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首页> 外文学位 >Prediction of persistence of fertilizer-derived cadmium in Oregon agricultural soils using equilibrium modeling and fertilizer release kinetics.
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Prediction of persistence of fertilizer-derived cadmium in Oregon agricultural soils using equilibrium modeling and fertilizer release kinetics.

机译：使用平衡模型和肥料释放动力学预测俄勒冈州农业土壤中肥料衍生的镉的持久性。

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Organic farming has become a multimillion dollar industry and while much emphasis is put on subsequent fertilizer inputs onto these fields, very little consideration is given to the prior fertilization activities of these soils. For a farm to be certified organic it means no harmful chemicals have been applied for at least three years.;The Kd values and adsorption trend of the soil sites was Pendleton > Klamath > Hyslop > Hermiston. The cadmium Kd values were most correlated to the pH of the soils (R2=0.94). The buffer capacity of the soils was highly correlated to the clay content (R2 = 0.98). The adsorption coefficients were important for predicting the doubling times of cadmium in the soils (Hermiston, 4.8yrs > Hyslop, 3.7yrs > Klamath, 2.9 yrs> Pendleton 2.3 yrs). Precipitation was not the most important parameter in predicting the mass loss due to leaching after three years (46.2, 19.9, 16.7 and 8.3 mg/ha-yr for Hyslop, Hermiston, Pendleton and Klamath respectively). The period was found to have a negligible effect on the background concentrations of cadmium in agricultural soils.;Scanning electron microscopy, X-ray diffraction and column displacement experiments were used to investigate the fertilizer kinetics of fertilizer-derived cadmium and the processes controlling the release of fertilizer-derived cadmium were found to be a Cd-phosphate phase, possibly cadmium hydroxyapaptite, and iron oxides. The release of Cd from phosphate fertilizer was slow so a local equilibrium model was appropriate for agricultural soils.;The overall hypothesis tested by this research was that equilibrium adsorption models can adequately represent the behavior of fertilizer-derived cadmium in Oregon agricultural soils and that such model results can be easily incorporated into risk assessment models, transport study models and persistence studies for organic or other sustainable farming considerations. Soil chemistry and soil characterization were used to calculate the doubling time and mass flux of cadmium-derived fertilizer in loamy and sandy agricultural soils with a rich farming history. We also investigated the processes controlling the release of fertilizer-derived cadmium in the micro scale zone around the fertilizer to determine if a local equilibrium model was appropriate for explaining cadmium behavior in agricultural soils.
机译：有机耕作已成为一个价值数百万美元的产业，尽管在这些领域上非常重视随后的肥料投入，但很少考虑这些土壤的先前施肥活动。对于获得有机认证的农场来说，这意味着至少三年没有使用任何有害化学物质。土壤位置的Kd值和吸附趋势为Pendleton> Klamath> Hyslop> Hermiston。镉的Kd值与土壤的pH值最相关（R2 = 0.94）。土壤的缓冲能力与粘土含量高度相关（R2 = 0.98）。吸附系数对于预测土壤中镉的倍增时间很重要（Hermiston，4.8年> Hyslop，3.7年> Klamath，2.9年> Pendleton 2.3年）。降水不是预测三年后因浸出引起的质量损失的最重要参数（Hyslop，Hermiston，Pendleton和Klamath分别为46.2、19.9、16.7和8.3 mg / ha-yr-ha-yr）。发现该时期对农业土壤中镉的本底浓度影响可忽略不计。;通过扫描电子显微镜，X射线衍射和柱位移实验研究了化肥衍生镉的肥料动力学及其控制释放的过程。肥料中的镉被发现是Cd-磷酸盐相，可能是羟基磷灰石镉和氧化铁。磷肥中Cd的释放缓慢，因此适合于农业土壤的局部平衡模型。本研究检验的总体假设是，平衡吸附模型可以充分代表俄勒冈州农业土壤中化肥衍生的镉的行为，因此可以将模型结果轻松地纳入风险评估模型，运输研究模型以及针对有机或其他可持续农业考虑因素的持久性研究。利用土壤化学和土壤特性，计算了具有悠久耕作历史的壤土和沙质农业土壤中镉衍生肥料的倍增时间和质量通量。我们还研究了在肥料周围的微尺度区域中控制源自肥料的镉释放的过程，以确定局部平衡模型是否适合解释农业土壤中的镉行为。

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  • 作者

    Mukome, Fungai.;

  • 作者单位

    Portland State University.;

  • 授予单位 Portland State University.;
  • 学科 Agriculture Soil Science.;Engineering Environmental.;Engineering Agricultural.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 149 p.
  • 总页数 149
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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