Water Resource Division, US Geological Survey, 934 Broadway, Suite 300, Tacoma, WA 98402, USA.
Environ Manage. 2010 Mar;45(3):603-15. doi: 10.1007/s00267-010-9435-0. Epub 2010 Feb 9.
This study examined the relative influence of nutrients (nitrogen and phosphorus) and habitat on algal biomass in five agricultural regions of the United States. Sites were selected to capture a range of nutrient conditions, with 136 sites distributed over five study areas. Samples were collected in either 2003 or 2004, and analyzed for nutrients (nitrogen and phosphorous) and algal biomass (chlorophyll a). Chlorophyll a was measured in three types of samples, fine-grained benthic material (CHL(FG)), coarse-grained stable substrate as in rock or wood (CHL(CG)), and water column (CHL(S)). Stream and riparian habitat were characterized at each site. TP ranged from 0.004-2.69 mg/l and TN from 0.15-21.5 mg/l, with TN concentrations highest in Nebraska and Indiana streams and TP highest in Nebraska. Benthic algal biomass ranged from 0.47-615 mg/m(2), with higher values generally associated with coarse-grained substrate. Seston chlorophyll ranged from 0.2-73.1 microg/l, with highest concentrations in Nebraska. Regression models were developed to predict algal biomass as a function of TP and/or TN. Seven models were statistically significant, six for TP and one for TN; r(2) values ranged from 0.03 to 0.44. No significant regression models could be developed for the two study areas in the Midwest. Model performance increased when stream habitat variables were incorporated, with 12 significant models and an increase in the r(2) values (0.16-0.54). Water temperature and percent riparian canopy cover were the most important physical variables in the models. While models that predict algal chlorophyll a as a function of nutrients can be useful, model strength is commonly low due to the overriding influence of stream habitat. Results from our study are presented in context of a nutrient-algal biomass conceptual model.
本研究考察了营养物质（氮和磷）和栖息地对美国五个农业区藻类生物量的相对影响。选择了这些地点以捕捉一系列营养条件，在五个研究区域内分布着 136 个地点。样品于 2003 年或 2004 年采集，并分析了营养物质（氮和磷）和藻类生物量（叶绿素 a）。叶绿素 a 在三种类型的样品中进行了测量，即细颗粒底栖物质（CHL(FG)）、岩石或木材等粗颗粒稳定基质中的叶绿素 a（CHL(CG)）和水柱中的叶绿素 a（CHL(S)）。每个地点的溪流和河岸栖息地都进行了特征描述。TP 范围为 0.004-2.69mg/L，TN 范围为 0.15-21.5mg/L，内布拉斯加州和印第安纳州溪流的 TN 浓度最高，内布拉斯加州的 TP 浓度最高。底栖藻类生物量范围为 0.47-615mg/m(2)，较高的值通常与粗颗粒基质相关。悬浮物叶绿素浓度范围为 0.2-73.1μg/l，内布拉斯加州的浓度最高。建立了回归模型，以预测藻类生物量作为 TP 和/或 TN 的函数。有 7 个模型具有统计学意义，6 个是关于 TP 的，1 个是关于 TN 的；r(2)值范围为 0.03-0.44。中西部的两个研究区域无法开发出具有统计学意义的回归模型。当将溪流栖息地变量纳入模型时，模型性能得到提高，有 12 个具有统计学意义的模型，r(2)值增加（0.16-0.54）。水温和河岸树冠覆盖率是模型中最重要的物理变量。虽然预测藻类叶绿素 a 作为营养物质函数的模型可能很有用，但由于溪流栖息地的压倒性影响，模型的强度通常较低。我们的研究结果在营养-藻类生物量概念模型的背景下呈现。
