Official Cruise Website

Gulf of Mexico and East Coast Carbon Cruise

Principal Investigators:

Joe Salisbury (PI, UNH)
Penny Vhalos (PI, UCONN)
Meg Graustein (UCONN)
Jennifer St.Louis (UNH)
Amanda Plagge (UNH)

Joe Salisbury, Ph.D student Amanda Plagge and MS student Jennifer St. Louis recently returned to UNH after participation in the Gulf of Mexico and East Coast Carbon Cruise. The cruise started in Galveston, TX on July 10, ended in Boston on August 4, and was the first comprehensive, synoptic survey of inorganic carbon, nutrients and other biogeochemical parameters for these coastal waters These efforts were implemented in support of the North American Carbon Program (NACP) and was supported by the NOAA/OAR and the NOAA GCC (Global Carbon Cycle) programs. The major objective is the determination of air-sea carbon dioxide fluxes in North American coastal regions. The NOAA Atlantic Oceanographic and Meteorological Laboratory (AOML) is the lead institution for the cruise. UNH was one of nine U.S. universities participating in this effort.

The UNH-UCONN team had several science-research objectives. First we sought to measure surface distributions of dissolved organic carbon (DOC) and its colored fraction (CDOC) to characterize how land fluxes may be influencing the distribution of these constituents. Second, we sought to determine if the surface coastal ocean could be organized into optical domains that would aid in the estimation of inorganic carbonate parameters (e.g. pCO2) from satellite platforms. Our third objective was to collect a comprehensive spatial dataset of carbonate parameters and inorganic ions for Jen’s Thesis. Her work seeks to understand the contribution of pelagic calcification to overall coastal ocean productivity.

Discrete water samples were also collected for analysis of dissolved organic and inorganic carbon, total alkalinity and pH, nutrients, fluorometric chlorophyll, HPLC chlorophyll, CDOM absorption, and caffeine. The suite of measurements will help us to connect results from our ongoing (2004-present) Western Gulf of Maine sampling efforts to the larger Gulf and to address several key issues related to coastal margin carbon dynamics.

UNH-UCONN Measurements:


Underway sampling

An integrated suite of underway-surface parameters was measured using the ship’s uncontaminated seawater supply. Approximately 6 liters per minute were diverted to flow sequentially through a 'bio-optics' sensor suite, consisting of an Aanderra Thermosalinograph, an Aanderra dissolved oxygen sensor, a Satlantic ISUS Nitrate sensor and WetLabs ‘Eco-triplet” product consisting of: fluorescence of colored organic; stimulated chlorophyll fluorescence and particle scattering at 660nm. The flow data were monitored and most sensors provided a reasonable range of data. Sensors were “blanked” periodically with DI water. Corrections for sensor drift will be applied at UNH. Periods when sensors apparently failed or gave suspicious data were logged and the logs will be used to cull the data.

Discrete Samples:

Dissolved Organic Carbon

DOC samples were collected using two slightly different sampling protocols for investigators (Joe Salisbury (UNH) and Penny Vlahos (UCONN)). Approximately 250 samples were collected for the UNH lab and 150 samples for the UCONN. Samples were taken at the surface,10m, below the thermocline and at the bottom. Nitrile gloves were worn and either silicon tubing was used to draw samples, or samples were drawn directly from the Niskin nipple into triple rinsed polycarbonate or glass bottles. Samples for UCONN were filtered using a nominal 0.7 µm pore size glass fibre filter (GFF) into acid washed 60 ml glass bottles with Teflon caps. UNH samples were filtered with a peristaltic pump with silica tubing through a Whatman 0.2 µm Polycap AS filter at low pressure. All UNH samples were frozen immediately after collection. UCONN samples were fixed with phosphoric acid and refrigerated in the ship’s cooler. Analysis will occur at the respective labs (below). For analysis the samples are thawed and acidified (UNH), then sparged with oxygen to remove inorganic carbon. The organic carbon is combusted and converted to carbon dioxide, which is measured by a non-dispersive infrared detector. UNH samples will be analyzed either by the Wm. MacDowell Lab at UNH or the Craig Carlson Lab, University of California Santa Barbara, UCSB. The UCONN samples will be run at Vlahos Lab.

Colored Dissolved Organic Matter (CDOM)

Approximately 250 CDOM samples were collected. They were filtered using the Whatman 0.2 µm Polycap AS (same filter and procedure as the DOC samples above) into a 125 ml amber glass bottle and refrigerated immediately. Three depths were typically sampled; surface, below the mixed layer and (less often) within the mixed layer. Analysis will be completed the University of Georgia by Heather Reader (Bill Miller’s Lab) , using a dual beam spectrophotometer.

Methane

Air samples were drawn from the Texas A&M equilibrator (under light pressure) via a needle, into clean, evacuated and sealed 100ml glass bottles. Approximately 300 surface samples were taken along the cruise track. Methane will be analyzed at Dr. Ruth Varner’s Lab (UNH) using a Gas Chromatograph.

Ca++, Sr++, Mg++

Samples for Calcium and Strontium and Magnesium analysis were taken at the surface at all stations, at 10m at approximately 1/2 the stations, and periodically from the underway water. We sampled with Nitrile gloves directly into 300ml triple DI-rinsed, then triple sample-rinsed polyethylene bottles. The bottles were stored in the ship’s cooler shortly after sampling. At UNH the samples will be filtered with Whatman GFF filters (which are retained for further analysis) and the filtrate analyzed either by Atomic Absorption or Induced Coupled Plasma analysis by Jennifer St. Louis, in Karen VonDamm’s “Hot-water” Lab at UNH. Filters will be desiccated then placed in clean, combusted 50ml glass bottles filled with 1M HCl. The filtrate will be diluted with DI water and further analyzed to determine the concentration of particulate Ca++, Sr++ and Mg++.

DIC

Periodic underway samples were taken for dissolved inorganic carbon. Approximately 100 samples were collected. We typically did not sample on stations where the AOML group provided coverage. The purpose of these sampling efforts were to collect underway surface data in interesting low-salinity or high chlorophyll regions not captured on the transect stations. Duplicate samples were drawn from the underway outflow into 20ml Teflon-capped glass bottles, poisoned with 0.1l saturated HgCl2 and refrigerated. Samples will be analyzed at J. Salisbury’s Lab (UNH) using an Apollo Scientific DIC analyzer based on Li-COR IR detector technology.

13DIC

Samples were taken by Meg Graustein for 13DIC at the surface, 10m below the thermocline and at the bottom at odd-numbered stations. Samples were taken from the Niskin using a silicon tube into triple sample-rinsed glass bottles. Samples were then stored in the ship’s cooler. Samples will be analyzed at the Vhalos Lab (UCONN) using a mass spectrometer.

POC

Meg Graustein of UCONN took particulate organic carbon samples (surface, 10m, below the thermocline and bottom) at every other station. Water was sampled via silicon tubing into triple-rinsed glass bottles. Between 80 and 200ml were filtered through pre-combusted Whatman GFF 0.45nm filters. The filters were taken off of the filtering apparatus, folded into quarters, wrapped in aluminum foils and frozen. The samples will be analyzed post-cruise at the Vhalos Lab (UCONN).

Large Volume Air sampling:

We collected air samples during steam time from one transect to another to map out atmospheric concentrations of Currently Used Pesticides and Perfluorinated organic compounds. A large volume air sampler was fitted with a pre-combusted 0.45 nominal GFF for particulates and a poly-urethane foam plug impregnated with C-18. During these sampling periods we collected 4 L of surface water from the in-line pumping system to extract for the same compounds in near surface waters and determine potential fluxes.



 

The RV Ron Brown surveyed a pattern of cross-shelf transects from Gulf of Mexico to the Gulf of Maine.

Map of in-water surface fCHL (log scale of mg/m^3).



Map of surface oxygen, shown as percent saturation.