洋河流域不同土地利用类型土壤硒(Se)分布及影响因素

基于洋河流域土地利用方式、海拔高度、土壤、植被类型等采集流域上下游171个代表性表层土壤(0~10 cm),系统地分析了土壤总硒(Se)含量、分布及影响因素.结果表明,洋河流域土壤总Se含量(以干重(dw)计,下同)在0.02~3.24mg·kg-1之间,几何平均值为0.30 mg·kg-1,高于北京平原(0.20 mg·kg-1)、河北平原(0.19 mg·kg-1)和全国平均值(0.29mg·kg-1).洋河流域少Se(0.13~0.18 mg·kg-1)土壤主要分布在怀安县、宣化县以及怀来县,多数地区土壤处于足Se水平(0.18~0.45 mg·kg-1),除此之外,在万全县、兴和县、天镇县及阳高县分布有富Se(0.45~2.0 mg·kg-1)土壤.不同土地利用类型中Se含量有所差异,Se平均含量由高到低分别为:林地城镇工矿用地草地农业用地,其中农业用地平均含量为0.28 mg·kg-1.成土母质、土壤类型对洋河流域Se含量影响较小.黏粒含量与洋河流域表层土壤中Se相关性最好.Se含量随海拔增高显著增加,随p H增加显著减小.TOC、Fe和Al含量也是影响土壤Se含量的重要因素.

Spatial Distribution of Se in Soils from Different Land Use Types and Its Influencing Factors Within the Yanghe Watershed, China

Based on different land use types, altitudes, soil and vegetation types etc, 171 representative topsoils(0-10 cm) were collected within the Yanghe watershed, China for determining the total concentrations, spatial distribution and influencing factors of selenium(Se). The results showed that the total selenium concentrations in soils within the watershed ranged from 0.02 to 3.24 mg·kg^-1 dry weight(dw). The geometric mean of Se in soils within the watershed was 0.30 mg·kg^-1, which was higher than those in Beijing plain(0.20 mg·kg^-1), Hebei plain(0.19 mg·kg^-1) and China(0.29 mg·kg^-1). Soils which lacked Se(0.13-0.18 mg·kg^-1) were mainly distributed in Huaian, Xuanhua, and Huailai counties. Se concentrations in most areas within the watershed were sufficient(0.18-0.45 mg·kg^-1). In addition, Wanquan, Xinghe, Tianzhen and Yanggao counties also had some selenium-rich areas. Concentrations of Se were different under different land use types. They were of the following order: forest land>industrial and mining land>grassland>agricultural land. Agricultural land had the lowest concentrations of Se, with a mean concentration of 0.28 mg·kg^-1. We also found that parent materials and soil types had no significant effects on soil Se concentrations within the Yanghe Watershed. The results indicated that Se concentrations were positively and significantly correlated with clay contents and altitudes, but negatively and significantly with pH values. Furthermore, TOC, Fe and Al concentrations were also important factors influencing the Se concentrations in soils within the Yanghe Watershed.