Kathryn E. Clark

Publications (3)5.62 Total impact

• Article: Dietary uptake and biomagnification of four chlorinated hydrocarbons by guppies

  Kathryn E. Clark, Donald Mackay
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  ABSTRACT: Laboratory experiments are described in which guppies (Poecilia reticulata) were fed food containing hexachlorobenzene, mirex, 2,2′,3,3′,4,4′,5,6′-octachlorobiphenyl, and octachlorodibenzofuran. The chemical concentrations in the food and the feeding rate were varied to determine the effect of these variables on the assimilation efficiency. Increasing the dietary intake by increasing the concentration (or fugacity) of a chemical in the food causes a proportional increase in the steady-state concentration or fugacity of the chemical in the fish; i.e., the assimilation efficiency is constant. Increasing the dietary intake by increasing the feeding rate produces a less than proportional increase in the steady-state concentration or fugacity of the chemical in the fish. This apparent drop in assimilation efficiency is the result of an increased rate of loss by egestion. Mirex and octachlorobiphenyl were observed to biomagnify; i.e., the steady-state fugacities achieved in the fish exceeded the fugacities in the food. These findings are in accord with the assertions of a fugacity model of bioaccumulation.
  Environmental Toxicology and Chemistry 10/2009; 10(9):1205 - 1217. · 2.81 Impact Factor
• Article: Bioconcentration of polybrominated benzenes and biphenyls and related superhydrophobic chemicals in fish: Role of bioavailability and elimination into the feces

  Frank A. P. C. Gobas, Kathryn E. Clark, Wan Ying Shiu, Donald Mackay
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  ABSTRACT: Bioconcentration data are reported for a series of superhydrophobic chemicals including polybrominated biphenyls, brominated benzenes, mirex and polychlorinated biphenyls in the guppy (Poecilia reticulata). The observed bioconcentration factors follow a linear relationship with the 1-octanol/water partition coefficient for chemicals with a log Kow of up to 6. For chemicals with higher Kow values, the bioconcentration factors were lower than expected from the linear relationship. This loss of linear correlation is shown to be caused by (a) a low fraction of bioavailable chemical in the water, (b) elimination of chemical into the feces, (c) an insufficient exposure time to achieve equilibrium and (d) fish growth. Procedures are presented by which the magnitudes and relative contributions of these factors to reducing the apparent bioconcentration factor from linearity can be determined.
  Environmental Toxicology and Chemistry 08/2009; 8(3):231 - 245. · 2.81 Impact Factor
• Source

  Available from: Frank Gobas

  Article: Model of organic chemical uptake and clearance by fish from food and water

  Kathryn E. Clark, Frank A. P. C. Gobas, Donald Mackay
  04/2002;