The dynamics of dissolved organic matter and associated water-soluble Cu in two Cu-contaminated soils amended with various organic matters
施用有机物料对污染土壤水溶性有机物和铜活性的动态影响

The changes of dissolved organic matter (DOM) and the associated Cu in Cu contaminated acidic and calcareous soils amended with green manure (Vicia faba L.), pig manure and sewage sludge were studied by pot experiment with ryegrass to explore organic wastes derived DOM effect on soil Cu dissolution and bioavailability. As compared to control without addition of organic wastes, the concentration of DOM in the organic wastes treated soils increased drastically by 0.4-7.5 folds in the initial phase, depending on organic wastes origins. The green manure treated soils exhibited the highest DOM level followed by the pig manure amended soil. However, DOM concentration in the treated soils reduced markedly as time elapsed due to DOM biodegradation, especially in the first week after the organic wastes application. The DOM decomposition rates of the soil treated with green manure, pig manure and sewage sludge were 65%,37.8% and 27%,respectively. It was found that DOM enhanced Cu dissolution greatly in two Cu contaminated soils amended with green manure and pig manure. In the initial application phase, water soluble Cu concentration were 3.6-5 times and 0 6 times higher in the green manure and pig manure treated soils than that in the control, The soluble Cu concentration was reduced with the decrease of DOM in the soils, exhibiting an obvious positive linear correlation. However, difference in the soluble Cu concentration between the sewage sludge treated soil and the control was not observed. Furthermore, copper uptake by ryegrass increased by 1.4-2.1 times in Cu contaminated calcareous soil and 1.4-1.6 times in Cu contaminated acidic soil due to the application of green manure and pig manure. On the contrast, the incorporation of sewage sludge into two tested soils resulted in the decrease of Cu uptake by ryegrass.