土壤中金属的生物可给性常应用于人体健康风险评价，如能准确地判定土壤中金属在胃肠阶段不同时间的溶出动态，研究者就可以更好地分析其对人体的健康风险。本文采集5种不同地区的重金属污染的土壤，利用改进的PBET方法，分别在胃阶段的20、40、60、80 min以及小肠阶段的1、2、3、4、5 h时取样并分析，探究土壤中8种金属元素（As、Al、Cd、Cr、Fe、Mn、Ni、Pb）的生物可给性和溶出动态，探讨造成金属溶出动态变化的影响因素，对其溶出机理进行初步探究。研究结果表明，Fe、Al的生物可给性较低，并且在胃肠阶段差异较小。与胃阶段相比，土壤中Pb、Cd的生物可给性在小肠阶段明显降低，而As、Mn、Cr、Ni的生物可给性在小肠阶段均升高。升幅最大的两个元素是Ni、Cr，其小肠阶段的平均生物可给性分别升高61.4%、29.9%。在溶出量随时间变化方面，在胃阶段，假定1 h时溶出率为100%。20 min时，土壤中Fe、Ni的平均溶出率较低，分别为59.3%、56.8%，其他6种金属元素的平均溶出率在71.2%~79.5%。As、Cd、Pb的溶出速率是先快后慢，Cr和Ni的溶出速率是先慢后快，而Fe、Mn、Al的溶出速率基本保持不变。在小肠阶段，假定4 h时溶出率为100%。Al、As、Cd、Mn的溶出率基本不变。1 h时，土壤中Cr（土壤A除外）、Ni的平均溶出率最低，分别为31.5%、32.7%，而5 h时，Fe、Cr、Ni的溶出率还在升高。由此可见，土壤中不同金属元素的生物可给性以及溶出动态是有明显差异的。%Bioaccessibility is always used in assessing human health risk, and the accurate determination of metal dynamic dissolution in the gastrointestinal phase can better understand of their harm to human health. In this paper, five soil samples were collected from different sites of China, and the bioaccessibility of these metals were determined by the modified PBET (Physiologically based extraction test) method. The sampling time were 20, 40, 60, 80 min for the gastric phase and 1, 2, 3, 4, 5 h for the small intestinal phase, respectively. The bioaccessibility and dynamic dissolution of eight metals (As, Al, Cd, Cr, Fe, Mn, Ni, Pb) were studied, and the influence factors and dissolution mechanism were studied. The results showed that the bioaccessibility of Fe and Al was almost same in the gastrointestinal phase. Compared with the results of the gastric phase, the bioaccessibility of Pb and Cd decreased distinctly in the small intestinal phase, while the bioaccessibility of As, Mn, Cr and Ni increased in the small intestinal phase. The highest increase of bioaccessibility were 61.4%and 29.9%for Ni and Cr, respectively. In the gastric phase, dissolution rate of soil metals was assumed to be 100%for the results of one hour. On 20 min, the dissolution rate of Fe and Ni was lower, 59.3%and 56.8%of the results of one hour respectively, and dissolution rate of other metals ranged from 71.2~79.5%. The dissolved speed of As, Cd and Pb appeared quickly first then became slow, while the trend was opposite for Cr and Ni, and Fe, Mn and Al increased at a steady speed. In the small intestine phase, dissolution rate of soil metals was assumed to be 100%for the results of four hour. The dissolution rate of Al, As, Cd and Mn remain unchanged. On one hour, dissolution rate of Cr (soil A excepted) and Ni was lower, 31.5%and 32.7%of the results of four hour respectively. On five hour, dissolution rate of Fe, Cr and Ni still increased. It’s obvious that bioaccessibility and dynamic dissolution of soil metals displayed a marked difference.
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