Table of Contents

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

Usage note: Time zone information was not received by BCO-DMO so it is unknown if the dates and times in this dataset are local or UTC. Please contact the dataset PI if you have questions about this.

Conductivity, Temperature and Depth (CTD) data and water samples were collected at various depths across 23 stations (total n = 68) from the Louisiana-Texas shelf in the Gulf of Mexico using the R/V Acadiana between September 18, 2017 and September 21, 2017. At all stations, a vertical profile of salinity, dissolved oxygen concentration and temperature was collected using a CTD. The CTD rosette was equipped with 6, 4 L Niskin bottles for collecting aqueous samples at specific depths. Water samples were collected using a single Niskin bottle per depth and were analyzed across various analytical instruments for nutrient concentrations.

Water samples were collected using a single Niskin bottle per depth on the CTD rosette. Samples for dissolved inorganic nutrients and dissolved organic carbon / total nitrogen were analyzed following the methods detailed in Roberts and Doty (2015) and Mason et al. (2016). Specifically, one niskin bottle, water samples for dissolved inorganic nutrients (NO₃⁻ + NO₂⁻, NO₂⁻, PO₄³−, SiO₂, and NH₄⁺) were analyzed in duplicate using a Lachat Instruments QuikChem FIA+ 8000 Series Automated Ion Analyzer with an ASX-400 Series XYZ autosampler after being filtered through acid-cleaned (10% HCl), 47 mm diameter, 0.2 µm pore size, membrane filters (Pall SuporR-200) under low vacuum pressure. Samples were analyzed for dissolved NO₃⁻ + NO₂⁻ (by Cu-Cd reduction followed by azo dye colorimetry), PO₄³ (by the automated ascorbic acid reduction method), SiO₂⁻, and dissolved NH₄⁺ (by phenate colorimetry) (APHA, 1992). Dissolved NO₂⁻ was determined separately by azo dye colorimetry (without Cu−Cd reduction). Standard curves were prepared using certified standard stock solutions (Hach, Loveland CO) and yielded r² values of ≥ 0.999. NO₃⁻ concentration was determined by difference between NO₃⁻ + NO₂⁻ and NO₂⁻.

Dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations were measured at least in triplicate on a Shimadzu TOC-VCSH Analyzer with TNM-1 Module (MDL 1.5 μmol C L−1, 0.3 μmol N L−1; Shimadzu Scientific Instruments, Columbia, MD) after being filtered through combusted (450°C), 47mm diameter Whatman GF/F filters under low vacuum pressure. Concentrations of dissolved organic nitrogen (DON) were determined by difference [DON=TDN−DIN].

All water chemistry data went through quality control checks. CTD instrument probes were calibrated prior to cruise departure.

CTD data were processed on Seabird's SBEDataProcessing-Win32.

BCO-DMO Processing:
- renamed fields to conform with BCO-DMO naming conventions;
- changed year from 2019 to 2017 for station F7, bottle 1.

NSF Award Abstract:
Understanding how extreme events, like hurricanes, impact coastal ecosystems and the cycling of elements like carbon and oxygen, is important for improving our ability to predict how the global carbon cycle will respond to climate. This team of investigators, who have already been working together on understanding the carbon cycle in the Gulf of Mexico continental shelves, have important recent data against which to measure the effects of the passage of Hurricane Harvey in August, 2017. They will sample the waters and sediments of the northwestern Gulf of Mexico in September, October, and January to assess Harvey's impacts on a timescale of weeks to months.

The researchers pose three specific questions: 1. Will the region become a major source of carbon dioxide to the atmosphere, releasing carbon accumulated in the bottom water and sediments, and will this potential impact be faster and greater than during normal fall and winter mixing events? Will this process acidify the surface water and for how long? 2. Will the metabolic balance be substantially pushed toward net heterotrophy as a result of the storm in comparison to other years? 3. Can the amount of material delivered or redeposited across the continental shelf by a tropical cyclone be considerably larger than that related to winter storm systems? The PIs will measure water column nutrients, oxygen, organic carbon, and inorganic carbon system parameters; determine water column and benthic metabolic and nutrient flux rates; and sediment organic matter deposition rates. They will also collect end member river samples. They will compare the immediate (mid-Sept) but limited post-hurricane data and one-month post-hurricane, more detailed data with those collected in July and April to study the impacts of the storms. they will also compare 2017-2018 seasonal data to seasonal data over the same region collected in the past (2006-2008 and 2009-2010). They will also compare the impacts of Hurricane Harvey to those of Hurricanes Katrina and Rita (2005) and Tropical Storm Cindy (June 2017). The project will involve graduate and postdoctoral research and work to communicate results to the public.