Federal Institute for Geosciences and Natural Resources, Hanover, Germany.
Fraunhofer Institute for Molecular Biology and Applied Ecology, Schmallenberg, Germany.
Ecotoxicology. 2022 Apr;31(3):524-535. doi: 10.1007/s10646-022-02529-3. Epub 2022 Mar 9.
The increasing use of antibacterial silver nanomaterials (AgNM) in consumer products leads to their release into sewers. High amounts of AgNM become retained in sewage sludge, which causes their accumulation in agricultural soils when sewage sludge is applied as fertilizer. This increase in AgNM arouses concerns about toxicity to soil organisms and transfer within trophic levels. Long-term field studies simulating the sewage sludge pathway to soils are sparse, and the effects of a second sewage sludge application are unknown. In this perennial field lysimeter study, a twofold application of AgNM (NM-300K, 2 + 3 mg AgNM/kg dry matter soil (DMS)) and a onefold application of silver nitrate (AgNO, 2 mg Ag/kg DMS) by sewage sludge to the uppermost 20 cm of the soil (Cambisol) were applied. The response of microorganisms to the applications was determined by measuring the inhibition of ammonium-oxidizing bacteria (AOB). Silver concentration in soil, leachates, and crops were measured after acid digestion by inductively coupled plasma mass spectrometry (ICP-MS). Almost no vertical Ag translocation to deeper soil layers and negligible Ag release to leachates suggest that soil is a large sink for AgNM and AgNO. For AgNM, an increase in toxicity to AOB was shown after the second sewage sludge application. The application of AgNO resulted in long-term toxicity comparable to the toxicity of AgNM. Low root uptake from both AgNM- and AgNO-spiked lysimeters to crops indicates their incomplete immobilization, which is why food chain uptake cannot completely be excluded. However, the root-shoot barrier for wheat (9.8 → 0.1 mg/kg) and skin body barrier for sugar beets (1.0 → 0.2 mg/kg) will further reduce the accumulation within trophic levels. Moreover, the applied AgNM concentration was above the predicted environmental concentration, which is why the root uptake might be negligible in agricultural practice.
抗菌纳米银材料（AgNM）在消费品中的使用日益增加，导致其释放到污水中。大量的 AgNM 会被污水污泥截留，当将污水污泥用作肥料时，AgNM 会在农业土壤中积累。AgNM 的这种增加引起了人们对其对土壤生物毒性以及在营养级内转移的担忧。模拟污水污泥进入土壤途径的长期田间研究很少，而且二次应用污水污泥的效果尚不清楚。在这项常年田间淋溶池研究中，通过污水污泥将 AgNM（NM-300K，2+3mgAgNM/公斤干物质土壤（DMS））进行两次应用，并将硝酸银（AgNO，2mgAg/kgDMS）进行一次应用，将其施加到土壤（棕色森林土）的最上层 20cm 处。通过测量氨氧化细菌（AOB）的抑制作用来确定应用对微生物的反应。用电感耦合等离子体质谱法（ICP-MS）对经酸消解后的土壤、浸出液和作物中的银浓度进行了测量。几乎没有银垂直迁移到深层土壤层，也没有银释放到浸出液中，这表明土壤是 AgNM 和 AgNO 的巨大汇。对于 AgNM，第二次应用污水污泥后，对 AOB 的毒性增加。AgNO 的应用导致了与 AgNM 相当的长期毒性。从添加 AgNM 和 AgNO 的淋溶池到作物的根系吸收量低表明其不完全固定，这就是为什么不能完全排除食物链吸收的原因。然而，小麦（9.8→0.1mg/kg）的根-茎屏障和甜菜（1.0→0.2mg/kg）的皮肤-体屏障将进一步减少营养级内的积累。此外，所施加的 AgNM 浓度高于预测的环境浓度，这就是为什么在农业实践中根系吸收可能可以忽略不计的原因。
