Proyecto Recuperación de áreas degradadas, Instituto de Investigaciones de la Amazonía Peruana (IIAP), Puerto Maldonado, Peru.
Centro de Innovación Científica Amazónica (CINCIA), Puerto Maldonado, 17000, Madre de Dios, Peru; Center for Energy, Environment and Sustainability, Wake Forest University, Winston-Salem, NC, 27106, Peru.
J Environ Manage. 2021 Jun 15;288:112364. doi: 10.1016/j.jenvman.2021.112364. Epub 2021 Mar 25.
Gold mining is the largest source of mercury (Hg) pollution worldwide. The discharge of mercury in the environment bears direct human health risks and is likely to increase cascading effects throughout local food chains. In the Peruvian Amazon the mining process consists of slashing and burning trees, followed by extraction of gold-bearing sediment, amalgamation with Hg and gold recovery, leading each year to the degradation of 6,000-10,000 ha and the release of 180 metric tons of Hg per year to the enviroment. The purpose of this study was to determine soil Hg levels in soils of abandoned alluvial gold mine spoils and undisturbed forest in the Madre de Dios region, the epicenter of alluvial gold mining in Peru. We selected gold mine spoils of the two most important technologies locally applied for gold extraction, i.e., Minimally Mechanized Mining (MMM) and Highly Mechanized Mining (HMM), in the native communities of Laberinto and Kotzimba, respectively. We collected 127 and 35 soil samples (0-20cm depth) from potentially contaminated sites and undisturbed forest, respectively. Physicochemical analysis and determination of Hg levels were determined for all soil samples. None of the samples had Hg concentrations above Peruvian, Canadian and British Environmental Quality Standards for Agricultural Soil (6.6mg/kg). Hg levels in MMM and HMM were not significantly different between the two areas. The main variables explaining variation of soil Hg concentrations were the vegetation cover, soil organic matter, soil pH and clay particle content, which explained up to 80% of data set variation. Surprisingly, highest Hg concentrations were found in untouched old-growth forest bordering the mine spoils, but there was also a trend of increasing Hg concentrations with the regenerating vegetation. Our findings suggest that Hg concentrations in old mine spoils are low and shouldn't stand in the way of efforts to restore soil conditions and develop sustainable land uses. However, it is urgent to end the use of Hg in mining operation to decrease human and environmental risks.
金矿开采是全球最大的汞（Hg）污染来源。汞在环境中的排放直接对人类健康构成威胁，并可能在当地食物链中引发级联效应。在秘鲁亚马逊地区，采矿过程包括砍伐和焚烧树木，然后提取含金沉积物，与汞混合并回收金，导致每年有 6000-10000 公顷土地退化，并向环境中释放 180 公吨汞。本研究旨在确定秘鲁亚马逊地区马德拉多斯地区废弃冲积金矿尾矿和未受干扰森林土壤中的土壤汞水平，该地区是秘鲁冲积金矿开采的中心。我们选择了当地应用于两种最重要的金矿提取技术的金矿尾矿，即最小机械化采矿（MMM）和高度机械化采矿（HMM），分别位于拉贝里托和科齐姆巴的土著社区。我们从潜在污染点和未受干扰的森林中分别采集了 127 个和 35 个土壤样本（0-20cm 深度）。对所有土壤样本进行了物理化学分析和汞含量测定。没有一个样本的汞浓度超过秘鲁、加拿大和英国农业土壤环境质量标准（6.6mg/kg）。这两个地区的 MMM 和 HMM 中的 Hg 浓度没有显著差异。解释土壤 Hg 浓度变化的主要变量是植被覆盖、土壤有机质、土壤 pH 值和粘粒含量，它们解释了数据集变化的 80%。令人惊讶的是，在毗邻尾矿的未受干扰的古老森林中发现了最高的 Hg 浓度，但随着植被的再生，Hg 浓度也呈上升趋势。我们的研究结果表明，古老尾矿中的 Hg 浓度较低，不应妨碍恢复土壤条件和开发可持续土地利用的努力。然而，迫切需要结束汞在采矿作业中的使用，以降低人类和环境风险。
