Available from the U.S. Geological Survey, Branch of Information Services, Box 25286, Denver Federal Center, Denver, CO 80225, USGS Water-Resources Investigations Report 974227, 34 p., 5 figs.
This document also is available in pdf format:
WRIR 974227
(Requires Adobe
Acrobat Reader)
Quality-control samples provide part of the information needed to estimate the bias and variability that result from sample collection, processing, and analysis. Quality-control samples of surface water collected for the Upper Colorado River National Water-Quality Assessment study unit for water years 199596 are presented and analyzed in this report. The types of quality-control samples collected include pre-processing split replicates, concurrent replicates, sequential replicates, post-processing split replicates, and field blanks.
Analysis of the pre-processing split replicates, concurrent replicates, sequential replicates, and post-processing split replicates is based on differences between analytical results of the environmental samples and analytical results of the quality-control samples. Results of these comparisons indicate that variability introduced by sample collection, processing, and handling is low and will not affect interpretation of the environmental data. The differences for most water-quality constituents is on the order of plus or minus 1 or 2 lowest rounding units. A lowest rounding unit is equivalent to the magnitude of the least significant figure reported for analytical results. The use of lowest rounding units avoids some of the difficulty in comparing differences between pairs of samples when concentrations span orders of magnitude and provides a measure of the practical significance of the effect of variability.
Analysis of field-blank quality-control samples indicates that with the exception of chloride and silica, no systematic contamination of samples is apparent. Chloride contamination probably was the result of incomplete rinsing of the dilute cleaning solution from the outlet ports of the decaport sample splitter. Silica contamination seems to have been introduced by the blank water. Sampling and processing procedures for water year 1997 have been modified as a result of these analyses.
Abstract
Introduction
Purpose and Scope
Acknowledgments
Quality-Control Sampling Program
Replicate Samples
Pre-Processing Split Replicates
Comparison of General Chemical Constituents
Comparison of Nutrients and Organic Carbon
Comparison of Trace Elements
Concurrent and Sequential Replicates
Comparison of General Chemical Constituents
Comparison of Nutrients and Organic Carbon
Post-Processing Split Replicates
Comparison of General Chemical Constituents
Comparison of Nutrients and Organic Carbon
Field Blanks
General Chemical Constituents
Nutrients and Organic Carbon
Conclusions
References Cited
Water Resources of Colorado
Contact: webmaster_co@usgs.gov
AccessibilityFOIAPrivacyPolicies and Notices | |