Marine Biology Section, Biology Department, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium.
Department of Biological Sciences, College of Science and Mathematics, Mindanao State University-Iligan Institute of Technology (MSU-IIT), Iligan, Philippines.
Arch Environ Contam Toxicol. 2019 Oct;77(3):421-431. doi: 10.1007/s00244-019-00652-7. Epub 2019 Jul 10.
Mercury (Hg), one of the most toxic heavy metals, is commonly used in the gold extraction process in small-scale mining operations in many countries. Our previous field work on the impact of mining on soil nematode assemblages in a small-scale mining area in Sibutad, the Philippines, revealed no significant negative effects despite sometimes strongly elevated Hg concentrations. Using a microcosm approach, we now applied similar Hg concentrations as commonly found in these field sites (2.5, 5, and 10 mg/kg Hg) and determined their impact on nematode assemblages from a different soil with different physicochemical soil attributes. Our results demonstrate (a) limited "bottling" effects (incubation effects) after a 45-day incubation period: a nematode abundance decrease of up to 37%, but absence of significant differences in diversity and nematode assemblage composition; (b) that total nematode abundance already decreased at Hg concentrations (2.5 mg/kg), which did not yield significant impacts on other nematode assemblage descriptors, such as assemblage composition and different diversity indices; and (c) that the Hg concentrations found in the Sibutad field sites can be detrimental to soil nematode assemblages. The discrepancy between our microcosm and the field-based results is probably related to differences in physicochemical soil attributes (e.g., OM contents, soil pH), which suggests that nematode-based environmental assessments should be interpreted in a context-dependent manner.
汞（Hg）是毒性最大的重金属之一，在许多国家的小规模采矿作业中常用于金矿提取过程。我们之前在菲律宾锡布图德的一个小规模矿区进行的关于采矿对土壤线虫群落影响的实地工作表明，尽管有时汞浓度升高幅度很大，但没有显著的负面影响。现在，我们采用微宇宙方法，应用了与这些实地站点中常见浓度相似的 Hg 浓度（2.5、5 和 10 mg/kg Hg），并确定了它们对来自不同土壤（具有不同理化土壤属性）的线虫群落的影响。我们的结果表明：（a）在 45 天的孵化期后，存在有限的“瓶装效应”（孵化效应）：线虫丰度下降高达 37%，但多样性和线虫群落组成无显著差异；（b）在 Hg 浓度（2.5 mg/kg）下，总线虫丰度已经下降，但对其他线虫群落描述符（如群落组成和不同多样性指数）没有显著影响；（c）在锡布图德实地站点发现的 Hg 浓度可能对土壤线虫群落有害。我们的微宇宙和基于实地的结果之间的差异可能与理化土壤属性（例如 OM 含量、土壤 pH 值）的差异有关，这表明基于线虫的环境评估应在上下文相关的方式下进行解释。
