Drought recorded by Ba?Ca in coastal benthic foraminifera

Abstract. Increasing occurrences of extreme weather events, such as the 2018 drought over northern Europe, are a concerning issue under global climate change. High-resolution archives natural hydroclimate proxies, rapidly accumulating sediments containing biogenic carbonates, offer potential to investigate frequency and mechanisms events in past. Droughts alter barium (Ba) concentration near-continent seawater through reduction Ba input from terrestrial runoff, which turn may be recorded changes chemical composition (Ba/Ca) foraminiferal calcium carbonates sediments. However, so far use Ba/Ca discharge indicator has been restricted planktonic foraminifera, despite high relative abundance benthic species coastal, shallow-water sites. Moreover, mainly used open-ocean records proxy for paleo-productivity. Here we report on new geochemical data set measured living (CTG-labeled) capability record river runoff gradient contrasting hydroclimatic conditions. Individual foraminifera (Bulimina marginata, Nonionellina labradorica) were analyzed by laser-ablation ICP-MS seasonal spatial within Gullmar Fjord, Swedish west coast, during 2018–2019. The results compared an extensive meteorological hydrological set, well sediment pore-water geochemistry. Benthic correlates significantly riverine runoff; however, signals contain both trends with distance source species-specific influences micro-habitat preferences. We deduce that shallow-infaunal especially suitable discuss influence water-column cycling. While source, water depth, geochemistry, effects need considered interpreting data, our demonstrate confidence past identify periods drought.