With the sampling by the Mackenzie River finished, it was time for us to continue steaming to the west back towards Barrow Canyon to finish up some work there before heading back to Dutch Harbor. It was a foggy and snowy day with a long steam ahead of us. In the evening, the skies cleared and the Northern Lights, Aurora borealis, illuminated the sky in a stunning display.
I have always dreamed about seeing the Northern Lights or Aurora Borealis and knowing that we are so far north and in prime Aurora season, I have made it a nightly ritual to go out on deck to check for clear skies. On a few evenings, the clouds have parted and the skies were illuminated with the shimmering green of the Aurora. I am very excited to have seen the Aurora on a few occasions on this cruise although have found photographing the Aurora from a moving ship to be quite challenging. I can now add the Aurora to the unique and extraordinary things I have seen on this expedition which have left me yearning for more time up here.
The Aurora with a silhouette of a buoy on deck
After completing our stations at the mouth of Amundsen Gulf, we transited to our next sampling area in the waters off of the Mackenzie River. We are sampling here to determine the role of freshwater from the river on the acidity of the ocean. The Mackenzie River is the largest river emptying into the Beaufort Sea; the only other being the Colville River which is one-tenth the size of the Mackenzie. Therefore the freshwater input from the Mackenzie may play an important role in the ocean chemistry of the Beaufort Sea and Arctic Ocean. The low alkalinity water from the river and high pCO2 (partial pressure) leads to decreased buffering capacity and higher acidity in the coastal waters.
While sampling near the river mouth, the water was clearly filled with silt from the river and the freshwater signal was high indicating that the river is playing an important role in the ocean chemistry of the area.
The new mooring buoy ready to be deployed
After recovering two moorings yesterday, the team did a quick turnaround due to impending weather and redeployed them today. Like recovering the mooring, deploying was quite an operation done with careful precision. The BS3 mooring with all of its various instruments was redeployed to collect data for another year adding to the time series of data from this location.
Fresh new instruments being deployed. An ADCP and pCO2 Sensor
The Mooring Anchor
Right before heading into the depths…
See you in a year…
With the mooring operations complete, we are moving on to Phase II of the expedition which involves a long steam northeast to the Canadian Archipelago where we will be completing CTDs and water sampling along the shelf. I am very exciting for this work as we will be heading into the ice!
The BS3 Mooring coming down the Port side of the ship after being released from its anchor
After continuing our sampling through the night, it was time to recover the BS3 mooring in the waters northeast of Barrow. The recovery of the mooring is quite an impressive process. This mooring was deployed on last year’s cruise and has been taking measurements of the water column for the past year creating an incredible data set that is key to understanding the Arctic shelf ecosystem. The instruments on the mooring have been collecting various measurements including temperature, salinity, nitrate, pCO2, and pH.
Everyone is anxious to get back to the lab to look at the data collected from these instruments and create a picture of what the water column looked like for the past year, from the open water of the fall through the ice-covered winter through the spring and summer melt until now. The changing ocean conditions affect the measurements tremendously as do currents and upwellings that occur seasonally in this area. By understanding these variables, the scientists can better understand what will happen when there is less ice in the future due to the warming climate.
Preparing the snowy deck for the recovery of the mooring
The small boat hooks a line from the boat onto the buoy
The first part of the mooring coming on board. The pCO2 censor is on the chain behind.
Successful recovery of the mooring!
Dr. Jeremy Mathis with his pCO2 censor from the mooring…excited to see the data!
The mooring will be re-deployed in the coming days to collect data for the next year.
In response to the imminent threat of climate change on the ocean, this expedition, the first National Science Foundation funded of its kind, will head to the Western Arctic Ocean to study ocean acidification. Human activities such as the burning of fossil fuels and changes in land use practices have led to an increase in atmospheric carbon dioxide and uptake of carbon by the ocean. These increased carbon dioxide concentrations lead to a decrease in the average pH of the surface waters of the ocean, a process called ocean acidification. The purpose of this expedition is to directly address questions of how human-induced climate change is affecting ocean chemistry in the Western Arctic Ocean.
The cold waters of the high latitudes are particularly vulnerable to ocean acidification due to increased solubility of carbon dioxide at low temperatures and low carbonate ion concentrations due to mixing patterns. This increased uptake in carbon dioxide along with the loss of sea ice and high rates of primary productivity over the continental shelves lead to increased ocean acidification in the Arctic Ocean and marginal seas. The rapid rates of change facing the high latitudes may have profound impacts on many organisms, particularly calcifying organisms that form calcium carbonate shells and hence need calcium carbonate minerals such as aragonite and calcite. Because of the sensitivity of these high latitude ecosystems to ocean acidification and their accelerated rates of change compared to lower latitudes, they become a real-time laboratory for understanding the changes and impacts of climate change on organisms and their possible cascading effects on the foodweb.
This study will be the first comprehensive assessment of the impacts of physical and biogeochemical processes on carbonate mineral saturation states and ocean acidification in the western Arctic Ocean and provide fundamental data for the understanding of ocean carbon cycle dynamics in the Pacific sector of the Arctic Ocean.