2 December, 1999
Thursday December 02, 1999
Got up at 0445 hours almost 6 hours of sleep. I feel a little better at least rest wise. I am still sore and really do not feel right. Went over to Crary lab to find Barb already busily at work. I worked on getting a journal out then worked on emails. I then played around with getting a final list of web sites for our parcticipant's last night. Actually this is half the class's last night, tomorrow we do the other half. I went back to dorm and rested for an hour.
Barb and I met for a couple of hours about the web sites and our final classes. Then I had to go to the "beauty parlor". I got a hair cut today (actually I had all five cut, it is cheaper that way). There are two lady barbers here. Remember there are, at least until February, about 1000 people here, then it drops down to about 325. This place must be like a ghost town in the winter season. It must also be a tad depressing too for remember once the sun finally sets in February it will NOT come up for about 5 months. By the way haircuts are free, just costs you the tip.
Class went well. Tonight's speaker was Kathy Welch; she is the senior lab manager for the LTER project, a brilliant and most pleasant young woman. Kathy pointed out that this is one of 21 LTER sites around the world, each one monitoring the long term (theoretically forever) ecology of various ecosystems type. The one in the dry valleys is one of the most extreme in the world, at least on a grand scale. The ecology in sulfur rich hot springs and at hydrothermal vents (places under the oceans where volcanoes spit molten rock into the sea and vent their gases as well) are much harsher, but they are, relatively speaking very very very small compared to the dry valleys, the coldest and driest place on earth. The limiting factor here is liquid water.
Kathy is a geochemist, but fielded questions, and fielded them very well I might add, from the areas of both physics and biology as well. Her major concerns were the lakes that are found in the dry valleys. She said those of the Taylor Valley; Bonney, Hoare and Fryxell are about 20 -40 meters deep with 3 - 6 meters or perennial ice cover, another lake in the Wright Valley, Vanda, is about 75 meters deep.
She explained that the only input into the lake is any glacial melt that might occur in the summer months and any snow that might fall. She pointed out that the lakes freeze at the water-ice interface, where the liquid and solid water meet, meaning they freeze from below and that most of the water is lost from its ice covered surface. This is where the ice sublimates, changes into gaseous water and leaves. I was shocked to learn that the average amount of ice lost each year by sublimating is about 1 1/2 meters (almost 5 feet). Unbelievable!
Kathy got into her area of expertise, the chemistry of the lakes. Lake Hoare, she described as quite boring because it is virtually fresh water from the top to the bottom. Surface salt concentration being (50 mg/l) and at the bottom (100 mg/l).
Lake Bonney on the other hand is a chemist's puzzle. The salt concentration here, on the average are 10 X saltier then sea water. Because when salt dissolves, or any solute for that matter, in water it lowers the freezing point of the water. The temperature in Lake Bonney is between -5oC and -7 oC and fresh water freezes at 0oC. So as Kathy says, when you take water samples form the lake the cold water "hurts your hands".
The real amazing part came when she described Lake Vanda. Kathy pointed out that the bottom of Lake Vanda is so salty that there is a "brine" (hypersaline) layer (very high salt concentration) on the bottom of the lake. This layer, about 60 meters below the 5 meters of permanent ice cover, covers the bottom. The significance of this is as follows: The extremely clear ice cover allows much light to penetrate to the bottom and there it hits the very salty and therefore very dense layer, and much of this energy gets trapped. The result is amazing. The temperature on the bottom of Lake Vanda, because of the trapping of this energy, is about 25oC or 77oF . (That is as warm as many of the tropical seas of the world.)
Kathy said that the salts are brought in by the glacial melt water "running" through stream beds that have salt on them. This salt has been deposited there, over thousands upon thousands of years, by winds carrying it up valley from the Ross Sea.
We closed out the class with Barb talking about the rotifers she studied in the mat in Lake Hoare. After class the gang went to the lab to see this mat. Exciting stuff! When we finished I returned to my dorm and sat and read until I guess 2300 then went to bed.
Penguin Pete the Polar man
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