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首页> 外文期刊>Environmental Science & Technology >Quantifying Uncertainties in Sequential Chemical Extraction of Soil Phosphorus Using XANES Spectroscopy
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Quantifying Uncertainties in Sequential Chemical Extraction of Soil Phosphorus Using XANES Spectroscopy

机译：XANES光谱法定量测定土壤中磷的不确定度

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摘要

Sequential chemical extraction has been widely used to study soil phosphorus (P) dynamics and inform nutrient management, but its efficacy for assigning P into biologically meaningful pools remains unknown. Here, we evaluated the accuracy of the modified Hedley extraction scheme using P K-edge X-ray absorption near-edge structure (XANES) spectroscopy for nine carbonate-free soil samples with diverse chemical and mineralogical properties resulting from different degrees of soil development. For most samples, the extraction markedly overestimated the pool size of calcium-bound P (Ca-P, extracted by 1 M HCI) due to (1) P redistribution during the alkaline extractions (0.5 M NaHCO_3 and then 0.1 M NaOH), creating new Ca-P via formation of Ca phosphates between NaOH-desorbed phosphate and exchangeable Ca~(2+) and/or (2) dissolution of poorly crystalline Fe and Al oxides by 1 M HCl, releasing P occluded by these oxides into solution. The first mechanism may occur in soils rich in well-crystallized minerals and exchangeable Ca~(2+) regardless of the presence or absence of CaCO_3, whereas the second mechanism likely operates in soils rich in poorly crystalline Fe and Al minerals. The overestimation of Ca-P simultaneously caused underestimation of the pools extracted by the alkaline solutions. Our findings identify key edaphic parameters that remarkably influenced the extractions, which will strengthen our understanding of soil P dynamics using this widely accepted procedure.
机译：顺序化学提取已被广泛用于研究土壤磷（P）的动力学并通知养分管理，但其将P分配到具有生物学意义的库中的功效仍然未知。在这里，我们使用P K边缘X射线吸收近边缘结构（XANES）光谱技术评估了9种无碳酸盐土壤样品的改良Hedley提取方案的准确性，这些土壤样品具有不同的土壤发育程度，具有不同的化学和矿物学特性。对于大多数样品，由于（1）碱性萃取过程中P的重新分布（0.5 M NaHCO_3然后0.1 M NaOH），因此萃取显着高估了钙结合的P（Ca-P，用1 M HCl萃取）的库大小。通过在NaOH解吸的磷酸盐与可交换的Ca〜（2+）和/或（2）结晶度差的Fe和Al氧化物被1 M HCl溶解之间形成Ca磷酸盐形成新的Ca-P，从而将这些氧化物所吸附的P释放到溶液中。无论是否存在CaCO_3，第一种机制可能发生在富含良好结晶矿物和可交换Ca〜（2+）的土壤中，而第二种机制可能在富含结晶性较差的Fe和Al矿物的土壤中发生。 Ca-P的高估同时导致碱性溶液提取的池的低估。我们的发现确定了明显影响提取的关键土壤参数，这将加强我们对土壤磷动力学的了解，这一方法被广泛接受。

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  • 来源
    《Environmental Science & Technology》 |2020年第4期|2257-2267|共11页
  • 作者

    Chunhao Gu; Than Dam; Stephen C. Hart; Benjamin L. Turner; Oliver A. Chadwick; Asmeret Asefaw Berhe; Yongfeng Hu; Mengqiang Zhu;

  • 作者单位

    Department of Ecosystem Science and Management University of Wyoming Laramie Wyoming 82071 United States;

    Department of Life & Environmental Sciences and Sierra Nevada Research Institute University of California Merced California 95343 United States;

    Smithsonian Tropical Research Institute 0843-03092 Balboa Panama;

    Department of Geography University of California Santa Barbara California 93106 United States;

    Canadian Light Source University of Saskatchewan Saskatoon Canada S7N 0X4;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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