As always, check out the “photos” tab to get a visual experience of this past week and our summer of 2017 on the North Slope.
This last week or so has been an exciting one. Unfortunately, the warm and dry summer has seized to continue here up at Toolik. Much of the last week has been filled with cooler temperatures, wind, and rain. Despite this turn in weather, the work carried on. On Monday, Thomas and I did some sediment coring from Fogs 2, 3 with Kristen, and safe to say things got a bit messy, but the cores came to the surface beautifully. These cores were then incubated in lab to measure production and respiration (i.e., production and uptake of oxygen) from the sediments. After coring, Thomas Hafen and I had a few extra hours to kill in the afternoon, thus we sampled fish for a bit on Fog 1. We caught a few Arctic Char (only Char and Slimy Sculpin occupy the Fog lakes) including a recap. A recap is a fish that was already caught and tagged with a unique identifier in the past. Taking a peek into our records, I discovered that this particular char was caught late last Aug and grew over 20mm and about 90g since then. Must have been quite the year of feeding and assimilation for this char. On Tuesday, Thomas and I leveled the platforms which will house the propane tanks at Fog 1,5 to get them ready to support those heavy tanks and other equipment that are soon to be delivered. We also downloaded our temperature loggers from the Fog lakes. These temperature profiles reflected the warm air temperatures that occurred the previous weeks. Surface temperatures of the Fogs approached 18-19°C during the warmest times of the week, which is about as high as the water temperatures get up here. These warm surface (epilimnion) temperatures persisted until about 3-4m, until they started to decrease substantially at the thermocline, indicating stratification in the lakes. The thermocline of the deeper Fogs 1,2,3 was at about 4.5m where the temperatures dropped 4-5°C in just a single meter, evidence of a strong separation between the epilimnion and hypolimnion. Fog 5, being the smaller more shallow lake had a thermocline that was about 1m or so more shallow than the larger Fogs. Beneath the thermocline, there was very little change in temperature. However, as mentioned above, the temperatures have cooled off since, and the wind has increased. These changes in the weather will likely have repercussions for the water temperatures of the Fogs; we shall see next time we download the data. Late Tuesday evening the rest of the Lake Warming team arrived from Utah. This included my advisor, PI on the project, and co-head of the LTER Lakes group at Toolik, Phaedra Budy as well as Co-PI Sarah Null and her MS student Thomas Balkcom, and researchers Gary Thiede and Peter MacKinnon. Work with this great crew continued for the remainder of the week. This included moving all of our equipment and setting the stage for the warming to begin. This involved ~7 sling loads via helicopter the first day alone. Thanks to CPS and Pollux Aviation and their great pilots, this task was a breeze. One of these sling loads included the core of the large Solarbee lake mixing instrument, which looked much like a UFO effortlessly floating through the air. Check out the photos. A pyranometer (solar radiation), temperature, and relative humidity sensor were also added to the Fog 1 weather station. This is important for understanding the heat budget for the Fog lakes and the data will primarily be used by Sarah and Thomas B for the modelling portion of this project. Thursday proved to be quite the day. After working away during the morning and eagerly waiting, our 48, 650 pound full propane tanks arrived from up the haul road during the afternoon. All 48 of these tanks were slung via helicopter after arrival, 24 being left near the lakes ready for replacement, 12 brought to two Lake Warming Units at Fog 1 and another 12 brought to one Lake Warming Unit at Fog 5. Wednesday thru Monday included long, wet days spent setting up the warming equipment on Fogs 1, 5. This included putting the Solarbee together and launching it from shore, hooking up the propane tanks, building larger and more elaborate add-ons to the platforms and housing area, situating the pumps, generators and heaters and preparing these items for the task of warming up our lakes. Each Lake Warming Unit is composed of 6-12 propane tanks, one propane generator, one heat pump, and a water pump. The intake pump propels the water through heated coils, and then this warmed water is sent back out into the lake via a deeper pump hose. In theory, this process is similar to heating a large (very, very large in our case) swimming pool. The water is currently coming out between 70 and 90 degrees F, but varies substantially with the flow. The recently deployed Solarbee (water mixer) is designed to circulate water up from a specified depth and distribute it out across the surface layers. At the level of intake the water is drawn in from all sides and forced upward and then propelled outward over the distribution dish at the surface, providing gentle mixing of the water column. The Solarbee is an efficient unit to operate given that it obtains all the energy it needs from the sun via three large solar panels mounted to its frame. To learn more about the Solarbee, how it operates, and potential applications, be sure to visit www.medorace.com. Currently, our Solarbee is pulling water from 4 meters (the top of the thermocline) and distributing it to the top of the water column. Also, it is attached to our bouy and anchors using a 15 meter tether which allows it to gently move around our large lake while mixing. After this week of hard work from the entire crew, including the helicopter pilots, a very important milestone occurred yesterday (Mon the 24th). Two of the three Warming Units were turned on, and the Solarbee (water mixer) officially started, marking the beginning of the lake warming experiment. The equipment will need to be continuously checked and maintained in order to assure they are properly pumping and warming. We are excited to see how our efforts will be reflected in whole lake temperature and more importantly, ecological and ecosystem changes. For the coming weeks our focus will be maintaining the equipment, developing a troubleshooting protocol, and putting the finishing touches on the warming stages. In addition, we will continue to monitor ecological conditions and states at all trophic levels. Thanks for tuning in to another update, hope to have another update within the next week filled with great news and of course more of our adventures from the North Slope.
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Author:
Nick Barrett- PhD student on Arctic Lake Warming project Check out my personal Twitter page for various tweets about the project: @WaterWorks_NB |