Matthew Dietrich*, Heather E. Golden, Jay R. Christensen, Charles R. Lane and Michael Dumelle,
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引用次数: 0
Abstract
Chlorophyll-a (Chl-a) is a commonly used proxy for algal biomass within surface waters, which can be indicative of harmful algal blooms. Excess nutrients, such as nitrogen or phosphorus, promote Chl-a production, often leading to eutrophication. However, little research exists on river nutrients-to-downstream lake Chl-a linkages at large watershed scales and across disparate climatic and physiographic regions. We found a significant positive relationship between measured total nitrogen (TN) and total phosphorus (TP) concentrations in upstream rivers and Chl-a concentrations in downstream lakes at the watershed scale (average area = 99.8 km2 [35.8–628.6 km2], n = 254 watersheds) throughout the conterminous United States (CONUS). Additionally, through spatial logistic regression models, we demonstrate that a small number of explanatory variables (2–3 per model) can accurately predict (77%–86% accuracy, AUC = 0.83–0.91) classifications of high or low riverine TN, TP, or lake Chl-a concentrations throughout the CONUS at the watershed scale. The predictive variables included vegetation type, runoff, tile drainage, temperature, and nitrogen inputs. This work supports the hypothesis that rivers supply nutrients that enhance Chl-a concentrations in downstream lakes and demonstrates the power of parsimonious models combined with spatial autocorrelation to accurately predict classifications of nutrient concentrations and Chl-a across the CONUS.
叶绿素-a (Chl-a)是地表水藻类生物量的常用代用物,它可以指示有害藻华的发生。过量的营养物质,如氮或磷,促进Chl-a的产生,经常导致富营养化。然而,在大流域尺度和不同的气候和地理区域,河流营养物质与下游湖泊Chl-a的联系研究很少。我们发现,在整个美国(CONUS)的流域尺度上(平均面积为99.8 km2 [35.8-628.6 km2], n = 254个流域),上游河流的总氮(TN)和总磷(TP)浓度与下游湖泊的Chl-a浓度之间存在显著的正相关。此外,通过空间逻辑回归模型,我们证明了在流域尺度上,少数解释变量(每个模型2-3个)可以准确预测整个CONUS流域河流TN、TP或湖泊Chl-a浓度的高低分类(准确率为77%-86%,AUC = 0.83-0.91)。预测变量包括植被类型、径流、排水、温度和氮输入。这项工作支持了河流提供的营养物质会提高下游湖泊中氯-a浓度的假设,并证明了简约模型结合空间自相关的能力,可以准确预测整个CONUS的营养物质浓度和氯-a的分类。
期刊介绍:
Environmental Science & Technology Letters serves as an international forum for brief communications on experimental or theoretical results of exceptional timeliness in all aspects of environmental science, both pure and applied. Published as soon as accepted, these communications are summarized in monthly issues. Additionally, the journal features short reviews on emerging topics in environmental science and technology.