Abstract: Fiber optic sensors include sensor regions in which an optical phase is modulated by an analyte to be detected. A long period fiber grating (LPG) is coupled to a coating that is arranged to selectively interact with the analyte. The resulting phase change is detected based on a transmission spectrum associated with the LPG so that analyte is detected and quantified. A plurality of such sensors is distributed along a fiber to form a sensor array that can be situated to detect analyte at a plurality of discrete regions.

Abstract: Fiber optic sensors include sensor regions in which an optical phase is modulated by an analyte to be detected. A long period fiber grating (LPG) is coupled to a coating that is arranged to selectively interact with the analyte. The resulting phase change is detected based on a transmission spectrum associated with the LPG so that analyte is detected and quantified. A plurality of such sensors is distributed along a fiber to form a sensor array that can be situated to detect analyte at a plurality of discrete regions.

Abstract: A method for determining a flux of a gas contained in a medium through a boundary of the medium comprises 1) measuring at least twice with a probe a concentration C of the gas over a time interval ?t and 2) determining the flux of the gas using the following mathematical equation: (I) where F is the gas flux, D is the diffusivity value and ?C is a variation in the gas concentration during the time interval ?t. The probe is placed proximate the boundary. The probe has a gas inlet, a cavity, a gas concentration sensor and a membrane. Each element is in fluid communication with each other so that the gas flows from the gas inlet through the membrane and contacts the gas concentration sensor.

Abstract: A method for determining a flux of a gas contained in a medium through a boundary of the medium comprises 1) measuring at least twice with a probe a concentration C of the gas over a time interval ?t and 2) determining the flux of the gas using the following mathematical equation: (I) where F is the gas flux, D is the diffusivity value and ?C is a variation in the gas concentration during the time interval ?t. The probe is placed proximate the boundary. The probe has a gas inlet, a cavity, a gas concentration sensor and a membrane. Each element is in fluid communication with each other so that the gas flows from the gas inlet through the membrane and contacts the gas concentration sensor.

Abstract: A method of measuring the surface flux of a component of a soil gas comprises placing a chamber for collecting said gas sealably in contact with a soil the chamber initially containing atmospheric gas. Then, the chamber is connected to a purging apparatus to purge the chamber of all measurable traces of the component. Then the soil is permitted to enter the chamber. The method uses a system for measuring the surface flux of the component. The system comprises a chamber having an open bottom for collecting soil gas, a venting port, an exhaust port having a valve and means to purge the chamber of the component.

Abstract: A probe for sampling a soil gas comprising a body having a cavity to which is connected an inlet and an outlet, and a gas permeable waterproof membrane wrapped around the body and sealing the cavity. The membrane allows the soil gas to flow across the membrane from the soil to the cavity. A method for measuring soil gas diffusivity comprising the step of circulating in a closed loop a carrier gas substantially at an atmospheric pressure through a diffusion gas sampling probe inserted in the soil and through a sensor used for the measurement of a concentration of at least a component of the soil gas.

Abstract: A probe for sampling a soil gas comprising a body having a cavity to which is connected an inlet and an outlet, and a gas permeable waterproof membrane wrapped around the body and sealing the cavity. The membrane allows the soil gas to flow across the membrane from the soil to the cavity. A method for measuring soil gas diffusivity comprising the step of circulating in a closed loop a carrier gas substantially at an atmospheric pressure through a diffusion gas sampling probe inserted in the soil and through a sensor used for the measurement of a concentration of at least a component of the soil gas.