土壤中六六六在消化道中生物可给性的体外测定

采用体外消化实验模拟了4种有机质含量不同的土壤中六六六在胃和小肠中的释放,重点验证了消化释放出来的六六六在固态消化残渣上的吸着现象以及该现象对测定消化率的影响的研究假设.结果表明,固相吸着对测定消化率有非常显著的影响,这在有机质含量偏高的土壤中尤其明显.吸着影响可以用不同液固比实验设计配合非线性拟合方法加以校正.对有机碳含量分别为0.63%、1.08%、1.60%和2.87%的4种土壤,未经校正的总六六六消化率的均值与标准差分别为(16.7±2.8)%、(11.6±2.0)%、6.9%和(26.4±1.3)%,校正后则分别达到16.7%、16.5%、16.5%和59.7%.显然,除有机质含量很低的样品,未经校正的测定结果显著低估了消化道吸收风险.

In-Vitro Determination of Bioaccessibility of Hexachlorocyclohexane in Soils in a Model Digestive System

An in vitro digestion model was used to mimic gastrointestinal digestion so as to determine bioaccessibility of hexachlorocyclohexane (HCHs) in soil. Four surface soil samples with various levels of contamination and organic matter contents were collected for the experiment without further spiking. A key hypothesis to be tested is that the sorption of a fraction of HCHs mobilized from soil into the digestive fluid on the solid phase leads to underestimation of the digestion coefficients. It was demonstrated that there were significant influence of the sorption on the results and the underestimation could be corrected by a multiple fluid/soil ratios experimental design. Without correction, the directly measured digestion coefficients were(16.7±2.8)%,(11.6±2.0)%, 6.9% and(26.4±1.3)% for soils with organic carbon contents of 0.63%, 1.08%, 1.60% and 2.87%, respectively, while the true values were 16.7%, 16.5%, 16.5% and 59.7%.