Comparison of different types of diffusive gradient in thin film samplers for measurement of dissolved methylmercury in freshwaters

Diffusive gradients in thin films for predicting methylmercury bioavailability in freshwaters after photodegradation

“…The diffusion coefficients of MeHg in the diffusive layer in the absence and in the presence of DOM in P-DGT were significantly different, with values of 2.54 Â 10 À6 and 1.67 Â 10 À6 cm 2 s À1 , respectively, at 26°C. These values agree with those that had been obtained previously (Fernandez-Gomez et al, 2014). Values of diffusivity for MeHg in the DGT diffusive layer in the absence and presence of DOM were not so different from each other as for inorganic Hg determined in a previous work (Fernandez-Gomez et al, 2011) which might suggest that MeHg-DOM complexes are more labile than Hg(II)-DOM complexes and have a higher dissociation rate constant.…”

Development of a Novel Equilibrium Passive Sampling Device for Methylmercury in Sediment and Soil Porewaters

“…Speciation modeling for isotherms run with added SRHA predicted virtually complete complexation of MeHg with SRHA. Compared to smaller MeHg complexes, MeHg complexed with DOM is both less diffusive and less bioavailable (Choi et al ; Fernández‐Gómez et al ). This experiment therefore represents an important contrast to the idealized scenario in the previous set of isotherms.…”

“…Polyethylene terephthalate is a relatively impermeable polymer, so both the cysteinylation of PET and the accumulation of MeHg by PET+Cys can be assumed to occur mostly on the sampler's surface. By contrast, agarose is permeable and readily permits diffusion of MeHg even in the presence of DOM (Fernández‐Gómez et al ). To verify a permeation‐based mechanism of accumulation by ag+AC, pieces of the material with contrasting surface area‐to‐volume ratios were exposed to aqueous MeHgSRHA and sampled along a time course.…”

“…A simple modeling exercise supports this contention. The diffusion coefficient (D) in agarose of MeHg complexed with DOM from a Nordic reservoir is 2.68 × 10 –6 cm 2 s –1 , only 15% lower than that of MeHg without DOM (Fernández‐Gómez et al ). Assuming that this value of D is similar to that of MeHgSRHA, a Fickian diffusion calculation predicts >90% equilibration by agarose within 1 d at a depth of 400 μm (the half‐thickness of our sampler).…”

Passive sampler measurements of inorganic arsenic species in environmental waters: A comparison between 3-mercapto-silica, ferrihydrite, Metsorb®, zinc ferrite, and zirconium dioxide binding gels

“…Note that redox speciation of dissolved iron was not impacted during batch experiments as shown Figure 2. Fe 2+ could be considered as a minor competing species with As(III), Hg 2+ [58], CH3Hg + [59][60][61] and Sb(III) [21] during the deployment of the 3MP DGT samplers in anoxic environment. Conversely, the other binding gels strongly accumulate Fe 2+ (75 -98 %).…”