Detection of methane plumes in the water column of Logatchev hydrothermal vent field,Mid-Atlantic Ridge |
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摘 要: | During DY105-17 cruise onboard the R/V "Da Yang Yi Hao" in 2005,methane concentrations in the wa-ter column above Logachev hydrothermal vent field were measured by applying stripping/trapping-gas chromatographic (GC) and the distinct methane plumes were detected. Results show that the back-ground methane concentration within the Logachev area is from 1.05 nmol/L to 1.68 nmol/L,signifi-cantly higher than the background level of the Atlantic abyssal plain of 0.4―0.5 nmol/L,suggesting that hydrothermal venting is a major source of dissolved methane to the ocean. The highest anomalies of methane concentrations in the water column range from 7.14 nmol/L to 113.9 nmol/L and occur just at 180―500 m above the seafloor. The distribution of methane concentration and the structural charac-teristics of hydrothermal plumes are strongly influenced by the supply of underlying hydrothermal fluids,the mixing process of ocean bottom currents and the microbial oxidation. Furthermore,the dif-ferences in distribution of methane plume between the station MAR-CTD3 and the other stations indi-cate a probable unknown hydrothermal vent site nearby. There occurs high concentration of methane along with temperature and nephelometry anomalies,which strongly confirms that the subtle meas-urement of methane concentration in water column is one of the effective ways to locate active sites of hydrothermal venting.
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Detection of methane plumes in the water column of Logatchev hydrothermal vent field, Mid-Atlantic Ridge |
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Abstract: | |
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Keywords: | Logachev vent field hydrothermal plume methane concentration anomalies |
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