Existing methods for total mercury and methylmercury determination in sediment and porewaters
were improved by applying open microwave heating for extraction of Hg species from the sample and
decomposition of MeHg prior to detection as Hg(II) by CV AFS. It was shown that nitric acid can
quantitatively leach Hg from sediment, already at a low microwave power (30 W, 5 min). Methylmercury can
be quantitatively leached from sediment by dilute sulphuric acid (1 mol/L) at a power of 60 W during 5
minutes, without being decomposed. So obtained extract can be further distilled with a reduced possibility
for artefactual MeHg formation, as it contains much lower levels of inorganic Hg, compared to the original
sediment. Microwave-assisted BrCl oxidation was shown to be more effective for decomposition of MeHg and
stable organomercury complexes in water solutions (sediment distillate and porewater), as compared with
BrCl oxidation at room-temperature. Therefore, the application of low-power microwave digestion can
significantly improve determination of Hg species in sediment and porewater, both in terms of time and
efficiency
