Thursday 5 May, 4PM CET
DR. ARNE BRATKIČ
ABSTRACT: FaSINaTE project (Fingerprinting Sea Ice Nutrients in Two dimEnsions) aimed to provide for the first time ever a detailed, submillimetre information of iron and other trace element distribution in the sea ice, thus providing paradigm changing information necessary for understanding biogeochemistry in this complex environment.
To achieve that, the Diffusive Gradient in Thin-films (DGT) approach was modified to withstand freezing of hydrogels during direct sea ice application. Metal-binding Chelex and SPR-IDA resins were used for sampling the sea ice, while the analysis of the gels was done using various methods and techniques, including laser ablation ICP-MS, thermal lens spectrometry (TLS), beam deflection spectrometry (BDS) and UV-VIS.
We developed and validated new method by coupling of DGT and BDS techniques. This resulted in a new, non-destructive method with improved LODs for 2-dimentional iron detection. Nevertheless, a practical difficulty of superimposing images obtained by different methods remains due to impermanent nature of sea ice samples. One of the main achievements of the BDS detection is the distinguishing of Fe species inside the gel, which is quite difficult to do in a solution since it is impossible to control the oxidation processes during extraction from a gel into an acid solution. The measurements confirm that iron in the sea ice samples is mainly present as Fe2+, which presents a new perspective of anoxic microbial biogeochemistry in the sea ice.
The project delivered entirely new data and shed new light on our understanding of iron redox distribution in heterogeneous sea ice and significantly improved spatial resolution of currently available methodology. As a first of its kind, FaSINaTE posed more questions than it answered, however, new tools for glaciology research are its major contribution.