Distribution and potential impacts of coloured dissolved organic matter (CDOM) in the Laptev Sea (Siberian Arctic)

• Main Authors: Hölemann, Jens, Heim, Birgit, Novikhin, Andrey, Loginova, Alexandra, Martynov, Fedor, Janout, Markus
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Arctic; Laptev Sea; laptev; lena river
• Online Access: https://oceanrep.geomar.de/id/eprint/26546/

The Lena River strongly influences physical, biological and chemical processes on the Laptev Sea shelf through vast amounts of freshwater runoff. The Lena river water is poor in nutrients and carries high concentrations of dissolved organic matter (DOM) and colored dissolved organic matter (CDOM). Here we present CDOM absorption complemented by profiles obtained with an in situ WETstar fluorometer during expeditions in August 2010 and 2011, in order to study the vertical and horizontal CDOM distribution on this shelf. The results show that the river Lena dominates the supply of CDOM which exhibits a conservative mixing behavior over a wide range of salinities. The low light penetration of the CDOM-rich river water in conjunction with low concentrations of dissolved phosphate and nitrate and a strong density stratification of the water column result in low chlorophyll a concentrations within and beneath the river plume. Outside of the river plume increased water transparency and the upward transport of phosphate and nitrate from nutrient enriched bottom waters lead to the formation of deep chlorophyll maxima at the pycnocline.