Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Resource Science, Hangzhou 310058, China.
Environ Sci Pollut Res Int. 2013 May;20(5):3140-8. doi: 10.1007/s11356-012-1234-0. Epub 2012 Oct 7.
In vitro digestion test can be applied to evaluate the bioaccessibility of soil metals by measuring the solubility of the metals in synthetic human digestive tract. Physiologically based extraction test (PBET), composed of sequential digestion of gastric and intestinal phase, is one of the frequently used in vitro digestion tests. In this study, the PBET was chosen to determine the bioaccessibility of Cu, Zn, and Pb in 14 mildly acidic and alkali (pH 5.87-8.30) soils. The phytoavailability of Cu, Zn, and Pb in the same soils was also measured using six single-extraction methods (0.1 M HNO₃, 0.4 M HOAc, 0.1 M NaNO₃, 0.01 M CaCl₂, 0.05 M EDTA, and 0.5 M DTPA). The extraction efficiencies of the methods were compared. The PBET had a strong ability to extract metals from soil, which was much greater than neutral salt extraction and close to dilute acid and complex extraction in spite of the last 2 h neutral intestinal digestion. The amounts of bioaccessible Cu, Zn, and Pb in the gastric phase and in the gastrointestinal phase were both largely determined by the total content of soil Cu, Zn, and Pb. But the results of gastrointestinal digestion reflected more differences resulting from element and soil types than those of gastric digestion did. It was noticed that most of variations in the amounts of soil Cu, Zn, and Pb extracted by EDTA were well explained by the total soil Cu, Zn, and Pb, as same as the PBET. Moreover, the solubility of Cu, Zn, and Pb in the gastric phase and gastrointestinal phase were all positively linearly correlated with the results of EDTA. It was suggested that EDTA extraction can be used to predict the bioaccessibility of Cu, Zn, and Pb in mildly acidic and alkali (pH > 5.8) soils, and the PBET and EDTA could be applied to measure, in a certain extent, the bioaccessibility and phytoavailability of Cu, Zn, and Pb in mildly acidic and alkali (pH > 5.8) soils at the same time.
体外消化试验可用于通过测量金属在合成人体消化道中的溶解度来评估土壤金属的生物可利用性。生理基础提取试验（PBET）由胃和肠相的顺序消化组成，是常用的体外消化试验之一。在这项研究中，选择 PBET 来确定 14 种微酸性和碱性（pH 5.87-8.30）土壤中 Cu、Zn 和 Pb 的生物可利用性。还使用六种单一提取方法（0.1 M HNO₃、0.4 M HOAc、0.1 M NaNO₃、0.01 M CaCl₂、0.05 M EDTA 和 0.5 M DTPA）测量了相同土壤中 Cu、Zn 和 Pb 的植物可利用性。比较了方法的提取效率。尽管最后 2 小时是中性肠道消化，但 PBET 具有从土壤中提取金属的强大能力，这比中性盐提取更强大，接近于稀酸和络合提取。胃相和胃肠相中的可生物利用的 Cu、Zn 和 Pb 量主要由土壤 Cu、Zn 和 Pb 的总量决定。但胃肠消化的结果反映了更多由于元素和土壤类型的差异，而不是胃消化的结果。注意到，EDTA 提取的土壤 Cu、Zn 和 Pb 量的大部分变化都可以很好地用总土壤 Cu、Zn 和 Pb 来解释，就像 PBET 一样。此外，Cu、Zn 和 Pb 在胃相和胃肠相中的溶解度均与 EDTA 的结果呈正线性相关。建议可以使用 EDTA 提取来预测微酸性和碱性（pH>5.8）土壤中 Cu、Zn 和 Pb 的生物可利用性，同时 PBET 和 EDTA 可以在一定程度上测量微酸性和碱性（pH>5.8）土壤中 Cu、Zn 和 Pb 的生物可利用性和植物可利用性。
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