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18 November, 1999McMurdo Station, Antarctica Thursday *****If photo's had not arrived with yesterday's journal (11/17/99), please go back and check them out. The Dry Valleys are spectacular! Today we had our first analytical day. Into evacuated vials(that means that there is a vacuum in the vials) Julie and Bess injected gas from the silver sample bags. We were hoping to see the presence of nitrous oxide. This gas would indicate that the process of denitrification is occurring. Denitrification puts nitrogen back into the atmosphere. Our atmosphere is about 79% nitrogen, so this gas is important. Other bacteria take nitrogen gas from the atmosphere and use it for metabolism making ammonia and nitrate. I took the vials into the Analytical Lab for analysis on the gas chromatograph (GC). The GC measures a variety of gaseous compounds. Each GC is fitted with a parcticular detector that is capable of recognizing specific compounds. Our detector will identify hydrogen, carbon dioxide, nitrous oxide, and acetylene (this is added to the sample bags to stop the denitrification process at the nitrous oxide stage). The GC will also quantitate the gases. That is, it can determine not only what gases are present, but also how much of the gas is present. The gas sample is injected, by a gas-tight syringe, into the injection port of the GC. We have installed into our GC a loop that measures exactly 1 mL of sample. The sample moves through these loops, called columns, eventually making it to the detector. Our detector is called an electron capture device (ECD). The ECD sends a signal to a computer and the computer draws a graph showing us the gases present and the concentration of each gas. Each "shot" on the GC takes about 10 minutes. We are running 88 shots each day. How long will it take us to complete our day's work? A very long time and that's assuming that everything is working properly! We were pleased to see that nitrous oxide WAS present in our samples that we collected from West Lake Bonney! This tells us that denitrification was probably occurring in the west lobe of the lake. The real mystery will happen when we begin to process samples from the east lobe. Though the same bacteria are present, previous data suggested that denitrification doesn't occur here. The group is going out tomorrow to collect from the east lobe. I'll stay back to run the GC. A quick note to tell you how small the world really is! Earlier this week a dear friend of mine, Dr. Mike Madigan, arrived at McMurdo for his first trip to the continent! Mike was the first person to ever give me a job as a professional! This was in 1981! He and his wife Nancy have been friends with me ever since! Mike will be the subject of a Polar Profile later this month! Welcome Mike to McMurdo and the great continent of Antarctica! It's good to see you again! Answer to yesterday's question: Robert F. Scott discovered the first of the Dry Valleys in 1903 and named it Taylor Valley after a famous geologist. Scott wrote "I cannot but think that this valley is a very wonderful place. We have seen today all the indications of colossal ice action and considerable water action, and yet neither of these agents is now at work...it is certainly a valley of the dead; even the great glacier which once pushed through it has withered away." Scott was mistaken when he called the Dry Valleys "dead". We now know that life can be found in the most fragile of places! Today's question: We are interested in the process of denitrification. We are measuring the presence of nitrous oxide, an intermediate step in the process. Why can't we measure the production of nitrogen? Polar Profile: This feature will return on Friday. Sharon JUST FOR KIDS!!!!! Today we had our first analytical day! We finally had samples that we could test! I worked on an instrument called a gas chromatograph (GC). The GC has loops of tubing called columns. The gases from our samples pass through these loops. When they reach a parcticular place, the gas is identified by the GC and the amount of the gas is determined. A computer 'reads' this information and draws a graph. Our GC can measure oxygen, carbon dioxide, nitrous oxide, and acetlyene. We are parcticularly interested in nitrous oxide. If this gas is present, then our bacteria are denitrifying. That is a big word! A bacteria that denitrifies, sends nitrogen gas back into our atmosphere. Did you know that our atmosphere, the air that you breathe, is mostly nitrogen? Does that surprise you? These bacteria are important because they return the nitrogen to the air. In our first samples, we found nitrous oxide! We were very excited! Answer to yesterday's question: Robert F. Scott discovered the first of the Dry Valleys in 1903 and named it Taylor Valley after a famous geologist. Scott wrote "I cannot but think that this valley is a very wonderful place. We have seen today all the indications of colossal ice action and considerable water action, and yet neither of these agents is now at work...it is certainly a valley of the dead; even the great glacier which once pushed through it has withered away." Scott was mistaken when he called the Dry Valleys "dead". We now know that life can be found in the most fragile of places! Today's question: We are interested in the process of denitrification. We are measuring the presence of nitrous oxide, a middle step in the process. Why can't we measure the production of nitrogen? Polar Profile: This feature will return on Friday. Sharon
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