I recently graduated from The University of Western Ontario with a degree in Environmental Science. During my fourth year I wrote a thesis on hydrothermal vent fluids and now I can't wait to learn about them aboard the R/V Thompson!
Files
Alexandra Powell
Alexandra Powell
Going Home...
Friday, September 02, 2011
I can't believe it's over. I am now sitting at the airport, waiting to board my flight back to Toronto, Canada... where there will be no oceans, no hydrothermal vents and none of the amazing people I've had the opportunity to meet and befriend over the last two weeks. I have never felt so sad to be saying good bye. But I am extremely grateful to have had such an incredible opportunity - to be thrown into the midst of leading experts from several oceanographic fields and to be a part of an ocean-going science team is a priceless experience. Over the last two weeks the crew, scientists and studnets of Visions'11 felt like my family. Having spent eight months studying hydrothermal vents in isolation at the University of Western Ontario, I can't express how happy it made me to find people with similar interests. Under such conditions, it was difficult to remember to regularly update this blog...
Some highlights of the trip for me have been:
- many, many late nights watching ROPOS traverse the ocean floor, exploring hydrothermal vents, lava flows, collapse features, and other stunning features of the deep deep sea; with narration from John Delaney and Deb Kelley.
- Helping Giora with CTD sampling for helium, methane and hydrogen. Learning how to use the gas chromatograph, prepare samples for helium isotope analysis and looking at the data afterwards
- hydrothermal vent mineralogy and deep sea geology lessons from Alden Denny
- Helping Monica prepare hydrothermal chimney samples for biological analyses back at the lab as she starts her second year of her masters...also very very late at night!
- Learning to crochet and make a butter pie crust (you need ICE COLD water, AND a food processor) from Sarah the cook, and playing guitar with her husband Gray; taking many a nap in Sarah's hammock on the bow of the Thompson- definitely my favorite nap spot on the ship!
- Watching stars and learning constellations from Giora, Cody and Tim
- Poetry night!
- presentations by Tim and Giora on the BP oil spill and plastics in the ocean respectively - oceanography and environmental science are totally, 100% integrate-able!!!!!
- Going to Gas Works on my last night in Seattle with Adrian, Audrey and Alden - the A team indeed!
- A night spent on the town in Victoria with amazing people
... This is not an experience I am going to forget. As they are calling for boarding now it's time to sign out. I hope I see all of these people again some day and I can't wait to do more science aboard the Thompson!
Rampant SciencE!
Wednesday, August 24, 2011
Today is the day... the day we will finally see some black smokin' hydrothermal chimneys! ROPOS is currently on its way down to the ASHES vent field, a site in Axial caldera with 7-8 hydrothermal chimneys. We are also going to unload the Sensor Bots and high speed camera ontot he sea floor, where they will be left for the next 5 or so days to blink their deep sea code, relaying information on temperature, pH, dissolved oxygen, ambient light and optical back scatter. This new technology is the start of the development of an array of deep-sea-sensing bots, that will provide invaluable information on ocean chemistry and the response of oceans to events such as the volcanic eruption that occurred at Axial Caldera in April.
Yesterday, ROPOS was used to survey the new lava flow in Axial Caldera - in some places, there is a 10m difference in height between the old flow and new flows! The cameras revealed many beautiful images of fresh, glassy basalts, pillow lavas, and multiple large collapse ponds and pillars. The orange colorus from oxidizing iron contrast beautifully with the black basalt under the light of the camera. We also came across a snow blower, a type of vent that forms after recent volcanic eruptions.
When not on ROPOS watch duty, I've been helping prepare the Sensor Bots for deployment, as well as aiding with, hydrogen, helium and methane sampling for fluids collected from CTDs (CTDs are used to collect water from hydrothermal 'plumes' - hydrothermal fluid that has mixed with the overlying seawater). The helium sampling process is pretty fun - the fluid taken for this gas has to be sealed in copper tubes to ensure that it is not contamined by atmospheric gas. We made the sample containers by cutting 1/2" copper tubing into 2' sections. On each section, we then flattened two 3" sections to ~5/16". Once filled with water, we re-roudned the tube. This created a vacuum in the tube, which we could use to ensure a sound seal of the water within the tubing, which is essential for accurate determination of the He concentration in the water. The helium isotope ratio is an excellent tracer of hydrothermal fluids since the isotope signature of the fluid is different from the isotope signature of the atmosphere. Isotopes are atoms of the same element, that have varying masses due to different numbers of neutrons in the nucleus. This causes them to behave differently in chemical and physical reactions, with light isotopes usually reacting faster than heavy isotopes. Different reservoirs of the element (for example the atmosphere, the ocean, and the subseafloor) can therefore have different isotope signatures as a result of the varying processes that occur bettransfer the element between the different reservoirs, causing the isotopes to fractionate between reservoirs. Since helium is not used in any reactions that occur within the ocean, (it's 'conservative') the signal of the hydrothermal fluid can be traced for miles. The helium samples will last for weeks inside the copper tubing, and will be taken to labs on land for analysis.
Aboard the ship, we can measure the methane and hydrogen concentrations using gas chromatography (GC). To remove methane and hydrogen from seawater, we first inject pure helium into the sample, providing air space for the tiny methane and hydrogen gas bubbles to escape into. Pure helium is run through the GC as a 'blank' gas - the sensors don't read it's presence, and it is just used to carry the hydrogen and methane through the 'column'. The column - is actually a long, narrow, hollow coil. We inject the methane and hydrogen gas (mixed with helium) into the GC and due to the difference in 'stickiness' and mass of hydrogen versus methane gas, they run through the coil at different rates, allowing them to separate. Sensors on the other side then measure first the concentration of hydrogen and then the concentration of methane as they exit the column. Hydrogen and methane are also excellent tracers of hydrothermal fluid - they can be used to determine the original source of the fluid and processes affecting it, as well as how old the hydrothermal plume they were sampled from is.
Alright, I'm sure you would love to read about more science, but there is lots else going on here as well! My hat is coming along quite nicely. I had an amazing lose in scrabble the other night to Sarah, one of the resident champions. There is a hammock set up at the bow of the boat which I use as my nightly star gazing spot - two nights ago I saw the biggest shooting star I have ever seen! The bow is also a great place to stretch out and lie in the sun. There are also many guitarists on board for musical entertainment, and a gym! Try running on a tredmill on a boat rocking side to side, in a room that is barely tall enough to fit you.... when the boat goes down on an up, watch out for your head!
There are so many people on board here who have traveled all over the world either as crew and cooks for various ships or other operations, or as scientists - it's such a great place to learn about and share experiences. I am continuing to have a great time abord the Thomas G. Thompson!
Sensor-bots and the Sea
Sunday, August 21, 2011
This is my first post from the Thompson, and my third day at sea. Although we have been in transit to Axial Volcano for the last two days, there has been no shortage of activities! The first day and night were pretty much a write-off thanks to seasickness! In fact, my strongest first impression aboard the Thompson came from the crew of this fine ship. They are some of the nicest people I have come across, and nursed me through my unpleasant evening. I would like to give a shout-out to Sarah in particular, who lent me her warm sweater and hand-crocheted hat – and then taught me how to crochet! Before the end of the cruise, I will have finished my own hat, and it will carry the memories of my first ever research cruise and the wonderful people I met aboard the ship.
Yesterday, I helped put together blue balls – sorry, I mean sensor-bots (patent pending?). Picture a clear sphere, the size of a fist, housing some electronics and batteries. On the surface of the sphere, 3 sensors for measuring pH, temperature or oxygen level report the environmental condition to the inner-electronics which convert the signal into basically a visual Morse code of flashing blue LED lights (hence blue balls). A high speed camera on the seafloor picks up the signal and stores it for later decoding on the ship. On this cruise, the plan is to position an array of these orbs near Axial Volcano so that pH, temperature and oxygen level can be monitored long-term in the vicinity of volcanic activity. No one has ever seen an underwater volcano erupt; yet there are hundreds of thousands of them surrounding the globe along the mid-ocean ridge! As the technology develops, these orbs may cover vast areas of the ocean and transmit data regularly to the OOI database. However, considering the depth of the volcanoes (usually >2000 m) and the extreme darkness of the deep sea, you can imagine what an engineering feat it is to produce independent sensors that can report back to the ship! Hopefully as the technology improves, we will be able to see the frequency of volcanic eruption and the chemical cycles it generates in both the deep-, mid- and shallow ocean.
That’s just one of the many projects I’ve taken part in so far… so there will be plenty more to come!
The Pre-Cruise Thought Process
Thursday, August 18, 2011
My name is Alexandra and I completed BSc with a major in Environmental Science this year. For my undergraduate thesis I analyzed a set of hydrothermal fluid samples taken from the East Scotia Ridge and my results allowed me infer conditions of sub-surface fluid flow and processes. Having gained some experience in data analysis I am really looking forward to completing the picture with sample acquisition and data collection on the R/V Thompson. So far we have had a few introductory workshops on some of the mapping and modeling software that we will be using (HIPS made by Caris and COVE, a modeling program developed for the regional scale nodes data) but the action starts tomorrow as we board the Thompson! Coming from London, Canada where I’ve been separated from all the preparation activity, it’s been a long wait for me!
Over the next two weeks I am going to build on my knowledge of ocean chemistry. Specifically, I would like to examine pre- and post eruption differences in water chemistry surrounding hydrothermal vents. The Mid-Ocean Ridge (MOR) is an underwater mountain chain, over 60,000 km long that defines the edges of tectonic plates. Upwelling magma beneath the ridge pushes the tectonic plates apart, generating new ocean crust as magma erupts and solidifies in the process. The new ocean crust is very porous, allowing seawater to penetrate into the seafloor. As the water sinks deeper it heats up and reacts with the surrounding rocks, becoming altered hydrothermal fluid. Eventually the sinking fluid nears the magma source where it becomes extremely hot and buoyant and forces its way back up to the surface. When an eruption occurs on the bottom of the ocean, the subsurface network of veins that allow fluid transport to occur can become altered, changing hydrothermal activity at the surface. Additionally, the influx of heat influences reactions between hydrothermal fluid and the solidifying ocean crust. These processes alter the influx of chemicals in the ocean with consequences for the surrounding biological activity. By measuring the chemical composition of hydrothermal fluids and the surrounding seawater, we can gain a better understanding of processes occurring beneath the seafloor.
