珠三角地区土壤重金属元素异常来源浅析及其环境质量评价

Origin of Heavy Metal Element Anomalies in Soils of the Pearl River Delta and its Environmental Quality Assessment

通过对广东省珠江三角洲地区土壤地球化学调查分析,发现一系列的重金属等土壤微量元素异常,各元素异常套合性较好。异常主要分布于珠江三角洲冲积平原区第四纪海陆交互沉积物,其次是高明三洲盆地、潭江冲积平原、广花盆地、博罗公庄及莲花山断裂带。通过对表层土壤与不同母质土壤中重金属含量进行对比,发现(1)Cr、Cd异常在不同土壤中分布相似,异常主要受水动力影响沉积形成;(2)Cu、Zn的分布格局主体受成土母质控制,但高含量区也叠加了人为因素的影响;(3)As高含量区分布主要受地质背景控制;(4)Pb异常分布较为零星,异常成因与矿床分布关系密切;(5)Hg异常主要分布于经济发达、城市化水平较高的城市及其周边地区,说明异常受人为影响较大,其次为典型矿致异常。综合以上分析,对珠江三角洲地区土壤综合环境质量进行评价,结果表明,区内土壤环境质量总体情况较好,一、二级土壤占总面积的77.2%。其中,适合种植绿色农产品区域占珠三角经济区土地面积的52.4%,满足无公害农产品土壤环境质量要求的区域占珠三角经济区土地面积的82.5%。

Based on the soil geochemical survey in the Pearl River Delta region of Guangdong Province, a serious of soil trace element anomalies, such as the heavy metals, can be found. These anomalous element have a good properties and mainly distributed in the quaternary sea-land interaction sediments of alluvial plains. They also exist in Sanzhou basin of Gaoming, alluvial plain of Tanjiang, Guanghua basin, Boluo Gongzhuang and Lianhuashan fault zone. Furthermore, heavy metal content in the surface soil and soils of different materials has been also compared in this study, which leads us to get several conclusions, including（1） Cr and Cd anomaly is similar in different soils. It is mainly impacted by the hydrodynamic depositional process;（2） the distribution of Cu and Zn was controlled by soil parent material, and may be also overlay the infl uence of human factors in some high content areas;（3） the geological background is the dominant factor to induce the high content of As metal element;（4） the distribution of Pb anomalies is sporadic and the origin of this anomaly is closely related to the distribution of ore deposits;（5） Hg anomalies mainly distributes in cities of economically developed or higher level of urbanization and its surrounding areas, this anomalies is associated with human activities and related ore deposit. These data can give an evaluation of soil environmental quality in the Pearl River Delta region. The results show that the overall situation of soil environmental quality is good, areas of one and two level soils can account 77.2% of the total area. Among them, 52.4% areas are suitable for the cultivation of green agricultural products, 82.5% areas can satisfy for the requirement of non pollution agricultural products.