Sources, Instream Transport, and Trends of Nitrogen, Phosphorus, and Sediment in the Lower Tennessee River Basin, 1980-96

Contents

Foreword

Glossary

Abstract

Introduction

Purpose and Scope

Description of the Lower Tennessee River Basin

Previous Investigations

Acknowledgments

Approach and Methods

Sources of Nitrogen and Phosphorus

Point Sources

Wastewater Discharge

Nonpoint Sources

Atmospheric Deposition

Inputs to Agricultural Lands

Fertilizer Application

Nitrogen Fixation

Crop Uptake

Livestock Waste

Additional Sources of Nitrogen and Phosphorus

Sources of Sediment

Instream Transport of Nitrogen, Phosphorus, and Sediment

Relation of Concentrations to Season, Streamflow, and Reach Location

Relation of Concentrations to Season

Relation of Concentrations to Streamflow

Downstream Variations in Concentrations

Instream Loads

Comparison of Inputs from Nutrient Sources with Nutrient Yields

Trends of Nitrogen, Phosphorus, and Sediment

Trends of Inputs

Trends of Instream Concentration

Conclusions

Implications for Data Collection and Analysis

Implications for Resource Management

References Cited

Appendix A. Sites where historical water-quality data collected from water year 1980 to 1996 are included in nutrient- and sediment-data analyses, lower Tennessee River Basin

Appendix B. Limitations of instream load estimates

Appendix C. Methods for quantifying inputs of nitrogen and phosphorus from point and nonpoint sources

Appendix D. Variation in nutrient concentrations with streamflow, and model estimate of streamflow variation in concentration, at selected sites in the lower Tennessee River Basin, 1980-96

Appendix E. Streamflow-duration characteristics for period of streamflow record, compared with characteristics for period of load computation, for load-computation sites in the lower Tennessee River Basin

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