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A novel mercury‐specific sequential extraction procedure (SEP) for the assessment of mercury (Hg) speciation in soils and sediments, with emphasis on studying the interaction between Hg and organic matter (OM), was developed and tested. It was applied to determine Hg speciation in floodplain topsoils and surface sediments along the Hg‐contaminated part of the river Elbe, and to simultaneously derive some information on the (re)mobilization potentials for Hg from these matrices. The majority of the total Hg in the ecosystem today is bound in the floodplains, which also still geographically reflect the historic emission record. Most of the Hg in both matrices is bound strongly to OM, suggesting low availability. However, distinct differences between Hg speciation in the floodplain soils and sediments were also discovered. Mercury deposited in the floodplains shows speciation patterns that indicate stronger fixation compared with Hg in the sediments. This difference is attributed to the association of Hg with larger quantities of OM, which presumably also has higher molecular weight (MW). By comparison, Hg in the sediments was distributed among weaker binding forms, which are more likely to liberate Hg. Particularly, sediments showed a total lack of sulfidic binding forms for Hg. Pronounced geographical trends were detected in the Hg speciation along the river transect, with a general downstream shift from weaker to stronger binding forms, probably due to increased association with OM. These studies indicate that Hg speciation in riverine ecosystems is dynamic and reflects the chemical mechanisms underlying (bio)geochemical processes like distribution and transport.

Thermal release analysis of mercury species in contaminated soils was performed by temperature controlled continuous heating of the samples in a furnace coupled to an Atomic Absorption Spectrophotometer (AAS). It was shown that this method allows the identification of different redox states of Hg-species through their characteristic releasing temperature ranges. The method was applied to Hg-contaminated samples from an inactive chlor-alkali production plant in former East Germany (GER), and from a gold mining area in Pocon6, Mato Grosso, Brazil (BRA), as well as synthetic soil samples obtained by spiking pre-heated soil matrices (GER and BRA) with the following mercury species: Hg °, Hg2C12, HgC12, HgO and HgS.The samples GER, in general, frequently showed the presence of Hg 2+ probably bound to humic substances, in the case of samples with higher total carbon content. Only in highly contaminated samples (>3000 ppm of mercury) was Hg ° the predominant species. The samples BRA more frequently showed the presence of mercury species in the lower oxidation states, i.e. Hg 1+ in combination 0 with Hg . The method allows observing changes in Hg-speciation in the samples with time, mainly changes among the oxidation states Hg U, Hg 1+ and Hg 2+.The treated GER matrix showed a stronger tendency to oxidise Hg-species than the BRA treated matrix, in which only added Hg ° is partially oxidised to Hg 1+ and Hg 2+. In contrast, the BRA matrix 2+ 1+showed a pronounced tendency to reduce spiked Hg to Hg . This may be the reason for the presence of Hg 1+ in the majority of original BRA samples. The method appears to be very useful to study speciation of mercury and its dynamics. It can be used as a tool for monitoring mercury oxidation states and/or reactions of mercury in soils.

Iodinated contrast media belong to the most frequently applied compounds in medicine. They exhibit a high polarity and are very persistent against metabolism by the organism and environmental degradation. A sensitive method for the determination of five iodinated contrast media in aqueous matrices is described. Solid phase extraction utilizing Isolute ENV+ material was used for sample enrichment. The contrast media were partially separated on a RP-C18 column, and detection was achieved using electrospray-tandem MS (API III plus and API 365) allowing the sensitive quantitation of these compounds down to the lower ng/L range. The recovery rates generally exceeded 70%, for spiked surface water as well as tap water. The analytes were detected in native samples such as municipal sewage treatment plant (STP) effluent, the river Rhine and even in tap water.