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甲烷厌氧氧化作用(AOM)在调控全球甲烷收支平衡以及缓解因甲烷引起的温室效应等方面扮演着十分重要的角色,成为近些年来海洋生物地球化学领域的研究热点之一。一般而言,海洋沉积物孔隙水硫酸盐还原主要是通过2种反应途径来完成,即氧化有机质途径和AOM途径。长期以来,与有机质氧化途径相关的硫酸盐还原作用研究已有充分展示,而由AOM驱动的硫酸盐还原及其对自生硫化铁形成与埋藏的重要贡献却被严重低估。侧重从生物地球化学、同位素地球化学等角度,综述近些年来不同环境条件下海洋沉积物AOM作用发生的地球化学证据和AOM对沉积物孔隙水硫酸盐消耗比例的贡献大小及其调控因素。AOM过程产生的H2S会与沉积物中活性铁结合形成自生铁硫化物。与沉积物浅表层条件相比,AOM过程固定的自生铁硫化物不容易发生再氧化,更利于在沉积物中埋藏保存起来。AOM与海洋沉积物硫酸盐还原作用相偶联,由AOM驱动的硫酸盐还原过程对海底自生铁硫化物形成与埋藏的重要贡献不容忽视。该综述有助加深对海洋沉积物AOM作用的认识及其对硫循环的全面理解。
Methane anaerobic oxidation (AOM) plays a very important role in regulating the global methane balance and alleviating the greenhouse effect caused by methane, and has become one of the hot topics in the field of marine biogeochemistry in recent years. In general, the sulfate reduction of pore water in marine sediments is accomplished mainly through two reaction pathways, the oxidative organic pathway and the AOM pathway. Sulfate reduction studies related to the organic oxidation pathway have long been well documented, and AOM-driven sulfate reduction and its significant contribution to the formation and burial of native iron sulfide have been seriously underestimated. The emphasis is on the geochemical evidence of AOM action of marine sediments under different environmental conditions in recent years and the contribution of AOM to the proportion of sulfate depletion in pore water of sediment from the aspects of biogeochemistry and isotope geochemistry. H2S produced by the AOM process combines with the active iron in the sediments to form auto-iron sulfides. Compared with the shallow superficial sediment conditions, the self-formed iron sulfide immobilized in the AOM process is not easily reoxidized, which makes it more beneficial to be buried in the sediment. AOM is coupled with the sulfate reduction of marine sediments. The AOM-driven sulfate reduction process can not neglect the important contribution to the formation and burial of seabed self-generating iron sulfides. This review helps deepen understanding of the role of AOM in marine sediments and their full understanding of the sulfur cycle.