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Response of Florida Shelf Ecosystems to Climate Change

Florida Shelf Geochemistry

Field Geochemistry

Multi-parameter Inorganic Carbon Analyzer (MICA)

University of South Florida research scientist, Dr. X. Liu, operates the MICA system onboard a U.S. Geological Survey cruise in July 2008.
University of South Florida research scientist, Dr. X. Liu, operates the MICA system onboard a U.S. Geological Survey cruise in July 2008.

computer screen
Computer monitor onboard USGS research vessel shows incoming data from MICA system.

The USGS is partnering with researchers at University of South Florida to employ state-of-the-art instrumentation to study seawater geochemistry. The Multi-parameter Inorganic Carbon Analyzer (MICA) apparatus, developed at USF by Dr. Robert Byrne’s laboratory, measures four seawater inorganic carbon system parameters simultaneously: pH, carbon dioxide fugacity (fCO2) or partial pressure (pCO2), and total dissolved inorganic carbon (DIC). These parameters are essential for carbon cycle investigations on global and local scales. Observational and modeling efforts rely on high-quality inorganic carbon data from field measurements. The goal of this effort is to establish Florida shelf baseline of pCO2, pH, and DIC values using small-vessel mounted MICA apparatus.

MICA is the result of efforts to improve instruments for determination of carbon parameters in seawater. In conventional methodologies, the four core parameters of the seawater inorganic carbon system are measured using diverse instrumentation (e.g., potentiometry, spectrophotometry, gas chromatography, non-dispersive infrared analysis, and coulometry). It is preferable to measure all parameters simultaneously. Spectrophotometric methods can be used to unify measurements of all parameters at relatively low cost, and have advantages for measuring inorganic carbon species in seawater. Available methodologies were engineered into a single system intended for high-resolution, underway-monitoring onboard research vessels.

Sampling standards and protocols for general watercraft and ships of opportunity deployment are being developed. A portable sea chest sampler will be constructed and installed on local USGS watercraft for testing purposes. TheMICA can be installed on other watercraft to gather ocean chemistry data for pH, pCO2, DIC, and atmospheric pCO2. Existing partnerships can be used to deploy MICA on non-agency vessels. Chemistry data for discrete water column profiles may also be gathered from water profile samplers (e.g. rosette sampler).

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