Development of an in situ fiber optic Raman system to monitor hydrothermal vents

摘要

The development of a field portable fiber optic Raman system modified from commercially available components that can operate remotely on battery power and withstand the corrosive environment of the hydrothermal vents is discussed.The Raman system is designed for continuous monitoring in the deep-sea environment.A 785 nm diode laser was used in conjunction with a sapphire ball fiber optic Raman probe,single board computer,and a CCD detector.Using the system at ambient conditions the detection limits of SO_4~(2-),CO_3~(2-)and NO_3~- were determined to be approximately 0.11,0.36 and 0.12 g L~(-1)respectively.Mimicking the cold conditions of the sea floor by placing the equipment in a refrigerator yielded slightly worse detection limits of approximately 0.16 g l~(-1)for SO_4~(-2)and 0.20 g l~(-1)for NO_3~-Addition of minerals commonly found in vent fluid plumes also decreased the detection limits to approximately 0.33 and 0.34 g L~(-1)respectively for SO_4~(-2)and NO_3~-.