Identifying Zinc Inputs to Heard and McDonald Islands Region using Zinc Concentrations and Isotopic Compositions

• Main Author: Mohamed, Fwziah Ali Abdalali
• Other Authors: Wieser, Michael E., Yang, Lu, Hobill, David W., Yau, Andrew W., Mayer, Bernhard
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Science 2020
• Subjects: Zinc hydrothermal inputs to the Southern Ocean; Education > Sciences; Antarctic; Heard; McDonald Islands; Southern Ocean; Antarc*; Institute for Marine and Antarctic Studies
• Online Access: http://hdl.handle.net/1880/112442; https://doi.org/10.11575/PRISM/38124

Zinc (Zn) availability in the ocean is thought to have the potential to impact the health and the biomass of phytoplankton communities in the ocean. The application of Zn isotopic composition is an effective approach to understand sources and environmental receptors of Zn in the ocean. An important challenge; however, is to measure the Zn isotopic composition reliably because of the limited range in Zn isotopic composition and the low amount of Zn found in the ocean. Zinc is a micronutrient that has received much attention due to its role in the biology of marine phytoplankton. Ocean surface water Zn concentrations are in the low nanomolar range, potentially limiting the growth of some phytoplankton species. Identifying and assessing Zn sources in the ocean can provide insights into the significance and the influence of Zn availability on phytoplankton growth. This thesis research project entails the development of a reliable method to explore the Zn sources in the vicinity of Heard and McDonald Islands, an Australian territory, in the Southern Ocean. The region of Heard and McDonald Islands, two of the most active volcanic islands in the world, is one of the regions in the Southern Ocean where large phytoplankton blooms are produced annually. This raises the possibility that the islands’ hydrothermal activity is releasing large amounts of trace elements including Zn to the water column thereby enhancing the biological productivity in the region. The development of the analytical method included a careful consideration of all factors that may affect Zn measurements, including Zn laboratory blanks introduced during the sample handling and preparation, isobaric interferences from the sample matrix, and the data reduction technique. Zinc concentrations and isotopic compositions were measured in seawater, suspended particles, sediments, and rock samples collected during the Heard Earth Ocean Biosphere Interactions (HEOBI) voyage in January and February of 2016 led by the Institute for Marine and Antarctic Studies ...