西南喀斯特石漠化土壤含氟量及其影响因素

Fluorine content and the influential factors of the soil in karst rocky desertification region in China's southwest

分析了西南喀斯特地区不同石漠化阶段土壤的含氟量及氟分布与土壤理化性质的关系,采用化学连续提取法研究不同石漠化阶段土壤氟的形态分布。结果表明:1)研究区土壤表层的全氟质量比为45.2～97.7mg/kg,平均为65.6mg/kg;水溶性氟的质量比为0.38～3.12 mg/kg,平均为1.44 mg/kg;2)随着石漠化的加重,土壤表层全氟总体上呈先增加后降低的趋势,水溶性氟的质量比则呈递减趋势;3)喀斯特地区土壤中全氟和水溶性氟在表土层中的质量比小于底土层;4)喀斯特地区土壤氟主要以残余态形式存在,占土壤全氟的96.62%,其次为水溶态,占2.19%,铁锰结合态、有机束缚态和交换态较少;5)喀斯特地区土壤全氟主要受土壤母质、生物作用和土壤无机胶体带电性能的影响,而水溶性氟主要受土壤无机胶体带电性能的影响;6)地域对喀斯特土壤的含氟量有显著影响,普定县土壤全氟及水溶性氟均显著高于荔波县,处于氟污染状态,荔波县则处于氟安全水平。

This paper takes it as its target to. research the soil fluorine content and its distribution of the karst rocky desertification ecosystem in China＇s southwest. The results of our investigation can be shown as follows. （ 1 ） The total fluorine of the experimental topsoil in the karst region has been found to roughly range from 45.2 mg/kg to 97.7 mg/kg, with an average of 65.6 mg/kg. The mass ratio of water soluble fluorine of the experimental topsoil is found to range from 0.38 mg/kg to 3.12 mg/kg, with an average of 1.44 mg/kg. （2） On the whole, with the aggravation of rocky desertification, the total fluorine of the experimental topsoil tends to increase in the initial rocky desertification stage, then tends to decrease. The water soluble fluorine mass ratio tends to decrease with the aggravation of rocky desertification. （3） The total fluorine in different soil profilescan be found to be the surface layer less than bottom layer, with the almost the same trend as in the mass ratio of soil water soluble fluorine. （4） It is also found that the residual fluorine to be the main form in the experimental soils, accounting for 96.62% of the total fluorine, which is followed by water soluble fluorine, Fe and Mn oxide bound fluorine, exchangeable fluorine and organic fluorine. （5） The soil parent material biological action and surface charge characteristics of inorganic colloids were found to be the major influential factors on the total fluorine Whereas the surface charge characteristics of inorganic colloids would be the dominating factor to the soil water soluble fluorine. （6） And last of all, a significant difference has been found between the soils in Puding County and those in Libo County, with the total fluorine and water soluble fluorine in Puding County being higher than that in Libo County. If soil water soluble fluorine was considered to be at the critical level, the soils in Puding County under investigation said contaminated, whereas that in Libe County is unpolluted.