Microplastics (MPs) are important exempla of the Anthropocene and are exerting an increasing impact on Earth’s carbon cycle. The huge imbalance between the MPs floating on the marine surface and those that are estimated to have been introduced into the ocean necessitates a detailed assessment of marine MP sinks. Here, we demonstrate that cold seep sediments, which are characterized by methane fluid seepage and a chemosynthetic ecosystem, effectively capture and accommodate small-scale (< 100 μm) MPs, with 16 types of MPs being detected. The abundance of MPs in the surface of the sediment is higher in methane-seepage locations than in non-seepage areas. Methane seepage is beneficial to the accumulation, fragmentation, increased diversity, and aging of MPs. In turn, the rough surfaces of MPs contribute to the sequestration of the electron acceptor ferric oxide, which is associated with the anaerobic oxidation of methane (AOM). The efficiency of the AOM determines whether the seeping methane (which has a greenhouse effect 83 times greater than that of CO over a 20-year period) can enter the atmosphere, which is important to the global methane cycle, since the deep-sea environment is regarded as the largest methane reservoir associated with natural gas hydrates.

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深海环境中微塑料与甲烷渗漏的相互作用

微塑料（MP）是人类世的重要典范，对地球碳循环的影响越来越大。漂浮在海洋表面的 MP 与估计被引入海洋的 MP 之间存在巨大的不平衡，因此需要对海洋 MP 汇进行详细评估。在这里，我们证明以甲烷流体渗流和化学合成生态系统为特征的冷泉沉积物可以有效捕获和容纳小规模（< 100 μm）的MP，并检测到16种MP。甲烷渗漏区域沉积物表面的MPs丰度高于非渗漏区域。甲烷渗流有利于MP的积累、破碎、多样性增加和老化。反过来，MP 的粗糙表面有助于电子受体氧化铁的螯合，这与甲烷的厌氧氧化 (AOM) 相关。AOM的效率决定了渗出的甲烷（其20年的温室效应是CO的83倍）能否进入大气，这对全球甲烷循环非常重要，因为深海环境被认为是最大的与天然气水合物相关的甲烷储层。