基于我国人群胃肠消化特征的土壤中As的人体可给性研究

基于我国人群胃肠消化特征，采用医学配方模拟胃肠消化方法测试了来自大连、湖南和广西的13个受重金属污染土壤中As的人体可给性，分析了土壤理化参数与可给性的相关关系及提取液中酶、胃肠液pH值、提取时间对As的人体可给性的影响.结果表明，医学配方可给性测试中，供试土样在胃、肠阶段As的人体可给性分别为5.03%~44.54%和10.77%~51.46%，平均值为18.08%、29.32%.胃阶段As的可给性浓度与土壤中总As含量w（TAs）、总P含量w（TP）极显著正相关，与总Al含量w（TAl）、土壤pH值、总有机质含量w（TOM）显著相关；肠阶段As的可给性浓度与土壤中w（TAs）、胃阶段As的可给性浓度、w（TP）极显著相关，与土壤pH值、w（TAl）和w（TOM）显著相关.胃阶段提取液中的胃蛋白酶显著降低了As的可给性，而肠阶段添加胰蛋白酶As的可给性没有明显变化.胃、肠阶段分别在pH值为0.9和5.0时可给性最大，0.9和5.0可分别作为土壤As在可给性测试过程中模拟胃肠液的pH值.胃、肠阶段在提取时间分别为1.0h、4.0h时可给性达到最大，且之后基本不变，1.0h、4.0h可作为模拟测试As在胃肠中可给性的提取时间.研究结果表明开展基于我国人群胃肠消化特征的土壤重金属人体可给性测试方法具有重要意义.

Study on arsenic bioaccessibility in soil based on Chinese gastrointestinal digestion characteristics

In order to considering the digestive characteristics of Chinese people, gastric and intestinal juice formulated in the Chinese Pharmacopoeia were used as digestive solutions in measuring as bioaccessibility of 13 soil samples collected from Dalian, Hunan and Guangxi in this study. The correlation between soil physicochemical parameters and As bioaccessibility was investigated, and the effects of enzymes and the pH of gastrointestinal fluid as well as the digestive duration on As bioaccessibility were explored. The results showed that the bioaccessibility of As in stomach and intestine were 5.03%~44.54% and 10.77%~51.46% respectively, with the arithmetic means at 18.08% and 29.32%. Two most significant factors influencing the As bioaccessibility in stomach were w(TAs) and w(TP), followed by w(TAl), pH of soil samples and w(TOM). The most significant factors in intestine were w(TAs), bioaccessible As in stomach and w(TP), followed by pH of soil samples, w(TAl) and w(TOM). The bioaccessible As in stomach was decreased due to the addition of pepsin while no significant change was observed by adding typsin to the digestive solution in intestine. The bioaccessibility of As reached the peaks at the pH 0.9 and 5.0 in stomach and intestine respectively and approach the maximum levels relatively stable by about 1.0h and 4.0h of extraction in stomach and intestine respectively. Therefore, digestion simulations for 1.0h in stomach fluid at pH 0.9 and for 4.0h in intestine fluid at pH 5.0 were recommended for As bioaccessibility measurement. The study also indicates that it is of great significance to further developing the bioaccessibility method based on the characteristics of Chinese gastrointestinal digestion.