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

二甲基硫（DMS）是海洋中最丰富的挥发性硫。根据CLAW假说（Charlson et al. 1987），海洋DMS的产生可能作为一种气候调节机制，通过一个涉及海洋表面温度、浮游植物、DMS、硫酸盐气溶胶形成和云反照率的反馈环，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。DMS是由许多浮游植物合成的有机化合物二甲基磺酰丙酸酯（DMSP）的酶裂解产生的。本研究的目的是根据2002/03年、2003/04年和2004/05年南部夏季的时间序列观测，确定生物过程对夏季南极海洋DMS动态的影响。本研究收集的野外资料于2005年进行综合。目前的研究结果表明，南极磷虾是南极海洋主要的食草大型浮游动物，它们的懒散摄食更可能是产生DMS和溶解DMSP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华的早期阶段观察到低浓度的溶解DMSP。由于这些生物生产过程以及DMS和DMSP的生产似乎受到海冰分布变化的影响，因此必须进一步研究以充分了解全球环境变化。

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.