Influence Of Ph On Release Of Phosphorus From Lake Sediments

Author : Kenneth J. Gibbons
Publisher :
ISBN 13 :
Total Pages : 63 pages
Book Rating : 4.:/5 (971 download)

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Download or read book Effect of Temperature on Phosphorus Release from Anoxic Western Lake Erie Sediments written by Kenneth J. Gibbons and published by . This book was released on 2015 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Laurentian Great Lakes contain approximately 2% of the world's freshwater and provide drinking water for more than 30 million people. Lake Erie is the shallowest and smallest of the Great Lakes. The western basin is the shallowest portion of Lake Erie and receives a majority of its water from the Maumee River and Detroit River. The Maumee River Watershed is the largest watershed in the Great Lakes and land use in the watershed dominated by urban and agricultural areas. Farm field run-off and combined sewer overflows from urban and agricultural areas contribute high concentrations of nutrients to the Maumee River. The high nutrient water flowing out of the Maumee River into the Western Basin of Lake Erie creates a good environment for Harmful Algal Blooms (HABs), which are primarily composed of Microcystis, to rapidly grow. HABs are a serious issue for Lake Erie because Microcystis produces a toxin that is harmful to humans. Research focused on decreasing HABs has identified phosphorus as the limiting nutrient. Phosphorus enters the lake through either external (phosphorus entering from outside the lake i.e. farm field run-off or inputs from tributaries) or internal loading (release of phosphorus from lake sediments). For Western Lake Erie, there are numerous studies on external loading of phosphorus, however there is considerably less research on internal phosphorus loading. Estimating internal loading of phosphorus is important because phosphorus concentrations in lake sediments can be orders of magnitude higher than phosphorus concentrations in lake water and can be a significant source of phosphorus. Phosphorus release rates from lake sediments can be affected by a variety of environmental factors such as pH, temperature, and dissolved oxygen concentration. If lake sediments become warmer and more hypoxic in response to climate change, the contribution of phosphorus from lake sediments may increase. The research conducted in this thesis investigates the effect of temperature on the release of phosphorus from anoxic lake sediments. This study aims to estimate phosphorus release rates for a range of temperatures under anoxic conditions for Western Lake Erie and to improve estimates of internal phosphorus loading. Sediment cores collected during the summer of 2014 and 2015 were incubated at 10°C, 20°C, 22°C, 27°C, and 30°C under anoxic conditions. Results from the sediment core incubations indicate that temperature, location, and duration of anoxia are significant influences on phosphorus release. Extrapolating the phosphorus release rates for the entire western basin, four days of anoxia at 30°C for the entire basin could result in the release of ~240 metric tons of phosphorus.