摘要:为解决土壤重金属污染问题，纳米零价铁(nZVI)被广泛应用且备受关注, 而nZVI对土壤无脊椎动物、土壤质量、微生物群落等的潜在影响缺乏系统的研究。本文以赤子爱胜蚓(Eisenia foetida) [蚯蚓密度为0、10条?kg?1(土)]为研究对象, 探讨不同浓度nZVI (nZVI土壤质量为0、0.05%、0.25%和0.50%) 暴露15 d、30 d和45 d后，蚯蚓-微生物-土壤生态系统的响应, 为评价nZVI的环境安全性提供参考。结果表明, 暴露45 d后, nZVI对蚯蚓存活率和生物量无显著影响, 0.50% nZVI处理的蚯蚓存活率和体内MDA含量与15 d相比分别降低27.66%和0.86 nmol?g?1; 而蚯蚓生物量和CAT活性分别增加1.20倍和2.62倍。门或属水平下, nZVI对土壤微生物相对丰度、多样性指数和丰度指数无显著影响; 与无添加nZVI处理相比，蚯蚓介导下 0.50% nZVI处理土壤中大团聚体(>250 μm)所占比例、团聚体平均重量直径和速效磷含量分别显著升高15.69%、12.59%和21.20%。蚯蚓介导下nZVI处理中土壤大团聚体所占比例、团聚体平均重量直径显著高于无蚯蚓投加的nZVI处理, 可见, nZVI胁迫下蚯蚓活动极显著提高土壤团聚体结构的稳定性(P<0.01)。本研究发现长期暴露nZVI对土壤微生物群落特征无显著影响, 但可以促进蚯蚓的生长, 从而进一步提高了土壤营养元素的生物有效性, 为nZVI应用于污染修复与治理的环境安全性评估提供了科学依据。
关键词:纳米零价铁/
赤子爱胜蚓/
毒性效应/
土壤团聚体/
细菌多样性
Abstract:Nano-zero-valent iron (nZVI) is widely used to remedy soil heavy metal pollution. However, the potential effects of nZVI on soil invertebrates, soil quality and microbial communities have not been well studied. In this study, we used Eisenia foetida (0, 10 pieces per kilogram soil) as the test species and examined the potential effects of nZVI (mass ratios of 0, 0.05%, 0.25%, and 0.50%) on the earthworm-bacteria-soil ecosystems after 15, 30, and 45 days of exposure. The results showed that after 45 days of exposure, there was no significant difference in survival rate and biomass of earthworms. The earthworm survival rate and content of malondialdehyde in the 0.50% nZVI system decreased by 27.66% and 0.86 nmol?g?1, respectively, compared with those on day 15. However, the earthworm biomass increased by 1.20 times, and the catalase activity increased by 2.62 times. At the phylum or genus level, nZVI had no significant effects on the relative abundance, diversity index, and abundance index of soil microorganisms. Compared with the 0 nZVI system, the proportion of soil large aggregates (>250 μm), the average weight diameter of soil aggregates, and the content of available phosphorus (P) in the 0.50% nZVI system increased by 15.69%, 12.59%, and 21.20% under earthworm-mediated conditions, respectively. The proportion of soil macroaggregates and the average weight diameter of soil aggregates in the earthworm and nZVI composite systems were significantly higher than those in the corresponding single nZVI system, and earthworm activity significantly improved the stability of soil aggregates under nZVI stress (P<0.01). In this study, we found that long-term exposure to nZVI had no significant toxic effects on the community characteristics of soil microorganisms but promoted the growth of earthworms, which further improved the bioavailability of soil nutrients. This study provides a scientific basis for environmental safety assessments of nZVI in soil restoration applications.
Key words:Nano-zero-valent iron/
Eisenia fetida/
Toxic effects/
Soil aggregates/
Bacterial diversity
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