Jogendra Singh

Urban air pollution poses a significant threat to human health and environmental quality, especially in rapidly urbanizing areas. This study aimed to analyze the spatio-temporal variations of air quality in Haridwar City, India, identifying critical pollution hotspots. A systematic air quality monitoring approach was adopted to assess the air quality at the high traffic density zones of Haridwar City. Key pollutants such as particulate matter (PM_2.5 and PM₁₀) and gaseous matter (NO₂ and SO₂) were monitored for 1 year starting from April 2023 to March 2024. The data was processed to calculate the air quality index (AQI) using normalization methodology and Central Pollution Control Board (CPCB) recommended methodology to rank the selected sites based on their pollution level. The data was also analyzed using principal component analysis (PCA) and cluster analysis (CA) techniques to identify pollution trends and hotspots. PM₁₀ concentrations {(UKH1-103.07 to 125.37 µg/m³), (UKH2-100.38 to 114.40 µg/m³), (UKH3-105.88 to 119.85 µg/m³), (UKH5-127.08 to 130.96 µg/m³), (UKH6-126.79 to 139.11 µg/m³)} exceeded permissible limits of National Ambient Air Quality Standards (NAAQS) of 24 h (100 µg/m³) at all the sites except at UKH4 (92.06 to 97.51 µg/m³) and 7 (43.08 to 52.09 µg/m³) (control) in all seasons. PM_2.5 concentrations were found below the permissible limits of NAAQS of 24 h (60 µg/m³) at all the sites except at UKH5 (75.16 to 77.99 µg/m³) in all seasons. Gaseous emissions (NO₂ and SO₂) were found below the permissible limits of NAAQS (80 μg/m³). Seasonal variations indicated elevated particulate matter levels in winter due to atmospheric stagnation. Spatial analysis identified five critical hotspots (UKH1, 2, 3, 5, and 6) with consistently poor air quality indices (AQI > 50). The study indicates the urgent need for targeted air pollution mitigation strategies like water sprinkling and the use of mist cannon to suppress the dust emissions, especially in high-risk zones.

Unregulated irrigation with partially industrial effluents may lead to heavy metal contamination in crops and pose significant human health risks, especially in developing countries like India. Therefore, the present study aimed to quantify six heavy metals (Cd, Cr, Cu, Fe, Mn, and Zn) in soil and wheat irrigated with paper mill effluent, assess plant responses, and evaluate associated health risks for consumers. For this, a field study was conducted across ten sites (five effluent-irrigated, five borewell-irrigated as control), analyzing soil and wheat tissues for metal concentrations and calculating risk indices including bioaccumulation factor (Bf), translocation factor (Tf), Dietary Intake of Metals (DIM < 1), Health Risk Index (HRI < 1), and Target Hazard Quotient (THQ < 1). Results indicated high concentrations of Cd and Cr in effluent-irrigated soils and wheat tissues (root > stem > leaves > grains) compared to control sites, with some values exceeding permissible limits. Although the THQ values for heavy metals were below 1, indicating a low immediate health risk, concentrations of Cd and Cr in both soil and crop tissues exceeded acceptable safety standards. This study provides empirical evidence supporting the need for effluent treatment and policy interventions to mitigate agricultural contamination from the use of industrial effluents and protect public health.

The present experiment aimed to examine the impact of nano urea (NU) and plant growth-promoting rhizobacteria (PGPR) on Reshmi amaranth (Amaranthus tricolor) growth under salt stress. Experiments were conducted using six different combinations of NaCl, NU, and PGPR for 35 days under greenhouse conditions. The results showed that salinity stress significantly (p < 0.05) reduced plant growth parameters, including shoot height, root length, fresh weight, and leaf area. However, the application of NU and PGPR, both individually and in combination, enhanced plant growth and physiological resilience under saline conditions. The NU + PGPR treatment yielded the best improvements, with a shoot height of 42.25 cm, root length of 34.79 cm, and fresh weight of 61.69 g, indicating a synergistic effect. Biochemical analysis showed that NaCl stress lowered chlorophyll (0.25 mg/g fwt.) and carotenoids (60.17 µg/100 g) and disrupted ionic homeostasis by increasing Na⁺ accumulation while reducing K⁺ and Ca²⁺ uptake. The combined NU and PGPR treatment restored ionic balance, with Na⁺ reduced to 58.12 mg and K⁺ and Ca²⁺ levels increasing to 115.25 mg and 78.70 mg, respectively. Stress markers such as malondialdehyde (MDA) and proline also showed significant reductions, while antioxidant enzyme activities stabilized under NU and PGPR application. Thus, this study indicated that NU and PGPR mitigate salt-induced stress by improving nutrient assimilation, promoting osmotic regulation, and enhancing antioxidative defenses in Reshmi amaranth.

The glass manufacturing industry produces hazardous effluent that is difficult to manage and causes numerous environmental problems when disposed of in the open. In this study, an attempt was made to study the phytoremediation feasibility of water lettuce (Pistia stratiotes L.), a free-floating aquatic macrophyte, for the removal of six heavy metals from glass industry effluent (GIE) at varying concentrations (0, 25, 50, 75, and 100%). After a 40-day experiment, the results showed that 25% GIE dilution showed maximum removal of heavy metals i.e., Cu (91.74%), Cr (95.29%), Fe (86.47%), Mn (92.95%), Pb (87.10%), and Zn (91.34%), respectively. The bioaccumulation, translocation, and Pearson correlation studies showed that the amount of heavy metals absorbed by vegetative parts of P. stratiotes was significantly correlated with concentrations. The highest biomass production, chlorophyll content, relative growth rate, and biomass productivity were also noted in the 25% GIE treatment. Moreover, the multiple linear regression models developed for the prediction of heavy metal uptake by P. stratiotes also showed good performance in determining the impact of GIE properties. The models showed a high coefficient of determination (R² > 0.99), low mean average normalizing error (MANE = 0.01), and high model efficiency (ME > 0.99) supporting the robustness of the developed equations. This study outlined an efficient method for the biological treatment of GIE using P. stratiotes to reduce risks associated with its unsafe disposal.

Mushroom cultivation produces a significant amount of wastewater containing high levels of both organic and inorganic contaminants. In this study, mushroom farm wastewater (MFW) was treated separately by aquatic macrophytes (Ceratophyllum demersum L.) and algae (Chlorella vulgaris). The laboratory experiments consisted of a constructed reactor planted with selected aquatic plants and a microalgal culture and operated for 16 days. The pollutant removal efficiency was evaluated using different experimental combinations such as control 1 (C. demersum using borewell water), control 2 (C. vulgaris using borewell water), T1 (C. demersum using MFW), and T2 (C. vulgaris using MFW), respectively. The results showed that the T1 treatment had the highest significant (p < 0.05) removal efficiency of selected pollutant parameters (total dissolved solids: 86.00%; biochemical oxygen demand: 83.10%; chemical oxygen demand: 86.60%; total nitrogen: 84.30%; total phosphorus: 75.60%). The kinetic studies using the first-order reaction model showed a good fit (R² > 0.8317) and the maximum rate constant (k) of pollutant reduction in T1 treatment. In addition, the growth, biochemical, and proximate parameters of both C. demersum and C. vulgaris were highest in the same treatment. Therefore, the proposed experiment offers a promising approach for the efficient and environmentally friendly treatment of MFW.

Salinity-induced soil degradation poses a significant challenge to agricultural productivity and requires innovative crop-management strategies. In this study, the synergistic effect of biochar and TiO₂ nanoparticles (NPs) obtained from moss (Leucobryum glaucum (Hedw.) Ångstr.) biomass on the growth, yield, biochemical, and enzymatic response of Chinese spinach (Amaranthus dubius L.) grown under salinity stress was investigated. Purposely, A. dubius was grown under different combinations of arable soil, biochar, TiO₂ NPs, and saline soils. The produced biochar and TiO₂ NPs were characterized using microscopy image analysis, X-ray diffraction patterns (XRD), energy-dispersive X-ray spectroscopy (EDX), zeta potential, particle size distribution, and Fourier-transform infrared spectroscopy (FTIR). The results showed that saline stress caused a significant (p < 0.05) decline in growth, yield, and biochemical constituents of A. dubius compared to control treatments. However, the combined application of biochar and TiO₂ NPs significantly (p < 0.05) alleviated the saline stress and resulted in optimum fresh weight (30.81 g/plant), dry weight (4.90 g/plant), shoot and root length (28.64 and 12.54 cm), lead number (17.50), leaf area (12.50 cm²/plant), chlorophyll (2.36 mg/g), carotenoids (2.85 mg/g), and relative water content (82.10%). Biochar and TiO₂-NP application helped to reduce the levels of stress enzymes such as catalase (2.93 µmol/min/mg P), superoxide dismutase (SOD: 2.47 EU/g P), peroxidase (POD: 40.03 EU/min/g P), and ascorbate peroxidase (3.10 mM/mg P) in saline soil. The findings of this study suggest that the combination of nanotechnology and biochar derived from unconventional biomass can be a viable option to mitigate salinity-related challenges and enhance crop yield.

In this study, the potential use of sewage sludge (SS) as a fertilizer source for cultivated Dhaincha (Sesbania bispinosa (Jacq.) W.Wight) crops was investigated. Field experiments were conducted using different doses of SS such as 0% (T0), 5% (T1), 10% (T2), and 15% (T3) to amend the soil (w/w). The findings showed that soil amended with SS significantly (p < 0.05) improved the response parameters of S. bispinosa with an increase in the dose of SS from 0% to 15%. In particular, the T3 treatment gave the best results (mean values) for plant growth and yield parameters such as plant height (380.59 cm), fresh weight (1.47 kg/plant), dry weight (0.27 kg/plant), base diameter (3.19 cm), seed yield (44.71 g/plant), total chlorophyll (3.15 mg/g fwt), carotenoids (0.88 mg/g fwt), carbohydrates (9.40 mg/g), and phenol (0.13 mg/g) contents. Moreover, the selected proximate and fiber characteristics of the S. bispinosa crop were significantly (p < 0.05) improved by the same treatment (T3); such as ash (7.25%), crude fiber (32.70%), crude protein (15.94%), lignin (24.60%), cellulose (37.25%), fiber weight (3.06 g/plant), stick weight (32.08 g/plant), fiber: stick ratio (0.10), fiber diameter (26.97 µm), ultimate tensile strength (855.98 MPa), strength (58.92 g/tex), density (1.54 g/cm³), and luster (45.65%) compared with the control treatment (T0). The bioaccumulation factor (BAF) studies showed that the S. bispinosa plant was capable of accumulating selected heavy metals from the soil following the order: Fe > Mn > Zn > Cu > Cd > Cr. The study suggested a sustainable approach for efficient soil fertilization and high-quality S. bispinosa fiber production that could minimize the environmental pollution caused by the unsafe disposal of SS.