A model predicting waterborne cadmium bioaccumulation in Gammarus pulex: The effects of dissolved organic ligands, calcium, and temperature

Abstract

Metal bioavailability depends on the presence of organic ligands in the water and on the concentrations of competitive cations. The present study aims at testing whether the diffusive gradient in thin films technique (DGT) could be used to take into account Cd speciation and its consequences on bioavailability in a bioaccumulation model and whether the influences of the Ca concentration and temperature also should be considered. Four kinetic experiments were conducted on Gammarus pulex: a calibration of Cd turnover rates and of the DGT lability in mineral water, a study of the influence f ethylenediaminetetraacetic acid (EDTA) and humic acids (HA) on uptake rates, and two experiments testing the influence of the Ca concentrations and temperature on Cd uptake clearance rates (ku). In mineral water, where Cd was considered fully labile, the ku was 0.46 L g⁻¹ d⁻¹, and the depuration rate was 0.032 d⁻¹. The initial Cd influxes were lowered significantly by additions of 10 μg L⁻¹ of EDTA or 10 mg L⁻¹ of HA in the water but not at 5 mg L⁻¹HA, even if DGT measurements proved that Cd formed Cd-HA complexes in that treatment. Increasing Ca concentrations lowered ku values, and a competitive inhibition model between Ca and Cd fitted the data. A 30% enhancement of k, values was observed when the temperature was increased by 8°C, which appeared comparatively as a weak effect. Thus, taking into account the metal speciation and the influence of the Ca concentration should improve Cd bioaccumulation modeling in amphipods. In freshwater, where metal bioavailability is reduced by the presence of dissolved organic matter, forecasting Cd waterborne uptake using the labile concentrations should allow robust comparisons between laboratory and field studies.

Modeling the effect of water chemistry on the bioaccumulation of waterborne cadmium in zebra mussels

“…This result corroborates previously published observations that Cd is accumulated through high affinity Ca channels [5] and inhibits the uptake pathway of this cation [32]. The competitive effect between Ca and Cd for binding sites on the gills' surface has been reported in various other species [5,7], as well as the competitive effect between Cd and Zn [8,31].…”

“…Indeed, the bioaccumulation and toxicity of Cd are modulated by different parameters such as Ca, Zn, and dissolved organic carbon (DOC) concentrations. Different studies reported a decreased bioaccumulation of Cd in different species when Ca concentration increased: Daphnia magna [4], Corbicula fluminea [5], Lymnea stagnalis [6], and Gammarus pulex [7]. It was also demonstrated that Zn had a protective effect on Cd toxicity [8,9].…”

Modelling copper bioaccumulation in Gammarus pulex and alterations of digestive metabolism

“…These predictive models are generally constructed in the laboratory by the establishment of kinetic parameters describing physiological mechanisms involved in the uptake of bioavailable metals and elimination of bioaccumulated metals. Such mechanistic approaches were successfully performed in various aquatic species including gammarids (Croteau and Luoma 2007;Liu et al 2002;Pellet et al 2009;Worms et al 2006). The major forms of bioaccumulated metal are represented by the free ions, which can directly interact with transport sites and across the biological membranes of aquatic organisms (Niyogi and Wood 2004).…”

To what extend the dam dredging can influence the background level of metals in the Rhine River: using chemical and biological long-term monitoring to answer

“…Fig. 5), which are thus mobile and available for aquatic organisms, as showed for gammarids with Cd and Cu (Pellet et al, 2009;Ferreira et al, 2013). For Cr and Pb, the increase in bioaccumulation could be explained by the enrichment of the effluent of pumping/dilution in organic matter and changes in SPM properties, hence enhancing their particulate bioavailability and subsequently their assimilation by mussels (Roditi et al, 2000;Bourgeault et al, 2010a;Bourgeault et al, 2011).…”

“…Among the chemical tools that have been developed, the Diffusive Gradient in Thin-films technique (DGT) is a speciation method that allows for the estimation of time-weighted average concentration of labile metals through in situ passive sampling (Tusseau-Vuillemin et al, 2007; Uher et al, 2011). The DGT-labile metallic fraction, which is composed of free inorganic metals and weak organic complexes, has been shown to be close to the bioavailable fraction for freshwater organisms exposed only by aqueous route (Ferreira et al, 2009;Pellet et al, 2009). In terms of biological tools, bioaccumulation studies using encaged organisms have gained importance for environmental risk assessment (Bervoets et al, 2005;Besse et al, 2012).…”