Bren School of Environmental Science and Management, ‡Earth Research Institute, §Center for the Environmental Implications of Nanotechnology (UC CEIN), and ∥Department of Ecology, Evolution, and Marine Biology, University of California , Santa Barbara, California 93106, United States.
Environ Sci Technol. 2013 Dec 17;47(24):14411-7. doi: 10.1021/es403385c. Epub 2013 Nov 27.
It has been reported that engineered nanoparticles (ENPs) alter soil bacterial communities, but the underlying mechanisms and environmental controls of such effects remain unknown. Besides direct toxicity, ENPs may indirectly affect soil bacteria by changing soil water availability or other properties. Alternatively, soil water or other environmental factors may mediate ENP effects on soil bacterial communities. To test, we incubated nano-TiO2-amended soils across a range of water potentials for 288 days. Following incubation, the soil water characteristics, organic matter, total carbon, total nitrogen, and respiration upon rewetting (an indicator of bioavailable organic carbon) were measured. Bacterial community shifts were characterized by terminal restriction fragment length polymorphism (T-RFLP). The endpoint soil water holding had been reported previously as not changing with this nano-TiO2 amendment; herein, we also found that some selected soil properties were unaffected by the treatments. However, we found that nano-TiO2 altered the bacterial community composition and reduced diversity. Nano-TiO2-induced community dissimilarities increased but tended to approach a plateau when soils became drier. Taken together, nano-TiO2 effects on soil bacteria appear to be a result of direct toxicity rather than indirectly through nano-TiO2 affecting soil water and organic matter pools. However, such directs effects of nano-TiO2 on soil bacterial communities are mediated by soil water.
据报道，工程纳米粒子（ENPs）会改变土壤细菌群落，但这种影响的潜在机制和环境控制因素尚不清楚。除了直接毒性外，ENPs 还可能通过改变土壤水分可用性或其他特性间接影响土壤细菌。或者，土壤水分或其他环境因素可能会调节 ENP 对土壤细菌群落的影响。为了进行测试，我们在不同水势下培养了纳米 TiO2 处理的土壤，时间为 288 天。培养后，测量了土壤水分特性、有机质、总碳、总氮和再润湿时的呼吸作用（生物可利用有机碳的指标）。通过末端限制性片段长度多态性（T-RFLP）来描述细菌群落的变化。此前曾报道过，添加这种纳米 TiO2 后土壤的最终持水能力不会发生变化；在此，我们还发现一些选定的土壤特性不受处理的影响。然而，我们发现纳米 TiO2 改变了细菌群落的组成并降低了多样性。当土壤变干燥时，纳米 TiO2 引起的群落差异增加，但趋于达到一个平台。总的来说，纳米 TiO2 对土壤细菌的影响似乎是直接毒性的结果，而不是通过纳米 TiO2 影响土壤水分和有机物库间接产生的。然而，纳米 TiO2 对土壤细菌群落的这种直接影响是由土壤水分介导的。
