Tang X-Y, Zhu Y-G, Chen S-B, Tang L-L, Chen X-P
Research Center for Eco-environmental Sciences, Chinese Academy of Sciences, 18 Shuanging Road, Beijing 100085, PR China.
Environ Int. 2004 Jun;30(4):531-7. doi: 10.1016/j.envint.2003.10.008.
The addition of P-containing amendments was found to effectively reduce the bioaccessibility of Pb in soils to the human, using an in vitro test. For all treatments with P additions, the removal of soluble Pb in the small intestinal phase was observed. The effectiveness of various P treatments in the small intestinal phase generally followed this order at the equivalent P addition level: hydroxyapatite (HA)>phosphate rock (PR)>HA+single super-phosphate (SSP)>SSP. The relatively low effectiveness of P amendments at the gastric phase may be explained by the high solubility of pyromorphite at relatively low pH of 1.7, compared with that at the neutral small intestinal pH. Single super-phosphate showed the best performance in minimizing the bioaccessibility of Pb in the gastric phase, possibly due to its highest solubility at pH 1.7. Single super-phosphate showed the best performance in minimizing the bioaccessibility of Pb in gastric phase, possibly due its highest solubility at pH 1.7. However, in the small intestinal phase, SSP appears to be the least effective amendment, possibly due to its lowest Ca supply level to replace Pb form exchangeable sites, as reflected by its lowest molar Ca/P ratio of 1:2. The disagreement of the sequential extraction results with that of the in vitro test results indicated that the sequential extraction was not suitable for the assessment of the effect of P addition on minimizing the bioaccessibility of Pb to human due to the formation of pyromorphite during the extraction procedure. Results from this study also suggested that the time required for the in vitro test might be shortened for fast screening.
通过体外试验发现，添加含磷改良剂可有效降低土壤中铅对人体的生物可及性。对于所有添加磷的处理，在小肠阶段均观察到可溶性铅的去除。在等效磷添加水平下，小肠阶段各种磷处理的有效性一般遵循以下顺序：羟基磷灰石（HA）>磷矿石（PR）>HA + 过磷酸钙（SSP）>过磷酸钙（SSP）。与中性小肠pH值下相比，在胃酸阶段磷改良剂效果相对较低可能是由于在pH值为1.7时磷氯铅矿的高溶解度。过磷酸钙在胃酸阶段使铅的生物可及性降至最低方面表现最佳，这可能是由于其在pH值为1.7时的溶解度最高。过磷酸钙在使胃酸阶段铅的生物可及性降至最低方面表现最佳，这可能是由于其在pH值为1.7时的溶解度最高。然而，在小肠阶段，过磷酸钙似乎是效果最差的改良剂，这可能是由于其向可交换位点提供用于替代铅的钙的水平最低，这从其最低的钙磷摩尔比1:2中可以看出。连续萃取结果与体外试验结果不一致，这表明由于在萃取过程中形成了磷氯铅矿，连续萃取不适用于评估添加磷对降低铅对人体生物可及性的影响。本研究结果还表明，体外试验所需时间可能可以缩短以进行快速筛选。
