摘要:
以土壤微生物生物量碳(Cmic)、土壤酶活性及微生物多样性为微生物学指标,以0.01mol·L-1 CaCl2 作为Cd有效态提取剂,以江西红壤和天津潮土为供试土壤,在室内25℃连续培养28d的条件下探讨了外源Cd对土壤微生物的生态毒理效应。结果表明:1)不同培养时间潮土CaCl2 提取态Cd含量均显著低于红壤,潮土微生物受到Cd的抑制作用也明显小于红壤。2)各微生物指标的敏感性不同,并受土壤类型和培养时间的影响,其中,脱氢酶的敏感性强于脲酶,微生物功能多样性指标中 Biolog Eco板上每孔的平均吸光值(AWCD)的敏感性强于Shannon指数;Cmic、脲酶、脱氢酶、AWCD和Shannon指数均在红壤中更为敏感。选取的5个微生物指标对Cd污染都有良好的响应,均可作为Cd污染土壤微生物生态毒理实验中的测试指标。在土壤酶指标中,可优先选取脱氢酶作为测试指标。3)Cd对Cmic、土壤酶、微生物功能多样性的抑制作用存在时间效应。14dCd对Cmic 的抑制作用大于28d,而对脲酶和脱氢酶的抑制作用小于28d。建议Cd污染土壤微生物生态毒理实验中将培养时间设置为28d或适当延长。4)28d时,红壤中Cd对Cmic、脱氢酶、脲酶、AWCD、Shannon指数的EC10 分别为1.31、0.26、0.93、0.08、22.71mg·kg-1,而在潮土中分别为1.97、0.69、13.12、0.09、>200mg·kg-1。
关键词:
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Cd
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红壤
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潮土
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微生物
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生态毒理
Abstract:
Soil microbial biomass C (Cmic), enzyme activities and microbial diversity were chosen as soil microbial indicators and the soil available Cd was determined by 0.01mol L-1 CaCl2 extraction. A laboratory incubation experiment was conducted to study toxic effects of Cd on soil microbial indicators in an udicferrosols from Jiangxi and an aquic-cambosols from Tianjin at 25℃ for 28 days. The results showed that CaCl2 -extractable Cd in aquic-cambosols was significantly lower than that in udic-ferrosols at different incubation time. And the microbial activity was less inhibited in the aquic-cambosols than that in the udic -ferrosols. The sensitivity of different microbial indicators to Cd was influenced by soil properties and incubation time. Dehydrogenase was more sensitive than urease. The average well color development (AWCD) was more sensitive as a microbial functional diversity index than Shannon index. All of the microbial indicators tested in aquic-cambosols were more sensitive in udic-ferrosols than these in aquiccambasols, which showed good response to exogenous Cd and therefore can be used in the microbial toxicity test of Cd pollution. There was significant time effect of Cd toxicity to soil microbial indicators. The toxic effect of Cd on Cmic at day 14was greater than that at day 28, but the toxic effect on dehydrogenase and urease at day 14was less than that at day 28. The 28-day incubation time was recommended for future microbial toxicity test of Cd pollution. At day 28, the EC10 of Cd for Cmic, dehydrogenase, urease, AWCD and Shannon index were 1.13, 0.26, 0.93, 0.08 and 22.71mg·kg-1 in udic-ferrosols, respectively. And in aquic-cambosols, the EC10 of Cd for these tested microbial indicators were 1.97, 0.69, 13.12, 0.09 and > 200mg·kg-1, respectively.
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