Widespread sources of silver nanoparticles (AgNPs) might threaten soil ecosystems. Most studies on NPs have been carried out in plant-free soils, which do not represent natural conditions. Monitoring the fate and possible effects of nanoparticles (NPs) in soil-plant systems is crucial for predicting their environmental consequences. Plant root systems might respond differently to Ag types/concentrations, associated with changes in microbially-induced soil structural stability as well as soil C pools but evidence is not available. Therefore, a greenhouse experiment was conducted in a factorial arrangement of treatments within a randomized block design. The treatments included: 1) soil types (loamy sand and sandy loam), 2) root systems (non-planted, wheat with fibrous roots and safflower with taproot), 3) Ag types (no-Ag added, AgNPs of mean size 38.6 nm, and AgNO), and 4) Ag concentrations (50 and 100 mg kg soil). Soil samples were collected from root zone and non-planted soil 110 days after sowing. Soil quality indicators including high energy moisture characteristic (HEMC) indicators, percent of water-stable aggregates (WSA), water-dispersible clay (DC), substrate-induced respiration (SIR), microbial biomass carbon (MBC) and metabolic quotient () were determined. The results showed that the soil structure was improved in the presence of Ag and plants. Structural stability indicators were greater in the safflower root zone followed by the wheat root zone and the non-planted soil. A clear effect of Ag on HEMC was observed in the 100 mg AgNPs kg treatment. The stability ratio (SR, ratio of fast-wetting to slow-wetting structural indexes) of the AgNPs-treated soils (SR = 0.79) was significantly greater than that of the AgNO-treated soils (SR = 0.78) followed by the control (no-Ag) soils (SR = 0.74). In the AgNO-treated soils, the SIR was significantly lower than in the AgNPs-treated soils. The SIR of the 50 mg kg Ag treatment (232 mg CO-C kg) was higher than the 100 mg kg (227 mg CO-C kg). Microbial biomass was significantly affected by Ag types/concentrations and all Ag-treated soils exhibited significantly lower MBC than control. The , the index of stress to microbial community, was significantly greater in the Ag-treated soils. Scanning electron microscope images confirmed that AgNPs altered the arrangement of particles which was greater in the higher AgNPs concentration. These results imply that multiple factors (root systems, soil texture, Ag type/concentration) may combine additively/regressively to affect soil quality indicators, which may have important consequences for soil ecosystem services.

中文翻译：

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银纳米粒子/硝酸盐和植物根系对两种质地不同土壤的质量指标和团聚体稳定性的相互作用


银纳米颗粒（AgNP）的广泛来源可能会威胁土壤生态系统。大多数关于纳米颗粒的研究都是在无植物的土壤中进行的，这并不代表自然条件。监测纳米颗粒 (NP) 在土壤-植物系统中的命运和可能的影响对于预测其环境后果至关重要。植物根系可能对银类型/浓度有不同的反应，这与微生物引起的土壤结构稳定性以及土壤碳库的变化有关，但尚无证据。因此，温室实验是在随机区组设计中以因子排列的处理方式进行的。处理包括：1) 土壤类型（壤土和沙壤土），2) 根系（非种植，有须根的小麦和有主根的红花），3) 银类型（未添加银，平均大小为 38.6 的银纳米粒子） nm 和 AgNO)，以及 4) Ag 浓度（50 和 100 mg kg 土壤）。播种后110天从根区和非种植土壤采集土壤样品。土壤质量指标包括高能水分特征（HEMC）指标、水稳定性团聚体百分比（WSA）、水分散性粘土（DC）、基质诱导呼吸（SIR）、微生物生物量碳（MBC）和代谢商（）被确定。结果表明，银和植物的存在改善了土壤结构。红花根区的结构稳定性指标较高，其次是小麦根区和未种植土壤。在 100 mg AgNPs kg 处理中观察到 Ag 对 HEMC 的明显影响。 AgNPs 处理的土壤 (SR = 0.79) 的稳定性比 (SR, 快润湿与慢润湿结构指数的比率) 显着大于 AgNO 处理的土壤 (SR = 0.78) 其次是对照（无银）土壤 (SR = 0.74)。在 AgNO 处理的土壤中，SIR 显着低于 AgNP 处理的土壤。 50 mg kg Ag 处理（232 mg CO-C kg）的 SIR 高于 100 mg kg（227 mg CO-C kg）。微生物生物量受到银类型/浓度的显着影响，所有经银处理的土壤的 MBC 均显着低于对照。微生物群落的应激指数在银处理的土壤中显着更大。扫描电子显微镜图像证实，AgNPs 改变了颗粒的排列，这种改变在 AgNPs 浓度较高时改变得更大。这些结果意味着多种因素（根系、土壤质地、银类型/浓度）可能会加性/回归性地结合起来影响土壤质量指标，这可能对土壤生态系统服务产生重要影响。