纳米羟基磷灰石对铅镉污染土壤重金属生物可给性的影响研究

Effects of Nano-hydroxyapatite on the Bioaccessibility of Heavy Metals in Soils Polluted by Pb and Cd

通过实验室模拟的方法,分别制备3种污染处理土壤:Pb污染土壤、Cd污染土壤与Pb-Cd复合污染土壤,然后分别向3种污染处理土壤中添加纳米羟基磷灰石,培养180 d,定期采样,并采取两种体外仿生消化方法——PBET法(Physiologically-Based Extraction Test)和USPM法(United States Pharmacopeia Methodology)模拟胃液测定土壤中Pb、Cd的生物可给性,通过对比分析,评价纳米羟基磷灰石对污染土壤重金属生物可给性的影响。研究结果表明,纳米羟基磷灰石显著降低了PBET法对土壤Pb、Cd的提取量,与对照相比,分别下降了44.84%和42.96%。Pb-Cd复合污染明显提高了PBET法对土壤Cd的提取量,但纳米羟基磷灰石处理与复合污染均没有显著影响USPM法对土壤Pb、Cd的提取量。PBET法对土壤Pb、Cd的提取结果与土壤p H值和修复处理呈显著负相关关系;而USPM法对土壤Pb、Cd的提取结果与培养时间呈显著负相关关系。PBET法与USPM法对土壤重金属的提取结果之间不存在显著相关关系,且USPM法对土壤重金属的提取能力显著高于PBET法。USPM法对土壤Pb、Cd的提取量平均分别为PBET法的2.4倍和1.9倍。

Pb-polluted,Cd-polluted and Pb-Cd polluted soils were prepared respectively in the lab.The polluted soils were incubatedfor180days and sampled regularly after nano-hydroxyapatite(n-HAP)treatment.The bioaccessibility of Pb and Cd in soils wasdetermined by the mimic gastric juices of two in-vitro digestion tests:USPM(United States Pharmacopeia Methodology)and PBET(Physiologically-Based Extraction Test).The effects of n-HAP on the bioaccessibility of soil Pb and Cd were assessed.The resultsshowed that n-HAP treatment decreased significantly the extracted amounts of Pb and Cd from soils by PBET,which declined by44.84%and42.96%compared to the control soil,respectively.Joint pollution of Pb and Cd promoted obviously the extractedamounts of Pb from soils by PBET.However,n-HAP treatment and joint pollution of Pb and Cd affected barely the extractedamounts of Pb and Cd from soils by USPM.The extracted amounts of Pb and Cd from soils by PBET showed significant negativerelationship with soil pH and n-HAP treatment while the extracted amounts of Pb and Cd from soils by USPM exhibited significantnegative relationship with incubation time.The bioaccessibility of soil Pb and Cd based on PBET was not significantly correlatedwith the corresponding extraction results by USPM.The ability of USPM to extract Pb and Cd from soils was much higher thanPBET.The extracted amounts of Pb and Cd from soils by USPM were respectively2.4and1.9times as much as that by PBET.