Introduction 1 Overview of bed-sediment study design 2 Planning for sample collection 5 Site location and selection of depositional zones Adapting to local conditions 5 Equipment 7 Samplers 8 Sieves 8 Equipment cleaning 11 Sample collection 15 Wadeable zone 15 Guillotine sampler 15 Spoon, scoop, or spatula sampler 16 Nonwadeable zone 17 Sample processing 17 Sieving 17 Trace elements 17 Sieve-frame method 17 Bag method 18 Decanting 18 Organic contaminants 18 Particle size 18 Preparation for shipping 18 Field documentation 19 Final cleaning 19 Quality assurance and quality control 19 Control of contamination 19 Control of variability 20 Verification 20 References cited 20 FIGURES 1. Map showing a typical depositional zone site 6 2. Diagram showing the Guillotine, a hand-held core sampler 9 3. Schematic diagram showing the Guillotine sampler in operation 10 TABLES 1. Analytical constituents for bed-sediment Occurrence Survey 4 2. Equipment and supplies for collecting and processing stream bed-sediment samples 3. Reference guide for collecting and processing stream bed-sediment samples 12 Contents III CONVERSION FACTORS, ABBREVIATIONS, AND ACRONYMS Conversion Factors Multiply By To obtain foot (ft) 0.3048 meter gallon (gal) 3.785 liter inch (in.) 25.4 millimeter square inch (in2) 645.2 square millimeter Temperature is given in degrees Celsius (°C), which can be converted to degrees Fahrenheit (°F) by the following equation:°F

No abstract

Glyphosate use in a watershed results in some occurrence in surface water; however, the watersheds most at risk for the offsite transport of glyphosate are those with high application rates, rainfall that results in overland runoff and a flow route that does not include transport through the soil.

No abstract

This paper is an introduction to the following series of papers that report on in-depth investigations that have been conducted at five agricultural study areas across the United States in order to gain insights into how environmental processes and agricultural practices interact to determine the transport and fate of agricultural chemicals in the environment. These are the first study areas in an ongoing national study. The study areas were selected, based on the combination of cropping patterns and hydrologic setting, as representative of nationally important agricultural settings to form a basis for extrapolation to unstudied areas. The holistic, watershed-scale study design that involves multiple environmental compartments and that employs both field observations and simulation modeling is presented. This paper introduces the overall study design and presents an overview of the hydrology of the five study areas.