Wavelet Processing On The In-situ Observation Data From A Seafloor Hydrothermal Area In The East Pacific Rise

The discovery of hydrothermal activity is another milestone after that established the theory of plate tectonics in geosciences. The activity and result of hydrotherm are excellent window which people study and understand various kinds effection of geology , geophysics , geochemical and subsurface biosphere within the earth. At present, it was generally thought that hydrothermal system and extreme biological phenomena are the combination of organic world and inorganic, and be of best target to study interactions of sphere layers, geosphere, biosphere, hydrosphere and etc.Manufactured various kinds of survey electrode which can work in hydrothermal environment seems extremely important to hydrothermal research. In our job, we try to manufacture a dissolved H₂S electrochemical sensor. The speed of response and sensitivity which we newly developed the Ag/Ag₂S working electrode are obviously superior to the traditional electrode, and the measured lower limit degree of dissloved sulphurated hydrogen expands from 10^-5 M to 10^-7M in seawater. It still has better low-temperature performance and longer lifetime. Temperature has a little effect on response signal of Ag/Ag2S electrode, and temperature need not correct within the range of 0～100℃centigrade.The independently manufactured sensor participated in AT7-11 voyage that USA NSF organizes in Feb. 2004, laid in seafloor hydrothermal location by "Alvin" manned deep-submergence vehicle in EPR9°50'N, which depth is of 2513 meters. The sensor has continuously worked in 12 days in seafloor, and collects hundreds of thousands of data. The measuring data shows that the seawater temperature range of hydrothermal area changes between 5.3℃～21.0℃, and the dissolved sulfureted hydrogen concentration between 0.6～18.3μmol/L, which is consistent with the test result received by other methods on the order of magnitude. The change of temperature and sulfureted hydrogen concentration shows certain periodicity.After EPR9°50'N seafloor hydrothermal in situ observation data processed with complex Morlet wavelet, we found that both temperature and sulphurated hydrogen concentration have periods of different time spaning, which obtains 13-hours(quasi-half-day-periods), 43 hours(quasi-two-days-periods) and 30 hours(quasi-mixed-periods). The sulphurated hydrogen concentration period is slightly longer than the temperature period, but the types are consistent with. The period of temperature and dissolved sulphurated hydrogen concentration after wavelet processed, is basically consistent with the one Tivey et al (2002) observes hydrothermal diffuse flow on the time span in the Juan de Fuca Ridge. This area indicative periodicity of hydrothermal activity, is likely indicated the fact that bottom currents influence by tide function. Periodic tidally function influences mixed proportion of the hydrotherm and bottom currents, and temperature and component of diffuse flow also change periodically.