Barium Isotopes

A users guide for applying barium isotopes in barite to constrain carbon export, ocean circulation, and marine chemistry through time.

In the marine environment barium isotope (δ138Ba) variations are driven by barite cycling. This Element examines these variations; evaluates their global, regional, local, and geological controls; and explores how δ138Ba can be exploited to constrain the origin of enigmatic sedimentary sulfates and study marine biogeochemistry over Earth's history.In the modern marine environment, barium isotope (δ138Ba) variations are primarily driven by barite cycling—barite incorporates 'light' Ba isotopes from solution, rendering the residual Ba reservoir enriched in 'heavy' Ba isotopes by a complementary amount. Since the processes of barite precipitation and dissolution are vertically segregated and spatially heterogeneous, barite cycling drives systematic variations in the barium isotope composition of seawater and sediments. This Element examines these variations; evaluates their global, regional, local, and geological controls; and, explores how δ138Ba can be exploited to constrain the origin of enigmatic sedimentary sulfates and to study marine biogeochemistry over Earth's history.