Development of the diffusive gradient in thin films technique for the measurement of labile mercury species in waters

Abstract The diffusive gradients in thin films (DGT) technique, utilizing resin gel with ion-exchange resin Duolite GT73 and new ion-exchange resin Ambersep GT74, was investigated for the accumulation of four mercury species (Hg 2+ , CH 3 Hg + , C 2 H 5 Hg + , C 6 H 5 Hg + ). The diffusion coefficients of mercury species in agarose gel calculated on the basis of Fick’s Law were mercury species-specific. The diffusion coefficients of Hg 2+ and CH 3 Hg + at 25 °C (9.07 ± 0.23 × 10 −6  cm 2  s −1 and 9.06 ± 0.30 × 10 −6  cm 2  s −1 , respectively) were very similar, but the diffusion coefficients of C 2 H 5 Hg + (6.87 ± 0.23 × 10 −6  cm 2  s −1 ) and C 6 H 5 Hg + (3.86 ± 0.19 × 10 −6  cm 2  s −1 ) were significantly lower. Influence of experimental conditions (pH, selected cations, chlorides and humic substance) on mercury species accumulation by DGT was studied. The DGT technique was applied to river water spiked with mercury species.