Coastal and estuarine regions are among the most dynamic of ocean environments. Concentrations of CO2 in these settings can be highly variable on all time and space scales with ranges of pCO2 varying from levels as low as open ocean, ~200-600 μatm, to as high as 5,000-10,000 μatm.
Variability over short time scales can result from:
- Water temperature changes
- Changes in river discharge from rain events
- Biology; diel cycles
- Wastewater discharge
- Storms, wind events
Variability over longer time scales can result from:
- Changes in biology; e.g. eutrification, or changes in dominant species
- Seasonal temperature and daylight changes
- Buildup of ice
- Industrialization and land use changes
- Seabed sediment reactions and organic breakdown, e.g., changes from aerobic to anaerobic conditions
There still exists a large uncertainty in estimates of carbon fluxes in coastal regions as a result of the great variability of CO2 concentrations. This variability increases the importance of measuring pCO2 in these areas, and the choice of sensor depends on the monitoring constraints, with large-scale, short-term changes being easily measured with the Mini CO2 sensor, and long-term changes requiring greater measurement stability and accuracy best suited to using the CO2-Pro™ series of instruments.
Best suited for measurements in coastal regions where short-term, large-range variability in dissolved CO2 concentrations and lower cost are of principal importance.