September 1st, 2008
On our way to the Indigirka river mouth, 72° N – 153° E. At 03:50 this morning, when some of us got up for a so-called “micro” sampling station, the East-Siberian Sea was almost flat and the sun was shining far above the horizon! A rare event because we have an almost continuous cloud cover since leaving Kirkenes, so this was fully enjoyed by the people that were up at this indecent time of the day. After filtering about 600 liters of water, taking 8 sediment cores and about 1 kilo of surface sediments it was time for coffee. At 9 am we had another micro station and now we are steaming towards the Indigirka river, the next-last Great Russian Arctic River that we will meet on our way East.
At this time of year, the rivers up north are already far past their spring flood, so the river plumes are not that large anymore. However, we still hope to collect some particles in the sea water that are coming from rivers, but since the water is very clear we know there is probably not much. A bit more than a week ago, we were steaming through the strait between Wraigatsch island (south of Novaja Zembla) and the mainland, and we could see that the filters suddenly became very brown-greenish, which means that we were probably collecting particles from the Pechora river that was pushed through this strait. Also in the Bhuorkhaya Gulf, east of the Lena river outflow, large amounts of brown material kept clogging our filters.
By analyzing these particles, in combination with all kind of other parameters we measure (temperature, salinity etc.) we can say a bit more on what happens to this river material when it enters the ocean. If it is all eaten up by bacteria or other organisms, producing carbon dioxide or methane, this could strongly enhance the greenhouse effect!
By taking sediments, we hope to collect a better signal from river outflow. But since the East-Siberian shelf seas are very shallow it is a challenge to find a nice deep spot in de sea bottom where sediments are accumulating. If the place is too shallow, ice is often building up in such amounts that it will mix the complete sea bottom and disturb all “our” sediments. In that case, we cannot establish a good chronology which is crucial to look back in time. We have our hopes up for the paleo-river canyon outside the Kolyma River, the last Great Russian Arctic River that we will sample in a few days from now. This river valley was formed during the last ice age when the sea level was much lower than now and the complete Siberian shelf was land. The Kolyma River mouth was lying a few hundred kilometers further north than now. When the ice starting melting, the sea level was rising again and now this river valley lies at the sea bottom; hopefully a perfect place to get nice, long and muddy sediment cores!
/Jorien Vonk, Graduate student