【摘要】 含硫有机化合物是水稻典型根系分泌物之一,土壤重金属具有优先与含硫有机官能团结合的趋势,研究含硫有机化合物对重金属铜的形态转化及生物有效性的影响可深入了解土壤铜的生物地球化学循环过程。通过室内淹水模拟实验,研究两种典型含硫有机化合物（半胱氨酸和甲硫氨酸）对铜形态转化的影响及其作用机制,以不添加任何含硫有机物的土壤作为对照,设置半胱氨酸(50、100 mg?kg^-1)、甲硫氨酸(50、100 mg?kg^-1)4个处理,保持5 cm左右的淹水层28 d,分别在淹水7、14、21、28d采集土壤样品,分析土壤理化性质及土壤中铜的化学形态。结果表明:随着淹水时间的延长,土壤pH先降低后升高,但含硫有机物的施加对pH影响不显著。淹水21 d后,施加含硫有机物提高了土壤CaCl₂提取态铜含量,而降低DTPA提取态铜含量,然而,淹水28 d后,DTPA提取态铜含量升高。同步辐射X射线近边吸收谱学（XANES）表明,淹水21d后,土壤铜的主要化学形态由缬氨酸铜、针铁矿铜及硫化亚铜组成,半胱氨酸和甲硫氨酸处理组中土壤缬氨酸铜类化合物占比分别增大15.9%和8.5%,与此同时针铁矿结合态铜占比分别降低19.3%和11.4%,且铜主要与缬氨酸的-NH₂结合。更多还原

【Abstract】 Organic compounds containing sulfur is one of the typical rice root exudates. Heavy metal has a very high affinity for reduced forms of organic sulfur, which makes it easier to bind with organic sulfur. Therefore, it is of critical importance to explore the effect of organic compounds containing sulfur on the speciation transformation of heavy metal copper（Cu） in paddy soil, which will enhance the understanding of the biogeochemical process of the Cu. By conducting laboratory flooding simulation experiment,two forms of organic compounds containing sulfur（cysteine and methionine） were applied in paddy soil to study their effect on the speciation transformation of Cu in soil. Soil without any addition of organic compounds containing sulfur was set as the control group, while cysteine(50, 100 mg?kg^-1) and methionine(50, 100 mg?kg^-1) was set as the four treatment groups. A 5 cm layer of deionized water above soil surface was kept to keep flooding condition for 28 d, soil sample was collected after 7 d, 14 d, 21 d and28 d respectively. The basic physicochemical property and the speciation of Cu in soil were analyzed. There was a trend of decrease first and then increase for the soil pH value with the extension of flooding time. However, the application of organic compounds containing sulfur showed no significant influence on soil pH value. The application of organic compounds containing sulfur increased the concentration of CaCl₂ extractable Cu in soil after flooding for 21 d, whereas, the concentration of DTPA extractable Cu in soil decreased. However, the concentration of DTPA extractable Cu in soil was increased by the application of organic compounds containing sulfur after 28 d’s flooding. The main speciation of Cu in soil after 21 d’s flooding was Cu-valine, Cu-goethite and Cu₂ S. The application of organic compounds containing sulfur increased the proportion of Cu-valine like compounds in soil flooded for 21 d. Compared with the control, addition of cysteine and methionine increased the proportion of Cu-valine by 15.9%and 8.5% respectively, while the proportion of Cu-goethite decreased by 19.3% and 11.4% respectively. Cu was more likely to bind with the function group of-NH₂ in valine.更多还原