Rothenberger Megan B, Hoyt Virginia, Germanoski Dru, Conlon Maricate, Wilson John, Hitchings Joshua
Biology Department, Lafayette College, Kunkel Hall, Easton, PA, 18042, USA.
Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, 03824, USA.
Environ Monit Assess. 2017 Jul;189(7):344. doi: 10.1007/s10661-017-6060-x. Epub 2017 Jun 20.
The proposed removal of three run-of-river dams (all ≤5-m height) in eastern Pennsylvania along lower Bushkill Creek, a tributary of the Delaware River, has provided a valuable opportunity for multidisciplinary research involving the collection of more than 5 years of pre-removal monitoring data, analysis of heavy metals in legacy sediment cores, and associated toxicity assays to determine the singular and interactive effects of lead, copper, and cadmium on survival and behavior of a common macroinvertebrate found in Bushkill Creek. Monitoring data were collected from sites approximately 35 m upstream and downstream of dams and reference sites located approximately 5 km upstream of all dams. Results indicate that oxygen levels, macroinvertebrate diversity, and proportion of sensitive taxa were significantly lower upstream and downstream of dams in comparison with upstream reference reaches. The strong correlation between water quality and macroinvertebrates in this system implies that removal of the lower three dams would lead to improvements in water quality, biotic integrity, and resilience in lower Bushkill Creek. Sediment analyses and toxicity assays suggest that dam removal and sediment mobilization may route contaminated sediments downstream at concentrations that may harm more sensitive biota. However, macroinvertebrate mortality and behavior were not significantly different from clean water controls for the large majority of toxicity assays. All together, these results suggest that dams 1-3 are good candidates for successful stream restoration but that the removals would best be planned in a way that mitigates potential impacts of contaminated legacy sediment.
在宾夕法尼亚州东部沿着特拉华河的一条支流——布什基尔溪下游，计划拆除三座径流式大坝（坝高均≤5米），这为多学科研究提供了宝贵机会，该研究涉及收集超过5年的拆除前监测数据、分析遗留沉积岩芯中的重金属，以及进行相关毒性测定，以确定铅、铜和镉对布什基尔溪中一种常见大型无脊椎动物的生存和行为的单一及交互影响。监测数据是从大坝上游和下游约35米处的地点以及位于所有大坝上游约5公里处的参考地点收集的。结果表明，与上游参考河段相比，大坝上游和下游的氧气水平、大型无脊椎动物多样性以及敏感分类群的比例显著较低。该系统中水质与大型无脊椎动物之间的强相关性意味着拆除下游三座大坝将改善布什基尔溪下游的水质、生物完整性和恢复力。沉积物分析和毒性测定表明，拆除大坝和沉积物移动可能会将受污染的沉积物顺流而下输送，其浓度可能会对更敏感的生物群造成危害。然而，在大多数毒性测定中，大型无脊椎动物的死亡率和行为与清洁水对照并无显著差异。总体而言，这些结果表明1 - 3号大坝是成功恢复溪流的良好候选对象，但拆除工作最好以减轻受污染遗留沉积物潜在影响的方式进行规划。
