三江平原土地利用方式变化对土壤锰形态影响

在充分调查三江平原不同土地利用方式下土壤中锰含量及其形态分布特征的基础上,探讨了环境因子与土壤中不同锰形态的关系,以揭示锰形态变化对土地利用变化改变的响应.湿地土壤中总锰(Mntot)含量处于较低水平.不同土地利用方式下,林地土壤中Mntot要高于湿地和农田.湿地垦殖为旱田,土壤Mntot有增加趋势;湿地垦殖为水田,土壤Mntot有减少趋势.三江平原土壤中锰主要以残渣态(Mnres)和可还原态(Mnred)为主,可交换态(Mnext)与可氧化态锰(Mnoxi)含量次之.湿地、旱田及水稻田这3种土地利用方式下,土壤中可氧化态锰含量占总锰比例差异显著.湿地垦殖方向不同,对土壤中可氧化态锰影响最大.三江平原土壤中Mntot及不同锰形态含量主要受到土壤中S、pH、DOC这3种环境因子影响.

Effects of Land Use on Manganese Distribution and Fractions in Wetland Soil of Sanjiang Plain, Northeast China

A detailed investigation was conducted to study the variations of manganese contents and fractions in soil under different land use patterns in Sanjiang Plain, Northeast China. The purpose of this work was to study the changes of manganese and its fractions during wetland cultivation and their relationships with environment factors. The results indicated that the total manganese contents (Mn_tot) were relatively low in wetland soils. When wetland was cultivated into dry farmland (corn field), Mn_tot showed an increasing trend, and when wetland was cultivated into rice paddy, Mn_tot manifested a decreasing trend. Among the four fractions of manganese in soil, the residual part (Mn_res) and the reducible part (Mn_red) were predominant while the acid extractable part (Mn_ext) and the oxidizable part (Mn_oxi) were secondary. During the cultivation of wetlands to corn field or rice paddy, Mn_oxi was the only part with significant change. Mn_tot and the transformations among manganese fractions were affected by many environmental factors, with sulfur content, pH and dissolved organic carbon playing leading roles.