A benthic flux from calcareous sediments results in non-conservative neodymium behavior during lateral transport: a study from the Tasman Sea

The neodymium isotopic (ε_Nd) signature is a widely used proxy in determining changes to ocean currents through Earth’s history. The application of ε_Nd as a proxy of water-mass circulation is based on an assumed quasi-conservative behavior of neodymium isotopes in the ocean. However, our understanding of the factors that govern the oceanic budget of neodymium, including the mechanisms controlling dominant sources and sinks, is not yet complete. Here, I present pore water and water-column neodymium concentration profiles from the western edge of the Tasman Sea to examine the influence of a benthic flux on the northward-flowing Circumpolar Deep Water (CDW). I find that the flux from this region’s calcareous sediments is similar in magnitude to the benthic flux observed in the North Pacific Ocean. In addition, water-column data show a significant increase in the neodymium concentration of the CDW as it moves through the Tasman Sea. Together, these findings indicate that regions with calcareous sediments can account for an important component of the benthic source of neodymium to the oceans.