.9, 18.3 and 15.3 %, respectively, compared to RDF. The maize grain yield with the application of 4.5 q ha^-1 of anaerobic RSC and 15 t ha^-1 FYM was at par. Application of FYM and composts significantly increased grain Si content over recommended dose of fertilizers. The maximum returns were found from the application of 4.5 q ha^-1 aerobic RSC followed by 15 tons ha^-1 FYM and 4.5 q ha^-1 anaerobic RSC. The application of RSC not only increased the grain and stover yield, but it also contributed towards efficient rice straw management. In addition, rice straw can supplement limited available FYM in agriculture in the region.

In the present study, nanocomposites having hierarchical nanoflowers (HNFs) -like morphology were synthesized by ultra-sonication approach. HNFs were ternary composite of MgFe₂O₄ and bentonite with boron-, phosphorous- co-doped graphene oxide (BPGO). The HNFs were fully characterized using different analytical tools viz. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectroscopy, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry and Mössbauer analysis. Transmission electron micrographs showed that chiffon-like BPGO nanosheets were wrapped on the MgFe₂O₄-bentonite surface, resulting in a porous flower-like morphology. The red-shift in XPS binding energies of HNFs as compared to MgFe₂O₄-bentoniteand BPGO revealed the presence of strong interactions between the two materials. Box–Behnken statistical methodology was employed to optimize adsorptive and photocatalytic parameters using Pb(II) and malathion as model pollutants, respectively. HNFs exhibited excellent adsorption ability for Pb(II) ions, with the Langmuir adsorption capacity of 654 mg g⁻¹ at optimized pH 6.0 and 96% photocatalytic degradation of malathion at pH 9.0 as compared to MgFe₂O₄-bentonite and BPGO. Results obtained in this study clearly indicate that HNFs are promising nanocomposite for the removal of inorganic and organic contaminants from the aqueous solutions.