ABSTRACT Silver (Ag) is a broadly toxic element, and the potential for its release into the soil environment is increasing with its increasing use in consumer products. The first objective of this study was to quantify the transport of Ag in three soils having different properties. Miscible displacement experiments were carried out using pulses of AgNO3 (200 mg Ag L−1 in 0.005 M Ca(NO3)2 background) applied to uniformly packed, water-saturated soil columns. Silver was mobile in all soils, with Ag breakthrough curve (BTC) having sharp to moderate influent fronts, high maximum concentrations relative to input, extensive tailing during leaching, and showing recoveries ranging from 65% to 84% of the amount applied. Differences in Ag mobility among the soils were consistent with results from sorption isotherm experiments. Another objective was to assess the influence of the presence of Zn on Ag transport using mixed pulses of 200 mg L−1 Ag and Zn (as nitrates in 0.005 M Ca(NO3)2). For all soils, the presence of Zn resulted in earlier arrival of Ag in the effluent solution, indicating reduced affinity of Ag due to competition and leading to very high recovery Ag and Zn (95%) for the least retentive soil. The BTC were approximately described using a transport model with linear reversible and first-order irreversible sorption but were well described with a multireaction model, which accounts for nonlinear kinetic reversible and irreversible reactions. Consistent with high mobility, irreversible processes were of minor importance. As with BTC, the nonlinear transport model gave better description of residual Ag and Zn concentrations in the soil columns than the linear model.

中文翻译：

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阳离子银在土壤中的迁移

摘要银 (Ag) 是一种广泛有毒的元素，随着其在消费品中的使用越来越多，其释放到土壤环境中的可能性也在增加。本研究的第一个目标是量化三种不同性质土壤中 Ag 的迁移。使用 AgNO3 脉冲（0.005 M Ca(NO3)2 背景中的 200 mg Ag L-1）应用于均匀填充的水饱和土壤柱，进行混相置换实验。银在所有土壤中都是可移动的，银突破曲线 (BTC) 具有尖锐到中等的流入前沿，相对于输入的最大浓度高，浸出过程中大量拖尾，并且显示回收率为应用量的 65% 至 84%。土壤中银迁移率的差异与吸附等温线实验的结果一致。另一个目标是使用 200 mg L-1 Ag 和 Zn（作为 0.005 M Ca(NO3)2 中的硝酸盐）的混合脉冲来评估 Zn 的存在对 Ag 传输的影响。对于所有土壤，Zn 的存在导致 Ag 提前到达流出液，这表明 Ag 的亲和力由于竞争而降低，并导致滞留性最低的土壤的 Ag 和 Zn 回收率非常高（95%）。使用具有线性可逆和一阶不可逆吸附的输运模型对 BTC 进行了近似描述，但使用多反应模型进行了很好的描述，该模型解释了非线性动力学可逆和不可逆反应。与高流动性一致，不可逆过程是次要的。与 BTC 一样，