摘要:
基于福建省龙海市4类典型成土母质的垂向土壤剖面样品分析数据,研究了常量组分和微量元素含量及剖面分布特征。结果表明:研究区在温暖湿润气候条件下,化学风化作用强烈,Ca、Mg、Na、Si、K淋失贫化,含量明显低于全国均值,Al、Fe则相对富集,风化淋溶系数( ba)和硅铝铁率( Saf)值远低于全国土壤,土壤风化程度达到脱硅富铝铁阶段,花岗岩类成土母岩区风化作用尤为强烈;剖面土壤环境质量总体较好,微量元素含量与成土母质密切有关,九龙江口冲海积成因(剖面1)土壤重金属含量明显高于其他3个剖面;多数微量元素垂向分布受常量组分的控制,As、Cd、Cu、Hg、Pb、Zn与土壤中Fe等组分具有显著正相关性。因表层土壤中细粒黏质组分随地表径流淋失或下渗迁移,导致表层土壤低Fe、Al和重金属元素;在生物地球化学循环和人为污染的影响下,Hg、Cd、Pb、Zn等在表层土壤呈富集特征;多数重金属元素的相对富集系数小于1.0,且表层土壤无明显富集特征,认为除Hg、Pb等少数重金属元素外,其他元素受人为污染影响较小。
Abstract:
Based on geochemical data collected along four profiles at different types of geological setting and soil parent materials from Longhai, Fujian Province, the authors studied the concentrations and distribution patterns of major elements and trace elements. The results show that chemical weathering is intense. A lot of elements such as Ca, Mg, Na, Si and K have been seriously leached, but Fe and Al have been accumulated. The weathering?leaching index ( ba value) and the ratio of Si to Fe and Al ( Saf value) of the study area under the warm and humid subtropical condition are much lower than the average values of the whole country. The weathering degree has reached the stage of Si loss and Al?Fe enrichment, especially for the soils derived from granite rocks. Soil environmental quality is quite good due to its relative low concentration of heavy metals. It is found that the concentrations of trace elements including heavy metals are mainly controlled by the parent materials, and their vertical distribution along these profiles is mainly controlled by major components and organic carbon, indicating significant correlation between them. The concentrations of trace elements along profile 1 de?rived from alluvial and marine sediments are much higher than those of other three profiles. The relative low concentrations of Fe, Al as well as heavy metals may be attributed to the leaching of fine clay particles by surface runoff and infiltration. Several kinds of heavy metals such as Hg, Cd, Pb and Zn show accumulation in top soils under bio?geochemical cycle and human activities. The relative en?richment factors of most heavy metals are less than 1, which means that the anthropogenic influence are not serious except for Hg and P.
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