| Original author(s) | Ernie Lewis and Doug Wallace |
|---|---|
| Initial release | 1998 |
| Written in | QBasic, MATLAB, Python, Microsoft Excel |
| Available in | English |
| Website | https://cdiac.ess-dive.lbl.gov/ftp/co2sys/ https://pyco2sys.readthedocs.io/en/latest/ https://ecology.wa.gov/Research-Data/Data-resources/Models-spreadsheets/Modeling-the-environment/Models-tools-for-TMDLs |
CO2SYS is a family ofsoftware programs that calculatechemical equilibria foraquaticinorganic carbon species and parameters. Their core function is to use any two of the four central inorganic carbon system parameters (pH,alkalinity,dissolved inorganic carbon, andpartial pressure of carbon dioxide) to calculate various chemical properties of the system. These programs are widely used byoceanographers andlimnologists to understand and predictchemical equilibria in natural waters.[1]
Chemical equilibria in marine and freshwater systems were calculated according to various conventions for most of the 20th century, which led to discrepancies among laboratories' calculations and limited scientific reproducibility.[2] CO2SYS was first published by Ernie Lewis and Doug Wallace in 1998 as a DOS-interface program written in QBasic.[1] Subsequent developments have included severalMATLAB implementations,[1][3] twoMicrosoft Excel templates,[1][4][5] aPython package "PyCO2SYS",[6] and anR package inspired by CO2SYS, "seacarb".[1][7] Development of the various CO2SYS programs continues as of 2021 with the addition of more chemical equilibrium parameters and compatibility with a wider range of environments, e.g.anoxic waters.[8]
The aquatic inorganic carbon system is composed of the various ionic, dissolved, solid, and/or gaseous forms of carbon dioxide in water. These species includedissolved carbon dioxide,carbonic acid,bicarbonateanion,carbonate anion,calcium carbonate,magnesium carbonate, and others. The relative amounts of each species in a body of water depends on physical variables including temperature and salinity, as well as chemical variables like pH and gas partial pressure. Variables like alkalinity and dissolved (or total) inorganic carbon further define a mass and charge balance that constrains the total state of the system.[9][10]
Given any two of the four central inorganic carbon system parameters (pH, alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide) the remainder may be derived by solving a system of equations that adhere to the principles ofchemical thermodynamics.[10]
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