Unravelling the importance of the Laptev Sea system in the Arctic biogeochemical cycling of nitrogen

点击翻译按钮获取中文摘要

This project will provide a quantitative assessment of the different nitrogen sources in the water column of the Laptev Sea. Stable nitrogen and oxygen isotopes of dissolved nitrate and organic nitrogen will be used together with hydro-chemical data and the isotopic composition of the water to study the role of riverine input of inorganic and organic nitrogen in the Arctic Ocean. The warming in the Arctic is causing an increase in river runoff and a thawing of the permafrost, which both lead to an increased flux of nitrogen to the coastal seas of the Arctic. It is still unclear if those phenomena will affect the Arctic primary productivity and uptake of atmospheric carbon because our knowledge of the nitrogen cycle in the Arctic is limited at best. The stable isotope approach suggested in this proposal is an efficient and cost-effective way of investigating nitrogen sources and cycling in the Laptev Sea and will be the first nitrate dual isotopes study performed in the Arctic Ocean. In addition to produce a robust estimation of the relative importance of nitrogen sources in the Laptev Sea, this project aims to understand the role of dissolved organic nitrogen in the Arctic nitrogen cycle and its potential role in the primary productivity on Arctic shelves by measuring its isotopic composition.