Ten intercomparison studies to determine the accuracy of pH and specific-conductance measurements, using dilute-nitric acid solutions, were managed by the U.S. Geological Survey for the National Atmospheric Deposition Program and the National Trends Network precipitation networks. These precipitation networks set quality-control goals for site-operator measurements of pH and specific conductance. The accuracy goal for pH is plus or minus 0.1 pH unit; the accuracy goal for specific conductance is plus or minus 4 microsiemens per centimeter at 25 degrees Celsius. These intercomparison studies indicated that an average of 65 percent of the site-operator pH measurements and 79 percent of the site-operator specific-conductance measurements met the quality-control goal. A statistical approach that is resistant to outliers was used to evaluate and illustrate the results obtained from these intercomparisons. (USGS)
Additional publication details
USGS Numbered Series
Average annual precipitation and runoff for Arkansas, 1951-1980
Water-Resources Investigations Report
4 maps on 1 sheet ; 38 x 45 cm. and 10 x 12 cm., sheet 94 x 117 cm., folded in envelope 31 x 23 cm.