Bioturbation effects on cadmium and zinc transfers from a contaminated sediment and on metal bioavailability to benthic bivalves

Abstract

The two main objectives of this study were to compare cadmium and zinc fluxes from a contaminated sediment to the water column in bioturbated and unbioturbated systems and jointly to analyze accumulation kinetics of these released metals by benthic filter-feeder bivalves. The experimental approach was based on indoor microcosms containing a two-compartment biotope: natural contaminated sediment (45 +/- 5 microg Cd/g, dry wt, and 1,938 +/- 56 microg Zn/g, dry wt) and water column. Four experimental conditions were studied: no organism added to the sediment-water biotope, presence of bivalves Corbicula fluminea, presence of Hexagenia rigida nymphs (bioturbation source), and presence of C. fluminea and H. rigida simultaneously. Results reveal that bioturbation produces a significant metal release into the water column via the resuspended sediment particles. The use of C. fluminea as an indicator of transferred metals in the water column shows that the metal bioavailability is very limited, quantities of cadmium and zinc bioaccumulated in the soft bodies being less than those measured in unbioturbated systems. This experimental study demonstrates that only the dissolved fraction resulting from diffusive metal fluxes across the sediment-water interface is bioavailable for this bivalve species.

Uptake, accumulation, and biotransformation of metal oxide nanoparticles by a marine suspension-feeder

“…Metal oxide ENPs that aggregate often do so by attaching to suspended particles that then settle to the seafloor where they accumulate in sediments or benthic biofilms [2]. Benthic invertebrates affect the fate and transport of micro-sized heavy metals and other pollutants by remobilizing them through physical disturbance (e.g., bioturbation), uptake, and biotransformation [35][36][37]. The few studies that have examined ENP fate and transport in marine sediments indicate that benthic organisms can affect nanoparticles and larger-sized contaminants in similar ways to some degree, although a great deal is still unknown because work so far has focused on nano-Ag [16,17].…”

Response of the hairy mussel Trichomya hirsuta to sediment-metal contamination in the presence of a bioturbator

“…To date, evidence that bioturbators can modify metal uptake is inconclusive. For example, Ciutat and Boudou (2003) reported no difference in cadmium and zinc accumulation in the bivalve C. fluminea in the presence of bioturbating larvae of the Mayfly H. rigida. Despite increases in turbidity and Cd and Zn concentrations in the particulate phase of the water column no difference in these metals in the tissues of the bivalve were reported.…”

“…This suggests that despite lead and zinc likely being bound as sulfide phases in deeper sediments, the metals maintain their bioavailability because of the continued cycling between pore waters and surface sediments due to physical mixing and bioturbation. Only one previous study (Ciutat and Boudou, 2003), however, has examined the effect of a bioturbator, the larvae of the Mayfly Hexagenia rigida, on metal uptake in a non-bioturbating organism, the bivalve Corbicula fluminea.…”

Metal partitioning and availability in estuarine surface sediments: Changes promoted by feeding activity of Scrobicularia plana and Liza ramada

“…The activities of benthic organisms, like feeding and borrowing, increase the turbidity and physical disturbance in the water-sediment interface, which may vary from affecting metal partitioning and toxicity sediments (Ciutat andBoudou, 2003, Green andChandler, 1994), to causing no evident alteration in that metal toxicity (Fleeger et al, 2006). It has been shown, for example, that the presence of some terrestrial invertebrates alters the speciation of metals and metalloids in soil and manure (Li et al, 2009, Sizmur et al, 2011a, Sizmur et al, 2011b.…”