Tissue-Specific Toxicokinetics of Aqueous Radium-226 in an Estuarine Mussel, Geukensia demissa

Radiological contamination of coastal habitats poses potential risk for native fauna, but the bioavailability of aqueous radium (Ra) and other dissolved metals to marine bivalves remains unclear. This study was the first to examine the tissue-specific disposition of aqueous Ra in a coastal mussel, specifically the Atlantic ribbed mussel . Most organ groups reached steady-state concentrations within 7 days during experimental exposure, with an average uptake rate constant of 0.0013 mL g d . When moved to Ra-free synthetic seawater, mussels rapidly eliminated aqueous Ra (average elimination rate constant 1.56 d ). The biological half-life for aqueous Ra ranged from 8.9 h for the gills and labial palps to 15.4 h for the muscle. Although previous field studies have demonstrated notable Ra accumulation in the soft tissues of marine mussels and that, for freshwater mussels, tissue-incorporated Ra derives primarily from the aqueous phase, our tissue-specific bioconcentration factors (BCFs) were on the order of (8.3 ± 1.5) × 10 indicating low accumulation potential of aqueous Ra in estuarine mussels. This suggests marine and estuarine mussels obtain Ra from an alternate route, such as particulate-sorbed Ra ingested during filter-feeding or from a contaminated food source.