A Primary Study On Mercury In Soil Of Different Agricultural Ecosystems

Mercury pollution in soil is considered threatening the people's food safety and thestability of ecosystem. Long-term application of fertilizers would influence the soil Hgconcentration. The soils of different agricultural ecosystems would differently response tothe long-term fertilization. This study was about mercury in soils of 6 agriculturalexperimental stations with long-term fertilization in China. We examined the Hgconcentration of soils with long-term fertilization in the three of agricultural ecosystems.Through analysis of Hg concentrations of soil profiles collected from the six agriculturalexperimental stations, we get the properties of Hg distributions along soil profiles. Wealso examined the Hg concentration in corn tissues and maize grain and rice. Selecting thethree soils for isothermal adsorption experiment, we obtained the maximum content ofadsorption from Langmuir equation. Finally, we try to isolate the Hg^R Bacillus from QYsoil, and do some experiments on Hg tolerance and volatilization. The main results wereas follows:1) There was difference among the Hg concentration of soils from different regions. Theorder of Hg concentration was Qiyang(QY)＞Taoyuan (TY)＞Fengqiu(FQ). Soilparent material plays important role in the Hg concentration of soil, but theagricultural management practices would influence the soil Hg concentration.Application of fertilizers for long-term induce different changes of soil Hgconcentration in the different agricultural ecosystems. The long-term P fertilizer willto some extent to contribute Hg to top soil in TY and FQ experimental stations.2) The Hg concentration of soil in A horizon (0.196 mg/kg) was higher than in Bhorizon (0.140 mg/kg) in TY and the contrary trend was observed in QY (A horizon:0.539 mg/kg, B horizon: 0.622 mg/kg), while no uniform trend was found in FQstation. Meanwile, we obtain the properties of Hg distributions along soil profiles inthe six regions, and the Hg concentration in top soils were observed higher than in thebottom soils in Changshu(CS), FQ, Hailun(HL) and Changwu(CW) stations.3) There was significant difference among the adsorption of Hg²⁺ on the soils of TY, QYand FQ. The maximum quantity of adsorption (X_m) 8137.811 mg/kg was found in FQ soils. The MBC of FQ soil, however, was close to the MBC of TY soil. Soil organicmatter plays an important role in the adsorption of Hg²⁺ on soil.4) The Hg concentration was found difference in corn tissues, and the order of Hgconcentration was leaf root＞stalk＞grain. The Hg concentrations in grain were alsodifferent among the maize, corn and rice, and the highest Hg concentration wasobserved in maize grain. The trend of higher Hg concentration was observed in therice with application of P fertilizer in TY station.5) The Hg^R Bacterium isolated from QY soil has a MIC of 80μM HgCl₂, and the highvolatilization (about90%) of Hg²⁺ was found in fresh LB containing 10μM HgCl₂.