Environmental Sciences Division, Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, TN 37831-6036, USA.
Environ Manage. 2010 Mar;45(3):563-76. doi: 10.1007/s00267-010-9425-2. Epub 2010 Jan 28.
The effects of pollutants on primary producers ramify through ecosystems because primary producers provide food and structure for higher trophic levels and they mediate the biogeochemical cycling of nutrients and contaminants. Periphyton (attached algae) were studied as part of a long-term biological monitoring program designed to guide remediation efforts by the Department of Energy's Y-12 National Security Complex on East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee. High concentrations of nutrients entering EFPC were responsible for elevated periphyton production and placed the stream in a state of eutrophy. High rates of primary production at upstream locations in EFPC were associated with alterations in both invertebrate and fish communities. Grazers represented >50% of the biomass of invertebrates and fish near the Y-12 Complex but <10% at downstream and reference sites. An index of epilithic periphyton production accounted for 95% of the site-to-site variation in biomass of grazing fish. Analyses of heavy metals in EFPC periphyton showed that concentrations of zinc, cadmium, copper and nickel in periphyton decreased exponentially with distance downstream from Y-12. Zinc uptake by periphyton was estimated to reduce the concentration of this metal in stream water approximately 60% over a 5-km reach of EFPC. Management options for mitigating eutrophy in EFPC include additional reductions in nutrient inputs and/or allowing streamside trees to grow and shade the stream. However, reducing periphyton growth may lead to greater downstream transport of contaminants while simultaneously causing higher concentrations of mercury and PCBs in fish at upstream sites.
污染物对初级生产者的影响在生态系统中蔓延，因为初级生产者为更高营养级别的生物提供食物和结构，并且它们介导营养物质和污染物的生物地球化学循环。周丛藻类（附着藻类）是作为长期生物监测计划的一部分进行研究的，该计划旨在指导美国能源部 Y-12 国家安全综合体在田纳西州橡树岭的东溪溪 (EFPC) 的修复工作。进入 EFPC 的高浓度营养物质是造成周丛藻类大量繁殖的原因，并使溪流处于富营养化状态。EFPC 上游地区的高初级生产力与无脊椎动物和鱼类群落的变化有关。在 Y-12 综合体附近，食草动物占无脊椎动物和鱼类生物量的 >50%，但在下游和参照点不到 10%。周丛藻类生物量的底栖周丛藻类生产指数解释了 95%的生物量变化。对 EFPC 周丛藻类中重金属的分析表明，周丛藻类中锌、镉、铜和镍的浓度随距离 Y-12 的增加呈指数下降。周丛藻类对锌的吸收估计使该金属在 EFPC 的 5 公里范围内的溪流水中的浓度降低了约 60%。减轻 EFPC 富营养化的管理选项包括进一步减少营养物质的输入和/或允许溪边树木生长并遮蔽溪流。然而，减少周丛藻类的生长可能会导致更多的污染物向下游输送，同时导致上游地点鱼类中汞和 PCB 的浓度更高。
