U.S. Geological Survey, South Atlantic Water Science Center, Columbia, SC, USA.
Great Smoky Mountains National Park, National Park Service, Gatlinburg, TN, USA.
Sci Total Environ. 2021 Aug 10;781:146711. doi: 10.1016/j.scitotenv.2021.146711. Epub 2021 Mar 25.
The United States (US) National Park Service (NPS) manages protected public lands to preserve biodiversity. Exposure to and effects of bioactive organic contaminants in NPS streams are challenges for resource managers. Recent assessment of pesticides and pharmaceuticals in protected-streams within the urbanized NPS Southeast Region (SER) indicated the importance of fluvial inflows from external sources as drivers of aquatic contaminant-mixture exposures. Great Smoky Mountains National Park (GRSM), lies within SER, has the highest biodiversity and annual visitation of NPS parks, but, in contrast to the previously studied systems, straddles a high-elevation hydrologic divide; this setting limits fluvial-inflows of contaminants but potentially increases visitation-driven contaminant deliveries. We leveraged the unique characteristics of GRSM to test further the importance of fluvial contaminant inflows as drivers of protected-stream exposures and to inform the relative importance of potential additional contaminant transport mechanisms, by comparing the estimated risks of 328 pesticides and pharmaceuticals in water at 16 GRSM stream locations to those estimated previously in SER streams. Extensive mixtures (31 compounds) were only observed in an atypical reach on the boundary of GRSM downstream of a wastewater discharge, while limited mixtures (2-5 compounds) were observed in one stream with elevated visitation pressure (recreational "tube floating"). The insecticide, imidacloprid, used to eradicate hemlock woolly adelgid, was detected in 8 (50%) streams. Infrequent exceedances of a cumulative ToxCast-based, exposure-activity ratio (Σ) 0.001 screening-level of concern suggested limited risk to non-target, aquatic vertebrates, whereas exceedances of a cumulative benchmark-based, invertebrate toxicity quotient (Σ) 0.1 screening level at 8 locations indicated generally high risk to invertebrates. The results are consistent with the importance of fluvial transport from extra-park sources as a driver of bioactive-contaminant mixture exposures in protected streams and illustrate the potential additional risks from visitation-driven and tactical-use-pesticides.
美国国家公园管理局（NPS）管理着受保护的公共土地，以保护生物多样性。NPS 溪流中生物活性有机污染物的暴露和影响对资源管理者来说是一个挑战。最近对城市化的 NPS 东南地区（SER）受保护溪流中的农药和药物进行了评估，表明外部来源的河流流入是水生污染物混合暴露的驱动因素。大烟山国家公园（GRSM）位于 SER 内，拥有 NPS 公园中最高的生物多样性和年游客量，但与之前研究的系统不同的是，它跨越了一个高海拔的水文分水岭；这种设置限制了污染物的河流流入，但可能会增加游客驱动的污染物输送。我们利用 GRSM 的独特特征，通过比较 16 个 GRSM 溪流位置的水中 328 种农药和药物的估计风险与之前在 SER 溪流中估计的风险，进一步测试了河流污染物流入作为受保护溪流暴露驱动因素的重要性，并为潜在的额外污染物运输机制的重要性提供了信息。在 GRSM 下游边界处一个废水排放口的下游一个典型河段，仅观察到广泛的混合物（31 种化合物），而在一个游客压力较高的溪流（娱乐“管浮”）中仅观察到有限的混合物（2-5 种化合物）。用于根除铁杉羊毛衣鱼的杀虫剂噻虫啉在 8 条溪流（50%）中被检出。基于 ToxCast 的累积暴露-活性比（Σ）0.001 筛查关注水平的罕见超标表明，对非目标水生脊椎动物的风险有限，而在 8 个地点基于累积基准的无脊椎动物毒性商（Σ）0.1 筛查水平的超标表明，对无脊椎动物的风险通常很高。结果与河流从公园外来源的运输作为保护溪流中生物活性污染物混合物暴露的驱动因素的重要性一致，并说明了来自游客驱动和战术使用农药的潜在额外风险。
