The nutrient distributions and characteristics in summer of Kongsfjorden, Arctic----results based on a 10-year observation

Lead Author Zhongqiang, Ji
Institution Contact The Second Institute of Oceanography, SOA, China 36# Baochubei Road, Hangzhou 310012, China
Co-Authors Haiyan Jin, The Second Institute of Oceanography, SOA, China; Shengquan Gao, The Second Institute of Oceanography, SOA, China; Yanpei Zhuang, The Second Institute of Oceanography, SOA, China; Jianfang Chen, The Second Institute of Oceanography, SOA, China;
Theme Theme 1: Vulnerability of Arctic Environments
Session Name 1.1 Climate Change and Environmental Management in the Arctic
Presentation Type Poster
Abstract text Kongsfjorden is a glacial fjord in Northwest Svalbard, Arctic. The water melting from glaciers in the inner fjord and the warm North Atlantic Current on the shelf will exchange with the fjord water, inducing the variations of the nutrients. We have conducted about 10 years of observations on early July from 2006 to 2015. Five sampling sites were set from outer fjord to inner fjord for long-term nutrients and Chlorophyll a study above 200m.
According to the 10-year observation, this study achieved a general pattern of the nutrients (i.e. nitrate, silicate and phosphate) distribution. During this period, the controlling water mass is the water from North Atlantic Current, i.e. Atlantic Water (AW; T>3℃,S>34.65) and Transformed Atlantic Water (TAW; T=1.0~3.0℃,S>34.65). In general, salinity, nitrate, phosphate and silicate were increasing with depth, in contrast, temperature and Chl a showed a decreasing trend.
The nutrient contents in AW and TAW is much higher than the limitation content, so in most of the water column, it shows a nutrient-rich pattern. The surface water plays an important role on the biological bump and the food web. In SW, the averaged nitrate, phosphate and silicate content were 0.8, 0.22 and 2.1 μmol/L. Together with the N/P and N/Si ratio (4.08 and 0.36 in average), they showed a status of nitrogen limitation. The water in SW is mainly from the tidal glacier and runoff, while, they play a different role on the contribution of nutrients, i.e. dilution and support, separately. In glacial water, the nutrient contents are lower than SW, however, in runoff, they are higher for silicate and nitrate (about 2.0-10.0μmol/L and 2.0μmol/L). Besides, another important factor influencing the nutrient distribution in SW is the growth of phytoplankton, which consumes a lot of nutrients and might induce the nitrogen limitation.