Differential bioaccumulation of heavy metals and organopollutants in the soft tissue and shell of the marine Gastropod, Austrocochlea constricta

Abstract

Austrocochlea constricta (Gastropodia) has the potential to act as a useful biomonitoring system of pollutants in the marine environment. The organism was used in the present study to investigate the distribution of both heavy metals and organopollutants in the soft tissue and shell of individuals sampled from various sites in the Newcastle region of New South Wales (Australia). The heavy metals and organopollutants were extracted from the mollusc and determined by atomic absorption spectroscopy (AAS) and gas chromatography-mass spectrometry (GC-MS), respectively. The heavy metals zinc, cadmium, copper, and lead were detected both within the soft tissue and the shell extract, but the proportions of these metals partitioned into the extracts were different for each location. It was concluded that the accurate evaluation of heavy metal exposure in Austrocochlea should include analyses of both soft tissue and shell fractions. The accumulation of aliphatic hydrocarbons was more rigorously partitioned between the two tissue types than the heavy metals. Short chain aliphatic hydrocarbons were limited to the soft tissue while the longer chain aliphatic hydrocarbons were primarily confined to the shell. The data suggest that the shell may act as a safe storage matrix for toxic contaminants resistant to soft tissue detoxification mechanisms. The organic contaminants measured in the shell can be utilized as a valuable indicator of refuse dumping or release of pulp mill effluent as well as petrochemical contamination from industrial and recreational activity.