|HOME SCHEDULE AUTHOR INDEX SUBJECT INDEX|
(P188) The influence of colloids on the toxicity of cadmium and fluoranthene to freshwater invertebrates.
Irvine, Cameron*,1, Burton, G.1, Greenberg, Marc1, 1 Institute for Environmental Quality, Wright State University, Dayton, Ohio, USA
ABSTRACT- Colloids comprise a potentially large surface area that bind hydrophobic and charged contaminants in aquatic systems. Their importance in contaminant transport is well known but the role of colloids in contaminant bioavailability is unclear and may be overlooked with some models. Sources of uptake other than the free ions (e.g., sorption, feeding) are influenced by aqueous colloidal material and may be an important source of contaminants to freshwater and marine invertebrates. The influence of colloid particulate matter on the exposure and toxicity of cadmium109 and 3Hfluoranthene to two freshwater invertebrates, Daphnia magna and Hyalella azteca, was evaluated in laboratory bioaccumulation and feeding inhibition tests. Test organisms were exposed to surface water collected from an Ohio stream treated by cross-flow ultrafiltration to separate ′colloidal′ material (<0.45 m — 10000 Daltons) and ′dissolved′ material (<10000 Daltons) subsequently spiked with model contaminants. Apparent bioconcentration factors correlated with particle abundance (r2=0.68) but not with organic carbon (r2=0.18). Significantly greater contaminant uptake (p<0.05) and lower feeding IC50, measured by -galactosidase activity (Cd=0.005 ppm or Flu≥0.16 ppm), were observed in colloidal fractions compared to dissolved fractions of test waters. Furthermore, organisms exposed to colloid fractions bioaccumulated less contaminant than in raw (unfiltered) stream water. Results were consistent despite changes in colloid concentrations between seasons and varied discharge events sampled and indicate that colloid-bound contaminants can be bioavailable to aquatic invertebrates where feeding may be a method of contaminant uptake.
Key words: colloids, ultrafiltration, sublethal, bioconcentration
Internet Services provided by|
Allen Press, Inc. | 810 E. 10th St. | Lawrence, Kansas 66044 USA
e-mail firstname.lastname@example.org | Web www.allenpress.com
All content is Copyright © 2002 SETAC