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甲烷渗漏及相伴随的甲烷厌氧氧化活动(AOM)能造成孔隙水中多种地球化学参数的异常.本研究开展了冲绳海槽西部陆坡两个站位孔隙水地球化学研究,研究发现两个孔存在甲烷渗漏及相关的地球化学异常,与背景孔相对比,甲烷渗漏A孔和C孔孔隙水存在随深度增加硫酸盐浓度线性梯度亏损、甲烷浓度显著增加和硫化氢浓度增加、总碱度浓度增加等特征,上述异常高值特征指示了两个研究站位A孔与C孔甲烷厌氧氧化的发育,基于硫酸盐浓度线性梯度亏损,利用硫酸盐浓度外推法识别甲烷-硫酸盐界面(SMI)深度分别为4.9和5.4mbsf,该较浅的SMI分布和线性的硫酸盐浓度亏损指示了下伏地层中较强的甲烷通量和强烈的甲烷厌氧氧化.
Methane seepage and accompanying anaerobic methane oxidation (AOM) can cause abnormalities in many geochemical parameters of pore water.In this study, the geochemical study of pore water at two stations in the western slope of the Okinawa Trough was carried out. It was found that two Methane leakage and related geochemical anomalies exist in the pores. Compared with the background pores, there is a linear gradient loss of methane concentration in pore A and pore C of methane leakage with increasing depth, the concentration of methane increases significantly and the concentration of hydrogen sulfide increases Alkalinity and other characteristics of the increase, the above abnormal high value characteristics indicate the two research stations A and C hole methane anaerobic oxidation development, based on a linear gradient loss of sulfate concentration, the use of sulfate concentration extrapolation to identify methane - sulfuric acid The salt interface (SMI) depths are 4.9 and 5.4 mbsf, respectively. This shallow SMI distribution and linear sulfate concentration depletion indicate strong methane flux and strong methane anaerobic oxidation in the underlying formation.