Photochemical Production and Biological Consumption of CO in the SML of Temperate Coastal Waters and Their Implications for Air‐Sea CO Exchange
Photochemical Production and Biological Consumption of CO in the SML of Temperate Coastal Waters and Their Implications for Air‐Sea CO Exchange
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DOI：
10.1029/2019jc015505
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发表时间：
2020-04
影响因子：
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通讯作者：
Youta Sugai;K. Tsuchiya;S. Shimode;T. Toda
中科院分区：
文献类型：
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作者：
Youta Sugai;K. Tsuchiya;S. Shimode;T. Toda
海表面微层位于海-气界面，位于海-气界面，通过海-气交换在全球生物地球化学循环和气候变化中起着关键作用，位于海洋水柱最上层，小于1 000μm。为了阐明SML中一氧化碳(CO)动力学的意义，在大气-海洋CO交换中，预计有活跃的光化学和生物过程，研究了温和沿海水域SML中CO的产生和消费及其海-气排放。从春季到秋季，光归一化CO的产生速率相对较高(中位数：2.57nM[kWh m−2]−1)，而发色溶解有机物的吸光度相对较高(0.55nM−1)。在水温较高时期(22.3C±22.7C)，生物CO消耗速率常数从春季到秋季表现出较高的数值(平均值为0.060±0.010−1)。计算的海-气CO通量(F)与次表层水中CO浓度的变化规律相似。对SML中CO的产生、消耗和海-气排放的比较表明，在全年的海-气CO交换中，SML中的生物消耗可以忽略不计，而SML中的光化学产生在夏季强光、活跃的生物生产和弱风条件下增强。此外，海水变暖实验发现，从春季到秋季，水温升高对生物CO消耗的刺激有趋势，这表明对全球变暖的负反馈但不显著。
The sea surface microlayer (SML), less than 1,000‐μm uppermost layer of the ocean water column, is located at the air‐sea interface and plays critical roles in global biogeochemical cycles and climate change through air‐sea gas exchange. To clarify the significance of the dynamics of carbon monoxide (CO) in the SML, where active photochemical and biological processes are expected, in air‐sea CO exchange, the production and consumption of CO in the SML and its sea‐air emission were investigated in temperate coastal waters. In the SML, the light‐normalized photochemical CO production rate was relatively high from spring to autumn (median: 2.57 nM [kWh m−2]−1) when relatively high absorbance of chromophoric dissolved organic matter (0.55 m−1) was observed. Biological CO consumption rate constant in the SML showed relatively high values from spring to autumn (mean ± standard deviation: 0.060 ± 0.010 h−1) during the period of relatively high water temperature (22.3 ± 2.7 °C). The calculated sea‐air CO flux (F) varied similarly to CO concentration in the subsurface water. Comparison among the production, consumption, and sea‐air emission of CO in the SML suggests that biological consumption in the SML can be ignored in air‐sea CO exchange throughout the year whereas photochemical production in the SML enhancesFduring summer under intense light, active biological production, and weak wind conditions. Further, seawater warming experiments found the tendency of the stimulation of biological CO consumption by water temperature increase from spring to autumn, which suggests negative but insignificant feedback on global warming.