改良剂对土壤铜镉有效性和微生物群落结构的影响

以一次性添加木炭、石灰和磷灰石稳定化修复4年后的土壤为研究对象,探讨了土壤中铜镉有效性和土壤微生物群落结构的变化.结果表明,3种改良剂的添加提高了土壤pH值,降低了土壤交换性酸和交换性铝的含量,使铜镉由活性态向非活性态和潜在活性态转化,其中磷灰石和石灰的处理效果优于木炭处理; Biolog测试发现,培养192h,木炭、石灰和磷灰石处理土壤AWCD值(0.61、0.76和0.70)分别是对照的1.33、1.65和1.52倍;且Shannon和McIntosh指数均较对照有所提高,表现为:石灰 > 磷灰石 > 木炭,表明改良剂处理后增加了土壤微生物对碳源的利用能力,提高了其功能多样性.PCR-DGGE分析结果显示,改良剂处理后土壤细菌优势群的数量显著增加,木炭、石灰和磷灰石处理Shannon指数分别比对照提高了0.22、0.39和0.24.相关性分析表明,土壤酸度和重金属有效性是影响稳定化修复重金属污染土壤细菌结构多样性差异的主要因素.

Availability of soil Cu and Cd and microbial community structure as affected by applications of amendments

Concentrations of available Cu and Cd, soil microbial community structure were investigated with one-time application of charcoal, lime, and apatite after four years in a heavy metal contaminated soil. Results showed that incorporation of amendments significantly increased soil pH, and decreased the concentrations of exchangeable acidity and aluminum. Lime and apatite were more effective than charcoal on transforming Cu and Cd from active to inactive fractions. The Biolog analysis showed that AWCD (average well color development) of charcoal (0.61), lime (0.76), and apatite (0.70) were 1.33, 1.65 and 1.52 times higher than that in the untreated soil at 192h. Moreover, the Shannon index, McIntosh index of soil microbes were higher in the amended soils compared with the control, and followed the order of lime > apatite > charcoal. The results indicated amendments treated soils all increased the abilities of the microbes to use carbon sources. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis showed that the amounts of dominant bacterial were significantly increased with the application of amendments. The Shannon index of soil microbes were increased 0.22, 0.39 and 0.24 in charcoal, lime and apatite compared with the control, respectively. Correlation analysis indicated that soil acidity and availability of Cu and Cd may be the main factors affecting the community structure of soil microbes in the soils.