应用in vitro法评估土壤性质对土壤中Pb的生物可给性的影响

Application of in Vitro Digestion Approach for Estimating Lead Bioaccessibility in Contaminated Soils: Influence of Soil Properties

选取22种典型土壤样品,应用2种in vitro(体外模拟)试验方法——SBET法(simple bioaccessibility extraction test,生物有效性简化提取法)和PBET法(physiologically-based extraction test,生物原理提取法),定量阐明土壤性质对Pb的生物可给性的影响.结果表明:①SBET法中Pb的生物可给性为18.78%～77.08%,平均值为44.14%;PBET法中Pb的生物可给性为0.72%～50.51%,平均值为13.77%.除赤红壤和贵州黄壤外,其余20种土壤样品均表现为SBET法中Pb的生物可给性显著高于PBET法,并且随着土壤pH的增长,2种方法的差距更加显著.②逐步回归分析结果表明,在SBET法中,对土壤Pb的生物可给性影响最大的因子是土壤中w(黏粒),其次为pH,二者可以解释69.49%的Pb的生物可给性的变化;在PBET法中,对土壤Pb的生物可给性影响最大的因子是pH,其次为w(黏粒),二者可以解释73.65%的Pb的生物可给性的变化.研究结果说明,污染土壤中Pb的生物可给性可以根据土壤pH和w(黏粒)进行预测.

A total of 22 samples of surface soil were collected from different areas in China to investigate the influence of soil properties on subsequent bioaccessibility of lead（Pb）.The bioaccessibility of Pb was evaluated by two in vitro extraction approaches.One is the simple bioaccessibility extraction test（SBET） and the other is the physiologically-based extraction test（PBET）.The results showed that： 1） the bioaccessibility of Pb for 22 soil samples extracted by SBET accounted for 18.78%-77.08% with 44.14% in average,while that extracted by PBET varied from 0.72%-50.51% with 13.77% in average.It was found that the bioaccessibility of Pb in soils extracted by SBET was significantly higher than that by PBET in 20 soil samples（except for latosolic red soil and yellow soil in Guizhou Province）.Differences between using two methods increased as soil pH increased.2） Under the circumstances of digestion study,multiple regression analysis showed that Pb bioaccessibility is related to pH level and clay content of soil.Using SBET method,the most important impact factor was clay content of soil and the next one was soil pH,while using PBET method,the most important one was soil pH and the second one was clay content of soil.These findings could provide the data that the bioaccessibility variation of Pb in 22 soil samples were 69.49% and 73.65% from SBET and PBET schemes,respectively.In conclusion,this investigation conveniently predicted potential ecological risks of Pb in soils by determining the properties（pH,clay content） of several soil types.