This investigation was undertaken to determine the effect of two different fly ashes [Kota and Inderprastha (IP)] amendment on the sorption behavior of metribuzin in three Indian soil types. The IP fly ash was very effective in increasing the metribuzin sorption in the soils. The sorption with IP amendment was increased by 15-92%, whereas with the Kota fly ash an increase in sorption by 13-38% was noted. The adsorption isotherms fitted very well to the Freundlich adsorption equation and, in general, slope (1/n) values less then unity were observed. Although both the fly ashes significantly decreased metribuzin desorption, the IP fly ash was comparatively more effective in retaining metribuzin in the soils. Metribuzin sorption in the IP fly ash-amended soils showed strong correlation with the fly ash content and compared to K(f)/K(d) values, K(FA) values (sorption normalized to fly ash content) showed less variation. Metribuzin sorption-desorption did not correlate to the organic carbon content of the soil-fly ash mixture. The study demonstrates that all coal fly ashes may not be effective in enhancing the sorption of metribuzin in soils to the same extent. However, among the fly ashes used in this study, the IP fly ash was observed to be significantly effective in enhancing the sorption of metribuzin in soils. This may play an important role in reducing the run off and leaching losses of the herbicide by retaining it in the soil.
"The results suggested a considerable reduction in the leaching losses of metribuzin in CFA-amended columns of all the three soil types and the effect increased with the level of CFA applied. The high efficiency of CFA in reducing the downward mobility of metribuzin in soils might be due to its high sorption affinity, as supported by findings of 15e92% increase in metribuzin sorption by three Indian soils; the effect though varied across the two CFAs and three soils used (Singh et al., 2012). These results demonstrate that not all coal fly ashes may be effective in enhancing the sorption of metribuzin in soils to the same extent. "
[Show abstract][Hide abstract] ABSTRACT: Coal fly ash (CFA), a by-product of coal combustion has been regarded as a problematic solid waste, mainly due to its potentially toxic trace elements, PTEs (e.g. Cd, Cr, Ni, Pb) and organic compounds (e.g. PCBs, PAHs) content. However, CFA is a useful source of essential plant nutrients (e.g. Ca, Mg, K, P, S, B, Fe, Cu and Zn). Uncontrolled land disposal of CFA is likely to cause undesirable changes in soil conditions, including contamination with PTEs, PAHs and PCBs. Prudent CFA land application offers considerable opportunities, particularly for nutrient supplementation, pH correction and ameliorating soil physical conditions (soil compaction, water retention and drainage). Since CFA contains little or no N and organic carbon, and CFA-borne P is not readily plant available, a mixture of CFA and manure or sewage sludge (SS) is better suited than CFA alone. Additionally, land application of such a mixture can mitigate the mobility of SS-borne PTEs, which is known to increase following cessation of SS application. Research analysis further shows that application of alkaline CFA with or without other amendments can help remediate at least marginally metal contaminated soils by immobilisation of mobile metal forms.
[Show abstract][Hide abstract] ABSTRACT: Application of low cost amendment for pesticide retention in soil is an important area of research in environmental sciences. The present study reports the potential of coal fly ash (Inderprastha and Badarpur), a waste from thermal power stations, for retaining soil applied metolachlor and atrazine within the application zone. Both the fly ashes were highly effective in reducing the leaching losses of metolachlor and atrazine and at 2% and 5% fly ash amendment levels the herbicides were retained in the top 15 cm profile of the column. However, fly ashes varied in their capacity in reducing the downward mobility of herbicides, as the Inderprastha fly ash was more effective than the Badarpur fly ash. Although fly ash contained heavy metals like Cr, Cu or Pb, but they were not detected in the leachate. Also, concentration of other metals like Zn, Mn and Fe in leachate decreased after fly ash amendment. Results of this study have implications in reducing the leaching losses of these herbicides in agricultural soils.
[Show abstract][Hide abstract] ABSTRACT: This study reports the effect of fly ash amendment on persistence of metribuzin in three Indian soil types. Fly ash [Inderprastha (IP) and Kota] was amended at 1, 2 and 5% levels. Metribuzin was more persistent in the flooded soils (predominantly anaerobic) than the nonflooded (aerobic) soils. Kota fly ash amendment to nonflooded soils slightly enhanced metribuzin persistence while IP fly ash reduced the herbicide persistence in nonflooded soils. In flooded soils both types of fly ash reduced metribuzin persistence, but the extent of the effect was specific to the soil and type of fly ash. A better effect was observed in low organic matter soils and IP fly ash was more effective than the Kota fly ash. The effect of fly ash amendment on metribuzin degradation in soils was more pronounced at higher dose of fly ash. No degradation of metribuzin was observed in the sterilized soils, both without and with fly ash, suggesting that degradation of metribuzin was microbial in nature. Deaminometribuzin was recovered as the only metabolite of metribuzin degradation.
Journal of Environmental Science and Health Part B 01/2013; 48(2):108-13. DOI:10.1080/03601234.2013.726893 · 1.20 Impact Factor
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