Methane and nitrous oxide emissions from an irrigated rice of North India

Upland rice was grown in the kharif season (June-September) under irrigated condition in New Delhi, India (28 degree 40'N and 77 degree 12'E) to monitor CH4 and N2O emission, as influenced by fertilizer urea, ammonium sulphate and potassium nitrate alone (at 120 kg ha-1) and mixed with dicyandiamide (DCD), added at 10% of applied N. The experimental soil was a typic ustochrept (Inceptisol), clay loam, in which rice (Oryza sativa L., var. Pusa-169, duration: 120-125 days) was grown and CH4 and N2O was monitored for 105 days by closed chamber method, starting from the 5 days and 1 day after transplanting, respectively. Methane fluxes had a considerable temporal variation (CV=52-77%) and ranged from 0.05 (ammonium sulphate) to 3.77 mg m-2 h-1 (urea). There was a significant increase in the CH4 emission on the application of fertilizers while addition of DCD with fertilizers reduced emissions. Total CH4 emission (105 days) ranged from 24.5 to 37.2 kg ha-1. Nitrous oxide fluxes were much lower than CH4 fluxes and had ranged from 0.18 to 100.5 g m-2 h-1 with very high temporal variation (CV=69-143%). Total seasonal N2O emission from different treatments ranged from 0.037 to 0.186 kg ha-1 which was a N loss of 0.10-0.12% of applied N. All the fertilizers significantly increased seasonal N2O emission while application of DCD reduced N2O emissions significantly in the range of 10-53%.     

Mammalian cell line-based bioassays for toxicological evaluation of landfill leachate treated by Pseudomonas sp. ISTDF1

Landfill leachate has become a serious environmental concern because of the presence of many hazardous compounds which even at trace levels are a threat to human health and environment. Therefore, it is important to assess the toxicity of leachate generated and discharge it conforming to the safety standards. The present work examined the efficiency of an earlier reported Pseudomonas sp. strain ISTDF1 for detoxification of leachate collected from Okhla landfill site (New Delhi, India). GC-MS analysis performed after treatment showed the removal of compounds like alpha-limonene diepoxide, brominated dioxin-2-one, Bisphenol A, nitromusk, phthalate derivative, and nitrobenzene originally found in untreated leachate. ICP-AES analysis for heavy metals also showed reduction in concentrations of Zn, Cd, Cr, Fe, Ni, and Pb bringing them within the limit of safety discharge. Methyl tetrazolium (MTT) assay for cytotoxicity, alkaline comet assay for genotoxicity, and 7-ethoxyresorufin-O-deethylase (EROD) assay for dioxin-like behavior were carried out in human hepato-carcinoma cell line HepG2 to evaluate the toxic potential of treated and untreated leachates. The bacterium reduced toxicity as shown by 2.5-fold reduction of MTT EC₅₀ value, 7-fold reduction in Olive Tail Moment, and 2.8-fold reduction in EROD induction after 240 h of bacterial treatment.     

Bioaccumulation of nutrient elements from fly ash-amended soil in Jatropha curcas L.: a biofuel crop

Fly ash (FA) from coal-burning industries may be a potential inorganic soil amendment; the insight of its nutrient release and supply to soil may enhance their agricultural use. The study was conducted to assess the ability of fly ash (a coal fired thermal plant waste) to reduce soil fertility depletion and to study bioaccumulation of mineral nutrients in Jatropha curcas grown on soils amended with fly ash. Fly ash was amended to field soil at six rates (0, 5, 10, 20, 40, and 70 % w/w) on which J. curcas was grown. After 8 months of growth, the height of jatropha plants was significantly increased at 5 and 10 % FA-amended soil, whereas, biomass significantly increased at 5, 10, and 20 % FA-amended soil compared to control soil (0 % FA). Leaf nutrients uptake, followed by stems and roots uptake were highly affected by fly ash amendment to soil. Most of nutrients accumulation were increased up to 20 % fly ash and decreased thereafter. The results of available nutrient analysis of soil revealed that availability of nitrogen, potassium, sulfur, copper, iron, mangnese, and zinc declined significantly at higher levels of fly ash amendments, whereas, availability of phosphorus increased at these levels. However, pH, organic carbon, and available boron were not influenced significantly by fly ash amendment to soil. Microbial biomass C, N, and ratio of microbial-C to organic C were significantly reduced at 20 % fly ash and higher amounts. This study revealed that J. curcas plants could gainfully utilize the nutrients available in fly ash by subsequently amending soil.     

Lead content in new decorative paints in India

The paint industry in India is broadly classified into two categories: organized sector and unorganized sector. Multinational and big Indian companies form the organized sector, whereas the small- and medium-scale industries which produce paints for the local market form the unorganized sector. The present study was undertaken to determine the level of lead in decorative paints in India. A total of 148 paint samples sourced from four organized sector companies and six unorganized sector companies were analyzed for the total lead content. Results of this study reveal that 39 % of the total paints tested (n = 148) contain lead more than 300 ppm, the voluntary limit prescribed by Bureau of Indian Standards, BIS (IS 15489:2011), and 45 % of the tested paints contain lead more than 90 ppm, the US limit. Further analysis of the data indicates that only 5 % of the tested paints manufactured by organized sector companies contain lead more than 300 ppm (n = 91), whereas 93 % of the tested paints manufactured by unorganized sector companies contain lead more than 300 ppm (n = 57). Comparison with earlier reported data suggests that while organized sector companies are gradually abandoning the use of lead-based compounds in their paints, the unorganized sector companies are still adding lead-based compounds intentionally in their paints despite the potential health hazards associated with it. The maximum concentration of lead obtained was 80,350 ppm in one of the paints manufactured by an unorganized sector company. The presence of high concentration of lead in yellow and green color paints indicates that color can be a predictor of lead content in decorative paints.