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22 July, 2000

July 22, 2000

Matanuska Glacier, Alaska

It appears as though we are finally making progress with our dye tracing experiment. We still have to analyze the samples taken from Little River Vent but we have measured dye coming out of both Mammoth Vent stations that were sampled. We weren’t surprised at that outcome. But we were fairly surprised to find nothing coming out at Trail Vent. We had figured that even if some did come out of Trail Vent that it would also have to come out at another location as well due to the water volumes entering the moulin exceeding those exiting Trail Vent. Based on what we’ve seen so far we don’t expect to see any dye coming out of Little River Vent. Aside from being farthest away from the moulin, it also lies northwest of the moulin. Both Mammoth vents and Trail vent are southwest and west of the Little River Vent respectively. Since Trail Vent is between the Mammoth Vents and Little River Vent it seems unlikely to expect it to show up when we do the analysis.

What is now interesting to us is whether or not we would have seen conductivity rises had we sampled the Mammoth Vents during our salt experiments. There are probes that were collecting conductivity every two hours at both Mammoth Vents but we cannot access that data. It is doubtful that we would have seen it ourselves had we tested the water that was collected there. At that time we weren’t controlling those ISCOs and they were sampling every two hours. The dye flow that we’ve observed has possibly come and gone within a two hour period. I say possibly because we only took samples for a four hour period and we saw dye for only two hours of that time period. Perhaps there’s still more dye that flushed out after that time span. If the flow does go through that quickly then we maybe would have seen just one high conductivity point and would have thought it was just a fluke.

What we would like to do now is repeat the same experiment a second time and possibly a third. We’re interested in seeing if similar results can be produced. We at least hope to establish that the moulin definitely is connecting to both of those Mammoth Vent stations. A second run could confirm that notion. In this first test we’ve found a double peak occurring at Mammoth-4. We’re not sure if there’s a similar feature at Mammoth-1 but there seems to be something there at the end. (Recall that there are numerous vents in this area and they are given different numbers). We might be seeing a second and possibly third flow of dye at Mammoth-1. We’re hoping to clear up that question with the second test. We will do some things differently in the second run. We would like to take samples for a longer period of time in order to determine whether or not the dye has completed its course through the conduits. We’d also like to take samples more frequently as well. It’s doubtful that we will continue watching Little River or Trail Vents and so we won’t have an increase in samples to analyze. That’s a good thing too as that part is tedious and time consuming work.

Marvin Giesting

Ben is taking readings with the fluorometer as I prepare to filter another water sample.

This a comparison of the results at both Mammoth Vents. The shape of the concentration spikes is what we'd expect them to look like with a steep rise followed by a shallow decrease. We're not sure what to think of the little spikes at the end of Mammoth-1 (M-1). We hope the second run will give us more details.

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