MEASUREMENT UNCERTAINTY IN THE NATIONAL SURFACE WATER SURVEY
Titel:
MEASUREMENT UNCERTAINTY IN THE NATIONAL SURFACE WATER SURVEY
Auteur:
Mericas, C. E. Schonbrod, Robert D.
Verschenen in:
Lake and reservoir management
Paginering:
Jaargang 3 (1987) nr. 1 pagina's 488-497
Jaar:
1987
Inhoud:
The National Surface Water Survey is a three-phase project conducted by the U.S. Environmental Protection Agency and designed to document the chemical and biological condition of surface waters considered susceptible to acidic deposition. During the Eastern Lake Survey - Phase l, 1,929 lake samples, including 125 field duplicates, and 245 field blanks were collected. Duplicate and blank samples were used to estimate system precision and quantitation limits for each of 19 chemical parameters. Precision estimates are typically calculated as a single value, based upon data at or above the quantitation limit, and are not applicable below that limit. Where sufficient data are available, a relationship may be developed between concentration and precision. The resulting model may be used to estimate measurement uncertainty at any given concentration, thus supplying precision information for very low concentration samples. Examples of the development of measurement uncertainty models for 19 selected analytes are presented and discussed.
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