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ID 07030
Also Known As T-1-07-GA
07030
Abstract University of California, Santa Cruz,United States Geological Survey, Woods Hole, Massachusetts. Chief Scientists: Ken Bruland, UC Santa Cruz, Chief Scientist, John Crusius, USGS, Woods Hole. Water Sampling data (VanVeengrab, watersamples, Niskinbottle, CTDmeter) of field activity 07030 (T-1-07-GA) in Gulf of Alaska, United States, North America, North Pacific from 08/15/2007 to 09/21/2007
Organization University of California, Santa Cruz
United States Geological Survey, Woods Hole, Massachusetts
Project/Theme Coastal Fluxes, Iron Delivery
Chief Scientist Ken Bruland
John Crusius
Activity Type Water Sampling
Platform Thomas G. Thompson
Area of Operation Gulf of Alaska, United States, North America, North Pacific, Gulf of Alaska
Bounding Coordinates
61.75000
-155.75000    -132.25000
54.25000
Ports LEAVE Seattle, WA
ARRIVE Dutch Harbor, AK
Dates 08/15/2007 (JD 227) to 09/21/2007 (JD 264)
Analog Materials No analog holdings.
Scanned Materials t-1-07-ga.map log (pdf)
Information Specialist
John Crusius
Crew
Ken Bruland UC Santa Cruz, Chief Scientist
John Crusius USGS
Andrew Schroth USGS
Geoffrey Smith UCSC
Bettina Sohst UCSC
Maeve Lohan Plymouth University, UK
Michael Lawrence UCSC
Sherry Lippiatt UCSC
Matthew Brown UCSC
Peter Rovegno UCSC
Raphe Kudela UCSC
Tawnya Peterson UCSC
Anna Rubin UCSC
Misty Blakely UCSC
Tina Voelker Colorado School of Mines
Paul Hansard Colorado School of Mines
Andy Vermilyea Colorado School of Mines
Florian Koch SUNY Stoney Brook
Yan Xu Princeton University
Patrick McGinn Princeton University
Dalin Shi Princeton University
Brian Hopkinson SIO, UCSD
Celine Gallon UCSC
Zeka Kuspa UCD
Brian Haley Germany
Mary Silver UCSC
Tyler Coale UCSC
Ana Cristina Garcia LSU
Equipment Used
VanVeengrab
watersamples
Niskinbottle
CTDmeter
Purpose
determining concentrations, sources and fluxes of dissolved
and particulate iron to the North Pacific ocean
Information to be Derived
Samples and Chemical
Analysis;specifically:  1) speciation and
bioavailability of particulate iron in the
Gulf;2) iron speciation in suspended sediment
from various tributaries;3) degree of solubility
of source iron in seawater;and 4) rate of
transport of iron-rich nearshore waters toward
iron-poor offshore regions of the Gulf
Summary
Iron is a nutrient that is believed to
limit primary productivity in about 30 to 40
percent of the ocean s surface waters, including
much of the northern North Pacific, where iron
addition has been shown to stimulate plankton
growth. By facilitating phytoplankton blooms,
iron supply to surface waters may lead to a
transfer of carbon to the deep sea and thus
decrease the concentration of atmospheric CO2.
Iron supply could also impact the fish yield of
ecosystems controlled by nutrient supply. Before
connections can be made between iron supply and
these broader topics, however, some fundamental
questions must be addressed, including (1) how
does naturally occurring iron move from the
continent to the open ocean? and (2) what
fraction of that iron is  bioavailable in a
form that is accessible by such organisms as
phytoplankton? Continental sources of iron to
the marine environment are numerous and include
airborne dust, riverine input, continental-shelf
sediment resuspension, submarine ground-water
discharge, and remobilization during sediment
diagenesis. However, the supply and
bioavailability of iron from these sources is
poorly constrained and likely to vary in both
time and space. Improving our understanding of
the processes governing iron transport and
bioavailability in marine waters could prove
critical in predicting the response of marine
ecosystems to environmental change. Some of the
specific research objectives of the cruise were
to (1) measure the iron content in waters of the
northwestern Gulf of Alaska, an area for which
few data existed; (2) examine how mixing of
iron-rich coastal waters with high-nutrient,
low-chlorophyll waters leads to enhanced
phytoplankton biomass in the northwestern Gulf
of Alaska; and (3) assess what fraction of the
particulate iron is  reactive  or bioavailable.
The cruise involved extensive water sampling in
both the coastal and offshore marine waters of
the Gulf of Alaska. Once in the gulf, the
Thompson tracked in and out of the
sediment-laden Alaska Coastal Current and the
offshore waters of the Alaska Gyre, while the
scientists collected both surface samples and
depth profiles and made various shipboard
measurements. The terrestrial sediment supply to
the Gulf of Alaska is large and primarily
glacially derived, a product of extensive
mechanical weathering of bedrock by glaciers
within the interior mountain ranges of Alaska
and by tidal glaciers flowing into the Gulf of
Alaska. The scientists observed suspended
glacial flour kilometers offshore in the Alaska
Coastal Current. This glacial sediment,
transported offshore by various processes, could
be an important source of iron to the waters of
the Alaska Gyre in this region. Schroth s
research focuses on determining the speciation
and bioavailability of  particulate  iron in the
Gulf of Alaska and on assessing the variations
in such parameters as a function of particulate
source. Schroth collected suspended-sediment
samples through filtration of both surface
waters (collected from Bruland s  fish
ultraclean surface-water-sampling system) and
water collected at depth (with an assembly
consisting of a Niskin bottle rosette and a
conductivity-temperature-depth [CTD] sensor).
These samples were collected in various
areas the sediment-laden Alaska Coastal
Current, sediment-rich near-bottom (nepheloid)
layers near the continental shelf of the Gulf of
Alaska, fiords immediately adjacent to tidal
glaciers draining areas with multiple bedrock
types, and offshore waters of the Alaska
Gyre to encompass an array of water masses
that could contain unique iron particulate
phases and distributions. Schroth will determine
the solid-phase speciation of iron in these
samples by using synchrotron-based
X-ray-absorption spectroscopy.   In addition,
Schroth will determine iron speciation in
suspended sediment from tributaries with
different catchment bedrock geology and degree
of glaciation in the Copper River drainage
system a primary source of sediment to the
Gulf of Alaska. Exposed glacial sediment was
also sampled at the toe of glaciers that differ
in catchment geology; Schroth will examine the
solubility of iron in this sediment when reacted
with seawater from the gulf. The terrestrial
component of this project will allow USGS
scientists to assess how iron speciation in
glacial sediment and bedrock influences the
reactivity of iron that is transported to the
Gulf of Alaska.  Specifically, Schroth s
research seeks to answer the following
questions:   What is the solid-phase speciation
of iron across different water masses and
biogeochemical gradients in the Gulf of Alaska,
and how does iron speciation relate to iron
bioavailability in these marine waters?  Does
the solid-phase speciation of iron vary by
terrestrial source, and what role do glaciers
and their catchment geology play in iron
reactivity in riverine and dust loads delivered
to the ocean near glaciated coasts?   Crusius
work involved examining the dynamics of mixing
of nearshore iron-rich waters with offshore
iron-poor waters, using radium isotopes as
tracers. Radium is enriched in nearshore surface
waters, both by desorption from sediment
surfaces and by discharge of saline ground
water. The goal of Crusius  work is to
understand the rates at which nearshore waters,
rich in iron, are transported toward offshore
iron-poor regions of the Gulf of Alaska using
the radium isotopes as tracers.
Notes
37 days at sea.
Determining concentrations, sources and
fluxes of dissolved and particulate iron to the
North Pacific ocean
Funding
NSF (Bruland portion) + NSF
Publications
Schroth, Andrew, and Crusius, John, USGS Researchers Participate in Research 
Cruise Studying Iron Biochemistry in the Gulf of Alaska, Sound Waves, March, 
2008, available on line at:
http://soundwaves.usgs.gov/2008/03/
Got Help? For 07030, we would appreciate any information on -- analog materials, contract, days at sea, dive count, kms of navigation, national plan, NGDC Info, owner, project number, scanned materials, seismic description, station count, station description, submersible, tabulated info.
Type Webpage KMZ Arc         Metadata         WHSC
Geochemical       data
Metadata data     txt  data  FAQ  xml data
Navigation data nav      
Samples data samp      
Times   050.times      

07030 location map of where navigation 

equipment operated

 
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