| LI Yuhong,ZHAN Liyang,ZHANG Jiexia,CHEN Liqi. 2015. Equilibrator-based measurements of dissolved methane in the surface ocean using an integrated cavity output laser absorption spectrometer. Acta Oceanologica Sinica, 34(6):34－41 |
| Equilibrator-based measurements of dissolved methane in the surface ocean using an integrated cavity output laser absorption spectrometer |
| 基于水-汽平衡器的离轴积分腔输出光谱法(ICOS)走航观测海水中溶解CH4 |
| Received:May 30, 2014 Revised:September 14, 2014 |
| DOI：10.1007/s13131-015-0685-9 |
| Key words:methane equilibrator off-axis integrated cavity output spectroscopy (ICOS) South Yellow Sea |
| 中文关键词: 溶解CH4 水-汽平衡器 离轴积分腔输出光谱法(ICOS) 南黄海 |
| 基金项目:The Scientific Research Foundation of Third Institute of Oceangraphy under contract No. 2013004; the National Natural Science Foundation of China (NSFC) under contract Nos 40906102 and 41230529; the CHINARE under contract Nos 2012-2013 (01-04-02), (01-02-01) and (03-04-02). |
| Author Name | Affiliation | E-mail | | LI Yuhong | Key Laboratory of Global Change and Marine-Atmospheric Chemistry, State Oceanic Administration, Xiamen 361005, China
Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China | | | ZHAN Liyang | Key Laboratory of Global Change and Marine-Atmospheric Chemistry, State Oceanic Administration, Xiamen 361005, China
Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China | zhanliyang@tio.org.cn | | ZHANG Jiexia | Key Laboratory of Global Change and Marine-Atmospheric Chemistry, State Oceanic Administration, Xiamen 361005, China
Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China | | | CHEN Liqi | Key Laboratory of Global Change and Marine-Atmospheric Chemistry, State Oceanic Administration, Xiamen 361005, China
Third Institute of Oceanography, State Oceanic Administration, Xiamen 361005, China | |
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| Abstract: |
| A new off-axis integrated cavity output spectroscopy (ICOS) is coupled to Weiss equilibrator for continuous highresolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator in freshwater at room temperature is determined via dis-equilibration and re-equilibration experiments. The constant for methane is about 40 min. The system is calibrated using a standard gas of 3.980×10-6, and the precision of the ICOS for methane is 0.07%. This system is equipped onboard to measure the spatial distribution in methane concentrations of South Yellow Sea (SYS) along the cruise track from Shanghai to Qingdao. Result shows that the methane concentration varies from 2.79 to 36.36 nmol/L, reveals a significant pattern of methane source in SYS, and a distinct decreasing trend from south to north. The peak value occurs at the coast area outside mouth of the Changjiang River, likely to be affected by the Changjiang diluted water mass dissolving a large amount of rich in methane. Moreover, all the surface waters are oversaturated, air-to-sea fluxes range from 98.59 to 5 485.35 μmol/(m2·d) (average value (1 169.74±1 398.46) μmol/(m2·d)), indicating a source region for methane to the atmosphere. |
| 中文摘要: |
| 基于水-汽平衡器的离轴积分腔输出光谱法以极高的精度连续观测表层海水中的溶解CH4。本文采用Weiss型水-汽平衡器模拟打破平衡-恢复平衡的实验,得到平衡器对于CH4的平衡时间常数τ约为40 min,选择3.980 ppm的标气进行校正,观测平均值为3.986 ppm,相对标准偏差0.07%,误差0.15%。观测了南黄海航迹线上表层海水中的溶解CH4,浓度范围为2.79-36.36 nmol/L,平均值为9.63±8.85 nmol/L,由南向北海水中溶解CH4浓度逐渐降低,长江口外海域为最高值,可能是受到富含CH4的长江冲淡水的影响,观测到的溶解CH4含量均为过饱和,通量范围为98.59-5485.35 μmol/(m2 d),平均值1169.74±1398.46 μmol/(m2 d),表明南黄海是大气中CH4的源。 |
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