Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile.
Centro Transdisciplinario de Estudios Ambientales y Desarrollo Humano Sostenible (CEAM), Universidad Austral de Chile, Valdivia, Chile.
Chemosphere. 2022 Aug;300:134517. doi: 10.1016/j.chemosphere.2022.134517. Epub 2022 Apr 6.
Metal contamination of soil has become a serious environmental problem worldwide. Many studies have attempted to infer metal ecotoxicity from soil microbial responses. However, much of the data from these studies tends to be inconsistent and difficult to interpret. We hypothesized that microbial response would be a useful indicator of metal toxicity in soils contaminated by copper mining in Chile. Eighty-four topsoils (0-20 cm) were collected from three areas historically contaminated by copper mining (total Cu: 46-1106 mg kg, soluble Cu: 0.05-2.3 mg kg, pCu: 6.3-10, pH: 5.1-7.8, organic matter: 1.1-10%, clay: 0-28%). Based on soil metal concentrations and ecotoxicity thresholds, Cu was expected to be toxic to microorganisms in the studied soils, while the effects of other metals (total Zn: 79-672, As: 1.9-60, Pb: 19-220, Cd: 0.4-5.1 mg kg) were expected to be minor. Soil microbial responses (microbial biomass and numbers, nitrogen mineralization and nitrification, and community-level physiological profiles) were also measured. The results showed that the different responses of soil microbes were not correlated with each other. Furthermore, the soil microbial responses were mainly influenced by the physicochemical properties of the soil, not by the metal concentrations in the soil. The effect of copper on the microbial response was either stimulating (positive) or toxic (negative). Of the soil microbial responses measured in this study, only the microbial biomass was useful for calculating dose-response curves. However, the microbial biomass response was not consistent among the different soil copper pools (total copper, soluble copper, and activity of free Cu ions). It is important to emphasize that the thresholds obtained for copper toxicity cannot be adopted in a robust manner because of the different microbial responses in different sampling areas. Thus, in the copper-contaminated soils under study, microbial response was found to be an unreliable indicator of metal toxicity.
土壤中的金属污染已成为全球范围内一个严重的环境问题。许多研究试图从土壤微生物响应中推断金属的生态毒性。然而，这些研究中的大部分数据往往不一致且难以解释。我们假设，在智利受铜矿开采污染的土壤中，微生物响应将是金属毒性的一个有用指标。从历史上受铜矿开采污染的三个地区（总铜：46-1106mgkg，可溶铜：0.05-2.3mgkg，pCu：6.3-10，pH：5.1-7.8，有机质：1.1-10%，粘土：0-28%）采集了 84 个表层土壤（0-20cm）。基于土壤金属浓度和生态毒性阈值，研究土壤中的铜预计对微生物有毒性，而其他金属（总锌：79-672，砷：1.9-60，铅：19-220，镉：0.4-5.1mgkg）的影响预计较小。还测量了土壤微生物响应（微生物生物量和数量、氮矿化和硝化以及群落水平生理特征）。结果表明，土壤微生物的不同响应彼此之间没有相关性。此外，土壤微生物响应主要受土壤理化性质的影响，而不受土壤中金属浓度的影响。铜对微生物响应的影响是刺激（正）或有毒（负）。在本研究中测量的土壤微生物响应中，只有微生物生物量可用于计算剂量-反应曲线。然而，微生物生物量的响应在不同的土壤铜库（总铜、可溶铜和游离铜离子活性）之间并不一致。重要的是要强调，由于在不同采样区域中微生物响应的不同，不能以稳健的方式采用铜毒性的阈值。因此，在所研究的受铜污染土壤中，微生物响应被发现是金属毒性的不可靠指标。
