By Lawrence W. Keenan, Ph.D. Edgar F. Lowe, Ph.D. Ed J. Dunne, Ph.D
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CHAPTER 7. BIOGEOCHEMISTRY by Lawrence W. Keenan, Ph.D. Edgar F. Lowe, Ph.D. Ed J. Dunne, Ph.D. Angelique M. K. Bochnak, Ph.D. K. Ramesh Reddy, Ph.D. Alan L. Wright, Ph.D. Jian Di St. Johns River Water Management District Palatka, Florida 2012 This page intentionally left blank. Table of Contents TABLE OF CONTENTS TABLE OF CONTENTS ........................................................................................................... III BIOGEOCHEMISTRY WORKING GROUP ........................................................................ VI LIST OF FIGURES .................................................................................................................. VII LIST OF TABLES ................................................................................................................... XIV ACRONYMS, ABBREVIATIONS, AND CONVERSION FACTORS.............................. XVI 1 ABSTRACT .................................................................................................................. 18 2 INTRODUCTION........................................................................................................ 19 2.1 Hydrologic and Biogeochemical Controls ................................................................. 20 2.2 Purpose and Objectives ............................................................................................... 21 2.3 Exchanges with Other Working Groups ................................................................... 22 2.4 Conceptual Model ........................................................................................................ 22 2.5 Assessment of River–Wetland Hydrology ................................................................. 23 2.6 Hydrologic Status and Trends .................................................................................... 25 2.7 Water Quality Status and Trends .............................................................................. 27 3 MATERIALS AND METHODS ................................................................................ 33 3.1 Digital Elevation Model ............................................................................................... 33 3.2 Assessment of River–Wetland Hydrology ................................................................. 33 3.3 Scenario Analyses and Ranking ................................................................................. 33 3.4 Synoptic Survey of Wetland Soils ............................................................................... 35 3.5 Lake Mass Balance Based on Full1995NN Hydrology ............................................. 35 3.6 Effect of Water Loss From Soil Air-drying) on Carbon and Nutrient Release ..... 36 3.7 Carbon, Nitrogen, and Phosphorus Releases ............................................................ 36 3.7.1 Effect of Intact Soil Core Diameter on Carbon and Nutrient Release ............... 38 3.7.2 Field Core Soil Analysis to Determine Carbon and Nutrient Releases ............. 38 3.7.3 Field Core Flooding to Determine Carbon and Nutrient Releases .................... 39 3.7.4 Site Water Correction and Dissolved Organic Carbon Release Rates ............... 40 3.8 Models ........................................................................................................................... 40 St. Johns River Water Management District 7-iii Chapter 7. Biogeochemistry 3.8.1 Wetland Constituent Release Model .................................................................. 40 3.8.2 Wetland Constituent Reduction Model .............................................................. 40 3.9 Lake Water Quality ..................................................................................................... 41 3.10 Projected Changes in Dissolved Oxygen Concentration .......................................... 41 4 RESULTS ..................................................................................................................... 42 4.1 Digital Elevation Model Results ................................................................................. 42 4.2 Assessment of River–Wetland Hydrology Results .................................................... 43 4.3 Hydrologic Analyses of Scenarios Results ................................................................. 46 4.4 Synoptic Survey of Wetland Soils Results ................................................................. 46 4.5 Inlet/Outlet Lake Mass Balance Based on Full1995NN Hydrology Results ........... 49 4.6 Effect of Soil Water Loss (Air-drying) on Carbon and Nutrient Release Results . 53 4.7 Carbon, Nitrogen, and Phosphorus Releases Results ............................................... 55 4.7.1 Influence of Core Diameter ............................................................................... 55 4.7.2 Field Core Soil Analysis to Determine Carbon and Nutrient Releases ............. 58 4.7.3 Field Core Flooding to Determine Carbon and Nutrient Releases .................... 59 4.7.4 Release of Dissolved Organic Carbon from Flooded Cores .............................. 60 4.7.5 Summary of Carbon and Nutrient Release Rate Estimates for Modeling ......... 63 4.7.6 Summary of Carbon and Nutrient Reduction Rate Coefficient Estimates for Modeling ............................................................................................................ 65 4.8 Models Results .............................................................................................................. 67 4.8.1 Wetland Constituent Release Model .................................................................. 67 4.8.2 Wetland Constituent Reduction Model .............................................................. 68 4.9 Relationships of Lake Water Quality Parameters and Dissolved Oxygen Results 73 4.10 Projected Changes in Dissolved Oxygen Concentration Results ............................. 75 5 DISCUSSION ............................................................................................................... 78 5.1 Discussion of General Effects ...................................................................................... 79 5.2 Effects by River Segment Using Scenario Full1995NN ............................................ 81 5.3 Example of Potential Effects Using Upstream Soils ................................................. 85 5.4 Uncertainty ................................................................................................................... 86 5.4.1 General Uncertainty ........................................................................................... 86 5.4.2 Uncertainty Level Determination by River Segment for Full1995NN Test Scenario.............................................................................................................. 87 5.5 Recommendations ........................................................................................................ 89 7-iv St. Johns River Water Supply Impact Study Table of Contents 6 ACKNOWLEDGEMENTS ........................................................................................ 91 7 REFERENCES ............................................................................................................. 92 8 APPENDICES FOR CHAPTER 7. BIOGEOCHEMISTRY .................................. 97 APPENDIX 7A. SYNOPTIC SOIL SURVEY MAPS, DATA, AND SUMMARY APPENDIX 7B. SAMPLE ANALYSIS METHODS IDENTIFICATION APPENDIX 7C. WETLAND CONSTITUENT RELEASE MODEL APPENDIX 7D. WETLAND CONSTITUENT REDUCTION MODEL APPENDIX 7E. BLUE CYPRESS SOIL RELEASE CALCULATIONS AND MODEL SIMULATIONS St. Johns River Water Management District 7-v Chapter 7. Biogeochemistry BIOGEOCHEMISTRY WORKING GROUP Name (Organization) Role Lawrence W. Keenan, Ph.D., SJRWMD Working Group Leader, Author Edgar F. Lowe, Ph.D., SJRWMD Author, Advisor, Editor Ed J. Dunne, Ph.D., SJRWMD Author, Analysis Angelique M. K. Bochnak, Ph.D., SJRWMD Author, Analysis K. Ramesh Reddy, Ph.D., Univ. of Fla. Author , Expert Advisor, Analysis Alan L. Wright, Ph.D., Univ. of Fla. Author , Expert Advisor, Analysis Jian Di, SJRWMD Author, Analysis Lawrence E. Battoe, Ph.D. SJRWMD Editor Palmer D. Kinser, SJRWMD Advisor Bill VanSickle, SJRWMD Analysis Ima Bujak, Ph.D., SJRWMD Advisor Robert Freese Ph.D., SJRWMD Advisor Clifford P. Neubauer, Ph.D., SJRWMD Advisor John Hendrickson, SJRWMD Advisor 7-vi St. Johns River Water Supply Impact Study List of Figures LIST OF FIGURES Figure 2–1. Conceptual model showing causal and predictive interactions with the indicated biological groups of biogeochemistry of wetland organic soils due to water withdrawals. DOC = dissolved organic carbon, TP = total phosphorus, TN = total nitrogen, DEM = Digital Elevation Model, N = nitrogen, P = phosphorus, TOC = total organic carbon, DO = dissolved oxygen, NPP = net primary production. ................................................................. 23 Figure 2–2. Median water elevation along the St. Johns River with river kilometers and river segment numbers (1 to 9). Data is from the Base1995NN scenario. Note that the environmental assessment for the water withdrawal ends at a weir in segment 8, where more than half of the river elevation drop has occurred. ................................................................................... 24 Figure 2–3. Time series analysis for observed water elevations at Lake Poinsett. (A) Simple regression of monthly water elevations indicates a significant decline in water elevations (NGVD29) at Highway 520 on