Dissolved gas monitoring systems
Ground gases are frequently encountered during the assessment and remediation processes that occur prior to redevelopment of potentially contaminated sites, and may also be encountered on land adjacent to such sites. As awareness of the issue has grown, so has the number of sites found to be impacted and requiring management. The consequences of failure to recognize and appropriately manage risks due to ground gases during the assessment and remediation of potentially contaminated land, or during the development of land adjacent to sites impacted by ground gases, may be significant. These consequences may range from construction delays and additional costs, through large legal liabilities to neighboring landholders, to adverse long-term health impacts or structural damage, injury and death due to gas explosions. These are not hypothetical consequences – all have occurred either in Australia or overseas. (Source EPA 2012/0932).
The Dissolved Gas Continuous Monitoring System instrument allows the measurement of water dissolved carbon dioxide and of the related water parameters.
The system is able to measure the concentration of gases (CO2, and/or optionally CH4 and VOC) dissolved in water. The system is based on the principle of a dynamic equilibrium between water and the air as the host gas. The amount of CO2 in the circulating gas phase is measured by the IR spectrometer, and it increases with time until it reaches the value corresponding to that at complete equilibrium with CO2 in water: PCO2(gas) PCO2(water). The concentration of CO2 is automatically measured in the air inside the chamber both before and after each re-equilibration cycle. The values of CO2 reached at the end of the equilibration time (about 20 min) represent the partial pressures of the CO2 in the natural system being studied at the measured water temperature.
A multiparameter water probe is used to measure other water parameters directly at the source. The system for extraction of the water sample from the source (spring, well, etc.) is customized on the installation site characteristics and on the customer requests.
The unit is powered by a battery recharged by solar modules. This is a completely automatic station which performs the measurements cycle, acquires and stores the data on a non-volatile memory. By means of a telemetry system the data can be transferred to receiving centre using the optimal telemetry system (Spread spectrum radio, satellite, 3G/4G mobile network).
The parameters measured by the system are:
- Dissolved carbon dioxide concentration
- (Optionally) Dissolved methane concentration
- (Optionally) Dissolved VOC concentration
- Water pH and temperature
- Water conductivity
Other parameters are available upon request.
Field of application
The main applications are:
- In volcanology, to understand the dynamics of volcanoes and for a global evaluation of the hazard connected with volcanic activity;
- Monitoring of geothermal areas.