淹水过程不同土层磷的释放研究

Phosphorus Release in Different Layers of Flooded Soils

采用土槽模拟实验研究了淹水土壤不同土层磷释放特征及影响因素。实验结果表明:淹水土壤不同土层磷释放呈锯齿状交替变化,但释放量有很大差异,中层释放量最低,上和下层释放量较高,最大磷浓度分别为0.0336mg/L和0.0517mg/L;而不同土层溶液中的亚铁和总铁量正好与之相反,中层铁释放量最大,上层次之,下层最低,且中层释铁量明显高于上层和下层;不同土层溶液随淹水时间pH趋于中性,Eh降低,其中中层溶液Eh下降的幅度大;淹水土壤溶液中各种不同形态铁的氧化物,如因水解和氧化形成的水铁矿以及蓝铁矿在一定程度上影响了土壤磷的释放;同时淹水增加了磷的扩散,地下水有一定量的磷累积。

A recireulating flume simulated experiment was carried out to estimate phosphorus release properties and infection in different layers of flooded soils. Results showed that phosphorus released from flooding soils presented indented alternation, but liberative quantity showed great difference between various soil layers, with quantity in middle-level at the least and higher in superstratum and substrate which the maximum of phosphorus concentration was 0.0336mg/L and 0.0517mg/L. Released quantity of ferrous and total iron presented reverse to the quantity of phosphorus, with the biggest in middle level and followed with superstratum and substrate. It was found that the released quantity of middle level was more than superstratum and substrate in evidence, pH value in soil solution approached seven along with inundation period, which was not propitious to phosphorus release. Flooding urged Eh value to descend and descendant range was the biggest in middle level. Phosphorus release in flooding soils was affected by ferric oxide-hydroxide, such as water iron ore formed by hydrolyzing or oxidation and blueness iron ore. Flooding enhanced phosphorus diffuse capacity that a mass of phosphorus cumulated in groundwater.