8282 - Laserfiche WebLink

Home Browse Search

482 B. C. Osmundson et al. Table 1. Results from tissue reference and research materials submitted as either ECRC blind samples or as MURR internal quality control samples Year QC Type MSC ID MURR ID, Measured Se (gg/g) Actual Se (gg/g) Mean Se %RSD 1994 NIST RM 50 tunab 11012 3.900 3.6 - 0.4 NIST bovine liver 15776 11009 1.200 1.1 __O.1 NIST bovine liver 1577° BL-730A 1.111 1.1 ±_O.1 1.11 n = 7 3.1 BL-731A 1.097 BL-732A 1.122 BL-733A 1.161 BL-734A 1.079 BL-735A 1.115 BL-721A 1.051 1995 Striped bass RMb 20002 2.20 2.26 ± 0.2 2.7 NIST bovine liver 1577c BL-701 1.15 1.1 ± 0.1 1.16n = 9 BL-702 1.11 BL-703 1.15 BL-704 1.19 BL-705 1.12 BL-706 1.18 BL-707 1.18 BL-708 1.20 BL-709 1.14 1996 NIST bovine liver 1577 BL-726A 1.06 1.1 ± 0.1 1.07 n = 6 3.6 BL-727A 1.01 BL-728A 1.09 BL-729A 1.12 BL-730A 1.08 BL-731A 1.07 a National Institute of Standards and Technology bovine liver Certified Standard Reference Material 1577 b Blind QC submitted from ECRC Analyzed by MURR as part of internal QC program Table 2. Mean selenium concentrations (gg/g dry weight) in Colorado pikeminnow muscle plugs collected during May and June 1994 in three stretches of the Colorado River, including Walter Walker State Wildlife area (WWSWA) and the Gunnison River Gunn. R. to Loma to Loma (minus Palisade to (rkma of Westwater WWSWA) WWSWA Gunn. R. Colo. R.) (200.8-245.5) (245.5-275.1) (263.1) (275.1-297.7) Mean 5.3 7.8 16.6 5.4 SD 1.3 4.5 8.8 1.7 n 2 8 16 13 Max 6.2 17.8 30.7 10.0 Min 4.4 4.1 4.4 3.2 # > TGb 0 2(25%) 12(75%) 1 (8%) a rkm = river kilometer b TG = Toxic guideline of 8 gg/g dry weight tions in nine of these 11 recaptured fish were significantly less (p < 0.05) in 1995 than in 1994 (Table 4). Nevertheless, mean values in 1995 still exceeded toxic guidelines proposed by Lemly (1996). There was also a reduction of water selenium concentrations in the Colorado River from 1994 to 1995 (Figure 2), which in turn probably resulted from a dilution effect from much higher spring flows during 1995 (Figure 3) (Ugland et al., 1994; Crowfoot et al., 1995). The correlation between Colorado River flows at the Colorado-Utah state line and water selenium concentrations (n = 21) was significant (p = 0.0004), with a coefficient of determination of 0.49. Thus, about 50% of the selenium concentrations in the water can be attributed to flow. Table 3. Mean selenium concentrations (gg/g dry weight) in Colorado pikeminnow muscle plugs collected at Walter Walker State Wildlife Area during 1994-1996 1994 1995 1996 Mean 16.6 9.4 9.4 SD 8.8 4.7 5 n 16 45 35 Max 30.7 22 21.5 Min 4.4 4.1 4.4 # > TGa 12(75%) 24(53%) 13(37.1%) a TG = Toxic guideline of 8 gg/g dry weight The relationship between flow in the Colorado River and selenium concentrations in fish muscle plugs was less straight- forward. Several factors most likely influence selenium concen- trations in muscle plugs, including: (1) selenium concentrations in food items, (2) previous selenium loads in muscle and other tissues, (3) staging and feeding locations of fish prior to capture, (4) feeding rate and weight gain of fish, (5) sex of fish (females can deposit selenium into eggs), and (6) magnitude, duration, and timing of spring runoff and peak flows. Selenium concentra- tions in water are not necessarily the best indicators of selenium in fish muscle because dietary items are the major pathway of selenium bioaccumulation (Lemly 1995). Muscle plugs in 1994 were collected during peak runoff in May and June, before the selenium concentration in the river at the Colorado-Utah state line raised from 3 to 8 gg/L between June 22 and July 22. Also, k ill