Variation in Trace Metal Concentrations in a Fluvial Environment, Ottawa River, Toledo, Ohio
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VARIATION IN TRACE METAL CONCENTRATIONS IN A FLUVIAL ENVIRONMENT, OTTAWA RIVER, TOLEDO, OHIO. Mitra B. Khadka A Thesis Submitted to the Graduate College of Bowling Green State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 2010 Committee: Sheila J. Roberts, Advisor James E. Evans Enrique Gomezdelcampo ii ABSTRACT Sheila J Roberts, Advisor Surface sediment samples were collected from a 1000 m meander reach of the Ottawa River, Ohio and analyzed for trace metals (Zn, Pb, Sr, Mn, Cu, Cr, Co, Ba, Ti, Cd, and Hg) by Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) to determine the local variability in their concentrations between geomorphic features. Eight metals (Zn, Pb, Sr, Mn, Cu, Cr, Co, and Ba) show significantly different concentrations between five fluvial geomorphic features namely, flood plains, point bars, lateral bars, pools, and riffles. Among the features, flood plains and lateral bars are places where flows are decelerated due to surface roughness and vegetation cover, promoting the deposition of fine-grained sediments and organic matter. Thus, flood plains and lateral bars consistently exhibit the highest metal concentrations. The lowest metal concentrations in point bars are attributed to relatively coarse-grained sediment and low organic matter content. The difference in mean metal concentration between flood plains and point bars ranges from 5 times for Co to 12.5 times for Pb. It was found that Zn, Sr, Mn, Cu, Cr, Co, and Ba are influenced by similar transport and interaction processes, and possibly have common sources, while Pb shows a weak to non-significant association with other metals indicating either a different mode of transport or separate anthropogenic sources. The concentrations of all metals in 89% of the samples are below the Threshold Effect Level (TEL) and the Probable Effect Level (PEL), and thus sediment contamination issues are to be minor concern in this section of the river. The finding that flood plains serve as sediment-associated metals sink can have important implications for monitoring and regulation, impact assessment, iii and remediation of contaminated sediments in metal contaminated section of the Ottawa River or for other rivers having similar geomorphological, hydrological, and sedmentological characters. iv Dedicated to my loving parents. v ACKNOWLEDGMENTS This thesis work is a product of innumerable help and support kindly provided to me by various people to whom I am highly indebted. At first, I would like to express my deep sense of gratitude to my loving parents for their continuous support and inspiration. I would like to express my profound gratitude to my advisor, Dr. Sheila J. Roberts for her worthy suggestions, encouragement, kind supervision, and generous co-operation, without which this thesis would not have taken its form. I am very much thankful to my thesis committee member, Dr. James E. Evans who provided helpful suggestions and great assistance during my field work and lab work. Similarly, I would like to thanks Dr. Enrique Gomezdelcampo for taking time to be on my committee and encouraging me at various occasions. I am also grateful to Dr. Shridhar for providing me a great help and support during trace metal analysis. My special thanks goes to Department of Geology, Bowling Green State University for providing financial support and to Wildwood Metropark, Toledo who gave me permission to conduct research and collect the sediment samples within the park area. Last but not least, I am very much obliged to my dear friends Hari, Senthil, Asako, and Bharat who helped me right from the beginning to the end of the work in various ways. vi TABLE OF CONTENTS Page INTRODUCTION......…........................................................................................................ 1 Previous Study ........................................................................................................... 3 STUDY AREA AND METHODOLOGY ............................................................................. 8 Background…. ........................................................................................................... 8 Bedrock Geology and Structure ..................................................................... 8 Glacial Geology ............................................................................................. 10 Soils…. .......................................................................................................... 14 Ottawa River .................................................................................................. 16 Drainage Basin Characteristics .......................................................... 16 Hydrometeorology ............................................................................. 18 Study Site ....................................................................................................... 20 Previous Studies ............................................................................................. 22 Methods…….............................................................................................................. 25 Geomorphic Features ..................................................................................... 25 Sediment Sampling ........................................................................................ 29 Grain Size Analysis and Organic Matter ....................................................... 30 Trace Metal Analysis ..................................................................................... 32 Quality Assurance .......................................................................................... 35 Statistical Analysis ......................................................................................... 36 RESULTS……………. ......................................................................................................... 38 Role of Fluvial Geomorphology ................................................................................ 38 Metal Variability between Geomorphic Features .......................................... 38 vii Pair-wise Comparison .................................................................................... 44 Upstream-Downstream Variation .................................................................. 45 Grain Size Distribution and Organic Matter .............................................................. 46 Correlation Analysis .................................................................................................. 48 Principal Component Analysis................................................................................... 52 Sediment Quality Assessment .................................................................................... 55 DISSCUSSION…….. ............................................................................................................ 58 Variation in Trace Metal Concentrations ................................................................... 58 Metal Association and Possible Sources .................................................................... 62 Sediment Pollution ..................................................................................................... 64 Implication….. ........................................................................................................... 65 SUMMARY AND CONCLUSIONS .................................................................................... 66 REFERENCES ...................................................................................................................... 68 APPENDICES ....................................................................................................................... 77 APPENDIX A. SAMPLE LOCATION ................................................................................ 78 APPENDIX B. TRACE METAL CONCENTRATION FOR ALL SAMPLES .................. 79 APPENDIX C. SAND, MUD, AND ORGANIC MATTER CONTENT ............................ 80 APPENDIX D. INDIVIDUAL SAMPLE GRAINSIZE STATISTICS ................................ 81 APPENDIX E. GEOMORPHIC FEATURES GRAINSIZE STATISTICS ......................... 97 viii LIST OF FIGURES Figure Page 1 Increase in metal concentration with decreasing sediments size in the River Ems ................................................................................................. 5 2 Bed rock geology of Toledo area showing the study area .......................................... 9 3 Figure showing the location and general extent of glacial lakes in the Lake Erie Basin from 16 Ka through 5 Ka ...................................................... 13 4 General soil map of Lucas County, Ohio showing location of the study area ........... 15 5 Ottawa River and Ten Mile Creek watershed ............................................................ 17 6 Mean Monthly Rainfall recorded at the Toledo Regional Airport ............................. 19 7 Mean daily discharge and precipitation hydrograph of the Ottawa River.................. 19 8 Areal view of the study section of the Ottawa River with sediment sample locations ......................................................................................................... 21 9 Trace metal concentration in Ottawa River sediments measured in river length from 0 to 14 km .................................................................................. 23 10 Photographs depicting the spatial distribution