Evaluation of environmental factors affecting yields of major dissolved ions of streams in the United States

Abstract

Introduction 1 Purpose and scope 2 Previous studies 2 Relationship between bedrock and ion concentration in streams 2 Relationship between atmospheric precipitation quality and ion concentration or transport in streams 3 Relationship between atmospheric precipitation quantity and ion concentration or transport in streams 3 Relationship between stream temperature and ion concentration or transport in streams 4 Relationship between human activity and ion concentration or transport in streams 4 Methods 5 Basin selection 5 Estimates of basin and stream characteristics 6 Atmospheric precipitation 6 Stream temperature 8 Population density 8 Major-dissolved-ion yields 8 Prediction of dissolved-ion yields 8 Results and discussion 10 Effect of rock type on yields 10 Effect of atmospheric precipitation on yields 13 Annual runoff 13 Sodium, chloride, and potassium 19 Magnesium, calcium, bicarbonate, and dissolved solids 19 Sulfate 21 Effect of human activity on yields 21 Effect of average stream temperature on yields 22 Uses and limitations of the multiple-linear-regression equations for predicting dissolvedion yields 22 Considerations for future studies 24 Summary 25 References cited 26 Appendix: Published references on basin geology 29 Conversion factors and abbreviations 39 FIGURES 1. Map showing locations of gaged sites for drainage basins underlain by single bedrock types 6 2. Graphs showing basin-population density in relation to average stream temperature and annual precipitation quantity 11 Contents III IV Contents