Abstract:

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.

Key words: selenium-rich soil, characteristics, genesis, Tianjin, organic fertilizer