Ohio Environmental Protection Agency, 4675 Homer-Ohio Lane, Groveport, OH 43125, USA.
Environ Manage. 2010 Apr;45(4):842-55. doi: 10.1007/s00267-010-9439-9. Epub 2010 Jan 28.
A mechanistic understanding of the effects of nutrient enrichment in lotic systems has been advanced over the last two decades such that identification of management thresholds for the prevention of eutrophication is now possible. This study describes relationships among primary nutrients (phosphorus and nitrogen), benthic chlorophyll a concentrations, daily dissolved oxygen (DO) concentrations, and the condition of macroinvertebrate and fish communities in small rivers and streams in Ohio, USA. Clear associations between nutrients, secondary response indicators (i.e., benthic chlorophyll and DO), and biological condition were found, and change points between the various indicators were identified for use in water quality criteria for nutrients in small rivers and streams (<1300 km(2)). A change point in benthic chlorophyll a density was detected at an inorganic nitrogen concentration of 0.435 mg/l (+/-0.599 SD), and a total phosphorus (TP) concentration of 0.038 mg/l (+/-0.085 SD). Daily variation in DO concentration was significantly related to benthic chlorophyll concentration and canopy cover, and a change point in 24-h DO concentration range was detected at a benthic chlorophyll level of 182 mg/m(2). The condition of macroinvertebrate communities was related to benthic chlorophyll concentration and both minimum and 24-h range of DO concentration. The condition of fish communities was best explained by habitat quality. The thresholds found in relationships between the stressor and the response variables, when interpreted in light of the uncertainty surrounding individual change points, may now serve as a framework for nutrient criteria in water quality standards.
在过去的二十年中，人们对流动系统中营养富集的影响机制有了更深入的了解，因此现在可以确定防止富营养化的管理阈值。本研究描述了美国俄亥俄州小河流和溪流中的主要营养物（磷和氮）、底栖叶绿素 a 浓度、每日溶解氧（DO）浓度以及大型无脊椎动物和鱼类群落状况之间的关系。研究发现，营养物、二次反应指标（即底栖叶绿素和 DO）与生物状况之间存在明显的关联，并确定了各种指标之间的转折点，可用于小河流和溪流中的营养物质水质标准（<1300km2）。在无机氮浓度为 0.435mg/l（+/-0.599SD）和总磷（TP）浓度为 0.038mg/l（+/-0.085SD）时，底栖叶绿素 a 密度出现转折点。DO 浓度的 24 小时变化与底栖叶绿素浓度和冠层覆盖显著相关，当底栖叶绿素水平达到 182mg/m2 时，检测到 24 小时 DO 浓度范围的转折点。大型无脊椎动物群落的状况与底栖叶绿素浓度以及 DO 浓度的最小值和 24 小时范围有关。鱼类群落的状况与栖息地质量的关系最密切。当结合个别转折点的不确定性对胁迫与响应变量之间的关系中发现的阈值进行解释时，它们现在可能成为水质标准中营养物标准的框架。
