Dissolved oxygen in ice-covered rivers: modeling and remediation

近年来，溶解氧（DO）浓度在阿萨巴斯卡河下降到水生生物的临界阈值以下，部分原因是点源负荷从工业废水沃茨。 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封河流中DO浓度的重要生态系统过程的理解存在知识缺口。本项目的目标是：（1）更好地了解影响冰封河流中氧浓度的因素，重点是沉积物需氧量（SOD）和冰封率;（2）改进阿萨巴斯卡河全年溶解氧的模拟;（3）评估低溶解氧事件对生态影响的程度和程度;（4）评价注氧作为补救措施的有效性。 一个由加拿大大学、工业界和政府的专家组成的小组将采取多学科方法进行实验室和实地实验，并研究数学模型，以实现项目目标。 我们预计，该项目的结果将为参与的加拿大公司提供（1）一个管理工具，可用于预测生物需氧量和营养物负荷在可变的环境河流条件下的影响，和（2）一个模型，以评估注氧的有效性和优化其操作。 该项目将促进我们对纸浆厂废水、沉积物中的堆积和成岩作用之间的关系以及SOD速率对这些因素的依赖性的理解。 这项研究将继续发展创新的研究能力，这是阿尔伯塔大学在预测冰盖以及使用微传感器和伪原位核心技术测量SOD率方面的首创，并将培养具有管理北方河流的独特专门知识的研究生。

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.