珠江三角洲平原区土壤Pb元素地球化学特征及其影响因素研究

以珠江三角洲平原为研究区域,对其7个区县102件水稻根系土样品进行土壤理化参数及Pb形态分析,探讨在第四系分布区土壤Pb全量及Pb活动态含量的特征及影响因素。结果表明:全部供试土壤样品中Pb元素平均含量为46.47mg/kg,略高于广东省土壤Pb含量背景值(36mg/kg),表现出一定的累积趋势。研究区自西北陆相沉积区至南部海陆交互相沉积区,元素含量增高。Pb元素主要以残渣态和铁锰氧化物形态赋存在土壤中,迁移能力弱。影响土壤Pb全量的因素主要有Al2O3、K2O、Tl、Mo;影响土壤Pb活动态的因素有Pb全量、pH、有机质、CEC、P、TFe2O3、Mn;其中,p H是控制Pb元素活动性的最主要因素。

Geochemical Characteristics and Influence Factors of Lead in the Soils of the Pearl River Delta Plain,China

This paper took the Pearl River Delta plain in Guangdong Province as the study area. We collected 102 surface soil samples from paddy fields and analyzed their physico-chemical parameters and Pb geochemical fractions.The main aims were to investigate the geochemical characteristics and to discuss the influence factors of total Pb contents and mobility fraction Pb contents in the soils. The results showed that the average value of total Pb contents in the soils was 46.47 mg/kg, which was slightly higher than the background value of soil Pb in Guangdong Province (36 mg/kg), indicating a certain accumulation trend. From northwest land sedimentary environment to south sea-land interaction sedimentary environment, the elements contents in the soils normally increased. Soil Pb were mainly composed of residual and Fe-Mn oxidation fraction with weak mobility. The factors affecting total Pb contents in the soils are aluminum oxide(Al₂O₃),potassium oxide (K₂O),thallium(Tl),molybdenum(Mo). The factors controlling the mobility fraction of Pb are total Pb contents, pH, organic matter contents, cation exchange capacity (CEC), phosphorus(P), iron oxide(TFe₂O₃) and manganese (Mn). Among these factors, pH is the most important factor controlling the mobility of soil Pb.