2-COMPARTMENT THERMODYNAMIC MODEL FOR BIOCONCENTRATION OF HYDROPHOBICORGANIC-CHEMICALS BY ALGA - QUANTITATIVE RELATIONSHIP BETWEEN BIOCONCENTRATION FACTOR AND SURFACE-AREA OF MARINE-ALGAE OR OCTANOL WATER PARTITION-COEFFICIENT/

A two-compartment thermodynamic model for bioconcentration of hydropho bic organic chemicals (HOCs) by algae was proposed. In the model, it w as assumed that 1) the bioconcentration is comparable to physicochemic al liquid-liquid partitioning, and is predominantly the result of inte rfacial processes of alga cells as well as HOC; 2) the surface excess quantity of HOC with respect to water phase can be expressed by Gibbs equation, and increases with increasing HOC concentration in alga cell s; 3) the hydrophobic nature of alga cells, wherein only dispersion in teraction contributes to their surface tension, remain almost unchange d after adsorption of HOC. From the model it was concluded that biocon centration factor (log BCF) has linear relation with specific surface area (log S) of alga cells, n-octanol/water partition coefficient (log K-OW) of HOC, and HOC concentration in the water (log C-W) respective ly. The model was tested by the bioconcentration of monochlorobenzene, 1,2-dichlorobenzene, 1,2,3,4-tetrachlorobenzene, and pentachlorobenze ne by marine algae including Chlorella marine, Nannochloropsis oculata , Pyramidomonas sp., Platymonas subcordiformis, and Phaeodactylum tric ornutum. BCF values were obtained not only with the bioconcentration m odel, but also with the combined bioconcentration and probability mode l. It was found that the bioconcentration factors of a chemical was in creaseing with the specific surface area (S) of different marine algae . (C) 1997 Elsevier Science Ltd.