Today’s Journal
For several weeks were waiting for the snow to melt. Then during the last two weeks of May, water in each of the water tracks was running over the notch in the weir with a lot of surface flow. The shift from peak flow to almost no surface flow happened in about a 7 to 10 days. It is likely that we will see surface flow again during storms.
Water track 4 at peak flow on May 24, 2012
Water track 4 on June 4, 2012, with just a small pool above the weir
Soil sipping
Since there is very little surface flow, we now need to look beneath the surface to continue to learn about the transport of nutrients in our water tracks. One of the ways we do this is by sipping soil water.
To sip soil we use a syringe and a metal straw with holds in the end
I am sipping soil water
Once the water is in the syringe, we follow the same protocol as we do for filtering water samples. We put a filter on the end of the syringe and filter the water into an isotope bottle and 60ml bottle. We are looking at water isotopes in our soil water, surface water, snow and precipitation. We will get isotope signatures from each of these water types and then be able to compare them with the water track water to see what water sources are influencing the water track water. We are running the 60ml bottle of water for cations, nitrogen and phosphorous in the lab back in Fairbanks.
Gas Equilibration
This procedure will allow us to measure the amount of carbon dioxide, methane and nitrous oxide in the water which tells us about soil respiration, methanogenesis, and nitrous oxide production (via nitrification or denitrification) that has occurred in soils. The gases that diffuse from the soil into the water will also diffuse into the atmosphere thus we can estimate the flux of gas from surface water to the atmosphere. These gasses are greenhouse gasses and measuring them is important for understanding whether water tracks are an important conduit of greenhouse gases from soils to the atmosphere.
In the field
We are also looking at the dissolved gasses in the water track water and we did our first gas evacuation last night. We take three water samples at each site and have to make sure there are no air bubbles in the syringe and we put them directly into a cooler underwater. This helps avoid introducing any atmospheric gasses into our samples.
Back in the lab
In the lab we pump 20ml of helium into our samples in a somewhat complex process done underwater.
You can see our set up with the helium tank and cooler.
After flushing the helium syringe, I attach the water sample syringe and push in the helium.
After the helium transfer, the syringes go back underwater in another cooler. Once we have 8 or 9 samples we shake for 5 minutes. This shaking allows the some of the gases in the water to diffuse into the helium gas.
After the shaking, we record the amount of gas and water in each syringe and then remove the gas by poking a needle into a evacuated glass vial, capturing the gas and carefully removing the needle.
Becca is reading of the amount of water in the syringe while Margit records.
Intense concentration while I transfer the gas into the evacuated glass vial. You don’t want to mess up this one!
This procedure was a stressful one, but once we did a few practice samples we got the hang of it.
Parting Shot
Tundra flowers are starting to emerge!