<%@ page import="java.util.*" %> <%@ page import="java.io.*" %> <%@ page import="edu.unh.sr.ccg.*" %> Coastal Carbon Group

Gulf of Maine Survey, November 2006

Principal Investigators: Doug Vandemark and Joe Salisbury

Chris Hunt and Doug Vandemark recently spent two weeks aboard the R/V Oceanus acquiring the first comprehensive spatial survey of several greenhouse (carbon dioxide and methane) and other dissolved gases in Gulf of Maine surface waters. The primary mission of the cruise, headed by Chief Scientist Bruce Keafer of the Woods Hole Oceanographic Institute, was to map (see map to the right) Alexandrium cyst population across the muddy bottom of the Gulf. Alexandrium is the organism responsible for red tide shellfish closures in our region. Their work involved collecting ocean bottom sediment cores at more than 150 sites across the region. Information on that program can be found at (http://www.whoi.edu/redtide/).

Our effort focused on measuring surface water properties using the UNH flow-through system usually deployed on the R/V Gulf Challenger as well as collection of discrete water samples for laboratory analysis. The underway measurement system includes a fast rate surface CO2 measurement system that allowed us to map out CO2 concentrations along the shiptrack (see image to the right) - providing a spatially dense snapshot of surface layer carbon dioxide across a large portion of this marginal sea. We also collected trace gas samples from both sides of the air-sea interface ( 3 m above and below the sea surface) at 60 measurement stations. These 1L canisters of air are being analyzed back in the laboratory by UNH/EOS researchers Ruth Varner and Barkley Sive to look at a suite of trace gases including methane, halocarbons, and carbon dioxide.

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.
Specific objectives related to these measurements include:

evaluation of spatial variations in the fall season surface carbon signature (carbon dioxide and total inorganic carbon (see maps to right) of the coastal Gulf of Maine

testing several relationships that we've developed for the Western Gulf of Maine including how well they translate to the wider Gulf; this encompasses relationships between alkalinity and salinity, CDOM and salinity, DOC and CDOM, fluorosensing derived CDOM and gelbstoff absorption

acquisition of the first spatial survey of surface layer methane for this region and evaluation of possible spatial dynamics associated with benthic sources

acquisition of a surface water caffeine concentration data set to evaluate the potential for caffeine as a tracer of point source land-ocean input (e.g. water treatment facilities) along the coastline

Much thanks to Bruce Keafer and Principal Investigator Dennis McGillicuddy for inviting us aboard and to all the crew for their support in making this a very successful cruise.

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Map of pCO2 spatial distribution along the cruise track.

Map of salinity along the cruise track.

Map of sea-surface temperature along the cruise track (in degrees C).