东南极夏季中山站邻近固定冰DMS、DMSP分布初探

PRELIMINARY INVESTIGATION OF THE DISTRIBUTION OF DIMETHYLSULFIDE(DMS) AND DIMETHYLSULFONIOPROPIONATE(DMSP) IN COASTAL FAST ICE NEAR ZHONGSHAN STATION OF EAST ANTARCTICA DURING THE AUSTRAL SUMMER

中国第30次南极科学考察期间,在中山站邻近固定冰区采集了两支海冰冰芯并首次分析其中的DMS、DMSP含量。结果表明,两支冰芯上层均含有较高浓度的DMSP+DMS,分别高达114.93及134.41 nmol·L-1。冰芯中DMS、DMSP+DMS浓度随深度的增加而递减。两支冰芯顶部DMSP+DMS高值的成因不同,冰芯1主要受藻类活动影响而产生DMSP+DMS高值,冰芯2主要是由于雪层及薄冰层阻碍,致使DMS在冰芯顶部聚集产生DMS高值。因为海冰底部较高生物量的海冰融化进入水体,所观测的剩余海冰底部Chl a、DMSP+DMS值均较低。在海冰的融化过程中,卤道内的卤水可发生垂向运输,致使冰芯中Chl a、DMSP+DMS的垂直分布有所不同。冰芯的Chl a、DMSP+DMS总量分别为6.79和10.20、51.83和88.41μmol·m-2,与前人研究结果比较,在海冰融化过程中,海冰中Chl a、DMSP+DMS总量变化的总趋势是递减的。

The distribution of dimethylsulfide （DMS） and dimethylsulfoniopropionate （DMSP） in ice cores was analyzed. The cores were drilled from coastal fast ice off Zhongshan Station in East Antarctica during the 30th Chinese National Antarctic Research Expedition. The highest concentrations of DMSP ＋ DMS were 114.93 nmol · L-1 and 134.41 nmol· L-1, observed in the top layer of two ice cores. Both DMS and DMSP ＋ DMS concentrations decreased from the top to bottom of the ice cores. There were two different factors controlling DMSP ＋ DMS in the upper layer of the ice cores; one was related to algal assemblages, and the other was related to DMS accumulation in the slush layer. This DMS accumulation occurs because the ice and snow layer covering the sea ice blocks the emission of DMS into the atmosphere. Concentrations of Chlorophyll a （ Chl a） and DMSP ＋ DMS were low in the bottom of ice cores because the bottom layer of sea ice with high biomass melted during the summer. During the sea ice melting season, gravity-related drainage of brine could alter the vertical distribution of Chl a and DMSP ＋ DMS. The integrated Chl a and DMSP ＋ DMS in ice cores analyzed during the present study （6.79 - 10.20 mg · m-2 and 51.83 - 88.41 μmol · m-2, respectively） were low compared with previous studies, indicating that the melt process could lead to a decline in biomass and DMSP ＋ DMS in ice cores.