Liao Min, Luo Yun-Kuo, Zhao Xiao-Min, Huang Chang-Yong
School of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310029, China.
J Zhejiang Univ Sci B. 2005 May;6(5):324-30. doi: 10.1631/jzus.2005.B0324.
Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity, including microbial biomass carbon (C(mic)), dehydrogenase activity (DHA) and basal respiration (BR), etc., C(mic), DHA, BR were used as bioindicators of the toxic effect of Cd in soil. This study was conducted to determine the effects of Cd on soil microbial biomass and its activity in a paddy soil. The inhibition of microbial biomass and its activity by different Cd concentrations was described by the kinetic model (M1) and the sigmoid dose-response model (M2) in order to calculate three ecological doses of Cd: ED(50), ED(10) and ED(5). Results showed that M2 was better fit than M1 for describing the ecological toxicity dose effect of cadmium on soil microbial biomass and its activity in a paddy soil. M2 for ED values (mg/kg soil) of C(mic), DHA, BR best fitted the measured paddy soil bioindicators. M2 showed that all ED values (mg/kg) increased in turn with increased incubation time. ED(50), ED(10) and ED(5) of C(mic) with M2 were increased in turn from 403.2, 141.1, 100.4 to 1000.7, 230.9, 144.8, respectively, after 10 d to 60 d of incubation. ED(50), ED(10) and ED(5) of DHA with M2 increased in turn from 67.6, 6.2, 1.5 to 101.1, 50.9, 41.0, respectively, after 10 d to 60 d of incubation. ED(50), ED(10) and ED(5) of BR with M2 increased in turn from 149.7, 6.5, 1.8 to 156.5, 50.8, 35.5, respectively, after 10 d to 60 d of incubation. So the ecological dose increased in turn with increased incubation time for M2 showed that toxicity of cadmium to soil microbial biomass and its activity was decreased with increased incubation time.
镉（Cd）在人类环境中广泛存在，对土壤微生物生物量或其活性具有毒性作用，包括微生物生物量碳（C(mic)）、脱氢酶活性（DHA）和基础呼吸（BR）等，C(mic)、DHA、BR被用作土壤中镉毒性效应的生物指标。本研究旨在确定镉对水稻土中土壤微生物生物量及其活性的影响。为了计算镉的三个生态剂量：ED(50)、ED(10)和ED(5)，采用动力学模型（M1）和S形剂量响应模型（M2）描述不同镉浓度对微生物生物量及其活性的抑制作用。结果表明，在描述镉对水稻土中土壤微生物生物量及其活性的生态毒性剂量效应方面，M2比M1拟合得更好。M2得出的C(mic)、DHA、BR的ED值（mg/kg土壤）与实测水稻土生物指标拟合度最佳。M2表明，随着培养时间的增加，所有ED值（mg/kg）依次增加。培养10 d至60 d后，M2得出的C(mic)的ED(50)、ED(10)和ED(5)分别从403.2、141.1、100.4依次增加到1000.7、230.9、144.8。培养10 d至60 d后，M2得出的DHA的ED(50)、ED(10)和ED(5)分别从67.6、6.2、1.5依次增加到101.1、50.9、41.0。培养10 d至60 d后，M2得出的BR的ED(50)、ED(10)和ED(5)分别从149.7、6.5、1.8依次增加到156.5、50.8、35.5。因此，M2显示随着培养时间增加生态剂量依次增加，表明镉对土壤微生物生物量及其活性的毒性随着培养时间增加而降低。
