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Sampling the Bratina Island Ponds 7 - Bratina Island Day 4

After the mammoth effort of day 3 (we got back to camp 8.30pm, had dinner and were processing samples until 1-2am) we decided to leave for our last pond an hour later so at 10am we began our journey to what we believed was called Egg pond and we now are sure is Huey, but regardless to its name it gave us the most amazing results yet.

The sampling began like any other, with the surface samples being fairly typical but as we moved further down the water column the geochemistry changed drastically, so much so that we began having to move down the water column in 0.5cm increments to ensure that we gained a representative view of that was going on right down this gradient. By the time we were 15cm from the bottom of this pond we had been sampling for over 2 hours, the conductivity (saltyness) of the pond had increased 5 times its concentration, the pH had decreased from alkaline to almost neutral and the oxygen concentration had become supersaturated (it was 5 times higher than the concentration we had begun with resulting in bubbles being brought to the surface).
Then things got really intresting, we must had moved to a depression below the cyanobacterial mat producing oxygen at the bottom of the pond because the oxygen took a rapid dive. At this time the water began to get darker and darker and started smelling like rotting seaweed, then like hydrogen sulfide, at this point the oxygen in the water was almost non-existant and the smell was quite pungant. We were relived to get to the bottom after 3.5 hours of sampling, 1-2 hours of setup we were ready to pack up the sampling rig and get back to the camp for lunch at 4pm. Cleaning the eqipment and sample processing took until 8pm, then dinner, a movie off my laptop and data entry into the wee small hours of the morning. It had been a great day, and an even better trip so far so much so that when we called in to Scott base for our daily sked, we arranged for an early pickup 2 days later. Below is a picture of me working in the labspace, and one of the huts, we were very lucky to have such great facilities thanks to Antarctica New Zealand which allowed us to process samples every night in relative comfort.


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