Assessing the in situ bioavailability of trace elements to snails using accumulation kinetics.
Résumé
In this study, the accumulation kinetics of cadmium (Cd), lead (Pb), arsenic (As) and antimony(Sb) were determined for 3 industrially impacted sites to assess the bioavailability of these contaminantsto the garden snail (Cantareus aspersus). Mono and multivariate regressions allowed the identificationof cation exchange capacity (CEC), silts and organic carbon content as the soil parameters modulatingthe in situ bioavailability of Cd and Pb. For all elements, the total concentrations in the soils were notgood predictor (not significant correlation) of the bioavailability to snails. The Cd, As and Sb assimilationfluxes were correlated with the calcium chloride (CaCl2) extract concentrations, but this correlationwas not observed with Pb. The total soil concentration coupled with soil properties best explained thevariation in Pb assimilation, whereas their influences on Cd bioavailability were lower, signifying thatother parameters such as contamination sources may modulate Cd bioavailability. Here, the As and Sbin situ accumulation kinetics are described for the first time and highlighted a slight bioavailability tosnails at the studied sites. The absence of a correlation between the As or Sb assimilation fluxes andtotal metals in the soil coupled with the absence of influence of soil properties on their bioavailabilitymay result from the speciation of these metalloids, which are known to modulate their mobility in soils.This study highlights the need to consider both physico-chemical and biological aspects of metal andmetalloid bioavailability to assess the risk of metal transfer from soil to organisms.