Methane cycling in Arctic shelf water and its relationship with phytoplankton biomass and DMSP
Methane cycling in Arctic shelf water and its relationship with phytoplankton biomass and DMSP
复制标题
DOI：
10.1016/j.marchem.2007.12.003
复制
发表时间：
2008-02-16
期刊：
影响因子：
3
通讯作者：
Dieckmann, G.
中科院分区：
文献类型：
--
作者：
Damm, E.;Kiene, R. P.;Dieckmann, G.
甲烷原位生产经常发生在含氧的上层海洋中。形成甲烷的主要途径是甲基营养产甲烷作用，而重要的甲基化底物是海洋浮游植物产生的DMSP（二甲基磺基丙酸）。在这里，我们报告了夏季浮游植物大量繁殖期间的原位甲烷产生/消耗周期，以及与极地陆架地区 Storfjorden（斯瓦尔巴群岛）DMSP 浓度的潜在联系。该研究基于 2005 年 8 月对 Delta C-13(CH4) 值、甲烷、叶绿素-a、颗粒物和溶解的 DMSP 浓度以及沿四个横断面的水温和盐度的测量。夏季，淡水的输入在 Storfjorden 形成了稳定的表层，在其下方发现了更致密的地下层。在水体中检测到相对于大气平衡浓度（约 3.5 nM）的甲烷过剩（5 至 55 nM），并且溶解甲烷（-52 至 -24 份千分之 PDB）的碳同位素特征与大气甲烷（-47 千分之 PDB）的碳同位素特征存在偏差。在地表水和地下水中观察到的甲烷羽流彼此不同，表明它们是独立产生的。夏季的地下水含有冬季沉积物中释放的甲烷，并随着时间的推移而氧化，留下富含 C-13 的残留甲烷。另一方面，地表水中含有最近产生的 13 C 贫化甲烷。我们认为甲烷的原位产生发生在夏季浮游植物大量繁殖期间。甲烷浓度增加到某个阈值，超过该阈值开始消耗甲烷。建立了甲烷产生-清除循环，这反映在变化的甲烷浓度和δ C-13(CH4) 值中。 DMSP 和甲烷呈负相关，表明 DMSP 可能是甲基营养型产甲烷作用的潜在底物。 (c) 2007 Elsevier B.V. 保留所有权利。
Methane in situ production occurs frequently in the oxygenated upper ocean. A principal pathway by which methane can be formed is methylotrophic methanogenesis, while an important methylated substrate is DMSP (dimethylsulfoniopropionate) produced by marine phytoplankton. Here we report on an in situ methane production/consumption cycle during a summer phytoplankton bloom and a potential link to DMSP concentration in Storfjorden (Svalbard Archipelago) - a polar shelf region. The study is based on measurements of delta C-13(CH4) values, concentrations of methane, chlorophyll-a, particulate and dissolved DMSP, as well as water temperature and salinity along four transects in August 2005. Freshwater input creates a stable surface layer in Storfjorden during summer, below which a denser subsurface layer is found. A methane surplus (between 5 and 55 nM) in relation to the atmospheric equilibrium concentration (about 3.5 nM) is detected in the water column and the carbon isotopic signatures of dissolved methane (-52 to -24 parts per thousand PDB) deviate from those of atmospheric methane (-47 parts per thousand PDB). The methane plumes observed in the surface and subsurface water differed from each other, suggesting that they are generated independently. The subsurface water in summertime contained methane that was released from sediments during winter, and oxidized over time, leaving the residual methane C-13-enriched. The surface water, on the other hand, contained recently produced, 13 C-depleted methane. We propose that methane in situ production occurs during the summer phytoplankton bloom. The concentration of methane increases up to a certain threshold value, above which methane consumption begins. A methane production-removal cycle is established, which is reflected in the varying methane concentrations and delta C-13(CH4) values. DMSP and methane are inversely correlated suggesting that DMSP could be a potential substrate for the methylotrophic methanogenesis. (c) 2007 Elsevier B.V. All rights reserved.