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首页> 外文期刊>Nature reviews Cancer >Phosphorus transformations in stream bank sediments in Iowa, USA, at varying redox potentials
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Phosphorus transformations in stream bank sediments in Iowa, USA, at varying redox potentials

机译：美国爱荷华州溪流沉积物中的磷转变，不同氧化还原潜力

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PurposeStream bank erosion is one of the main sources of suspended sediments in stream water, and it often carries phosphorus with it. With a controlled laboratory study, we investigated the changes in different forms of P in stream bank sediments at varying redox potentials. We hypothesized that there could be increases in labile forms of solid-phase P under low redox conditions.Materials and methodsSediment samples representing four major stratigraphic units were collected from alluvial banks of Walnut Creek in Jasper County, Iowa: Camp Creek, Roberts Creek, and Gunder members of the Holocene-age De Forest Formation and pre-Illinoian till, a glacial deposit that is older than 500,000years. We compared three treatments: no anaerobic incubation, anaerobic incubation, and anaerobic incubation with addition of glucose. After each treatment, soil P fractions were determined and classified as water-extractable P, labile P, slowly cycling P, stable P, and residual P. Labile P is extractable with 0.5M NaHCO3, slowly cycling P is extractable with 0.1M NaOH or 1M HCl, stable P is extractable with concentrated HCl, and residual P is associated with acid-insoluble compounds in the soil.Results and discussionRedox potential of the equilibrated systems was significantly less when sediments were incubated anaerobically than when they were not incubated, especially when glucose was added to the anaerobic incubation. Variations in redox potential did not significantly affect the total P, organic or inorganic stable P, or residual P in the sediments. In contrast, we found that the amount of inorganic labile P tended to increase at the same time that slowly cycling P associated with Fe decreased.ConclusionsThe younger sediments, higher in the stratigraphic profile and with more organic matter, had greater labile P and slowly cycling P that was associated with Fe, reflecting a greater potential to contribute to elevated levels of P in the stream water if subjected to low redox potential in the stream environment. The forms of P in the four bank sediments were redistributed among the fractions by reducing conditions. There was an increase in the concentration of inorganic labile P, which coincided with a decrease in slowly cycling P associated with Fe, especially in the Holocene-age sediments. These sediments appear to have a greater potential to contribute to elevated levels of P in the stream water when they are subjected to low redox potential in the stream environment.
机译：PurposeStream银行侵蚀是流水中悬浮沉积物的主要来源之一，它通常携带磷。通过受控的实验室研究，我们在不同氧化还原潜力下调查了流银行沉积物中不同形式的P的变化。我们假设在低氧化还原条件下，可以在不稳定形式的固相P中增加了不稳定形式的固相P.，代表四个主要地层单位的材料和方法采用贾斯珀县的核桃溪核桃溪的冲积库，罗伯特河，罗伯茨溪，全新候De Forest Comboration和伊利诺伊前的枪手成员，冰川矿床超过500,000年。我们比较了三种治疗方法：无厌氧孵育，厌氧孵育和加入葡萄糖的厌氧孵育。在每次治疗后，测定土壤P馏分并将其分类为可燃可燃的P，不稳定的P，缓慢循环P，稳定的P和残留的P.不稳定的P.效果，慢慢循环P可用0.1M NaOH萃取1M HCl，稳定的P可用浓HCl萃取，并且残留的P与土壤中的酸不溶性化合物相关。当沉积物孵育比未孵育时，平衡系统的差异和讨论的潜力显着较大，特别是当它们将葡萄糖加入到厌氧孵育中。氧化还原潜力的变化没有显着影响沉积物中的总P，有机或无机稳定P或残留P.相比之下，我们发现无机稳定性P的量趋于同时增加，同时慢慢循环p减少。结论沉积物，地层剖面较高，具有更多有机物质，具有更大的不稳定P和慢慢循环与Fe相关联的p，如果在流环境中经受低氧化还原潜力，则反映出有助于在流水中升高的P水平的潜力。通过还原条件，在馏分中重新分布了四个银行沉积物中的p的形式。无机不合格P的浓度增加，这与与Fe相关的缓慢循环P的减少，特别是在全茂沉积物中。当它们在流环境中经受低氧化还原潜力时，这些沉积物似乎具有更大的潜力在流水中升高到流水中。

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