| Summary: | 依托2010年夏季中国第四次北极科学考察,通过对高纬度极地冰下水和冰芯的营养盐的连续观测及表层水颗粒物的藻类色素分析,获取了夏季快速融冰下冰水界面营养盐和光合色素的分布信息.结果表明调查期问表层水磷酸盐和硅酸盐相对于无机氮更丰富(依据Redfield比值),表现为显著的氮限制.而冰芯无机氮浓度相对更高,融冰释放对水体无机氮有一定的补充.色素分析显示岩藻黄素(Fuco)和叶绿素α(Chl α)是水体颗粒物的主要光合色素.在8月15日-8月18日期间,叶绿素c(Clc),硅藻黄素(Diato),硅甲藻黄素(Diadino)和岩藻黄素(Fuco)分别达到6,22,73和922 μg·m-3,体现了硅藻在群落中的优势地位.岩藻黄素(Fuco)的浓度在融冰快速期间有巨大的提升,主要来源于冰芯底部释放的衰老的冰生硅藻和浮游硅藻的生长.此外,青绿黄素(Prasino)和叶黄素(Lut)与岩藻黄素(Fuco)分布模式有明显的差异,暗示青绿藻和绿藻与硅藻对海冰融化的不同响应.During the fourth Chinese National Arctic Research Expedition cruise in summer 2010, a time-series observation was carried out to examine the response of nutrients and phytoplankton community in the ice-water interface to the ice melting ice in the central Arctic Ocean. Phosphate and silicate in the ice-water interface were rich relative to dissolved inorganic nitrogen (DIN), based on the Redfield ratio (16N:1P:16Si), suggesting that DIN was the potential limiting nutrient. DIN concentrations in the sea ice were about 3-4 times that in the surface seawater, indicating that melting ice delivered DIN to the surface water. Pigment analysis showed that fucoxanthin and chlorophyll a contribute to carotenoids and chlorophylls in particles. The mean concentrations of chlorophyll c, diatoxanthin, diadinoxanthin and fucoxanthin from 15 August to 18 August were 6 µg.m-3, 22µg.m-3, 73µg.m-3 and 922µg.m-3, respectively, suggesting that diatoms dominated in the phytoplankton community composition. Furthermore, a notable enhancement in fucoxanthin and chlorophyll a during a large-scale ice melting was likely attributed to senescent diatoms released from the bottom sea-ice as well as phytoplankton diatoms growth in the water column due to the input of nutrients (i.e., DIN) and reducing light limitation from melting ice. Temporal distribution patterns of prasinoxanthin and lutein differed from fucoxanthin, indicating that the response of green algae and diatoms to ice melting were different.
|
|---|