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<br />This concentration is 16 times the maximum recommended selenium concentration <br />of 1 ~g/g wet weight in edible tissue (Fan and others, 1988). No duck or <br />goose samples were submitted for analysis during this study to determine <br />actual selenium concentrations in bird tissue that would be consumed by <br />humans. <br /> <br />One sample of young voles collected at Sweitzer Lake had a selenium <br />concentration of 4.3 ~g/g dry weight (table 23). This concentration was in <br />the lower range of selenium concentrations in voles at Kesterson National <br />Wildlife Refuge (Ohlendorf, 1989), where selenium toxicity was a problem. <br /> <br />Selenium in biota, Gunnison and Uncompahgre Rivers and tributaries <br /> <br />Selenium concentrations in fish, invertebrate, and aquatic plant samples <br />were comparable between samples collected from the Gunnison River at Delta <br />(site 3) and at the Escalante State Wildlife Area (site 10). Selenium con- <br />centrations in fish collected from the Gunnison River can be compared in <br />figure 16 and in table 13. Selenium concentrations in biota samples collected <br />at Sweitzer Lake (site 7) and at the Gunnison River at Escalante State <br />Wildlife Area (site 10) can be compared in figures 18 and 19. Selenium <br />concentrations in invertebrate and aquatic plant samples collected from the <br />Gunnison River are summarized in table 14. <br /> <br />Selenium concentrations in fish samples collected from the Gunnison River <br />at Escalante State Wildlife Area ranged from 1.9 ~g/g dry weight in a round- <br />tail chub to 10.3 ~g/g dry weight in a carp (table 20). Carp, fathead <br />minnows, and green sunfish had the largest selenium concentrations of the <br />eight fish species analyzed. Non-parametric statistical tests (significance <br />level of 0.05) indicated that selenium concentrations were significantly less <br />in fish collected at the wildlife area (site 10) than in fish collected at <br />Sweitzer Lake (site 7). However, five of the eight fish samples collected at <br />the wildlife area (table 20) had selenium concentrations greater than the NCBP <br />85th-percentile concentration of 2.8 ~g/g dry weight. <br /> <br />Selenium concentrations in fish samples collected from the Gunnison River <br />at Delta (site 3) and at Escalante State Wildlife Area (site 10) were not <br />significantly different (significance level of 0.05). Selenium concentrations <br />in fish collected from the Gunnison River at Delta ranged from 1.8 ~g/g dry <br />weight in a white sucker sample to 9.5 ~g/g dry weight in a fathead minnow <br />sample (table 20). A leopard frog sample collected at Delta had a concentra- <br />tion of 8.2 ~g/g dry weight. <br /> <br />Background selenium concentrations in biota for the Gunnison River may be <br />represented by the samples collected at the reference site, Gunnison River <br />below the Gunnison Tunnel (site 2). Biota samples collected at this site <br />contained less selenium (table 20) than biota at the downstream sites. This <br />corresponded to small concentrations of selenium (less than 1 ~g/L) in water <br />samples collected at the same site (table 16). The average selenium concen- <br />tration in the four fish samples collected below the Gunnison Tunnel was <br />2.4 ~g/g dry weight. <br /> <br />58 <br />