U.S. GEOTRACES team completes 64 day Arctic expedition

On Sunday October 11 the USCGC Healy arrived in Dutch Harbor, Alaska successfully completing the U.S. GEOTRACES Arctic expedition. As we approached Dutch Harbor Captain Jason Hamilton gathered the science party and crew together for final remarks. He thanked everyone onboard for a successful mission, congratulated us for being part of the United States’ first solo mission to the North Pole on a surface vessel, and for working together through 64 days at sea.

Scientifically we accomplished ambitious goals to create one of the most unique chemical datasets of the Arctic Ocean. We were able to capture multiple points in the annual cycle of Arctic ice from late summer thawing, to thick multi-year ice at the North Pole, and early fall re-freezing. This data is vital to our understanding of how decreasing ice cover and thickness in the Arctic Ocean will change the chemistry and ecosystem dynamics of the basin in the near future.

Part of our cruise transect repeated hydrography stations that were occupied by previous missions in 1994, and 2005. Preliminary results show what we expected – the mixed layer at these locations is warmer and less saline due to melting ice over the past 20 years. NASA has used satellites to monitor sea ice change since 1978 and now oceanographers are accumulating enough data to piece together how these changes are affecting the Arctic Ocean. For many of the elements measured by the U.S. GEOTRACES program (i.e. mercury), there is no historical data for comparison; this is time zero for ocean chemistry in the Arctic and it could not have come at a more pivotal time. Temperatures in the Arctic are rising faster than anywhere else on the planet. The paramount of stepping off the ship at the North Pole this September was not that we were part of a small group of people to reach the top of the world, but that within our lifetime future explorers could be sailing through open water with no summer ice to walk on.

Two months is a long time to be at sea but we were rewarded on this trip with many once in a lifetime experiences (polar bears, northern lights, pictures with Santa at the North Pole to name a few!). I feel very lucky to have stumbled onto this career path and each adventure motivates me to work harder to keep moving forward with my work.

What’s next: After a few days relaxing in Dutch Harbor (and mingling with the Discovery Channel’s Deadliest Catch crew – it’s crabbing season!) the science party made their way home and the Coast Guard began their transit back to the Healy’s base port in Seattle, WA. The Healy will stop in Nome, Alaska to pick up family members who will sail the last few days of the transit and catch up with their loved ones. In November scientists will travel to Seattle to collect gear and samples, and then the work continues! It will take 2-3 years to analyze all of the samples that were collected on board, to interpret our results, and write manuscripts.

I would like to thank you for reading my blog this summer and taking an interest in the Arctic Ocean. A special thanks to Abigail Doyle who managed my postings above 75 N when I was without internet. I will continue to post sporadically between expeditions, please click the “follow” link if you would like to receive email updates. Stay curious!

“A mind that is stretched by a new experience can never go back to its old dimensions.” -Oliver Wendell Holmes, Jr.

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Fruit lottery

As an update to my previous post, I am happy to report that the helicopter that delivered two government officials to the Healy this week also came with a bag of fruit. There was not enough fruit to feed over 100 people so ten lucky souls were chosen at random and gifted a piece of real, live, fresh fruit (may I remind you we have not had fresh fruit or vegetables for over one month). The fruit lottery was a big deal, names were read over the loud speaker after dinner with only a five minute window to claim your prize. I was not lucky enough to be chosen for the lottery, but lucky enough to be sitting next to Phoebe Lam who shared her orange with the whole table :)



Farewell to the Arctic

Moments ago we crossed latitudinal line 66 °N officially exiting the Arctic. We intended to sample two more stations in the Bering Strait but all further science operations have been canceled due to rough seas. We will reach the Diomede Islands sometime this afternoon and enter port in Dutch Harbor on the morning of October 12. For now we are packing up labs, organizing samples, and enjoying our last few days at sea.

Earlier this week, two government officials arrived via helicopter from Barrow, Alaska to observe the Healy’s underway operations through to Dutch Harbor. Wearing flight helmets with ear and eye protection we were able to stand on deck to watch the craft land and practice lowering a man basket before returning to land. The following morning the helicopter was back for a medevac flight, transporting an ill crew member back to land for emergency medical attention. Medical emergencies on a ship can be dangerous, there are two medical officers on board the Healy but their resources are limited at-sea. The Polarstern (German GEOTRACES) also experienced a medical emergency in the Arctic forcing the ship to change course and head for land, both patients we have heard, are doing well.

helicopter 2

helicopter 3

helicopter 1

Aurora Borealis


Aurora Borealis from the USCGC Healy in the Arctic Ocean. U.S. Coast Guard photo by Petty Officer 2nd Class Cory J. Mendenhall.

At night the skies have been alive with dancing green light and shooting stars. The Aurora Borealis occurs when electrically charged particles from the sun (solar wind) interact with gases in Earth’s atmosphere. Solar wind is deflected by Earth’s magnetic field over most of the planet, but the magnetic field is weaker at the north and south poles allowing some particles to enter the atmosphere. We have seen mostly green auroras that are created when solar wind interacts with oxygen within 60 miles of Earth’s surface, there have also been some hints of red light from the interaction with oxygen at higher altitudes. Blue and purple colors can occur when solar wind interacts with nitrogen. All night you will find people on various decks of the ship with their heads up to the sky or faces pressed against the glass windows of the bridge which is kept dark to navigate at night. The U.S. National Oceanic and Atmospheric Administration uses satellite data and computer models to predict the location and visibility of the aurora everyday, we have been seeing a 4 out of 10 on the visibility scale and even that is spectacular.

aurora 2

U.S. Coast Guard photo by Petty Officer 2nd Class Cory J. Mendenhall.

Sampling Seawater from the Arctic Ocean

The most abundant elements in seawater are salt ions (sodium, chloride, sulfate, magnesium, calcium, etc.), and on average one liter of seawater contains 35 grams of dissolved salt (one liter of seawater weighs roughly 1000 grams so salinity is measured as parts per thousand). The GEOTRACES program specializes in measuring the least abundant elements in the ocean, referred to as “trace-elements.” Concentrations of the trace-element mercury, for example, are often less than 0.000 000 000 200 grams dissolved in one liter of seawater (parts per trillion). From this perspective, finding a needle in a haystack sounds easier than searching for mercury in the ocean.

Because these elements are found at such low concentrations, even a small amount of contamination can significantly alter a sample. Collecting contamination-free samples is a delicate process – imagine the challenges that arise when looking for trace amounts of iron in seawater collected from a giant rusty ship! The GEOTRACES program has developed specific sampling protocols that include a number of inventive solutions such as plastic shower caps, Kevlar line, and hand carrying 4 ft long GoFlo bottles. The photos below outline the procedure for collecting contamination-free vertical profiles of seawater from the ocean surface to the ocean floor.

small boat

Outside of the ice pack surface water is collected from a small boat with acid-cleaned plastic tubing and a peristaltic pump. Away from the ship, the small boat slowly moves forward as surface water is pumped into a large carboy. Only water deeper than 20 meters is collected from the ship to avoid contamination from the Healy’s metal hull.

GTC deployment

Full depth profiles are collected in specially designed GoFlo bottles. The bottles are long cylinders with openings at both ends and are lined with high quality plastic (Teflon) that can withstand acid-washing to remove contaminants. In this image the GoFlo bottles are attached a plastic-coated rosette for deployment off the aft deck. Top and bottom openings of each GoFlo bottle are covered with shower caps to prevent exposure to air contaminants; shower caps remain in place while the rosette is on deck and are removed immediately before deployment. The center of this console is equipped with CTD sensors to measure pressure, conductivity, and temperature.


The rosette is suspended from a non-metal conducting cable (dissected version shown above). Internal wires allow transmission of data from the CTD to a computer onboard the ship, the white material is braided Kevlar that gives the cable strength, and the outer coating is polyester that creates a water-tight seal.

CTD trace

Inside the ship scientists watch a live feed from the CTD sensors which unveils the hydrography of the water column as the rosette descends to the bottom of the ocean. Using this information, the group selects water sampling depths to capture specific features such low salinity values that may indicate the presence of a specific water mass or maximum chlorophyll values where the most algae should be found. As the rosette ascends to the surface, the GoFlo bottles are electronically triggered to close, capturing up to 24 different depths in one cast.

carrying bottles

On deck each GoFlo bottle is detached from the rosette and carried by hand into a specially designed van that serves as a clean laboratory. HEPA filters push particle free-air into the van creating positive pressure that eliminates dust penetration and deck shoes are left outside to minimize contamination sources.


Inside the van each seawater sample is identified by a 5 digit code and filtered into pre-cleaned sample bottles. Some bottles are delivered to onboard laboratories where the samples are processed immediately, other bottles are preserved with acid and frozen for analysis months later back in onshore labs across the United States.


GEOTRACES Cross-over Station Abandoned due to Rough Weather


Photo taken from the bridge of the Healy, strong winds blowing sea spray up to the fifth deck of the ship.

This morning the decision was made to abandon the U.S. – Canadian GEOTRACES cross-over station due to rough weather. The cross-over station was designed to compare results with Canadian researchers who occupied the same location in mid-September to ensure the accuracy of our measurements within the international oceanographic community. Over the past two days we have been on stand-by waiting for the winds to subside below 20 knots in order to safely deploy our equipment. We were able to complete some rosette casts to sample radioisotopes, however, attempts to collect water and particles for trace-metal analysis were abandoned as cable lines frayed under pressure from strong surface currents. Rough weather is predicted to stick around this location for days so we are heading south towards our finals stations, and calmer seas.

The Canadian GEOTRACES team also encountered rough seas at this station but the weather cleared long enough to complete their work. The Canadian team’s sampling wire also suffered some minor damage, but it wasn’t from the weather. A curious polar bear and her two cubs were caught gnawing on the ship’s wire, luckily the bears lost interest before any serious damage was done (check out this link for the full story). Perhaps this cross-over station just wasn’t meant to be.