Study on Dimethylsulfide production by phytoplankton based on time-serial observations in the Antarctic Ocean

二甲基硫化物(DMS)是海洋中含量最丰富的挥发性硫。根据爪子假说(Charlson et al.1987年)，海洋DMS的生产可通过涉及表层海洋温度、浮游植物、DMS、硫酸盐气溶胶形成和云反照率的反馈循环作为气候调节机制，尽管这种反馈的存在尚未得到证实。最近，人们的注意力集中在评估海洋中DMS的汇和来源以及控制海洋环境中DMS循环的过程上。二甲基磺酸丙酯(DMSP)是一种由多种浮游植物合成的有机化合物，在酶作用下产生DMS。根据2002/03、2003/04和2004/05三个南半球夏季的时间序列观测资料，研究了夏季生物过程对南极海洋DMS动态的影响。本研究收集的实地数据是2005年综合的。目前的结果表明，南极磷虾作为南极海洋的优势食草型大型浮游动物，草率取食是产生DMS和溶解DMSP的更可能的机制。此外，生长阶段似乎与硅藻产生DMSP有关。这可能导致在自然条件下硅藻水华早期观察到的低浓度溶解DMSP。由于生物生产的这些过程以及DMS和DMSP的生产似乎受到海冰分布变化的影响，因此必须进行进一步的研究，以全面了解全球环境变化。

Dimethylsulfide (DMS) is the most abundant form of volatile sulfur in the ocean. According to the CLAW hypothesis (Charlson et al. 1987), marine DMS production may act as a climate regulatory mechanism via a feedback loop involving surface ocean temperature, phytoplankton, DMS, sulfate aerosol formation, and cloud albedo, although the existence of this feedback has not been proven. Recently, attention has been focused on assessing sinks and sources of DMS in the oceans and on the processes controlling the cycling of DMS in the marine environment. DMS is produced by the enzymatic cleavage of dimethylsulfoniopropionate (DMSP), an organic compound synthesized by many phytoplankton species. The objective of this study was to determine the influence of biological processes on DMS dynamics in the Antarctic Ocean during the summertime, based on the time-serial observations in the austral summers of 2002/03, 2003/04, and 2004/05. The field data collected in the present study was synthesized in 2005. The present results show that sloppy feeding by Antarctic krill, which is the dominant herbivorousis macrozooplankton of the Antarctic Ocean, a more likely mechanism for producing DMS and dissolved DMSP. Moreover growth phase seems to be related DMSP production by diatoms. This may result in the low concentrations of dissolved DMSP observed in the early stage of diatom blooms under natural conditions. Since these processes on biological production as well as DMS and DMSP production are seem to be affected by variations of sea ice distribution, further study must be required to fully understand the global environment change.