污灌区盐分累积对污染土壤汞释放通量的影响

采用优化设计的动态通量箱，对不同盐分（NaCl和Na₂SO₄）和盐度（0~5%）的盐渍化土壤土-气界面的汞交换通量进行动态监测，研究盐渍化对污灌区土壤汞和大气释放的影响.结果表明：（1）两种盐分类型对土壤Hg释放的影响呈相反趋势.与未发生盐渍化的对照土壤相比，随着NaCl盐度梯度的上升，土壤Hg释放通量呈现上升趋势，5%盐度处理下，Hg通量均值与对照相比提高了48.94%；而随着Na₂SO₄盐度梯度的上升，土壤Hg释放通量呈现下降趋势，5%盐度处理下，Hg通量均值与对照相比降低了20.62%.（2）土壤盐分含量与土壤汞释放通量均值之间呈线性关系.对于NaCl，含量x（g/kg）与汞通量y ng/（m²·h）]之间的模型为y=0.8258x+86.709（R²=0.9734），对于Na₂SO₄，模型为y=-0.3354x+85.997（R²=0.9581）.从研究结果来看，高浓度的NaCl环境对土壤汞释放通量有显著影响，土壤的盐渍化趋势会使汞释放及作物吸收风险更趋严重.

A simulation study of mercury release fluxes from soils under different salinity levels in the wastewater-irrigated area

This research was design to study the effects of salinity on mercury release from soils.Atmospheric mercury (Hg) was measured by using the optimized dynamic flux chamber to monitor the air/soil exchange of mercury from soils spiked with NaCl and Na₂SO₄ at 0~5% level,respectively.The results manifested that,compared with the control soil (no exogenous salt spiked),soil Hg emission flux showed a rising trend with the increase of NaCl salinity level which the Hg flux increased by 48.94% at the 5% salinity treatments,while soil Hg flux showed a decline trend with the increase of Na₂SO₄ salinity level which the Hg flux decreased 20.62% at the 5% salinity treatments.Furthermore,there was a linear relationship between the soil salt content and the mean soil Hg emission flux.The model between the content of x(g/kg) and the Hg flux of y ng/(m²·h)]is y=0.8258x + 86.709(R²=0.9734) for NaCl,and the model is y=-0.3354x + 85.997(R²=0.9581) for Na₂SO₄.The results illustrate that soil Hg emission flux can significantly affected by NaCl with high concentration.The trend of salinization of soil will lead to more serious risk of Hg emission and crop absorption.