Abstract

The Equatorial Pacific Ocean (EPO) is among the most productive oceanic regions and is characterized by strong CO2 outgassing, playing a pivotal role in the global carbon cycle. Here, we present the distributions of micronutrients along the German GEOTRACES GP11 transect in the EPO during a developing El Niño. This study aims to assess the biogeochemical controls governing micronutrient distributions along the transect, which are critical for elucidating potential linkages between surface productivity and nutrient supply. Model estimates combined with observational constraints indicate that equatorial upwelling and strong zonal currents exert primary controls on micronutrient fluxes and biological uptake ratios. These findings have important implications for the bioavailability of micronutrients in the surface EPO under an increasing frequency of extreme El Niño and La Niña events, which modulate upwelling strength and Equatorial Undercurrent (EUC) intensity across the EPO. Overall, this study highlights the differential impacts of water mass mixing and vertical processes including, organic matter remineralization, particle scavenging, and benthic fluxes, on micronutrient distributions in the EPO and provides new insights into their inter-basin variability and biogeochemical cycling in the Pacific Ocean. About the speaker: Dr. Naman Deep Singh is a geochemist and completed his integrated BS-MS degree at the Indian Institute of Science Education and Research (IISER) between 2010 and 2015, followed by a Ph.D. at the Physical Research Laboratory from 2015 to 2020. He is currently working as a postdoctoral researcher at GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany. His research interests focus on understanding the biogeochemical cycling of trace metals in the ocean and their influence on biological ocean productivity and chemical weathering processes in terrestrial systems.