【摘要】 通过在不同含水量 (田间持水量的 6 0 % :对照处理 ;田间持水量的 2 5 0 % :淹水处理 )和不同温度 (2 0℃ ,2 5℃ ,30℃ )条件下的室内培养 ,对江苏省里下河地区池杉湿地林土壤的二价铁离子 (Fe2 + )浓度 ,氧化还原电位 (Eh)及 p H值进行了研究。结果表明 ,与对照处理相比 ,淹水土壤的 p H值和 Fe2 + 浓度明显提高 (P<0 .0 1) ,而 Eh值则明显降低 (P<0 .0 1)。在淹水条件下 ,高温处理的土壤 p H值和 Fe2 +浓度明显高于低温处理土壤 (P<0 .0 1) ,Eh值则相反。研究表明 ,土壤 Eh值与 p H值之间存在着密切的 3次方程式关系 (P<0 .0 0 1)。就里下河地区湿地林土壤而言 ,Eh值下降至 2 0 0 m V以下时 ,才会有大量的铁元素被还原为Fe2 +。更多还原

【Abstract】 Iron transformations impact the physical and chemical properties of forested wetland soils and influence the development and stabilization of soil structure. Although it is well known that paddy soils are subject to a succession of iron transformations from ferric to ferrous states under reducing conditions, the dynamics of iron in submerged forest soils have been less studied in China. Transformations of iron, changes in soil redox potential （Eh）, and soil pH variations associated with submergence are interrelated, but have not been adequately elucidated in the forested wetland soil in China. To increase the productivity of forested wetlands, it is, however, imperative to understand these relationships. We, therefore, studied the dynamics of Fe²⁺, Eh and pH under different moisture and temperature regimes using the incubation method. Soil samples （Eutric gleyed paddy soils-China system of soil classification） were collected from a 20 year-old pondcypress （Taxodium ascendens Brongn.） plantation, at the Mapen forest research site in Gaoyou city, Jiangsu province, where it is naturally flooded approximately for about two months （from July to September）. The soil pH was 6.18 and the total carbon, total nitrogen, and total iron concentrations of soil were 27.6, 2.7 and 21.5 g/kg respectively.Fresh soil sample （20g） sifted through a 2 mm sieve, and adjusted to approximately 60% （control） or 250% （flooding） water holding capacity was put in a glass jar （140 ml） covered by a cap （having a 2 mm hole to ensure aeration）. The jars were incubated at 20, 25, and 30℃, and the soil moisture was adjusted once every week. Changes in pH, Fe²⁺ concentrations and Eh were monitored at regular intervals （up to 80 days after incubation）. Compared to control, pH and Fe²⁺ concentrations increased and Eh decreased rapidly in the flooding treatment （P<0.01）. When flooded, soil pH and Fe²⁺ concentrations were higher （P<0.01） and Eh was lower （P<0.01） in the 30℃ treatment than other temperature regimes. However, differences in Fe²⁺ concentrations and Eh under the control were not significant among the temperature treatments. The Fe²⁺ concentrations increased significantly when the Eh was lower than 200 mV. The prediction equation: y=-293.2x³+5302.1x²-32039x+65167 （x: pH; y: Eh （mV）, R²=0.969, P<0.001）, used to evaluate the interrelationships between pH and Eh gave a reasonably good fit.更多还原