Brominated methane compounds and isoprene in surface seawater of Sagami Bay: Concentrations, fluxes, and relationships with phytoplankton assemblages
Brominated methane compounds and isoprene in surface seawater of Sagami Bay: Concentrations, fluxes, and relationships with phytoplankton assemblages
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DOI：
10.1016/j.marchem.2012.04.001
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发表时间：
2012-04
期刊：
影响因子：
3
通讯作者：
M. Kurihara;Motoko Iseda;T. Ioriya;N. Horimoto;J. Kanda;T. Ishimaru;Y. Yamaguchi;S. Hashimoto
中科院分区：
文献类型：
--
作者：
M. Kurihara;Motoko Iseda;T. Ioriya;N. Horimoto;J. Kanda;T. Ishimaru;Y. Yamaguchi;S. Hashimoto
于2001年4月至12月对相模湾表层水中溴二氯甲烷(CHBrCl2)、氯二溴甲烷(CHBr2Cl)、溴仿(CHBr3)和异戊二烯(Ip2)的浓度以及浮游植物的细胞数进行了测定，以评价它们的生物来源及其对海洋边界层中BR的相对贡献。平均(极差)叶绿素a(Chl.A)4-12月浓度为0.46(0.23-1.0)μg L−1。对细胞体积随时间变化的观察表明，4月、7月和12月的样本中硅藻占优势，6月和9月的样本中甲藻占优势。在5月、8月、10月和11月的样品中，当硅藻不存在时，球藻的数量相对较多。痕量气体的平均浓度分别为7.4pmoL L−1CHBrCl2、8.4pmoL L−1CHBr2Cl3、33.8pmoL L−1CHBr3和7.3pmo1−1异戊二烯。海-气平均通量分别为7.4nmolm−2d−1CHBrCl2、8.7nmolm−2d−1CHBr2Cl、32.2nmolm−2d−1CHBr3和5.9nmolm−2d−1异戊二烯。CHBrCl2与CHBr2Cl2呈显著正相关(r2=0.79，n=48，p<；0.001)。然而，溴仿与CHBrCl2或CHBr2Cl2没有相关性。这些结果表明，CHBrCl2和CHBr2Cl2在表层海水中的生成和去向相似，而CHBr2Cl2和CHBrCl2的生成和去向与CHBr3不同。异戊二烯与Chl呈显著正相关。A浓度(R2=0.49，n=8，p=0.05)。Chl之间无显著相关性。A和任何溴化甲烷(即CHBrCl2、CHBr2Cl和CHBr3)。在本研究中，没有任何个体或群体的浮游植物可以被认为是CHBr3(或CHBrCl2，CHBr2Cl)的来源。因此，这一结果突显了利用Chl估算海水中溴代甲烷产量的难度。数据或浮游植物组合分析以及确定控制溴化甲烷生产的基本因素的必要性。估算了从海洋到大气的短暂溴代甲烷的溴通量：CHBrCl2为7.4nmolBrm−2d−1，CHBr2Cl为17.4nmolBrm−2d−1，CHBr3为96.5nmolBrm−2d−1。BrCHBr3/BrCHBrCl2对海洋边界层中溴的相对贡献率为5.2±0.6(11月)至27±5.5(9月)。我们的结果强调了CHBr3作为海洋大气溴来源的重要性。
Concentrations of bromodichloromethane (CHBrCl2), chlorodibromomethane (CHBr2Cl), bromoform (CHBr3) and isoprene were measured along with cell counts of phytoplankton in the surface waters of Sagami Bay, from April 2001 to December 2001, to evaluate their biological sources and their relative contributions to Br in the marine boundary layer. The mean (range) chlorophyll a (Chl. a) concentrations were 0.46 (0.23–1.0) μg L−1from April to December. Observations of temporal variations in cell volume showed that diatoms were predominant in the April, July, and December samples, and that dinoflagellates were dominant in the June and September samples. In the May, August, October and November samples, coccolithophorids were relatively more abundant when diatoms were absent. The mean concentrations of trace gases were 7.4pmol L−1CHBrCl2, 8.4pmol L−1CHBr2Cl, 33.8pmol L−1CHBr3, and 7.3pmol L−1isoprene. The mean sea-to-air fluxes of trace gases were 7.4nmolm−2d−1CHBrCl2, 8.7nmolm−2d−1CHBr2Cl, 32.2nmolm−2d−1CHBr3, and 5.9nmolm−2d−1isoprene. A significant positive correlation between CHBrCl2and CHBr2Cl was observed in this study (r2=0.79, n=48, p<0.001). Bromoform, however, was not correlated with CHBrCl2or CHBr2Cl. These results suggest that the production and fate of CHBrCl2and CHBr2Cl in the surface seawater were similar, and that the production and fate of CHBr2Cl and CHBrCl2were different from those of CHBr3. A significant positive correlation was observed between the isoprene and Chl. a concentrations (r2=0.49, n=8, p=0.05). No significant correlation was found between Chl. a and any of brominated methanes (i.e., CHBrCl2, CHBr2Cl, and CHBr3). No individual or group of phytoplankton could be attributed as the source of CHBr3(or CHBrCl2, CHBr2Cl) in this study. The results thus highlighted the difficulty of estimating production of brominated methanes in seawater using Chl. a data or phytoplankton assemblage analysis and the necessity of determining the essential factors that control production of brominated methanes. The bromine fluxes of short-lived brominated methanes from the ocean to the atmosphere were estimated at 7.4nmolBrm−2d−1for CHBrCl2, 17.4nmolBrm−2d−1for CHBr2Cl, and 96.5nmolBrm−2d−1for CHBr3. The relative contribution of CHBr3to bromine in the marine boundary layer from surface ocean was calculated to be from 5.2±0.6 (November) to 27±5.5 (September) for BrCHBr3/BrCHBrCl2. Our results underscore the importance of CHBr3as a source of atmospheric bromine from the ocean.