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选取珠江三角洲冲积平原区4个不同沉积相带的第四系岩心做元素全量分析,并对4种重金属进行了赋存形态分数分析,揭示了珠江三角洲第四系元素地球化学特征主要受物源和沉积环境的控制。不同沉积环境下物源的影响程度不同,物源在三角洲平原相的沉积环境下影响强度最大,在海陆交互强烈的沉积环境下,物源的影响减弱,海陆交互作用的影响增强。不同重金属元素由于自身化学性质的差异,其对沉积环境的敏感程度有所不同。研究区Cd富集显著,且其活性态比例最高、潜在生态风险最大;而As,Hg和Pb的富集程度较弱,且As和Hg主要以残渣态的形式存在,Pb主要以残渣态和铁锰氧化物态为主,它们的生态风险相对较低。不同的沉积环境下p H等理化指标对Cd形态的影响不同,Cd的活动态主要与p H和淋滤系数有关。
Based on the analysis of the elemental abundance of Quaternary cores in four different sedimentary facies in the alluvial plain of the Pearl River Delta and the analysis of the occurrences of four heavy metals, it is revealed that the geochemical characteristics of Quaternary elements in the Pearl River Delta are mainly affected by the source And sedimentary environment control. Different sedimentary environments have different degrees of influence on provenance, and the provenance has the greatest influence in the depositional environment of the delta plain. Under the strong interaction between land and sea, the influence of provenance is weakened and the interaction between land and sea is enhanced. Different heavy metal elements have different sensitivity to sedimentary environment because of their different chemical properties. The Cd concentration in the study area is significant, with the highest proportion of active states and the highest potential ecological risk. However, the accumulation of As, Hg and Pb is weak, and As and Hg are mainly in the form of residuals. Fe-Mn oxide-based, their ecological risk is relatively low. The effects of physical and chemical indexes, such as p H, on the Cd speciation are different under different depositional environments. The activity of Cd is mainly related to p H and leaching coefficient.