Wow Caroline. I take it you are writing a paper or something. Your questions deal with Antarctica in general. For the most part I can only answer for our neck of the woods at McMurdo and maybe the South Pole Station.
1) population: Mcmurdo is the main logistics base for this side of antarctica. In the summer everyone going to or from any of the camps or stations must pass through Mcmurdo first. The population peaks out at around 1100 give or take a few hundred. In the winter around 200 people stay behind to rebuild the base and get it ready for the next science season.
2) The age range is from 18 (possibly less as a boy or girl scout comes down here each year)
3)The longest resident. As far as I know almost everyone leaves at the end of a one year to 14 month contract. A few people have stayed on for double seasons but that is a rarity. There are many people who work half year contracts and have been coming back each year for as long as 15 years or more.
4)Science/Medical…? Every type of person you could think of comes down here.Because the base is a small town we have plumbers, electricians, cooks, doctor, heavy equipment operators, clerical positions, snow shovelers, heavy equipment operators and so on and so on….
5)Population Ratio. I’m not sure on that one. I would guess 60/40 to 70/30 male to female. Interesting though that every year there are more and more females. Plenty of plumbers, electricians etc are women.
6)Different Countries. Pretty much just the US here as we are a US base, We have 2 from New Zealand and at least a couple from Canada. Just next door is the New Zealand base. There is at least one Brit there. In the summer the Italian Antarctic Program personnel come here first before heading off to Terra Nova Base. Also the russians going to Vostok also pass through here. The summer science groups generally include scientists from all over the world.
7)Animals. Ah the most common question of all. Actually there are no polar bears in Antarctica. They are only in the North pole area. We have Weddell seals, Adellie and Emporer penguins, a large seagull like bird called a skua (they feed on the penguin nests). If the ice melts in front of Mcmurdo we will sometimes get orca whales and minke whales and leopard seals. Pets are prohibited by the Antarctic Treaty. They are too afraid of viruses like Parvo getting into the seal populations.
8) Septic. In past years sewage was dumped into the ocean. Since the National Science Foundation took over they have been diligent about not causing pollution. They are building a sewage treatment plant this winter and all the solids will be dried and shipped back to the states for processing. On a similar note, every last piece of trash is recycled and sent back on our year for processing. We have up to 14 bins that we have to sort our trash.
9)Depression- The summer season is jam packed with people and there are regular flights in and out so depression is not a problem. It’s a little worse if you stay the winter. The sun sets for the last time in April and doesn’t come up again until August. May June and July are pretty much dark all the time. To deal with this we all have to go through a battery of Psychological testing in order to spend the winter. That weeds out some. For the rest we are a close community and help each other the best we can.
10) Lastly who owns antarctica. It’s a good question. By treaty nobody can own it. It is set aside for science purposes. There are many countries that lay claim to it. you can see the map on the Where is Ross Island page to see all the different countries.