Microwave-assisted determination of total mercury and methylmercury in sediment and porewater

Existing methods for total mercury and methylmercury determination in sedim ent and porewaters were improved by applying open microwave heating for ext raction of Hg species from the sample and decomposition of MeHg prior to de tection as Hg(ll) by CV AFS. It was shown that nitric acid can quantitative ly leach Hg from sediment, already at a low microwave power (30 W, 5 min). Methylmercury can be quantitatively leached from sediment by dilute sulphur ic acid (1 mol/L) at a power of 60 W during 5 minutes, without being decomp osed. So obtained extract can be further distilled with a reduced possibili ty for artefactual MeHg formation, as it contains much lower levels of inor ganic Hg, compared to the original sediment. Microwave-assisted BrCl oxidat ion was shown to be more effective for decomposition of MeHg and stable org anomercury complexes in water solutions (sediment distillate and porewater) , as compared with BrCl oxidation at room-temperature. Therefore, the appli cation of low-power microwave digestion can significantly improve determina tion of Hg species in sediment and porewater, both in terms of time and eff iciency.