Nearshore environments are typically supersaturated with the potent greenhouse gases methane and carbon dioxide, due to intense remineralization of the elevated supply of organic carbon in these systems. These environments are characterized by overlapping biogeochemical gradients and heterogeneous morphology, and the overall spatial variability in nearshore greenhouse gas concentrations remains unclear. We measured surface water partial pressures of carbon dioxide and methane synoptically with water quality parameters in the coastal Baltic Sea, covering two ice-free seasons. The high-frequency flow-through data revealed sites with recurring very high partial pressures of carbon dioxide and methane (i.e., hot spots) scattered around the 50 km × 40 km study area, exceeding overall partial pressure averages by 455 μatm (CH₄) and 2396 μatm (CO₂). High partial pressures were linked with elevated inputs of allochthonous and autochthonous organic matter, underpinning the major role of organic enrichment of coastal environments in global carbon cycling.

中文翻译：

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沿海近岸环境中持续存在的二氧化碳和甲烷热点

由于这些系统中有机碳供应量增加的强烈再矿化，近岸环境通常被强效温室气体甲烷和二氧化碳过饱和。这些环境的特点是生物地球化学梯度重叠和形态异质，近岸温室气体浓度的总体空间变异性仍不清楚。我们对波罗的海沿海的地表水二氧化碳和甲烷分压以及水质参数进行了天气参数测量，覆盖了两个无冰季节。高频流量数据揭示了在 50 km × 40 km 研究区域周围散布着反复出现的极高二氧化碳和甲烷分压（即热点）的地点，超过总体分压平均值 455 μ  atm (CH ₄ ) 和 2396  μ atm (CO ₂ )。高分压与外来和本地有机质输入的增加有关，支撑了沿海环境有机富集在全球碳循环中的主要作用。