NITROGEN FLUXES AND DYNAMICS IN AN URBAN WATERSHED By JIEXUAN LUO A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2015 © 2015 Jiexuan Luo To my family ACKNOWLEDGMENTS I would like to express my sincere gratitude to Dr. George J. Hochmuth, who is the chair of my supervisory committee. His strong support and patient guidance provided me courage, energy and enthusiasm to complete this dissertation. I also would like to acknowledge the members of my supervisory committee, Dr. Mark W. Clark, Dr. Matthew J. Cohen and Dr. John J. Sansalone for their inputs throughout my study. Special thanks go to Dawn Lucas and Greg Means for providing me with great field support and laboratory support. I would like to acknowledge Larry Korhnak and Ray Thomas for giving me help in deployment of SUNAs and Bobby Hensley for guiding me with tracer studies. Thanks also go to Hao Zhang for his valuable suggestions and information regarding storm chasing. I also would like to thank my lab mates, Rishi Prasad, Rajendra Gautam, Amanda Desormeaux and Ann Couch for their kindly help in the field. At last, I owe my deepest gratitude to my dearest parents, Mr. Huanming Luo and Mrs. Ruiyun Jiang, and my beloved husband, Yunhan Wang. They provided more than one hundred percent support for my study. Words cannot express how much their love and understanding meant to me. 4 TABLE OF CONTENTS page ACKNOWLEDGMENTS .................................................................................................. 4 LIST OF TABLES ............................................................................................................ 8 LIST OF FIGURES ........................................................................................................ 10 ABSTRACT ................................................................................................................... 10 CHAPTER 1 LITERATURE REVIEW: MAJOR NITROGEN FLUXES FROM A GLOBAL AND REGIONAL URBAN VIEW AND URBAN NITROGEN MANAGEMENT PRACTICES ........................................................................................................... 14 Introduction ............................................................................................................. 14 Overview of Major Global N Fluxes ........................................................................ 14 Two Natural Processes to Produce Reactive Nitrogen ..................................... 14 Human Alterations of N Cycling ........................................................................ 16 Consequences of the Alterations to the N Cycle .............................................. 18 N Fluxes In Urban Ecosystems ............................................................................... 19 The Introduction of a Nutrient Mass Budget Concept ....................................... 19 Major N Fluxes in Urban Ecosystems .............................................................. 21 Urban N Management Practices ............................................................................. 29 Turfgrass N Management ................................................................................. 29 Stormwater Runoff Management ...................................................................... 33 Introduction Of High Resolution In Situ Nitrate Sensor ........................................... 36 Sampling Techniques and Strategies-Manual Sampling Vs Autosampler Sampling ....................................................................................................... 37 Conventional Analysis Methods Vs In Situ Continuous N Sensors .................. 39 Conclusions ............................................................................................................ 41 2 NITROGEN FLUXES FROM THREE DIFFERENT SMALL URBAN CATCHMENTS ....................................................................................................... 44 Introduction ............................................................................................................. 44 Materials And Methods ........................................................................................... 46 Study Area ........................................................................................................ 46 General Method ................................................................................................ 48 Flow Measurement ........................................................................................... 49 Precipitation Measurement ............................................................................... 51 Baseflow and Stormflow Sampling ................................................................... 51 Data Analysis ................................................................................................... 53 Results And Discussion .......................................................................................... 54 Hydrological Factors in the Three Catchments ................................................. 54 5 Rainfall-discharge Relationship ........................................................................ 56 N Loads Estimation .......................................................................................... 57 Conclusions ............................................................................................................ 60 3 NITROGEN BUDGETS FOR A SMALL URBAN WATERSHED AND THE NITROGEN FLUXES FOR THE DRAINAGE TO THE WATERSHED .................... 62 Introduction ............................................................................................................. 62 Materials and Methods............................................................................................ 65 Study Area ........................................................................................................ 65 General Research Approach ............................................................................ 68 Flow Measurement/Estimation ......................................................................... 69 Baseflow Sampling ........................................................................................... 70 Data Analysis ................................................................................................... 71 Results and Discussions ......................................................................................... 72 Discharge for Each Catchment ......................................................................... 72 Water Budgets for Lake Alice Watershed ......................................................... 75 Lake Alice N Budget Estimation ....................................................................... 77 Spatial Changes in NO3-N Concentrations ....................................................... 82 TKN Concentrations ......................................................................................... 85 Conclusions ............................................................................................................ 86 4 URBAN STORMFLOW NITRATE-NITROGEN CONCENTRATIONS AND LOADS DETERMINED BY HIGH RESOLUTION IN SITU NITRATE SENSOR AND AUTOSAMPLERS .......................................................................................... 88 Introduction ............................................................................................................. 88 Materials and Methods............................................................................................ 91 Study Area ........................................................................................................ 91 Flow Measurement ........................................................................................... 92 Autosampler Stormflow Sampling .................................................................... 93 SUNA Stormflow Sampling ............................................................................... 93 Data Analysis ................................................................................................... 97 Results and Discussion........................................................................................... 98 Comparisons Of Autosampler/SUNA NO3-N Concentrations in Storm Events ........................................................................................................... 98 Event Mean Concentrations from Autosamplers and SUNAs......................... 105 Event NO3-N Mass ......................................................................................... 106 Conclusions .......................................................................................................... 108 5 CHARACTERIZATION OF NITRATE NITROGEN CONCENTRATION AND DISCHARGE RELATIONSHIP IN A SMALL URBAN CATCHMENT MONITORED BY HIGH RESOLUTION NITRATE SENSOR ................................ 111 Introduction ........................................................................................................... 111 Materials and Methods.......................................................................................... 114 Study Area ...................................................................................................... 114 6 Flow Measurement ......................................................................................... 115 Precipitation Measurement ............................................................................