Virginia Polytechnic Institute and State University, Virginia Water Resources Research Center, Virginia Tech, 310 West Campus Dr, RM 210, Blacksburg, VA 24061, USA.
Virginia Polytechnic Institute and State University, School of Plant and Environmental Sciences, Virginia Tech, 185 Ag Quad Ln, RM 416, Blacksburg, VA 24061, USA.
Sci Total Environ. 2020 May 15;717:137216. doi: 10.1016/j.scitotenv.2020.137216. Epub 2020 Feb 8.
Elevated dissolved major ions (salinization) from surface coal mining are a common impact to central Appalachian headwater streams. Salinization is associated with alterations of benthic macroinvertebrate communities, as many organisms are adapted to the naturally dilute streams of the region. These geochemical and biological alterations have been observed in streams decades after mining, but it remains unclear whether and at what rate water quality and aquatic biota recover after mining. To address this issue, we analyzed temporal trends in specific conductance (SC), ion matrix ratios, and benthic macroinvertebrate communities over an eight-year period in 23 headwater streams, including 18 salinized by surface coal mining. We found strong, negative correlations between SC and diversity of benthic macroinvertebrate communities. Temporal trend analysis demonstrated limited recovery of water chemistry to natural background conditions. Five of the 18 mining-influenced streams exhibited declining SC; however, annual rates of decline in these streams ranged from 1.9% to 3.7% of mean annual SC, suggesting long time periods will be required to reach established benchmark values (ca. 25 years) or values observed in our five reference study streams (ca. 40 years). Similarly, there was limited evidence for recovery of macroinvertebrate community metrics, even in the few mining-influenced streams with decreasing SC. These findings indicate that salinization and its biological effects persist, likely for decades, in central Appalachian headwater streams. Our work also highlights the value of long-term monitoring data for assessing recovery potential of salinized freshwaters, as well as the need for improved understanding of water quality and biological recovery processes and time frames.
地表煤矿开采导致的溶解主要离子（盐化作用）是阿巴拉契亚中部源头溪流的常见影响因素。盐化作用与底栖大型无脊椎动物群落的改变有关，因为许多生物适应该地区自然稀释的溪流。这些地球化学和生物变化在采矿几十年后就已经观察到，但仍不清楚水质和水生生物群在采矿后是否以及以多快的速度恢复。为了解决这个问题，我们在 23 条源头溪流中进行了为期八年的时间趋势分析，其中包括 18 条受到地表煤矿开采影响的溪流，分析了电导率（SC）、离子矩阵比和底栖大型无脊椎动物群落的时间趋势。我们发现 SC 与底栖大型无脊椎动物群落的多样性之间存在强烈的负相关关系。时间趋势分析表明，水化学对自然背景条件的恢复有限。在受采矿影响的 18 条溪流中，有 5 条溪流的 SC 呈下降趋势；然而，这些溪流的年下降率在其平均年 SC 的 1.9%至 3.7%之间，这表明需要很长时间才能达到既定的基准值（约 25 年）或我们 5 条参考研究溪流中观察到的值（约 40 年）。同样，即使在 SC 下降的少数受采矿影响的溪流中，大型无脊椎动物群落指标的恢复也很有限。这些发现表明，盐化作用及其生物效应在阿巴拉契亚中部源头溪流中持续存在，可能持续数十年。我们的工作还强调了长期监测数据在评估盐化淡水恢复潜力方面的价值，以及需要更好地了解水质和生物恢复过程和时间框架。
