Redox reactions and phosphorus release in re‐flooded soils of an altered wetland
Redox reactions and phosphorus release in re‐flooded soils of an altered wetland
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DOI：
10.1111/j.1365-2389.2004.00692.x
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发表时间：
2005-08
影响因子：
4.2
通讯作者：
M. Shenker;S. Seitelbach;S. Brand;A. Haim;M. Litaor
中科院分区：
文献类型：
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作者：
M. Shenker;S. Seitelbach;S. Brand;A. Haim;M. Litaor
土地磷流失可能是影响地表水质量的主要因素。我们研究了湿地土壤中的磷释放机制，这些土壤已经排水并耕种了四十年，然后重新淹没。我们测量了田间两个地点以及在生物地球化学微观世界中培养的四种泥炭和钙质土壤的氧化还原、pH 和溶液成分。培养120天期间的氧化还原和pH测量以及由此产生的土壤溶液组成表明，导致P释放的主要过程是氢氧化铁的还原溶解，其中吸附了P并在其中吸留了P。 Fe：P摩尔比随着减少时间的增加而增加，从重新淹没第一周的1以下到120天后的15-60。这表明无论是在土壤剖面内还是在排水沟内，土壤溶液再氧化后磷的保留能力都会增加。贫方解石、富含石膏的泥炭土的长期淹没增加了土壤溶液相对于羟基磷灰石和偶尔的β-Ca3(PO4)2(c)的过饱和度，这表明尽管Ca浓度较高，但Ca-P沉淀速率不足以维持Ca-P系统的饱和状态。在钙质土壤中，Ca-P系统在整个培养期内有效控制了土壤溶液中的磷活性。在这两种情况下，Ca-P 矿物的沉淀可能是重要的 P 保留机制。
Phosphorus loss from land can be a major factor affecting surface water quality. We studied P‐release mechanisms in wetland soils that had been drained and cultivated for four decades and then re‐flooded. We measured redox, pH and solution composition in two sites in the field and in four peat and calcareous soils incubated in biogeochemical microcosms. The redox and pH measurements during the 120 days of incubation and the resulting soil solution composition indicated that the main process leading to P release is reductive dissolution of ferric hydroxides on which P was adsorbed and in which P was occluded. The molar Fe:P ratio increased with period of reduction from below 1 in the first week of re‐flooding to 15–60 after 120 days. This suggests an increased P‐retention capacity upon reoxidation of the soil solution, whether within the soil profile or in the drainage canals. Prolonged flooding of the calcite‐poor, gypsum‐rich peat soils increased the oversaturation of soil solutions with respect to hydroxyapatite and occasionally β‐Ca3(PO4)2(c), indicating that in spite of the large Ca concentration, the rate of Ca‐P precipitation was insufficient to maintain the saturation status of the Ca‐P system. In the calcareous soils the Ca‐P system effectively controlled the P activity in soil solution throughout the incubation period. In both cases the precipitation of Ca‐P minerals could be an important P‐retention mechanism.