Uptake rates of selected polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides by mussels and SPMDs under laboratory conditions

Abstract

Use of biological surrogates for indicating relative levels of environmental contaminants has aroused increasing attention as an alternative to the use of bioaccumulator organisms, such as mussels. Huckins form of semi-permeable membrane device (SPMD) is one of the successful surrogates developed for monitoring trace organic pollutants in aquatic environments. The device is composed of nonporous, layflat polyethylene tubing with a thin layer of nonpolar lipid (triolein) sealed within. Pollutants pass through the polymeric membrane and partition into the lipid, where they are accumulated. This device can substitute for mussels as sentinel monitors, particularly where mussel deployment is impractical. SPMDs also circumvent many problems associated with mussels, such as metabolism of absorbed pollutants, and the susceptibility of biological uptake to physiological condition of the animals. In this project, semi-batch seawater experiments were conducted to follow the uptake and release of selected PAHs (anthracene, fluoranthene, pyrene & benzo(a)pyrene) and organochlorine pesticides (α-HCH, aldrin, dieldrin & p,p'-DDT) in SPMDs and green-lipped mussels (Perna viridis). Mathematical models were applied to describe the uptake and elimination curves of the contaminants for SPMDs. Kinetic parameters such as uptake rate constants, equilibrium triolein/water partitioning coefficients and average analyte sampling rates were calculated. These kinetic constants could be useful in estimating contaminant water concentrations from their concentrations in SPMDs deployed in monitoring sites.