COMPARISON OF AQUEOUS AND SOLID-PHASE UPTAKE FOR HEXACHLOROBENZENE IN THE TELLINID CLAM MACOMA-NASUTA (CONRAD) - A MASS BALANCE APPROACH

The uptake of sediment‐associated hexachlorobenzene (HCB) by the deposit‐feeding clam Macoma nasuta (Conrad) was determined using a clam ventilation chamber. Clams were exposed to [14C]HCB‐dosed sediment, and the 14C amounts were measured in inhalant and exhalant waters, fecal pellets and soft tissues. The volume of water the clam ventilated and the amount of fecal pellets produced were measured. The contributions of 10 possible uptake routes to HCB tissue residues were estimated using a bioenergetic‐based bioaccumulation model. Mass balance results indicate that uptake of HCB by the gut from ingested solids was the single most important route, accounting for 63 to 84% of HCB tissue residues. The next largest route was uptake from interstitial water ventilated across the gills, which accounted for 11 to 12% of tissue residues. Uptake of HCB from overlying water was minimal. These results indicate that sediment‐bound HCB is bioavailable to benthic deposit feeders such as Macoma and supports the contention that ingested sediment is an important uptake route for highly lipophilic pollutants. Copyright © 1990 SETAC