Linear correlation between Dissolved Gaseous Mercury and Dissolved Inorganic Carbon opens new modelling perspectives

Science Highlights

30 August 2022

Živković and his colleagues (2022, see reference below) led a close study of the mercury speciation on 354 samples (24 profiles from surface to bottom) along the 40°S GEOTRACES section (GA10). For the first time, they demonstrate that dissolved gaseous mercury (DGM) concentrations are related to the water depth, the concentrations of macronutrients but moreover to the Dissolved Inorganic Carbon (DIC) concentration as seen by the linear correlations between DGM and DIC (and DGM and DIC of biogeochemical origin). Their interpretation is that DGM is photochemically produced in surface layers, and related to the remineralization of the labile organic matter down to 1000 m and the refractory one in the deep layers. They propose that DIC might be a proxy for DGM in biogeochemical models, as demonstrated by a good agreement between measured and calculated DGM values in different world oceans.

Figure: Dissolved gaseous mercury (DGM) in seawater shows linear correlation with dissolved inorganic carbon (DIC; red triangles) and biologically mediated change in dissolved inorganic carbon (DICbio, green squares). This indicates a possibility that oxidized mercury fraction (HgII) is converted to its elemental form (Hg0) during the remineralization of organic matter (breakdown into its simplest inorganic form). Data are from twenty stations in the South Atlantic Ocean, collected along a 40°S transect from surface to 5240 m depth.

Reference

Živković, I., Humphreys, M. P., Achterberg, E. P., Dumousseaud, C., Woodward, E. M. S., Bojanić, N., Šolić, M., Bratkič, A., Kotnik, J., Vahčič, M., Obu Vazner, K., Begu, E., Fajon, V., Shlyapnikov, Y., & Horvat, M. (2022). Enhanced mercury reduction in the South Atlantic Ocean during carbon remineralization. Marine Pollution Bulletin, 178, 113644. doi: 10.1016/j.marpolbul.2022.113644

Latest highlights

Continuous record of the Antarctic Circumpolar Current latitude over the last glacial-interglacial cycles

The meridional positions of the oceanic fronts separating subtropical and Antarctic waters are key to constraining the mechanisms that drive the degassing of deeply-stored CO2 at the end of the glacial periods…

23 Million Years of iron sources reconstructed in the Northwest Pacific Ocean using iron isotopes in a ferromanganese crust

Using iron isotopes and elemental records, Chu and co-workers analysed an iron-manganese crust recovered from the Hongyan Seamount, and reconstructed the sources of dissolved Fe to the Northwest Pacific Ocean…

Variability of the past deep-water masses in the Arabian Sea over the last 41ka

Shukla and colleagues propose a high-resolution authigenic ƐNd record measured from a sediment core located in the eastern Arabian Sea…

Arctic outflows to Davis Strait and the Labrador Sea traced by radionuclide distributions

This study demonstrates that Arctic outflows through the Canadian Arctic Archipelago play a much more significant role than previously recognised.

Rechercher