The persistence, toxic nature and potential to accumulate along food chain make heavy metal from industrial effluent a focus in coastal contamination in Hong Kong. In natural environment, metal can accumulate in bivalves through two distinct phases: the particulate phase and dissolved phase. A bioenergetic-based kinetic model is developed to assess the exposure pathway of metal accumulation in marine invertebrate. This model is advanced in separating the different exposure pathways and predicting metal accumulation in animals without measuring too many parameters from the environment. The aim of this study is to quantify three important physiological parameters that need to be incorporated into the model to predict the metal bioavailability in aquatic animals. These physiological param...[ Read more ]

The persistence, toxic nature and potential to accumulate along food chain make heavy metal from industrial effluent a focus in coastal contamination in Hong Kong. In natural environment, metal can accumulate in bivalves through two distinct phases: the particulate phase and dissolved phase. A bioenergetic-based kinetic model is developed to assess the exposure pathway of metal accumulation in marine invertebrate. This model is advanced in separating the different exposure pathways and predicting metal accumulation in animals without measuring too many parameters from the environment. The aim of this study is to quantify three important physiological parameters that need to be incorporated into the model to predict the metal bioavailability in aquatic animals. These physiological parameters include assimilation efficiency (AE), metal uptake rate constant from dissolved phase (K_u) and metal efflux rate constant (K_e). The variability of these parameters under a suit of environmental and physiological condition would also be investigated experimentally.

Result from radiotracer technique reveals that both mussels and clams were able to accumulate metals from particulate as well as dissolved phase. In addition, this study demonstrate that metal uptake from these two phases were comparable to the widely studied temperate bivalves. For factors affecting metal assimilation from food, cytoplasmic distribution of metal in food particles affect Cd AE in clams while a positive relation was observed between Cr AE and its gut passage time in clams. Metal uptake from dissolved phase was primarily increased with the increase in dissolved metal concentration. It is primarily decreased with increase in salinity and bivalves' body size. The physiological parameters quantified in this study are critical to validate the bioenergetic-based kinetic model and assess the suitability of both bivalves as biomonitors in Hong Kong waters. The information we gathered is important for comparing the relative importance of metal from different exposure pathway and help in establishing reliable water quality criteria.