Release Mechanism of Available Phosphorus from Sediments in Grand Lake St. Marys
Olsen P Method
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Publisher:The Ohio State University
Series/Report no.:The Ohio State University. Department of Civil, Environmental and Geodetic Engineering Undergraduate Research Theses; 2014
Grand Lake St. Marys (GLSM) is Ohio’s largest inland lake and the public drinking water supply for the City of Celina with over 10,000 in population. The 2007 National Lake Assessment (NLA) has discovered extreme levels of Microcystin and eutrophication in GLSM, jeopardizing public safety and aggravating difficulties in drinking water treatment. This project aims at estimating the internal releasing rate of available phosphorus – a main contributor to phytoplanktonic growth and blue-green algae bloom – from GLSM’s sediments, complementary to external P sources such as agricultural runoffs. Water and sediment samples were collected in summer 2013 at six locations along the lake bank. Initial tests showed an average phosphorus concentration of 0.258mg/L in lake water and 41.16ppm in sediments. Later tests in six months displayed significant decrease of average phosphorus contents to 0.056mg/L in lake water samples and 13.92ppm in sediment samples. The release rate of phosphorus from sediments was estimated by lab simulation of stable lake condition. Hourly sampling and testing were performed for multiple trials. Resultant plots of phosphorus concentration versus time indicate that the model mirrors the general trend of first order decay reactions. This study aims to provide some perspectives on internal phosphorus release in GLSM and suggest possible improvements on similar studies in future.
Academic Major: Environmental Engineering
College of Engineering
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