| Taking Alkaline saline soil of Tianjin as the research object, in wetting and drying did the influence of the movement of water and salt to the migration and transformation of heavy metals by using soil column simulation experiment, did the digestion of experimental soil by using microwave digestion method, and using Tessier continuous extraction to extract five kinds of forms, using inductively coupled plasma mass spectrometer (ICP-MS) measured the heavy metals(Cr, Ni, Cu, Zn, Cd and Pb) total amount of sampling sites, and analyzed its correlation of some physical quantities, fitting equation are obtained. The results showed that:Heavy metal Cd, Cr, Ni, Cu and Pb, their total content and the form content are in a opposite trend to the moisture content change trend, the influence of Moisture content and salinity on Cd form content reduces in the order of the exchange state, carbonate state, iron and manganese oxidation state and the organic combination state. The change ment of the exchangeable state plays a main role in the total content of Cd;Heavy metal content decreases with the increase of moisture content and salinity.Apart from the Cd, the rest of the four heavy metals form transformation mainly exist between the iron and manganese oxidation state and the organic combination state.As the result of soluble heavy metals lost along with the moisture migration, total heavy metal content and each form of them was significantly negative correlated with water content.there’s a very significant positive correlation between the content of exchangeable state of Cr, Ni, Cu are and their salinity, the correlation coefficient in the turn of big to small is:Ni (0.316)> Cu> Cr (0.231)(0.274).There’s a extremely significant positive correlation between the form content of Cd, Cr, Ni, Cu, Pb and the total content of the heavy metals, its correlation sequence is Cr-Cu (0.873)> Cu Pb (0.866)> Ni-Cu Pb (0.772)-(0.842)> Cr> Ni-Pb (0.761)> Cr-Ni-Cr (0.720)> Cd (0.695)> Cd, Cu, Cd-(0.620)> Pb> Cd-Ni (0.478)(0.450). Under the same condition, the change trend of heavy metal total content of Cd, Cr, Ni, Cu, Pb are similarity, its the result of that their migration and transformation is affected by the water and salt movement.In the same dry-wet alternate condition, but different salinity condition, heavy metal content decreases with increasing salinity; in the same salinity condition, but different dry-wet alternate condition, heavy metal content also decreases with the increase of moisture content. The result is Cl-has a decomposed and deposition effect to the heavy metals, and heavy metals can move with the water, even out of the soil system. |
