北京市城郊土壤镉对小白菜的毒性及其影响因素

Cd Toxicity to Chinese Cabbage and Its Influencing Factors in Suburban Soil of Beijing

[目的]研究北京城郊土壤中Cd对小白菜的毒性,并探究其影响因素,为北京城郊土壤中Cd污染生态风险评价提供一定的科学依据.[方法]采集了北京城郊6个区县的土壤样品,外源添加不同浓度镉（Cd）后,通过盆栽试验研究了不同采样点土壤Cd对小白菜的毒性及其影响因素.[结果]当土壤Cd添加浓度在0～ 12 mg/kg范围内变化时,小白菜均能正常生长,地上部生物量随土壤Cd浓度变化无规律.6个采样点小白菜地上部Cd含量与土壤总Cd及有效态Cd浓度均呈0.05水平显著的线性相关性,但土壤之间小白菜地上部Cd含量与总Cd的线性方程的斜率变化倍数（2.24）要大于有效态的斜率变化（1.34）,且所有处理（n=36）中土壤有效态Cd浓度与小白菜地上部Cd含量的相关关系（R^2=0.86,P＜0.001）优于土壤总Cd （R^2 =0.81,P＜0.001）.[结论]土壤有机质和CEC是北京城郊土壤Cd毒性的主要影响因素.利用DTPA提取的有效态Cd能更好地表示不同理化性质土壤中Cd的毒性.

[Objective] Cd toxicity to Chinese cabbage and its influencing factors in suburban soil of Beijing were studied aiming to provide certain scientific basis for ecological risk evaluation of Cd pollution in this area.[Method] Soil samples from six districts of Beijing suburban were collected to investigate Cd toxicity to Chinese cabbage and its influencing factors by pot experiment.[Result] Chinese cabbage could grow normally with the increase of Cd concentration from 0 mg/kg to 12 mg/kg,and their aboveground biomass also didn＇ t change significantly.It was found that there were significant linear relationship between Cd content in aerial part and soil total Cd and available Cd concentration at each sampling point,but the slopes of the former （2.24） was greater than that of the latter （1.34）.The correlation between Cd content in aerial part of Chinese cabbage and the available Cd （R^2 =0.86,P 〈 0.001） appeared more significantly than the concentration of total Cd （R^2 =0.81,P 〈 0.001） when all treatments （n =36） were taken into consideration.[Conclusion] The soil organic matter and CEC were the main factors influencing the Cd toxicity.The available Cd using DTPA could better represent the toxicity of Cd in soil that had different physical and chemical properties.