| Abstract: | A continuing quality-assurance program has been operated by the U.S. Geographical Survey to evaluate any bias introduced by routine handling, shipping, and laboratory analyses of wet-deposition samples collected in the National Atmospheric Deposition Program (NADP) and National Trends Network (NTN). Blind-audit samples having a variety of constituent concentrations and values were selected. Only blind-audit samples with constituent concentrations and values less than the 95th-percentile concentration for natural wet-deposition samples were included in the analysis. Of the major ions, there was a significant increase of Ca2+, Mg2+, K+ SO42+ and Cl- in samples handled according to standard protocols and shipped in NADP/NTN sample-collection buckets. For 1979-1987, graphs of smoothed data showing the estimated contaminations in blind-audit samples indicate a decrease in the median concentration and ranges of Ca2+, Mg2+ and SO42- contamination of blind-audit samples shipped in sample-collection buckets. Part of the contamination detected in blind-audit samples can be attributed to contact with the sample-collection bucket and lid; however, additional sources also seem to contaminate the blind-audit sample. Apparent decreases in the magnitude and range of sample contamination may be caused by differences in sample-collection bucket- and lid-washing procedures by the NADP/NTN Central Analytical Laboratory. Although the degree of bias is minimal for most constituents, summaries of the NADP/NTN data base may contain overestimates of Ca2+, Mg2+, Na-, K+, SO42- and Cl- concentrations, and underestimates of H+ concentrations. |
| Genre: | Article |
| ProdID: | 70015738 |
| Citation Author: | See, R. B.; Schroder, L. J.; Willoughby, T. C. |
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| Citation End Page: | 1806 |
| Citation Issue: | 8 |
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| Citation Language: | English |
| Citation Larger Work Title: | Atmospheric Environment |
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| Citation Number Of Pages: | 6 |
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| Citation Search Results Text: | A quality-assurance assessment for constituents reported by the National Atmospheric Deposition Program and the National Trends Network; 1989; Article; Journal; Atmospheric Environment; See, R. B.; Schroder, L. J.; Willoughby, T. C. |
| Citation Start Page: | 1801 |
| Citation Volume: | 23 |
| Citation Year: | 1989 |
| Type: | citation/reference |
| Text: | A quality-assurance assessment for constituents reported by the National Atmospheric Deposition Program and the National Trends Network; 1989; Article; Journal; Atmospheric Environment; See, R. B.; Schroder, L. J.; Willoughby, T. C. |
| URL (THUMBNAIL): | http://pubs.er.usgs.gov/thumbnails/outside_thumb.jpg |
| Date Other: | Sun, 1 Jan 1989 00:00 -0600 |
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