Composition and origin of lipid biomarkers in the surface sediments from the southern Challenger Deep, Mariana Trench  

作　　者：Hongxiang Guan Linying Chen Min Luo Lihua Liu Shengyi Mao Huangmin Ge Mei Zhang Jiasong Fang Duofu Chen 

机构地区：[1]Key Laboratory of Gas Hydrate, Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences [2]Laboratory for Marine Geology, Qingdao National Laboratory for Marine Science and Technology [3]Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University

出　　处：《Geoscience Frontiers》2019年第1期351-360,共10页地学前缘（英文版）

基　　金：supported by Qingdao National Labo-ratory for Marine Science and Technology (Grant Nos.QNLM2016ORP0210 and QNLM2016ORP0208); the NSFC (GrantNos. 41473080, 41606091, and 41703077);the Strategic PriorityResearch Program of the Chinese Academy of Sciences (Grant No.XDB06030102);the Shanghai Sailing Program (No.17YF1407800);JF is grateful for the support by the NSFC (Grant Nos.91328208 and 41373071)

摘　　要：The surface sediments collected from the southern Mariana Trench at water depths between ca.4900 m and 7068 m were studied using lipid biomarker analyses to reveal the origin and distribution of organic matters. For all samples, an unresolved complex mixture(UCM) was present in the hydrocarbon fractions, wherein resistant component tricyclic terpanes were detected but C_(27)-C _(29) regular steranes and hopanes indicative of a higher molecular weight range of petroleum were almost absent.This biomarker distribution patterns suggested that the UCM and tricyclic terpanes may be introduced by contamination of diesel fuels or shipping activities and oil seepage elsewhere. The well-developed faults and strike-slip faults in the Mariana subduction zone may serve as passages for the petroleum hydrocarbons. In addition, the relative high contents of even n-alkanes and low Carbon Preference Indices indicated that the n-alkanes were mainly derived from bacteria or algae. For GDGTs, the predominance of GDGT-0 and crenarchaeol, together with low GDGT-0/Crenarchaeol ratios(ranging from0.86 to 1.64), suggests that the GDGTs in samples from the southern Mariana Trench were mainly derived from planktic Thaumarchaeota. However, the high GDGT-0/crenarchaeol ratio(10.5) in sample BC07 suggests that the GDGTs probably were introduced by methanogens in a more anoxic environment. Furthermore, the n-alkanes C_(19)-C_(22) and the n-fatty acids C_(20:0)-C_(22:0) were depleted in^(13)C by 3‰ compared to n-alkanes C_(16)-C_(18) and the n-fatty acids C_(14:0)-C_(18:0), respectively, which was interpreted to result from the preferential reaction of fatty acid fragments with carbon "lighter" terminal carboxyl groups during carbon chain elongation from the precursors to products. The abundance of total alkanes, carboxylic acids, alcohols and total lipids were generally increased along the down-going seaward plate, suggesting the lateral organic matter inputs play an important role in organic matter accumulation in hadal trenches. The extremeThe surface sediments collected from the southern Mariana Trench at water depths between ca.4900 m and 7068 m were studied using lipid biomarker analyses to reveal the origin and distribution of organic matters. For all samples, an unresolved complex mixture(UCM) was present in the hydrocarbon fractions, wherein resistant component tricyclic terpanes were detected but C_(27)-C _(29) regular steranes and hopanes indicative of a higher molecular weight range of petroleum were almost absent.This biomarker distribution patterns suggested that the UCM and tricyclic terpanes may be introduced by contamination of diesel fuels or shipping activities and oil seepage elsewhere. The well-developed faults and strike-slip faults in the Mariana subduction zone may serve as passages for the petroleum hydrocarbons. In addition, the relative high contents of even n-alkanes and low Carbon Preference Indices indicated that the n-alkanes were mainly derived from bacteria or algae. For GDGTs, the predominance of GDGT-0 and crenarchaeol, together with low GDGT-0/Crenarchaeol ratios(ranging from0.86 to 1.64), suggests that the GDGTs in samples from the southern Mariana Trench were mainly derived from planktic Thaumarchaeota. However, the high GDGT-0/crenarchaeol ratio(10.5) in sample BC07 suggests that the GDGTs probably were introduced by methanogens in a more anoxic environment. Furthermore, the n-alkanes C_(19)-C_(22) and the n-fatty acids C_(20:0)-C_(22:0) were depleted in^(13)C by 3‰ compared to n-alkanes C_(16)-C_(18) and the n-fatty acids C_(14:0)-C_(18:0), respectively, which was interpreted to result from the preferential reaction of fatty acid fragments with carbon "lighter" terminal carboxyl groups during carbon chain elongation from the precursors to products. The abundance of total alkanes, carboxylic acids, alcohols and total lipids were generally increased along the down-going seaward plate, suggesting the lateral organic matter inputs play an important role in organic matter accumulation in hadal trenches. The extreme

关 键 词：MARIANA TRENCH LIPID biomarkers Organic matter TOPOGRAPHY Hydrodynamics 

分 类 号：P[天文地球]