Environmental Electrochemistry as a Tool for Water and Air Quality Monitoring

Voltammetric and polarographic methods at the Hg electrode were used to study presence of sulfur species in different contrasting natural samples: stratified anoxic lakes, seawater lake Rogoznica Lake (Croatia) and crater lake Pavin Lake (France); rain precipitation and sea-aerosols. In all of these investigated samples typical HgS reduction voltammetric peak, characteristic for many different reduced sulfur species (RSS, sulfide, elemental sulfur, polysulfides, labile metal sulfide species, orgnosulfur compounds) was recorded at about -0.6 V vs. Ag/AgCl reference electrode. In addition to, in Pavin Lake anoxic samples voltammetric peaks characteristic for the presence of free Fe(II) and FeS nanoparticles were recorded at -1.4 V and around -0.45 V, respectively. Depending on experimental conditions (oxidative and/or reductive accumulation, different accumulation times and potentials or different stripping technique, acidification and purging) it is possible to make distinguish between different sulfur species. This work clearly shows a large potential of electrochemistry to be used as powerful analytical technique for determination and speciation of different reduced sulfur species in dissolved and colloidal phases in natural waters.