Redox dynamics resulting from chemical and physical fluxes in surficial permeable sediments

University Of Hawaii, Honolulu

Investigators

Abstract

The ability to make in situ measurements of analytes on relevant spatial and temporal scales and the need for robust porewater transport characterizations have limited measurements of chemical fluxes within permeable sediments. Two scientists from the University of Hawaii will combine in situ electrochemistry, modeling, traditional geochemistry, and an eddy correlation oxygen flux measuring system to address the biogeochemical fluxes from nearshore permeable sediments. The research will be carried out at the Kilo Nalu Cabled Nearshore Reef Observatory which will provide (1) data acquisition and data dissemination systems; (2) accessible power and high bandwidth communications for in situ instruments; (3) a wide range of physical oceanographic measurements; and (4) Oahu?s south shore has a wide and predictable variety of surface wave conditions and land-based inputs that impact the redox-sensitive biogeochemistry of its permeable sediments. Results from this study will be used to (1) improve our understanding of the interaction between these active, carbon recycling sediments and the overlying water column; (2) examine in detail the temporal and spatial variability of key redox-reactive chemical species; (3) quantify the relative contributions of benthic photosynthesis, sand ripple position, currents and waves, and episodic organic loading events to redox oscillations; and 4) integrate fine-scale chemical measurements with porewater velocity modeling to calculate biogeochemical fluxes. As regards broader impacts, this project will significantly further our knowledge of the solute fluxes across the permeable sediment/seawater interface, as well as improve our understanding of biogeochemical processes within these types of sediments. In addition, this research would make novel in situ sensor technology available to the ocean sciences community. Outreach activities include education of the public via the Bishop Museum and providing information on their research for websites and educational videos displayed in Waikiki hotels. One postdoc, one graduate student and one undergraduate student would be supported and trained as part of this project.