NEW pCO2 System
Measure the partial pressure of CO2 and trace gases in an aquatic system
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Why measure partial pressure of carbon dioxide (pCO2)?
pCO2 measurements can help researchers better understand the role of CO2 in atmospheric and aquatic environments. For instance, increased levels of pCO2 in the atmosphere can contribute to the greenhouse effect, so the quantification of pCO2 levels can provide insight into anthropogenic and other CO2 emissions and their potential relationships to climate change.
Aquatic research also uses pCO2 measurements to explore ocean acidification. As atmospheric pCO2 levels increase, more CO2 dissolves in the body of water below until it reaches equilibrium. This measurement is important to oceanic and climate change researchers because an increase of dissolved CO2 in the oceans can cause a decline in pH. This can negatively impact aquatic life.
In addition, pCO2 measurements offer further insights into the biological process, such as photosynthesis and respiration, of aquatic organisms.
What is pCO2?
pCO2, or the partial pressure of carbon dioxide (CO2), is the measure of CO2 gas in solution. It represents the pressure that CO2 gas exerts in a mixture of gases—such as a body of water or the atmosphere. For aquatic carbon systems (e.g., freshwater or saltwater systems), pCO2 is expressed as CO2(aq) and reported in micro atmospheres (μatm).
Advantages of the Underway pCO2 System
- Takes measurements in 3 to 4 minutes
- Built with a durable frame, suited for a variety of applications and deployment locations
- Can be used in freshwater or seawater environments
- Connects to up to five gas standards
- Established research method published in scientific journals
How our system works
Each pCO2 system includes two instruments: a pCO2 analyzer and a gas analyzer. The pCO2 analyzer is composed of a two-stage showerhead equilibrator, water filters, a gas selection valve, wind and weather sensors, and a computer with proprietary software for data collection and analysis.
A pCO2 system uses the relationship between gaseous and dissolved CO2 to accurately measure pCO2. A water sample is first pumped into the system’s equilibrator using an external pump; meanwhile, an air sample from the equilibrator headspace passes through a drying system, which consists of an electronic cooling system and a Nafion drying tube, to remove any moisture.
Salinity and temperature are measured using a Seabird SBE-45 Thermosalinograph, and water intake temperature and salinity are measured at the time of intake. In addition, each pCO2 system takes barometric pressure and water vapor pressure into account.
All pCO2 systems use the Airmar Weather Station, which provides air temperature and wind measurements as well as GPS location. If the system is a premium package, it includes a dissolved oxygen sensor (Aanderaa 4835 DO), a fluorescence and turbidity sensor (Turner Designs Cyclops 7F), and a pH sensor.
| Part | LI-5400A | LI-5405A | LI-5410A | LI-5415A |
|---|---|---|---|---|
| LI-7815 CO2/H2O Trace Gas Analyzer |  |
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| LI-850 CO2/H2O Gas Analyzer | |
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| Airmar Weather Station | |
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| Seabird SBE-45 Thermosalinograph | |
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| Aanderaa 4835 DO, Turner Designs Cyclops 7F, & pH Sensor | |
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Specifications
General
- Power requirements: 110 VAC; 60 Hz or 220 VAC; 50Hz
- Power fuse: 3-Amp slow blow
- Reference gases: Three to five standard gases; should cover the sample concentration range
- Precision: Better than 2 ppm
- PC system: Windows® 10
- Communication: USB
- Operating environment: Indoor, shipboard, or outdoor with protection
- Operating temperature: Room temperature
- Operating humidity: Up to 85%
- Positioning: Horizontal use only (never turn the system upside down)
- Dimensions: 69 cm × 51 cm × 41 cm (H × W × D∥
- Weight: 43 kg
- Storage temperature: 0 °C to 50 °C
Specifications subject to change without notice.
References
Broecker, W. S., & Peng, T. H. (1982). Tracers in the sea (Vol. 690). Palisades, New York: Lamont-Doherty Geological Observatory, Columbia University.
Weiss, R.F. (1974). Carbon dioxide in water and seawater: the solubility of a non-ideal gas. Marine Chemistry, 2(3), pp.203–215. doi:https://doi.org/10.1016/0304-4203(74)90015-2.
Wanninkhof, R. (2014). Relationship between wind speed and gas exchange over the ocean revisited. Limnology and Oceanography: Methods, 12(6), pp.351–362. doi:https://doi.org/10.4319/lom.2014.12.351.
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