Dissolved oxygen in ice-covered rivers: modeling and remediation

近年来，阿萨巴斯卡河的溶解氧浓度下降到水生生物的临界阈值以下，部分原因是工业废水的点源负荷。以前校准的模型未能预测这些低DO浓度，表明我们目前对控制大型冰盖河流DO浓度的重要生态系统过程的了解存在差距。该项目的目标是(1)更好地了解影响冰盖河流中氧浓度的因素，重点是沉积物需氧量(SOD)和冰盖比；(2)改进阿萨巴斯卡河全年的DO模拟；(3)评估低DO事件对生态影响的程度和程度；以及(4)评估注氧作为补救措施的有效性。来自加拿大一所大学、行业和政府的专家团队将采取多学科方法进行实验室和现场实验，并研究数学模型，以实现项目目标。我们预计这个项目的结果将为参与的加拿大公司提供(1)一个管理工具，可以用来预测在不同环境河流条件下生物需氧量和营养物质负荷的影响，以及(2)一个评估氧气注入效果和优化其运行的模型。该项目将促进我们对纸浆厂废水、表层沉积物中的堆积和成岩作用之间的关系以及这些因素对超氧化物歧化酶速率的依赖关系的理解。这项研究将继续发展阿尔伯塔大学率先在冰盖预测以及使用微型传感器和伪现场核心技术测量超氧化物歧化率方面的创新研究能力，并培训具有与管理北方河流相关的独特专业知识的研究生。

In recent years, dissolved oxygen (DO) concentration in the Athabasca River decreased below critical thresholds for aquatic organisms, due in part to point-source loading from industrial waste waters. Previously calibrated models failed to predict these low DO concentrations, indicating a knowledge gap in our current understanding of important ecosystem processes that control DO concentrations in large ice-covered rivers. The objectives of this project are (1) to gain a better understanding of the factors affecting oxygen concentration in ice-covered rivers, with a focus on sediment oxygen demand (SOD) and ice-cover ratio; (2) to improve year-round DO modeling in the Athabasca River; (3) to assess the extent and magnitude of ecological impacts from low DO events; and (4) to evaluate the effectiveness of oxygen injection as a remedy measure. A team of experts from a Canadian university, industry and government will take a multi-disciplinary approach to conduct the laboratory and field experiments and study mathematical models to achieve the project objectives. We expect the results of this project will provide participating Canadian companies with (1) a management tool that can be used to predict the impacts of biological oxygen demand and nutrient loading under variable ambient river conditions, and (2) a model to evaluate the effectiveness of oxygen injection and optimize its operation. The project will advance our understanding of the relationships between pulp mill effluents, accumulation and diagenesis in surficial sediments, and the dependence of SOD rates on these factors. The research will continue to develop innovative research capacities, pioneered at the University of Alberta in the prediction of ice cover as well as the use of microsensor and pseudo-in situ core techniques for measuring SOD rates, and to train graduate students with unique expertise relevant to managing northern rivers.