Title:

The carbon cycle of Glacier Bay, Alaska; primary productivity, the importance of terrestrial inputs and the air-sea CO₂ exchange.

Objective:

To get an overall model of the carbon cycle in Glacier Bay, Alaska. This includes quantifying primary productivity, identifying the importance of terrestrial sources of carbon and determining air-sea CO2 exchange.

Why?

The dissolved inorganic carbon (DIC) system has never been measured in Glacier Bay. By measuring total DIC, organic carbon, analyzing the ¹³δC isotope ratio and finding pCO₂ of the surface water, the objective will be accomplished. Coastal regions vary widely and tend to be less studied than open ocean basins, so knowing more about the carbon cycling in Glacier Bay may allow us to draw parallels to less studied glacial fjords (Zhang 1997). Being able to quantify the amount of CO2 taken in or given off at G.B., increases our understanding of the role that bays play in the global air-sea carbon exchange. Studying the relationship between the sea and atmosphere with regards to pCO₂ has been important in accurately quantifying the world's CO₂ budget (Jacobson et al 2007). Determining the location of the source of inorganic carbon to the system is another well studied topic that has not been investigated at Glacier Bay. Knowing the source of carbon to a system allows other researchers to learn about biological, physical and chemical processes occurring in the system (Miller 1995).

What?

Approximately 60 surface water samples will be collected and analyzed for pCO₂ by measuring alkalinity using Gran titration method and total dissolved inorganic carbon (DIC) by the a carbon extraction process defined by (Quay et. al. 1992). At 5 stations inside the park, depth profiles will be taken from the surface down to below the mixed layer. These samples will be measured for total DIC as well as on a mass spectrometer for their ¹³δC/¹²δC isotope ratio. Finally, hand net tows will occur at all stations and samples will be collected to later be analyzed for their organic carbon.

Where?

Samples will be taken at locations from the entrance of Glacier Bay to the back of the west arm. As many as 15 stations will be used for the collection of surface water, and 5 stations will be chosen to take samples from the water column beyond the photic mixed layer. 5 depths will be chosen for sampling at each of the five "deep" stations. Exact locations will be determined at the time of sampling depending on where the photic layer boundary is positioned on the day of testing. Stations will be chosen to attempt to test water that varies in chlorophyll content, PAR, and proximity to river/glacier freshwater inputs.

How?

Equipment (shipboard):

-Gran titrator: to carry out alkalinity measurements using the Gran method
-CTD with Niskin rosette: to gather water samples
-Ground glass stoppered sample bottles for DIC/¹³δC samples
-Nitric Acid: needed for Gran titration
-Mercuric chloride: for poisoning of the DIC and plankton samples.

-Hand net tow for phytoplankton.

-150mL plastic bottles for plankton collection.

Equipment (ashore):

-DIC extraction line and associated materials: to isolate the carbon from the water samples
-Mass Spectrometer (Finnigan MAT 251 or 252): for ¹³δC analysis of the isolated carbon

-Elemental analyzer to measure isotope ratio of organic carbon.
-Database (Globalview): to determine atmospheric values of pCO₂

Who?

Paul Quay is an advisor because of his expertise in dissolved inorganic carbon measurement and extraction techniques including stable isotope analysis. Johnny Stutsman, with similar expertise will also be involved in oversight and training during the mass spectrometer analysis phase of the project. Rick Keil is the final advisor because of his expertise in carbon cycling, DOC and alkalinity. He or his lab will provide use, oversight and training for use of the Gran titrator.

References:

The following references will be used in my research. The list will grow.

GLOBALVIEW-CO2: Cooperative Atmospheric Data Integration Project - Carbon
Dioxide. CD-ROM, NOAA CMDL, Boulder, Colorado [Also available on Internet via anonymous FTP to ftp.cmdl.noaa.gov, Path: ccg/co2/GLOBALVIEW], 2003.

Haraldsson, C., L. G. Anderson, M. Hassellov, S. Hulth, and K. Olsson. 1997. Rapid, high-precision potentiometric titration of alkalinity in ocean and sediment pore waters. Deep-Sea Research Part I-Oceanographic Research Papers 44: 2031-2044.

Jacobson, A. R., S. E. M. Fletcher, N. Gruber, J. L. Sarmiento, and M. Gloor. 2007. A joint atmosphere-ocean inversion for surface fluxes of carbon dioxide: 1. Methods and global-scale fluxes (vol 21, art no GB1019, 2007). Global Biogeochemical Cycles 21.

Miller, W. L., and R. G. Zepp. 1995. Photochemical Production Of Dissolved Inorganic Carbon From Terrestrial Organic-Matter - Significance To The Oceanic Organic-Carbon Cycle. Geophysical Research Letters 22: 417-420.

Quay, P. D., B. Tilbrook, and C. S. Wong. 1992. Oceanic Uptake Of Fossil-Fuel Co2 - C-13 Evidence. Science 256: 74-79.

Zhang, J. R., and P. D. Quay. 1997. The total organic carbon export rate based on C-13 and C-12 of DIC budgets in the equatorial Pacific region. Deep-Sea Research Part Ii-Topical Studies In Oceanography 44: 2163-2190.