August 20, 2006 – Paramushir, Day Four, How do you core a lake?
August 20, 2006 – Paramushir, Day Four, How do you core a lake?
Aug 25 2006, 05:14 PM
Group: TREC Team
Joined: 18-April 06
Member No.: 31
August 20, 2006 – Paramushir, Day Four
NOTE: The eight days of journal entries from August 17-24 were written while I was camping ashore at Pernatoye Lake, along Vasil’ev Bay on southern Paramushir Island. I am typing them in mostly verbatim from my handwritten journal from the field – with just minor editing/additions for content and clarity – now that I am back on the Gipanis.
August 20 - 5:30 pm
We actually DID get a quick change in the weather. Last night it was raining again, but this morning – no rain, only high fog. So the geologists set out to try to finish digging their peat excavation that they started two days ago (2.25 m so far, probably go to at least 4 m deep) and the palynologists and I set out to core the lake sediments. It took a little while to get all of the gear to the lake and out to the platform that Sasha, Pasha and Tolya had anchored 2 days ago over the desired coring location. But eventually we got everything and everyone situated.
It was too difficult to put me in a place where I cold assist and still see the core itself after it was extruded, so I sat in the transport dinghy. It was a good place to see both the coring equipment at it worked and the core itself after it came out. By the time everyone was set, the sun was out and there was only a little wind. I soon had removed at least 2 layers to be more comfortable. (See picture below)
A view of the mountains on Paramushir directly to the north of us at Lake Pernatoye on one of the two glorious weather days that we experienced. We were on Paramushir for 7 days and only saw the mountains clearly for the greater part of two of them.
Sasha, Pasha and Tolya worked the coring equipment on top of the platform, which was constructed of two large, heavyweight pieces of at least 1-inch plywood supported between two inflatable dinghies by two 1-inch metal pipes about 3 meters long. In one dinghy, Pat sat with the equipment to describe, label and store the cores and in the other dinghy the extension rods that would be needed as the coring moved deeper into the sediments were waiting. As they worked, Pat kept careful track of the depth so that they could lower the corer and extension rods to the appropriate depth. Then the square rod that would then push the corer past the piston and deeper into the sediments was slid up and turned to lock it. Pasha kept the cable on the piston that was now at the top of the core tight and Tolya and Sasha pushed the corer down past the piston. After the corer was pushed deep enough, the rods and corer were lifted up and each meter or so of sediment was extruded from the corer by pushing the piston back into the coring rod.
Slowly, about 1 meter at a time, Sasha, Pasha and Tolya worked to push the Livingston (the man who invented it is named such) corer into the sediments and the pulling the sediment core back up. Then they would push out the sediment core on to a board covered with aluminum foil and plastic wrap. Pat would keep track of the depth of the core, take measurements and make any particular notes about the core, such as sand/tephra layers and label the core after it was wrapped up. When the cores are further analyzed back in the lab, it will be very important to know which end is up on each core and their order/depth. Before each core is wrapped in plastic wrap and aluminum foil to kept it wet and protected, any end pieces that are just mud that had fallen into the hole between coring steps is removed and noted. Typically, this was about 2 centimeters. These can be recognized because they are soft mud rather than packed sediments. (See pictures below)
On the left: Alexander “Sasha” Pakhamov (standing), Pavel “Pasha” Minyuk (kneeling behind corer) and Anatoly “Tolya” Lozhkin (bending over in yellow) work the lake coring equipment – affectionately known as “Mr. Livingston” after its creator.
In the center: Pat Anderson works to measure one of the first cores while Anatoly Lozhkin observes. The general public should note the use of an improvised measuring instrument. When we got out to the platform, the meter stick could not be located, so a replacement was created.
On the right: A close up of one of the sand or tephra layers in the core. These could most easily be identified by the change in texture, more than color.
Eventually, they get to depths where it is more difficult to push the length of rods because of the friction along the sides of the hole or to more compact layers that are more difficult to core. At this point, they buckle a collar onto the rods and use a handled tool that slips over the top of the rods to gain more leverage. Sometimes, even with this additional assistance they aren’t able to push the corer a full meter or get to the “bottom” of the core. The “bottom” could be when they hit gravel or cobbles (like a river bottom), solid sand (like a beach) or, as happened this day, peaty sediments that are so compact that they can’t get through them and have to stop.
They worked today from about 9 am to 5 pm and were able to get 2 cores of about 3.5 – 5 meters each, which is adequate. There were many evident layers of sandy material that could be from tsunamis or tephras, but they didn’t find the Kuril Lake tephra.
The last thing to be done was to take a sample at the water/mud interface. The Livingston corer doesn’t do a very good job of collecting these sediments – they are so soft that the piston tends to just “smash” them together. Then when the first core is removed, there is so much water in the top of the corer, that these sediments are then washed away as the core is extruded. To solve both of these problems, a long, thick clear plastic tube is pushed down into the upper portion of the lake sediments. Then the top is plugged with a rubber stopper and as the tube is removed, another rubber stopper is pushed into the bottom of the tube to hold the sediments. This sample is then transported back to shore in a vertical position so that the sediments at the surface are not disturbed or mixed.
Once we were back on shore and cleaned up a bit, Pat, Tolya and I worked to take the samples from the plastic tube. This was done by removing the upper stopper and pushing the lower stopper upwards through the plastic tube with a long wooden dowel. The dowel was marked in centimeter increments, so once the sediments were at the top of the plastic tube, each separate centimeter of mud was slowly pushed out and scraped into its own sample bag by Tolya. I assisted in this endeavor by slowly pushing the dowel. (See picture below)
And so we completed a very successful day in Paramushir.
Anatoly Lozhkin, Pat Anderson and I work to take samples from the uppermost section of lake sediments from Lake Pernatoye. As I slowly pushed the tube down a centimeter at a time, Tolya scraped the sediments into a sample bag that had been labeled by Pat.
|NSF Acknowledgment & Disclaimer||Time is now: 28th April 2016 - 09:19 PM|