The main goal of this research is achieving a new understanding of biogeochemical processes of trace metals in sediments based on DGT (Diffusive Gradient in Thin Films) sampling in combination with 2 dimension high resolution imaging of trace metals and sulfide by Laser ablation ICPMS on the resin gels at a resolution down to 10 µm. The reason is that micro-scale processes in sediment porewaters play an important role in the mobilization/precipitation of the trace metals. The influence of humic and fulvic acids on these micro-scale processes will also be studied. The software Visual MINTEQ will be used to calculate the equilibrium composition of the porewaters and to predict precipitation/dissolution processes.
A second objective is to study Hg and methylmercury (MMHg) biogeochemistry in sediment porewaters. First the characteristics and performance of DGTs including existing hydrogels and new mercaptopropyl resins for the determination of MMHg will be tested. Afterwards, the speciation of inorganic Hg and MMHg in sediment porewaters will be carried out.
The third objective is to develop a new diffusive controlled passive sampler for determining dissolved organic pollutant concentrations in sediment porewaters. The actual passive samplers either do not use a diffusive controlled layer or use a ceramic tube both systems being not adapted for studying porewaters. In collaboration with COMOC (UGent), flat macroporous layers will be synthesized using either exocasting or cryogels. With the latter method, the pore size is somewhat more variable but it is a very ecologic (green chemistry) process.
