天津市西郊富硒土壤地球化学特征和成因分析

为了查明天津市西郊富硒土壤的地球化学特征和成因,开展针对土壤-大气-水体-作物的调查研究工作。结果显示:研究区土壤Se元素平均值为0.66 mg/kg,是天津市土壤背景值的2.87倍,有83%为富硒土壤。土壤Se元素被颗粒状有机物质大量固定和吸附,富集于耕层土壤。耕层土壤Se元素与粗砂粒、细砂粒、Pb、Zn、Cd、Cu、Hg、N、P等指标显著正相关,与黏粒、粉粒、Na、K、Mg、As、CEC、pH等指标显著负相关。农民大量持续使用富含Se的有机肥是土壤Se元素显著富集的主要原因,占输入总通量的86.55%;大气沉降是次要原因,占13.35%。研究区土壤Se元素的年增加量为0.019 mg/kg,按2.77%的速度逐年增长。

The Analysis of Geochemical Characteristics and Genesis of Selenium-rich Soil in Western Suburb of Tianjin

In order to find out the geochemical characteristics and genesis of selenium-rich soil in western suburb of Tianjin, we carried out soil-water-atmosphere-plant investigations and subsequent study. The results show: the average value of soil selenium in the study area is 0.66 mg/kg, which is 2.87 times of the background value, 83% soil samples from the study area are selenium-rich soil. Selenium in soil is mainly immobilized and absorbed by particulate organic matter, and accumulated in surface soil. Selenium in surface soil has significant positive correlations with coarse sand, fine sand, Pb, Zn, Cd, Cu, Hg, N, P; and has significant negative correlations with silt, clay, Na, K, Mg, As, CEC, pH. The extensive use of organic fertilizers is the major cause of selenium accumulation in the study area, which occupies 86.55% of total input influx, atmospheric deposition is the secondary factor, occupies 13.35% of total. Selenium concentration in soil of the study area increases 2.77% which is 0.019 mg/kg annually.