南海东沙海域甲烷渗漏活动对不同Fe组分和P形态组成的影响  

Methane seepage impacts the compositions of different iron speciations and phosphorus fractions in the Dongsha area of the South China Sea

作　　者：胡钰[1,2] 刘春阳 陈庆王 陈琳莹 冯东 HU Yu;LIU Chunyang;CHEN Qingwang;CHEN Linying;FENG Dong(Shanghai Engineering Research Center of Hadal Science and Technology,College of Marine Sciences,Shanghai Ocean University,Shanghai 201306,China;Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou),Guangzhou 511458,Guangdong,China)

机构地区：[1]上海海洋大学海洋科学学院上海深渊科学工程技术研究中心,上海201306 [2]南方海洋科学与工程广东省实验室(广州),广东广州511458

出　　处：《地球化学》2023年第4期439-447,共9页Geochimica

基　　金：国家自然科学基金项目(41730528、91858208、41606048);南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0506);上海市浦江人才计划项目(21PJ1404700)联合资助。

摘　　要：大陆边缘海底广泛发育甲烷渗漏活动,可以显著改变区域甚至全球海洋C、S循环,潜在影响深部生物圈的Fe、P等循环过程。然而目前对甲烷渗漏活动影响Fe-P耦合特征以及P循环的程度了解有限。本研究选取南海东沙海域发育甲烷渗漏活动的冷泉站位和临近不发育甲烷渗漏活动的背景站位,分析采集的柱状沉积物中不同Fe组分和P形态组成。2个站位对比结果显示,甲烷渗漏活动促使易还原的铁氧化物和磁铁矿含量减少,导致可还原的铁氧化物增多,同时引起铁氧化物吸附的P和自生P含量明显增加。因此,甲烷渗漏活动会显著地影响沉积物中铁氧化物的形成,进一步影响铁氧化物吸附磷酸盐的丰度,有利于磷灰石等自生磷酸盐沉积。这种不同形态Fe和P对甲烷渗漏活动的响应模式在大陆边缘环境可能普遍存在,影响该环境中Fe、P循环和最终的P埋藏。Methane seepages occur widely on the seafloor and/or in marine sediments along continental margins,affecting submarine carbon and sulfur cycling on regional or global scales and potentially influencing iron and phosphorus cycling in the deep biosphere.However,the coupling mechanism between iron,phosphorus,and phosphorus cycling influenced by methane seepages in marine sediments remains unelucidated.Here,we analyzed different iron speciation and phosphorus fractions of sediment cores collected at a seep-impacted site and a nearby background site(not subject to seepage influence)from the Dongsha area of the South China Sea.Comparing the two sites revealed a decrease in easily reducible iron oxides and magnetite and an increase in reducible iron oxides,iron oxide-bound phosphorus,and authigenic phosphorus-induced by the methane seepage.Therefore,the methane seepage influenced iron oxide and associated phosphorus formation and distribution,facilitating authigenic phosphorus precipitation such as apatite.This pattern of different iron and phosphorus fractions due to seepages might prevail in methane seepage environments on the continental margins,impacting iron and phosphorus cycling and phosphorus burial in such environments.

关 键 词：甲烷渗漏 甲烷厌氧氧化 自生沉积 P形态 Fe组分 南海 

分 类 号：P67[天文地球—海洋地质]