Department of Natural Resource Sciences, McGill University, Ste.-Anne-de-Bellevue, Quebec, Canada.
Environ Toxicol Chem. 2012 Jan;31(1):184-93. doi: 10.1002/etc.714. Epub 2011 Nov 18.
Nanometer-sized titanium dioxide (nano-TiO(2) ) is found in a number of commercial products; however, its effects on soil biota are largely unknown. In the present study, earthworms (Eisenia andrei and Eisenia fetida) were exposed to three types of commercially available, uncoated TiO(2) nanomaterials with nominal diameters of 5, 10, and 21 nm. Nanomaterials were characterized for particle size, agglomeration, surface charge, chemical composition, and purity. Standard lethality, reproduction, and avoidance tests, as well as a juvenile growth test, were conducted in artificial soil or field soil amended with nano-TiO(2) by two methods, liquid dispersion and dry powder mixing. All studies included a micrometer-sized TiO(2) control. Exposure to field and artificial soil containing between 200 and 10,000 mg nano-TiO(2) per kilogram of dry soil (mg/kg) had no significant effect (p > 0.05) on juvenile survival and growth, adult earthworm survival, cocoon production, cocoon viability, or total number of juveniles hatched from these cocoons. However, earthworms avoided artificial soils amended with nano-TiO(2) . The lowest concentration at which avoidance was observed was between 1,000 and 5,000 mg nano-TiO(2) per kilogram of soil, depending on the TiO(2) nanomaterial applied. Furthermore, earthworms differentiated between soils amended with 10,000 mg/kg nano-TiO(2) and micrometer-sized TiO(2) . A positive relationship between earthworm avoidance and TiO(2) specific surface area was observed, but the relationship between avoidance and primary particle size was not determined because of the agglomeration and aggregation of nano-TiO(2) materials. Biological mechanisms that may explain earthworm avoidance of nano-TiO(2) are discussed. Results of the present study indicate that earthworms can detect nano-TiO(2) in soil, although exposure has no apparent effect on survival or standard reproductive parameters.
纳米级二氧化钛（nano-TiO(2)）存在于许多商业产品中；然而，其对土壤生物群的影响在很大程度上是未知的。在本研究中，使用三种市售的未涂层 TiO(2)纳米材料（标称直径分别为 5、10 和 21nm）暴露于赤子爱胜蚓（Eisenia andrei 和 Eisenia fetida）。对纳米材料的粒径、团聚、表面电荷、化学成分和纯度进行了表征。在人工土壤或添加纳米-TiO(2)的田间土壤中，通过两种方法（液体分散和干粉混合）进行了标准致死率、繁殖和回避试验以及幼体生长试验。所有研究均包括微米级 TiO(2)对照。暴露于含有 200 至 10000mg/kg 纳米-TiO(2)的田间和人工土壤（mg/kg）中对幼体存活率和生长、成年蚯蚓存活率、茧产量、茧活力或从这些茧中孵化的幼体总数没有显著影响（p>0.05）。然而，蚯蚓回避添加纳米-TiO(2)的人工土壤。观察到回避的最低浓度为 1000 至 5000mg/kg 土壤，具体取决于所应用的 TiO(2)纳米材料。此外，蚯蚓区分了添加 10000mg/kg 纳米-TiO(2)和微米级 TiO(2)的土壤。观察到蚯蚓回避与 TiO(2)比表面积之间存在正相关关系，但由于纳米-TiO(2)材料的团聚和聚集，无法确定回避与初级粒径之间的关系。讨论了可能解释蚯蚓回避纳米-TiO(2)的生物学机制。本研究结果表明，尽管暴露对生存或标准繁殖参数没有明显影响，但蚯蚓可以在土壤中检测到纳米-TiO(2)。
