Bioaccumulation of XXXX by marine organisms.

@entity1 @entity2555 @entity2556 @entity10333 @entity505
@entity2555 ( @entity2556 ) are ubiquitous in the marine environment, occurring at their highest environmental concentrations around urban centers. While they can occur naturally, the highest concentrations are mainly from @entity1 activities, and the primary sources are combustion products and petroleum. Two factors, lipid and organic @entity505 , control to a large extent the partitioning behavior of @entity2556 in sediment, water, and tissue; the more hydrophobic a compound, the greater the partitioning to these phases. These two factors, along with the @entity10333 -water partition coefficient, are the best predictors of this partitioning and can be used to determine @entity2556 behavior and its bioavailability in the environment. It is well known that the lipid of organisms contains the highest levels of hydrophobic compounds such as @entity2556 , and that organic @entity505 associated with sediment or dissolved in water can have the greatest influence on @entity2556 bioavailability. Partitioning of combustion-derived @entity2556 between water and sediment may be much less than predicted, possibly because associations with particles are much stronger than expected. This reduced partitioning may produce erroneous results in predicting bioaccumulation where uptake from water is important. Accumulation of @entity2556 occurs in all marine organisms; however, there is a wide range in tissue concentrations from variable environmental concentrations, level and time of exposure, and species ability to metabolize these compounds. @entity2556 generally partition into lipid-rich tissues, and their metabolites can be found in most tissues. In fish, liver and bile accumulate the highest levels of parent @entity2556 and metabolites; hence, these are the best tissues to analyze when determining @entity2556 exposure. In invertebrates, the highest concentrations can be found in the internal organs, such as the hepatopancreas, and tissue concentrations appear to follow seasonal cycles, which may be related to variations in lipid content or spawning cycles. The major route of uptake for @entity2556 has been debated for years. For the more water-soluble @entity2556 , it is believed that the main route of uptake is through ventilated water and that the more hydrophobic compounds are taken in mainly through ingestion of food or sediment. There are many variables, such as chemical hydrophobicity, uptake efficiency, feeding rate, and ventilatory volume, which may affect the outcome. The route of uptake may be an important issue for short-term events; however, under long-term exposure and equilibrium conditions between water, prey, and sediment, the route of uptake may be immaterial because the same tissue burdens will be achieved regardless of uptake routes.(ABSTRACT TRUNCATED AT 400 WORDS)
