Accumulation and depuration of 2,3,7,8-tetrachlorodibenzofuran and octachlorodibenzo-p-dioxin by caddisfly larvae (Hydropsyche bidens (ross)) in miniature laboratory streams
✍ Scribed by Georgine M. Pastershank; Derek C.G. Muir; Wayne L. Fairchild
- Book ID
- 102202475
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 149 KB
- Volume
- 18
- Category
- Article
- ISSN
- 0730-7268
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✦ Synopsis
The uptake and depuration kinetics of [ 3 H]-2,3,7,8-tetrachlorodibenzofuran ([ 3 H]TCDF) and [ 14 C]-1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin ([ 14 C]OCDD) were studied in the filter-feeding caddisfly Hydropsyche bidens (Ross), using artificial laboratory streams. Dietary and water-borne routes of uptake were compared. Biomagnification factors (BMFs) ranged from 0.003 to 0.08 for TCDF and 0.003 to 0.007 for OCDD. The BMFs were significantly lower at higher exposure concentrations and for an earlier larval instar. Assimilation efficiencies for TCDF and OCDD were estimated to be 9.2 and 4.9%, respectively, based on an estimated feeding rate of 0.09 g/g body weight/d. Depuration of TCDF followed first-order kinetics with t 1/2 Յ 28 d. Depuration of OCDD was biphasic with an initial rapid t 1/2 of Ͻ2.9 d, followed by a slow rate of depuration. The initial rapid rate of depuration of OCDD could be explained by the loss of the gut contents. Depuration rates of TCDF and OCDD were not affected by a 33% increase in stream velocity from 16 to 24 cm/s or by changing contaminant concentrations in food. Nonfeeding caddisfly pupae accumulated approximately one tenth of the concentration of TCDF and OCDD that was accumulated by filter-feeding larvae under the same conditions. For the nonfeeding pupae, 10-d lipid-normalized bioconcentration factors for TCDF (1.0 ϫ 10 5 ) were 10-fold higher than for OCDD (9.2 ϫ 10 3 ).