Degradation of nitroaromatic herbicides in wetland sediments

详细信息    Degradation of nitroaromatic herbicides in wetland sediments

• 出版日期：2002.
• 页数：112 p. :
• 第一责任说明：Theodore Paul Klupinski.
• 分类号：a875.4
• ISBN：0493634436(ebk.) :

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02h0026378 20111128111904.0 cr un||||||||| 111128s2002 xx ||||f|||d||||||||eng | AAI3049053 0493634436(ebk.) : CNY371.35 NGL NGL NGL a875.4 Klupinski, Theodore Paul. Degradation of nitroaromatic herbicides in wetland sediments [electronic resource] / Theodore Paul Klupinski. 2002. 112 p. : digital, PDF file. Source: Dissertation Abstracts International, Volume: 63-04, Section: B, page: 1761. ; Adviser: Yu-Ping Chin. Thesis (Ph.D.)--The Ohio State University, 2002. Includes bibliographical references. Contamination of surface waters and sediments from nonpoint sources is a major environmental concern. Pesticides and herbicides contribute significantly to this problem due to their widespread usage on agricultural land, from which they can be transported by surface runoff. In wetlands and lakes, these compounds may exhibit a variety of behaviors, including degradation, persistence in the water column, or sorption to sediments. As many pesticides/herbicides may pose toxic risks, it is important to understand the factors that influence the fate of these contaminants in surface waters. This dissertation discusses the role of abiotic reactions in the sediment-mediated degradation of two nitroaromatic herbicides: trifluralin (2,6-dinitro-N,N-dipropyl-4-(trifluoromethyl)benzenamine) and pentachloronitrobenzene (C6Cl5NO2).;Laboratory reactions were conducted in mixtures of Fe(II) and goethite (α-FeOOH). Both herbicides reacted rapidly in the presence of 500 μM Fe(II) and 100 mg/L goethite at near-neutral pHs. These conditions are comparable to those that have been observed in natural sediments, suggesting the potential environmental relevance of these results.;In the Fe(II)/goethite media, trifluralin is degraded to yield at least eight intermediates and five products. The results revealed the occurrence of three distinct reaction pathways: reduction of nitro groups, dealkylation of propylamines, and cyclization to form benzimidazoles. The observed products have all been reported by others in field studies of trifluralin degradation, which was generally assumed to be a biologically mediated process.;C6Cl5NO2 reacted with Fe(II)/goethite to yield only the reduced product pentachloroaniline (C6Cl 5NH2). Extensive kinetics studies suggested that the reaction may be correlated with a distinct sorbed Fe(II) species, rather than with the total amount of sorbed Fe(II). Additionally, the reactions do not display true second-order kinetic behavior, indicating that the surface association of C6Cl5NO2 may affect the degradation rate.;Finally, C6Cl5NO2 was degraded in porewaters isolated from the sediments of a freshwater wetland. The measured rate constants are consistent with the hypothesis that Fe(II)/iron oxides promote the reaction. In total, the results of this research demonstrate that abiotic reactions in sediments may significantly influence the environmental fate of nitroaromatic herbicides. Herbicides Biodegradation. Electronic books. aeBook. aCN bNGL http://proquest.calis.edu.cn/umi/detail_usmark.jsp?searchword=pub_number%3DAAI3049053&singlesearch=no&channelid=%CF%B8%C0%C0&record=1 NGL Bs1091 rCNY371.35 ; h1 bs1108