基于复合DGT和2D-DIFS模型研究稻田土壤汞锰的迁移动力学及生物有效性

The centre government has emphasized the food security as a primary goal for the development of the national modern agriculture in the China's 12th Five-year Plan. One of the important issues regarding the food security is, for example, the contamination caused by heavy metals. Recently, mercury (Hg) and manganese (Mn) pollution have frequently been reported for paddy soils in Wahshan area, Guizhou, China. However, the dynamic of the combined pollution effects and the translocation process of Hg and Mn in paddy soils still remain unknown. It is really difficult to accurately measure bioavailable concentrations of Hg and Mn and to identify their migration pathways in soils using traditional methods. Though the DGT technique and DIFS model have been proved to be an effective method to solve the above mentioned problem, no research was reported regarding the application of DGT technique to investigate the coupling contamination effects of Hg and Mn in soils, due to the the fact that two different resin gels are needed to absorb these two metals, while conventional DGT methods employ only one adsorbent for absorbing one metal. In this work, we try to generate a mixed binding gel as resin gel by mixing two different adsorbents together and use this combined DGT method to measure Hg2+ and Mn2+ concentrations in paddy soil. This new developped DGT method will be used for in situ measurement of Hg2+ and Mn2+ concentrations in paddy ecosystem in Wanshan area, Guizhou. By coupling with 2D-DIFS model, we will systematically investigate the transformation dynamic of Hg and Mn between solid and solution, and identify the bioavailable phases (the chemical compounds) of Hg and Mn within the contaminated paddy soil system. These results can provide potential information for control of Hg and Mn pollution in paddy soil.

国家"十二五"规划纲要，把保障粮食安全作为发展现代农业的首要目标。而粮食安全的新忧已经次第而来,如重金属污染。最近，贵州万山地区汞、锰污染引起广泛关注。但对万山稻田土壤汞、锰复合污染机理的认识仍不清楚，且传统方法不能准确测量汞、锰的生物有效性，更不能描述其在土壤固-液两相之间的迁移过程。DGT技术及DIFS模型能有效地解决这一问题，但DGT技术的研究与应用主要基于单一的吸附剂，需要制作两张DGT胶分别吸附汞、锰元素。本研究将两种吸附剂（3-MFSG吸附Hg2+和Chelex100吸附Mn2+）混合制作一张DGT胶，建立一种原位富集稻田土壤汞、锰元素的新型复合DGT技术。并应用于万山区域科学界定汞、锰复合污染现状，结合2D-DIFS模型解析万山区域土壤-水稻系统中汞、锰在固-液两相迁移的动力学过程，探寻稻田生态系统汞、锰复合污染机理，为万山区域土壤汞、锰污染综合治理提供理论依据。