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摘要
Soil dissolved organic matter (DOM) greatly influences metal solid-solution partitioning. The heterogeneity dissolved organic carbon (DOC) of quality and quantity and their influences on metal speciation in subtropics agricultural soils are not well evaluated. A field survey was conducted to investigate DOC characteristics and their relationship with soil cadmium (Cd) and copper (Cu) partitioning. Both DOC concentrations and metal solid-solution coefficients (K-d) varied largely among different soils. Relatively low concentrations of soil DOC were observed in wide range of soil sites with > 90% of the soils below 100 mg L-1 and K-d were from 4.92 to 107.20 L kg(-1) and from 112.20 to 776.25 L kg(-1) for Cd and Cu, respectively. The absorbance spectral at 254 nm (SUVA(254)) represented aromatic strongly correlated with SUVA(260) (r = 0.999, P < 0.01) signified the hydrophobic components of DOM. The spectral slope ratio values (S-R) ranged from 0.15 to 2.58 with the values were near 1, implying that the DOM had similar sources with large molecular weight. The positive significant correlations were observed between spectral parameters (SUVA(254) and SUVA(260)) and K-d, with negatively correlation between S-R and K-d, further demonstrating that DOM structure characteristic with high aromaticity, hydrophobicity, or large molecular weight would be benefit for metals partitioning in soil solid phase. Soil OC, electric conductivity, and solution pH were important significant factors predicting DOC contents with R-2 increased from 0.22 to 0.74. Similarly, soil pH and soil OC were both the most important factors positively explaining the Cd and Cu partitioning variation with R-2 increased from 0.48 to 0.77.
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单位武汉大学
