Abstracts

Distribution Features of Nutrients and their Relationship in the Arctic Ocean

Shengquan Gao¹, Jianfang Chen², Hongliang Li³, Yong Lu⁴, Haisheng Zhang^5
1Key Lab of Marine Ecosystem and Biogeochemistry, SOA, Second Institute of Oceanography, SOA, China, 36 Baochubeilu Road, Hangzhou 310012, China, Hangzhou, 310012, China, gaosq88@163.com
²Key Lab of Marine Ecosystem and Biogeochemistry, SOA, Second Institute of Oceanography, SOA, China, 36 Baochubeilu Road, Hangzhou 310012, China, Hangzhou, 310012, China
³Key Lab of Marine Ecosystem and Biogeochemistry, SOA, Second Institute of Oceanography, SOA, China, 36 Baochubeilu Road, Hangzhou 310012, China, Hangzhou, 310012, China
⁴Key Lab of Marine Ecosystem and Biogeochemistry, SOA, Second Institute of Oceanography, SOA, China, 36 Baochubeilu Road, Hangzhou 310012, China, Hangzhou, 310012, China
⁵Key Lab of Marine Ecosystem and Biogeochemistry, SOA, Second Institute of Oceanography, SOA, China, 36 Baochubeilu Road, Hangzhou 310012, China, Hangzhou, 310012, China

DIN (DIN= nitrite+nitrate+ammonia), phosphate, silicate and dissolved oxygen in the water column of the Chukchi Sea and the Canada Basin were determined during the third Chinese Arctic Research Expedition in summer 2008. The results showed that the average concentrations of DIN, phosphate and silicate in the surface water were 0.55µM, 0.65µM and 4.44µM respectively in the surveyed area. The high concentrations of nutrients in the surface water appeared mainly in the southern area of the Chukchi shelf and the low values occurred in the middle area of the Canada Basin. The averages of N/P, Si/P and N/Si ratios in the waters above depth 100m were 3.63, 9.36 and 0.38 respectively, which were much lower than Redfield ratios. The depletion in DIN with respect to phosphate and silicate was predominantly characteristic in the most of the Chukchi Sea and the Canada Basin. The nutrient maximum in the water column of the Canada Basin is a distinctive feature due to steady, strong halocline, which separates the cold, relatively fresh upper layer from the underlying warmer, more saline Atlantic layer and hold back the exchange of water up and down. It was shown that the water depth of nutrient maximum decreased from 200m to 100m with the latitude increase (from 74º19.19?N to 85º24.24?N) and it was associated with potential density of sigma-t 26.5–26.8 in the surveyed area, suggesting that POM produced in the upper zone was held on the isopycnal surface while they sank down and nutrients were regenerated and accumulated in that depth. Good relationships between nutrients and AOU above the depth of nutrient maximum implied that nutrients at the depth of nutrient maximum originated from the decomposition of POM, whereas their relationships in deep waters were quite different from the upper waters.

Abstract Categories: 1.3 Integrated Studies of the Arctic System