香港土壤研究Ⅶ.BCR提取法研究重金属的形态及其潜在环境风险

HONG KONG SOIL RESEARCHES Ⅶ.RESEARCH ON FRACTIONS OF HEAVY METALS AND THEIR POTENTIAL ENVIRON-MENTAL RISKS IN SOIL BASED ON BCR SEQUENTIAL EXTRACTION

基于类型土壤的重金属元素形态分析研究相对较少,本研究以香港地区7个亚纲的土壤剖面为例,利用欧共体参比司(BCR)制定的三步连续提取法研究了类型土壤中重金属Cd、Cu、Pb和Zn的化学形态及其潜在环境风险。结果表明,Pb、Cd和Zn元素除残留态外,HOAc溶解态的比例也相对较高,但不同类型的土壤有所差别,而Cu元素则以残留态和可氧化态为主。在这7种类型土壤中,正常潜育土和湿润淋溶土中的重金属潜在环境风险相对较高,而在这4种重金属元素中,又以Pb元素的潜在环境风险最大。

Not many reports are available on researches on chemical fractions of heavy metals based on soil types.In this project,seven soil profiles,representing the seven sub-classes of soils typical of Hong Kong,were collected for analysis of chemical fractions of heavy metals（Cd,Cu,Pb and Zn） in these types of soils and their potential environmental risks,using three-step sequential extraction procedure laid down by the EC Reference Bureau（BCR）.Potential environmental risk of the heavy metals in the soils was also addressed based on the relative contents of chemical fractions.Results indicate that besides some residual forms a substantial proportion of HOAc-soluble Cd,Pb and Zn was observed in the soils and varied with soil types.Copper fractions were dominated by residual and reducible phases（bound to organic matter and sulfide） in all the seven types of soils.Heavy metals in Orthic Gleysols and Udic Luvisols posed relatively higher potential risks to the biota and environment than in the others.Of the four metals lead was the highest in potential environmental risk.