Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Samples for quantification of the different cobalamin forms were collected at a six of depths within the euphotic zone (5-250m). Seawater was collected from each CTD depth using Niskin bottles and immediately filtered. Cobalamins were analyzed as in 1 Suffridge et al. (2017). Two liters of seawater were filtered through µm pore-size filters and then preconcentrated using a C18 resin (HF Bondesil (Agilent Technologies) and analyzed by liquid chromatography/triple mass spectrometry (LC/MS/MS/MS). The LC-MS system consists of a ThermoTSQ Quantum Access electro-spray ionization triple quadrupole mass spectrometer, coupled to a Thermo Accela High Speed Liquid Chromatography system. The LC system used a stable- bond C18 reversed-phase column (DiscoveryHSC18 10cm × 2.1mm,5 μm column, Supelco Analytical) with a100 μL sample loop.In order to increase the sensitivity and precision,theLC/MS was run in full-loop mode (100 μl/injection).

The LC-MS system used for the pigment quantification consists of a Thermo TSQ Quantum Access electro-spray ionization triple quadruple mass spectrometer, coupled to a Thermo Accela High Speed Liquid Chromatography pump and auto-sampler.

The LC-MS data was processed using Xcalibur and LCQUAN quantitative softwares from Thermo Scientific.

BCO-DMO Processing:
- modified parameter names (removed units, renamed date and time columns);
- re-formatted date to yyyy-mm-dd (was m/dd/yyyy);
- split time column into start and end times;
- converted lat and lon from degrees and minutes to decimal degrees.

NSF Award Abstract:
Volatile halogenated hydrocarbon gases, in this case halomethanes, are produced naturally by organisms in the ocean; which then serves as a source of these biogenic gases to the atmosphere. Their chemical reactions in the atmosphere are very similar to those of anthropogenic chlorofluorocarbons (CFCs). While CFCs are well-studied because they consume the ozone in the upper atmosphere that shields the earth from harmful ultraviolet radiation, halomethanes have been largely neglected, even though they currently account for 25% of the ozone depletion. As anthropogenic CFC levels steadily decline, however, halomethanes are predicted to account for 50% of ozone depletion by 2050. Based on limited study thus far, marine halomethane production has been ascribed mainly to phytoplankton and macro algae. This project will build on new and compelling data that suggests marine heterotrophic bacteria could also be major producers of halomethanes. The data produced here will provide the critical evaluation required to address discrepancies in global halomethane budgets which currently are out of balance due to an unknown source to the atmosphere, evaluating the hypothesis that marine heterotrophic bacteria can supply this missing source. Concerns over the stability of the earth's stratospheric ozone layer make this valuable and necessary research with added value of providing support for engaged undergraduate, graduate, and postdoctoral education at the University of Southern California.

Past research on the production of marine halomethanes has focused on phytoplankton and macro algae, while potential bacterial contributions to the processe have been neglected. This research proposes to study the role of marine heterotrophic bacteria on the production of halomethanes. It has been noted in past studies that there are discrepancies in the global atmospheric halomethane budget, and it is possible this is due to a large missing bacterial source. Additionally, this research will evaluate the potential importance of vitamin B12, methionine, and vanadium cofactors on the synthesis of halomethanes in bacteria. A large portion of marine bacteria cannot synthesize methylation co-enzymes, and therefore, would require available B12, methionine, and vanadium from external sources to complete the methylation step. This study will also measure concentrations of halomethanes, B12, methionine, and vanadium in upwelling regions as well as at a long-term time series site in order to put constraints on the variability of halomethanes concentrations for use in global linked air-sea models.