Rapid sea-ice retreat in the Arctic Ocean can promote the release of methane (CH₄) from microbe and from sediment on the continental shelf. The released methane can be the cause or effect of strong climate feedback. Nevertheless, few observations have been reported of temporal changes of dissolved CH₄ in the Arctic Ocean, especially in western coastal shelf areas (Chukchi Sea and Bering Strait). This study therefore describes the spatial and temporal distributions of the concentrations and stable carbon isotope ratios (δ¹³C value) of CH₄ in the western Arctic Ocean during August–October in 2012 and 2013. In both years, surface water was supersaturated with CH₄ with respect to the atmosphere, but concentrations in 2013 were 2–3 times higher than in 2012. In 2012, the concentrations in the bottom layer were higher (up to 55.9 nmol kg⁻¹), whereas δ¹³C values were lower (down to −63.8‰) than in the surface layer, indicating that CH₄ was produced mainly by organic matter degradation in seafloor sediment via methanogens. In 2013, however, because of stronger vertical mixing than in 2012, vertical gradients of CH₄ concentration and δ¹³C value were not prominent. Short-term (19 days) time series observations were also conducted at a fixed station in 2013. An episodic high CH₄ concentration in the surface layer (17.2 nmol kg⁻¹ with δ¹³C = −52.9‰) observed after a strong wind event suggests that CH₄ production is accelerated because nutrients are supplied from the bottom of the mixed layer increase plankton activity. These findings suggest that the dynamic variation of dissolved CH₄ in the Chukchi Sea in autumn 2012 and 2013 depended mainly on the strength of stratification by sea-ice melt water. Strong winds increase biological activity in the surface layer, consequently accelerating CH₄ production.

北冰洋海冰快速退缩可促进微生物和大陆架沉积物中甲烷（CH _{4 ）的释放。}释放的甲烷可能是强烈气候反馈的原因或影响。然而，很少有关于北冰洋溶解 CH ₄随时间变化的观测报告，特别是在西部沿海大陆架地区（楚科奇海和白令海峡）。因此，本研究描述了2012 年 8 月至 2013 年 8 月至 10 月期间北冰洋西部CH _{4浓度和稳定碳同位素比（δ} ¹³ C 值）的时空分布。在这两年中，地表水都被 CH 过饱和₄相对于大气而言，但 2013 年的浓度是 2012 年的 2-3 倍。2012 年，底层的浓度较高（高达 55.9 nmol kg ^-1），而 δ ¹³ C 值较低（下降到-63.8‰），表明CH ₄主要是通过产甲烷菌降解海底沉积物中的有机物产生的。而2013年由于垂直混合比2012年更强，CH ₄浓度和δ ¹³ C值的垂直梯度不明显。2013 年还在一个固定站进行了短期（19 天）时间序列观测。表层CH _{4浓度偶发性高（17.2 nmol kg} ^-1δ ¹³ C = -52.9‰) 在强风事件后观察到表明 CH ₄的产生加速了，因为从混合层底部提供的养分增加了浮游生物的活动。这些发现表明，2012年和2013年秋季楚科奇海溶解CH ₄的动态变化主要取决于海冰融水的分层强度。强风增加了表层的生物活性，从而加速了 CH ₄的产生。