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| Variation of fluorescence spectrum of DOM and the behavior change of DOM complexed with Cu (Ⅱ) before and after vermicomposting of livestock excrement |
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Abstract Livestock excrement amended with sawdusts was vermicomposted and investigated for alterations of molecular weight and fluorescence spectrum of dissolved organic matter (DOM) before and after vermicomposting. The results demonstrated after earthworm treatment, the molecular weight of DOM decreased in general, and its distribution range became larger while its molecular weight was still higher than the treatment without earthworm. The content as well as the scale of molecular structure aromatization of fulvic acid in DOM after vermicomposting was significantly increased. The analysis of fluorescence spectrum in terms of DOM complexed with Cu(Ⅱ)further revealed the effect that fluorescence quenching of Cu (Ⅱ) on DOM was remarkable, and DOM from vermicompost was more likely to complex with Cu (Ⅱ) and could lead to a shortening of its straight chain or the pyrolysis of aromatic group. Groups such as —OH and —NH2 in DOM engaged in the complexation with Cu (Ⅱ). Moreover, fulvic acid in DOM after vermicomposting was more conducive to the complexation with Cu (Ⅱ).
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Received: 31 October 2011
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