Suspended matter redistribution and potential nutrient export from land to sea, Disko, West Grenland

by Thor Markussen

During two cruises in July 2013, studies were carried out in Kuanersuit Sulluat, the inner, northeastern part of Disko Fjord, and in Disko Bay close to Røde Elv, West Greenland, to understand the fluxes and processes of dissolved and particulate biogenic and minerogenic matter from the melt water river when entering the estuarine fjord environment.

The changes in sizes of particulate suspended matter in the water column was measured over time and over distance from the outlet using two different in situ suspended particle sizers, and the particulate and dissolved matter will be characterized from filtered water samples. The water column properties were measured with CTD’s (Conductivity, Temperature, Depth sampler). The aim is to get a better understanding of the governing processes for flocculation/aggregation of the newly eroded suspended matter when entering Arctic estuaries, in order to better understand sediment transport and deposition processes, and to get better insights into this part of the nutrient (carbon, nitrogen and iron) cycles. Will aggregation of the high minerogenic sediment loads increase sizes to a point where the matter potentially settles out? Will this potentially also remove e.g. carbon from the system by burial at depth? And what controls the processes other than the physics of the water; the observed fluctuations in iron content or the organic matter?

These are questions that have been studied in temperate systems but remain unknowns in the Arctic environments. Large variations in e.g. iron content of the water were seen during the month of July and a monitoring station has been set up in the river Røde Elv near Arctic Station to get a first estimation of the annual changes in the suspended load on the western part of Disko Island.

For more information, contact Thor Markussen.