Refinement of sampling methods for analysis of nutrients in surface waters

摘要

Where long-term monitoring data is not available, or the nature of the watershed is changing rapidly, or data is limited, a cost-effective monitoring plan must be developed to ascertain nutrient concentrations in streams, stream nutrient load, and watershed nutrient yield. To accomplish this, nutrient monitoring must occur during baseflow, stormflow, and wetflow conditions. Wetflow refers to flow regimes between stormflow and baseflow. Using a 12-hr sampling interval before, during, and after rainfall events of different intensities allows accurate measurement of nutrient concentrations. These data allow determination of nutrients (ammonia-N, nitrite-nitrate-N, and total phosphorus) correlation with flow. Research on three different-sized watersheds in the Piedmont of west Georgia ranging from about 1 to 6295 km2 (0.4 to 2430 mi2) (Chattahoochee River at Whitesburg, Georgia) indicate that the best sampling methods are dependent on the size of the watershed, proportions of forest cover and impermeable surface, and intensity of nutrient influx from point sources and nonpoint sources.