To assess environmental risks related to the mobility and toxicity of AgNPs, the chemical availability of AgNPs and polyvinylpyrrolidone-coated AgNPs (PVP-AgNPs) in three agricultural soils was quantified in a pot experiment. Porewater collection and soil extractions with 0.01 M CaCl₂, 0.4 M Glycine (pH 1.5) and 0.05 M NH₄-EDTA were performed. The effect on soil exoenzyme activities was also assessed. Porewater concentration was low (<0.4% and <0.04% of dosed Ag, for AgNPs and PVP-AgNPs, respectively) and only detected in acidic soils (pH 4.4 and 4.9). The PVP-coating reduced the downward mobility of AgNPs in soil and possibly also their dissolution rate (and subsequent release of dissolved Ag⁺ ions into porewater). The effect of variation in organic matter on soil enzymatic activity was larger than that of AgNPs, as no significant additional inhibitory effect from Ag could be observed. Only at low pH and in the presence of complexing ligands that form very stable Ag complexes (0.4 M Glycine extraction at pH 1.5) up to 58% of the Ag added to soil was released (independently of PVP coating). An extraction with glycine is proposed as a useful indicator of potentially available Ag in soils.

中文翻译：

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Ag纳米颗粒在农业土壤中的溶解及其对土壤外酶活性的影响

为了评估与AgNPs的迁移和毒性有关的环境风险，通过盆栽实验对AgNPs和聚乙烯吡咯烷酮涂层的AgNPs（PVP-AgNPs）在三种农业土壤中的化学利用率进行了定量。用0.01M的CaCl孔隙水收集和土壤提取₂，0.4M甘氨酸（pH为1.5）和0.05M的NH ₄进行-EDTA。还评估了对土壤外酶活性的影响。孔隙水浓度很低（分别对AgNPs和PVP-AgNPs分别小于剂量的Ag的0.4％和<0.04％），并且仅在酸性土壤（pH 4.4和4.9）中检测到。PVP涂层降低了土壤中AgNP的向下迁移率，并可能降低了它们的溶解速率（以及随后释放的溶解的Ag ⁺离子进入孔隙水）。有机物变化对土壤酶活性的影响大于AgNPs，因为没有观察到明显的Ag附加抑制作用。仅在低pH值下，并且在形成非常稳定的Ag复合物（在pH 1.5时为0.4 M甘氨酸萃取）的配位配体存在下，最多58％的Ag被释放到土壤中（独立于PVP涂层）。建议用甘氨酸提取作为土壤中潜在可用银的有用指示剂。