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Thursday, 24th of July 2014
A year has passed and we, the COPER group members from AWI, are on our way to Herschel Island again. As always, under the leadership of Hugues Lantuit but this year with slightly different members than last year: COPER PhD students Anna Konopczak, George Tanski and Jaroš Obu, master student Samuel Stettner and laboratory technician Ute Bastian.
As in the previous year, the vegetation specialist from Edinburgh Isla Myers-Smith will also be joining us with her assistant Clara Flintrop. Our research partners from Geological Survey of Canada Gavin Manson and technician Angus Robertson are also joining us.
And, this year, we are welcoming Scott Lamoureux and Ashley Rudy from the Queens University and Nina Stark and Brandon Quinn from Virginia Tech University who will be new to the team.
And what is our research about?
We are investigating the thawing of permafrost on Herschel Island in the Canadian Arctic and the impact of this thaw to the Arctic carbon cycle. The cold temperatures in tundra ecosystems slow down the degradation and decomposition of dead plants. Organic material from these plants accumulates in the soil over centuries and becomes frozen in permafrost. Now, with the rising temperatures and thawing of permafrost, this organic material is becoming exposed. Once thawed, the organic material is degraded by different microorganisms producing carbon dioxide and methane which are greenhouse gasses and can cause additional warming of the atmosphere.
The consequence of the fast warming in the Arctic means that sea ice retreats more rapidly in the spring and forms later in the autumn. Fewer months of ice cover means that the erosion of coasts can progress more rapidly with the longer period of open water and greater wave exposure. When these waves hit the coast made of soft sediment and ground ice, they erode it very fast. In some places, this coastal erosion can be greater than 1 meter per year. The coasts of Herschel Island and the Yukon Arctic coast are particularly vulnerable to coastal erosion. Our main research question of this expedition is to figure out the rates of coastal erosion and how much carbon is being released and turned to carbon dioxide and methane.
The focus of the group's research this year will be the continuation of study of a big retrogressive thaw slump (part of the coast that is quickly moving inland with small landslides and mudflows) on Herschel Island. We will install a weather station, instruments that measure outflow of a stream, a water sampler and time-lapse cameras. We plan to install loggers in boreholes to measure permafrost thermal regimes on different parts of island to measure the temperature of the permafrost.
Coastal erosion is another important focus of the group. A new student in our group, Anna Konopczak, will measure positions of the shoreline in Yukon Coast together with Gavin Manson to precisely quantify the rate of coastal retreat. Jaroš Obu will join them to measure coastal slopes stability and profiles to find out why different parts of the coasts erode at faster and slower rates.
George Tanski, who started his PhD in February, will continue his work on organic carbon. He will be sampling sea water and underwater sediment around the island to see how fast the carbon is degrading once it enters the sea. He will be accompanied on the boat by Nina Stark who will map the sea sediment texture. Isla Myers-Smith will continue her work on the vegetation by conducting plot surveys to see how much shrubs are expanding in relation to the changing climate. Scott Lamoureux and Ashley Rudy will be monitoring the watersheds of two streams on Herschel Island to compare to the long-term monitoring that they are conducting on Cape Bounty, in the Canadian High Arctic. We are all very grateful to Ute Bastian, Samuel Stettner and Clara Flintrop who will support our scientific work with their help.
We finished our preparations in Inuvik and the cargo is ready to be transported to Herschel Island. Four De Havilland Twin Otter airplanes will carry four tons of our equipment and food. Together with us they will have to land on an only 200 meters long airstrip on the beach on Herschel Island. We are all looking forward to what will hopefully be a great field season and exciting science adventure.
Written by Jaroš and Isla
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Wednesday, 6th of August 2014
As soon as we started our departure to Herschel Island, the weather started to dictate our work. The fog on the island caused few delays of our flights so we only managed one flight per day, with some of us arriving a day and a half late.
The weather soon started to get stormy with a rain and winds up to 60 km/h. The temperatures dropped to 4°C and we were able to watch the snowflakes mixed with the rain hitting the window of our warm trapper's house on Herschel Island base. However, this weather was still suitable for repacking of our freight, testing the instruments and preparing them for the transport to the sites.
The strong wind and a bad visibility didn't allow the helicopter flights, which were planned for the first days of expedition. So we had to postpone the four days of coast survey of Yukon Coast. Nevertheless, despite the stormy weather, there were few hours of calmer weather with sun rays and brief views on snowed British Mountains. We used these moments for the first visits of our sites.
We checked the permafrost temperature and moisture loggers on polygonal field of a drained lake. We immediately spotted two broken wooden poles to which our loggers were attached. The presence of muskox fur revealed that poles had previously served as their scratching posts. But the loggers were still in a good shape so we only had to bring new poles.
Meanwhile Isla and Clara started with their vegetation surveys on Collinson Head. Once the rain and winds died down a bit, measuring the plants in the 12 long-term plots in two of the island's vegetation zones became feasible, but rather chilly work when it is 4°C outside.
Clara and Isla like to bring lots of snacks for their long days in the field and they try to run around the tundra and jump up and down every half an hour or so to keep warm. After finishing most of their work for the day they hiked out to the top of the mud cliffs to warm up and look for whales. After sitting for quite a while, they saw a bowhead (Greenland) whale swimming in the water.
It took several breaths, letting out puffs of water vapour into the air, rolled on its back showing its fins and tail, and even sticking its head out of the water, perhaps looking in their direction. Then it took one last breath and took a deep dive and was gone.
We were able to do our first trips with boat as well. Gavin and Angus managed to deploy their sea current, tide and wave measuring instruments in Workboat Passage and on the East side of the island. After the six days on the island, there was a suitable day for the installation of weather station and fume channel on the Slump D.
We successfully installed construction and instrument for weather station in two hours. After four hours of digging in a mud, we placed the flume channel in the outlet gully of the slump. We were just finishing the installation when a mudflow came flowing down the gully, just like chocolate fountain. Luckily the mud displaced the channel only for few metres and didn't damage it much.
Despite the weather, animals and unexpected events, we have continued with our research. The helicopter has been rescheduled for the third week of expedition and we easily repaired the logger poles. As we observed, the mudflows in Slump D are very frequent this year so we decided to move our flume measurements to the new watershed that we are beginning to monitor this year as a part of a long-term programme on permafrost in transition across Canada (The ADAPT programme).
Now we are waiting for some more sunny days and are optimistically beginning the second week of the expedition on the Herschel Island. Though, we might have to wait bit longer for the good weather as a storm with rain and wind arrived today leaving time to finish this blog post!
Written by Jaroš and Isla
Wednesday, 20th of August 2014
Herschel Island is famous for tundra covered with white cotton grass (Eriophorum vaginatum) tussock blossoms, which forms distinctive 30cm-high hummocks which are fairly difficult to walk across.
If you step on hummock, you feel as you are about to loose your balance, and sometimes you do! If you step in between the hummocks your foot can sink in to plenty of plant litter and you can also fall over!
These hummocks are believed to be created by cryoturbation or the cotton grass tussocks. The cryoturbation is the process of vertical mixing of soil layers that is caused by freezing and thawing in the active layer above the permafrost.
The mixing of the soil layers leads to organic material from the top layers being transported deep into the soil profile and mineral soil from below becoming exposed on the surface of the ground. For this reason, there are also patches of bare ground in many parts of Herschel Island, known as frost boils.
The part of our scientific work is to determine how much carbon is stored in the soils of Herschel Island. Our monitoring of watersheds (areas above point of the stream where the water drains into) includes mapping of this soil carbon.
Samuel was in charge in taking soil samples of the active layer for AWI master student Isabell Eischeid. Hugues and Jaroš helped him to dig 23 soil pits while Isla and Clara surveyed the vegetation in these same places. Later analyses will tell us how much carbon is stored in these soils and whether the amount of carbon relates to the vegetation and active layer depth.
This carbon is being activated by disturbances and stream erosion and being transported from the soil throught the watershed. We are measuring the stream discharge from the Ice Creek watershed with a flume channel station and sampling water to see how much carbon is being released.
The lengthening growing season on Herschel Island and slightly warmer winter temperatures in some years has led to an increase in the active layer depth over the last three decades.
One of the questions our research team (in particular Isla and Clara from team shrub) is investigating is whether these changes have been leading to an increase in the vegetation on the island. We have observed more shrub cover in repeat photographs of the ice creek catchment and on the flood plain near the Pauline Cove settlement.
And, we have found an increase in shrub and grass vegetation in the long-term plots that have been monitored since 1999.
Satellite imagery shows a strong greening of the island, which could be related to the increases in the vegetation.
The only areas where vegetation cover is disappearing are cliffs and slumps. This is because the vegetation cover is completely removed by the remarkable disturbances occurring there. Isla, Jaroš and the team are collaborating with Robert Fraser from the Canadian Centre for Earth Observation and Mapping to explore how the tundra greening might relate to vegetation change on the island.
After three weeks of stormy and cloudy weather, in the last week of our expedition, we were finally woken up in the morning by rays of sun. This means that the helicopter finally arrived and we are looking forward to our surveys of the remote places of Herschel Island and the Yukon Coast.
Written by Jaroš and Isla
Monday, 1st of September 2014
Herschel Island was formed as an ice thrust moraine. This means that the glacier excavated the sea floor and deposited it together with the ice. For this reason the ground is characterised by an abundant massive ground ice and soft sediment. And the mainland coasts have similar composition as well.
When this ice and sediment are exposed to sea waves, they erode very quickly. Either very steep bluffs or retrogressive thaw slumps can form. The retreat of coasts and slump headwalls is one of the topics that are in the main interest of our group.
Anna and Gavin are interested in the rates of Yukon Coast retreat and the factors that cause the difference of erosion.
Jaroš is studying the elevation changes in the coastal transect by comparing two LIDAR digital elevation models.
When the helicopter arrived, we spent four days surveying the study sites between Komakuk and King Point with DGPS and measuring the shear strength of the ground.
Measurements showed that coastline is retreating for several meters per year on the most exposed places.
Calculations based on LIDAR DEMs showed that on an exposed part of the coast on the northern part of the island, the 15000 m3 (which equals to approx. 600 trucks of material) material was moved on 2500 m2 area (one third of football field) during one year.
Beside the important material loads that are released into sea, the coastal erosion endangers the buildings that are placed along the coasts.
Although we didn't do any flume measurements at slump D this year, we did other planned surveys. Anna, Jaroš and Gavin measured the exact headwall positions at slumps A, B, C and D with the DGPS to compare them with positions from previous years in order to estimate progression inland.
The second activity on slump D was taking active layer samples for George's PhD research.
He wants to find out how much organic carbon that has been activated by slump disturbances has been released as carbon dioxide and methane and how much of it has been redeposited.
Now when the rainy and grey days are over, we all enjoy the sun rays, colourful sunsets and the full moon which started illuminating the evening dusk, which came with the end of the polar day.
But the most of excitement brought the helicopter since everyone had a chance to fly and see the island from the air.
On the day that the helicopter left, we finished most of our scientific activities. This means that our stay on the Herschel Island is slowly coming to an end and we are all now slowly starting to pack our samples and equipment.
Written by Jaroš