The export of barium into the marine benthic realm assessed through Ba/Ca of benthic foraminifera – approaching a novel calibration

Global warming and changes in precipitation patterns are of increasing concern for populations in the Mediterranean region. Exploiting regional paleoenvironmental archives helps to understand how climatic parameters changed regionally in past periods which serve as future climate analogues. Prominently, benthic foraminifera serve as proxy carriers to unravel variability of paleo-temperature, -salinity, -pH, -productivity and –oxygenation. Besides the faunal composition of a defined sediment sample, the geochemical signature recorded in the shells is a constantly investigated proxy signal. Recently, the Ba/Ca has been proposed to track changes in barium content of marine bottom waters. In fact, barium concentrations in the benthic (shallow) marine environment either reflect directly riverine input or export productivity via barite as part of the organic matter sinking to the seafloor. We use core-top material of dead and live (Rose Bengal stained) specimens from a water depth range of 600-1500 m throughout the Northern Aegean Sea, to quantify variability of Ba/Ca across two different species with hyaline shells (Melonis baarleanus and Uvigerina mediterranea) and different sediment sampling depths. Using Laser Ablation ICP-MS we can further assess the intratest variability of Ba/Caforam. Moreover, we compare the Ba/Caforam to measured bottom water [Ba/Ca] from the same locality and consider a multitude of factors for approaching this novel core-top calibration. First results show that the species-specific partition coefficients are matching those of published laboratory experiments and core-top calibrations for hyaline benthic foraminifera. We show the application of high-resolution sampling techniques in the benthic environment to assess the complex present-day situation.