Sustained release of Zn from zinc sulfide nanoparticles (ZnS NPs) amplified the bioaccessibility of Zn in soil: Adsorption dynamics and dissolution kinetics.

Controlled-release micronutrient supplementation to provide better bioavailable zinc (Zn) under alkaline soil conditions is a concept of commercial pertinence for sustainable agriculture. High pH stable nano-scaled ZnS is the material under study in the present investigation where the adsorption dynamics and dissolution kinetics of sono-chemically synthesized zinc sulfide nanoparticles (ZnS NPs) were evaluated in comparison to ZnSO4 in Lufa 2.2 soil for supplementation of Zn. The mechanism of adsorption of ZnS NPs and ZnSO4 onto Lufa 2.2 soil was well explained by fitting into the Freundlich adsorption model and pseudo-second order equation. ZnS NPs reflected the stronger ability to get adsorbed on the Lufa 2.2 soil as compared to metal ions, due to higher surface reactivity of NPs and higher Kf value (0.557) than ZnSO4 (0.463). Time relevant enhancement in extractability of Zn from ZnS NPs amended soil and diminution in extractability of Zn from ZnSO4 spiked soil was observed in bioavailability studies. The increased labile pool of Zn from ZnS NPs amended soil over time was due to their slow dissolution in soil and could be adjusted to consider as "sustained released ZnS NPs". Dissolution of ZnS nanoparticles (NPs) in Lufa 2.2 soil adhered to the first-order extraction model, exhibiting extended half-lives of 27.72 days (low dose) and 28.87 days (high dose). This supported prolonged stability, increased reactivity, and reduced ecological risk compared to conventional Zn salt fertilizers, promoting enhanced crop productivity.

Exploring the combined effect of heavy metals on accumulation efficiency of Salix alba raised on lead and cadmium contaminated soils.

The present study illustrated that Salix alba can accumulate high level of Pb and Cd in different plant parts, with maximum accumulation in roots followed by stem and leaves in the order Cd > Pb > Cd + Pb. The phytoremediation evaluation factors such as bioconcentration factor (BCF) and translocation factor (TF) was higher for Cd over Pb in all plant parts, further the BCF for both Pb and Cd was maximum in root (BCF > 1) followed by stem and leaves. Higher accumulation of Cd over the Pb was observed inside the plant tissues due to Cd mimics with other elements and gets transported through respective transporters. The combined treatment of Pb and Cd affected the bioaccumulation at every treatment level suggesting the negative effect among both elements. Higher survival rate (>85%) was recorded up to 200mgPb/kg and 15mgCd/kg, while further increase in metal concentration reduced the plant efficiency to remediate contaminated soils, hence results in declined survival rate. The FTIR analysis revealed that Pb and Cd accumulation in plants induced changes in carboxy, amino, hydroxyl and phosphate groups that ultimately caused alteration in physiological and biochemical processes of plant and thus provided an insight to the interaction, binding and accumulation of heavy metals.

The present study conferred that Salix alba is a heavy metal (Pb and Cd) excluder plant on the basis of phytoremediation efficiency evaluation factors such BCF >1 (root) and TF <1. The correlation studies suggested the negative correlation among Pb and Cd accumulation and morphological traits. Physiological studies indicated that Pb and Cd accumulation negatively affect chlorophyll concentration and the antioxidant mechanism of plants gets activated, further these results are confirmed with FTIR studies, which reported the alteration in functional groups and associated compounds in plant tissues under Pb and Cd stress.

Reflecting on changes in the drinking and irrigation water quality of rivers Beas, Satluj and confluence waters.

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.