碳酸盐岩风化形成的土壤剖面上氟的分布及影响因素

Distribution Characteristics of Fluorine in Soils Profiles Developed on Carbonate Rocks and its Influencing Factors

选择贵州省新蒲、平坝和罗吏地区的3个碳酸盐岩原地就位风化成土剖面为研究对象,通过对剖面土壤中氟形态、矿物组成、主量地球化学元素和理化性质等的测定实验,讨论了土壤剖面中氟的赋存形态、分布特征及与影响机制。结果表明:罗吏、平坝和新蒲3个剖面残渣态氟含量分别介于896~1 667 mg/kg、897~2 827 mg/kg和1 386~2 852 mg/kg之间,均占各剖面总氟含量的98%以上,3个碳酸盐岩风化形成的土壤剖面中氟主要为残渣结合态;除罗吏剖面外,其它几个剖面吸附性强的无定形铁铝氧化物、结晶态铁铝氧化物与氟含量皆无显著中度以上正相关,有机碳甚至在三个剖面中和氟显著负相关,表明吸附作用对氟富集的贡献有限;次生粘土矿物是氟的主要载体,且主要以残渣态的形式存在于粘土矿物的晶格中,但氟含量与粘粒含量相关性并不显著;采用SPSS软件对氟与各种理化性质进行多元逐步回归分析,回归方程表明镁对氟富集具有重要作用。

Three in situ soil profiles developing from carbonate rocks in Xinpu,Pingba,and Jishou area of Guizhou Province were selected. In order to understand speciation,distribution characteristics of fluorine and influencing mechanism,consecutive extraction of fluorine and determination of mineral composition,main geochemical elements and physicochemical properties were conducted. Results show that the soil residual fluorine（ Res-F） content ranges from 896 to 1 667 mg/kg in Luoli,897 to 2 827 mg/kg in Pingba and 1 386 to 2 852 mg/kg in Xinpu area. Fluorine is mostly（〉 98%） in the residue of the soils. The correlations of fluorine with clay particle,amorphous aluminum and iron oxides,crystalline iron and aluminum oxides appeare no significantly moderately positive in the soil profiles except Luoli area; organic matter and fluorine even appear significantly negative in three soil profiles,indicating that the contribution of adsorption for fluoride enrichment is limited. Clay minerals are the major carriers of fluorine in the soils,and fluoride mainly exists in the lattice of the clay mineral in the form of a residual state. However,no significant correlation is found between the clay and fluorine contents in the soils from the same profile. The stepwise regression equation shows that Mg plays an important role in the enrichment of fluorine.