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首页> 外文期刊>Environmental Science & Technology >Modeling salt-dependent proton binding by organic soils with the MICA-Donnan and Stockholm Humic models
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Modeling salt-dependent proton binding by organic soils with the MICA-Donnan and Stockholm Humic models

机译：用MICA-Donnan和Stockholm Humic模型模拟有机土壤与盐有关的质子结合

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Models are available for simulations of proton dissociation and cation binding by natural organic matter; two examples are the NICA-Donnan and Stockholm Humic (SHM) models. To model proton and metal binding, it is necessary to properly account for the ionic strength dependence of proton dissociation. In previous applications of the models for soils it was assumed that the electrostatic interactions for solid-phase humic substances were the same as in solution;this assumption was recently challenged. Therefore, we reanalyzed previously published acid-base titrations of acid-washed Sphagnum peat, and we produced additional data sets for two Sphagnum peats and two Spodosol Oe horizons. For the soil suspensions, the original NICA-Donnan and SHM models, which were developed for dissolved humic substances, underestimated the observed salt dependence considerably. When a fixed Donnan volume of 1 L kg(-1) for humic substances in the solid phase was used, the NICA-Donnan model fits were much improved. Also for SHM, slight changes produced improved model fits. The models also produced acceptable simulations of the dissolved Ca, Mg, and Cd concentrations, provided that cation selectivity was introduced. In conclusion, the proposed extensions to the NICA-Donnan and SHM models were shown to predict the salt dependence of solid-phase humic substances more satisfactorily than earlier model versions.
机译：模型可用于模拟质子离解和天然有机物与阳离子的结合； NICA-Donnan和Stockholm Humic（SHM）模型就是两个例子。为了模拟质子和金属的结合，必须适当考虑质子解离的离子强度依赖性。在以前的土壤模型应用中，假设固相腐殖质的静电相互作用与溶液中的静电相互作用相同；这一假设最近受到了挑战。因此，我们重新分析了先前发布的酸洗泥炭泥炭的酸碱滴定法，并为两个泥炭泥炭和两个Spodosol Oe层位生成了附加数据集。对于土壤悬浮液，为溶解的腐殖质而开发的原始NICA-Donnan和SHM模型大大低估了观察到的盐分依赖性。当固相中腐殖质的Donnan固定体积为1 L kg（-1）时，NICA-Donnan模型的拟合度大大提高。同样对于SHM，轻微的更改也改善了模型拟合。如果引入了阳离子选择性，该模型还可以对溶解的Ca，Mg和Cd浓度进行可接受的模拟。总之，对NICA-Donnan和SHM模型的拟议扩展显示出比早期模型版本更令人满意地预测了固相腐殖质对盐的依赖性。

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