Distributions of short-lived iodocarbons and biogenic trace gases in the open ocean and atmosphere in the western North Pacific
Distributions of short-lived iodocarbons and biogenic trace gases in the open ocean and atmosphere in the western North Pacific
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DOI：
10.1016/j.marchem.2009.12.001
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发表时间：
2010-02
期刊：
影响因子：
3
通讯作者：
M. Kurihara;M. Kimura;Yoko Iwamoto;Y. Narita;A. Ooki;Y.-J. Eum;A. Tsuda;Koji Suzuki;Y. Tani-Y.-T
中科院分区：
文献类型：
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作者：
M. Kurihara;M. Kimura;Yoko Iwamoto;Y. Narita;A. Ooki;Y.-J. Eum;A. Tsuda;Koji Suzuki;Y. Tani-Y.-T
生物成因的微量气体，特别是对大气化学很重要的卤甲烷，从海洋中释放出来，并将卤素带到对流层和平流层。2007年春季，在北太平洋西部（37-43°N, 143-146°E）测量了海水中10种卤代烃和异戊二烯的浓度。基于对这些物种的大气和海洋测量，还估计了CH3Cl、CH3Br、CH2ClI和ch2i2的海洋空气通量。温度-盐度散点图分析将采样站划分为好潮地区、津潮暖流地区和黑潮地区。水柱（5-100m）中气体的平均（范围）浓度为114 (56-150)pmolL−1CH3Cl, 6.9 (4.1-19.4) pmolL−1CH3Br, 1.7 (0.7-2.9) pmolL−1CH3I, 1.9 (0.9-4.1) pmolL−1chbrcl, 4.8 (3.2-8.1) pmolL−1chbr2, 1.0 (0.6-1.8) pmolL−1CHBr2Cl, 1.2 (0.7-2.0) pmolL−1CHBr2Cl, 10.8 (4.7-24.5) pmolL−1CHBr3, 1.7 (0.7-5.4) pmolL−1CHBr3, 3.0 (< 0.1-22.2) pmolL−1chi2和19.7 (3.8-68.2)pmolL−1chi2异戊二烯。异戊二烯的最大浓度出现在本研究中发现的异戊二烯的浓度最高的Oyashio地区，该地区叶绿素a的浓度最高（最大值为2.94µgL−1）。然而，CH3Br、CH2ClI和ch2i2的峰值出现在津garu暖流区，叶绿素a浓度不高（最大值为0.65µgL−1）。叶绿素a大小分馏结果表明，在以微型浮游植物为主的站点中，卤甲烷的含量较高。这些结果表明微浮游生物作为卤化碳生产的可能来源的重要性。叶绿素b、prasinoxanthin与CH2I2（r2=0.69、r2=0.71）、CH2ClI （r2=0.87、r2=0.77）呈显著正相关。这些结果表明，一些葡萄属植物可能参与了ch2i2和CH2ClI的产生。其他化合物在海水中的垂直剖面上没有峰。在深度剖面上，CH2ClI的峰位于CH2I2的峰之上；这些剖面表明，光化学反应可以从海水中的ch2i2生成CH2ClI。空气中CH3Cl、CH3Br和CH2ClI的平均混合比和范围分别为548（524-609）、12.1（8.6-19.0）和0.27 (0.03-0.90)pptv。大气中未检测到ch2i2 （<1pptv）。各站CH3Br饱和度异常均为正（海温变化范围为1.7 ~ 19℃）。CH2ClI在海水中浓度最高的站点附近也观察到CH2ClI在空气中的混合比最高；CH2ClI和ch2i2的海气通量分别为3.8和1.6nmolm−2day−1。这些结果表明，海水中CH2ClI和ch2i2的产生是遥远大气中有机碘化合物的重要来源。
Biogenic trace gases, especially halomethanes, which are important with respect to atmospheric chemistry, are released from the ocean and carry halogens to the troposphere and stratosphere. The concentrations of 10 halocarbons and isoprene in seawater were measured during the spring of 2007 in the western North Pacific Ocean (37–43° N, 143–146° E). Sea–air fluxes of CH3Cl, CH3Br, CH2ClI, and CH2I2were also estimated based upon the atmospheric as well as oceanic measurement of these species. Temperature–salinity scatter diagram analyses divided the sampling stations into the Oyashio region, Tsugaru warm current region, and Kuroshio region. Mean (range) concentrations of the gases in the water columns (5–100m) were 114 (56–150) pmolL−1CH3Cl, 6.9 (4.1–19.4) pmolL−1CH3Br, 1.7 (0.7–2.9) pmolL−1CH3I, 1.9 (0.9–4.1) pmolL−1CH2BrCl, 4.8 (3.2–8.1) pmolL−1CH2Br2, 1.0 (0.6–1.8) pmolL−1CHBrCl2, 1.2 (0.7–2.0) pmolL−1CHBr2Cl, 10.8 (4.7–24.5) pmolL−1CHBr3, 1.7 (0.7–5.4) pmolL−1CH2ClI, 3.0 (<0.1–22.2) pmolL−1CH2I2, and 19.7 (3.8–68.2) pmolL−1isoprene. The maximum concentration of isoprene was observed in the Oyashio region, where concentrations of chlorophyll a (maximum: 2.94µgL−1) were highest in the present study. However, the peaks of CH3Br, CH2ClI, and CH2I2were observed in the Tsugaru warm current region, where concentrations of chlorophyll a were not as high (maximum: 0.65µgL−1). The results of chlorophyll a size fractionation showed a high occurrence of halomethanes in the stations dominated by pico-sized phytoplankton. These results indicate the importance of picoplankton as a possible source of halocarbon production. Chlorophyll b and prasinoxanthin had a statistically significant positive correlation with CH2I2(r2=0.69 and r2=0.71, respectively) and with CH2ClI (r2=0.87 and r2=0.77, respectively). These results suggest that some species of prasinophytes might contribute to CH2I2and CH2ClI production. For other compounds, there was no peak in the vertical profile in seawater. In the depth profiles, the peak of CH2ClI was observed above the peak of CH2I2; these profiles suggest that a photochemical reaction could yield CH2ClI from CH2I2in seawater. The mean mixing ratio and range of CH3Cl, CH3Br, and CH2ClI in the air were measured as 548 (524–609), 12.1 (8.6–19.0), and 0.27 (0.03–0.90) pptv, respectively. CH2I2was not detected in the atmosphere (<1pptv). The saturation anomaly of CH3Br was positive at all stations (the sea surface temperature varied from 1.7°C to 19°C). The highest mixing ratio of CH2ClI in air was also observed near the station at which the highest concentration of CH2ClI was observed in seawater; the sea-to-air fluxes of CH2ClI and CH2I2were 3.8 and 1.6nmolm−2day−1, respectively. These results suggest that the production of CH2ClI and CH2I2in seawater is an important source of organic iodine compounds in the remote atmosphere.