By Katie Pratt, DCO Communications Director, University of Rhode Island, USA
"At a conceptual level, Earth scientists know that plate tectonics is about big things, but it's rare to be able to experience this viscerally. Usually on field trips we see a fault scarp here and a volcano there and have to put the larger features together in our imagination. One of the great privileges of being a part of Trail by Fire has been simply driving along the Andean volcanic zones, day by day, week by week, getting a feel for just how big they are." –Trail by Fire blog
For many DCO researchers, deep carbon science requires extensive field work. Deep Life scientists spend weeks to months on research cruises investigating mid-ocean ridges, or venture underground into gold mines to collect valuable microbial samples from the deepest habitable zones on Earth. For some Reservoirs and Fluxes scientists, traversing the dangerous slopes of active volcanoes is the only way to measure carbon emitted from their peaks. Scientists in the Deep Energy Community hunt for sources of methane, collecting samples to answer decades-old questions about geologic energy production. Even within the largely lab-based Extreme Physics and Chemistry Community, some researchers venture out into nature, collecting rare zircons or other minerals that hold clues about Earth’s past.
As of early 2016, DCO scientists have explored over 80 sites in more than 30 countries. These expeditions involved 250 scientists from numerous disciplines. To explore these sites and read updates and publications from the scientists involved, visit the Field Studies Browser and interactive map.
Volcanoes: DCO’s Charismatic Megafauna
Volcanoes are windows to deep Earth. When active, they belch carbon dioxide and other gases into the atmosphere, while spewing ash and lava in theatrical displays. To many, volcanoes are natural hazards, heralding destruction with their violent eruptions. And while DCO scientists respect them as such, they are drawn to them in search of information about Earth’s interior.
Within the Reservoirs and Fluxes Community, a group of volcanologists have come together to form DECADE (DEep CArbon DEgassing). DECADE scientists focus on the carbon coming out of volcanoes, carbon that once was stored in Earth’s mantle. They want to know how much carbon is emitted at all times, and so have begun a campaign to outfit close to 20 volcanoes with permanent monitoring stations. These stations collect a constant stream of data, allowing DECADE researchers and their collaborators around the world to monitor this aspect of the deep carbon cycle in real time. With each of Earth’s active volcanoes displaying unique degassing activity, efforts such as these are critical to quantifying the rate of deep Earth carbon degassing.
In late 2015, DECADE scientists Taryn Lopez (University of Alaska Fairbanks, USA) and Tobias Fischer (University of New Mexico, USA) participated in a US National Science Foundation GeoPRISMs expedition to the Western Aleutian Islands. While not installing permanent monitoring stations, they were able to collect data on several volcanoes in this arc. As part of the expedition, they made use of helicopter time to take measurements of volcanic plume gases, and hiked into the craters of these island volcanoes to collect samples for their collaborators in the Deep Life Community. The scientists published their first results in April 2016 . Fischer and Lopez also collected several hours worth of video using GoPro video cameras while on this month-long cruise, and worked with the DCO Engagement Team to create this short video about the expedition:
November 2015 saw the start of the Trail by Fire Expedition, a several months-long trek from Peru to the southern tip of Chile. The Trail by Fire team, Yves Moussallam (Team leader, Scripps Institution of Oceanography, USA), Nial Peters (University of Cambridge, UK), Philipson Bani (Institute of Research for the Development, France/Indonesia), Ian Schipper (University of Wellington, New Zealand), Aaron Curtis (New Mexico Institute of Mining and Technology, USA), and Talfan Barnie (The Open University, UK), received a grant from the Royal Geographic Society to outfit a Land Rover as a mobile volcano observatory. With additional funding from DCO and others, they set out to collect data on every volcano along their route, from Peru to Southern Chile. Read more about this expedition on the team’s blog.
DCO scientists are also working on capturing a global view of Earth’s volcanism using data from orbiting satellites. Brendan McCormick (University of Cambridge, UK), Christoph Popp (Federal Office of Meteorology and Climatology MeteoSwiss, Switzerland), and Ben Andrews and Elizabeth Cottrell (both at the Smithsonian Institution, USA) recently compiled 10 years of satellite observations from OMI, AIRS, SCIAMACHY, and GOME-2 to investigate sulfur dioxide degassing from Anatahan volcano in the Mariana Islands . Along with Kelly Chance (Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA.), Popp, Cottrell and colleagues are using these satellite data to look at volcanic carbon dioxide emissions, a process made particularly challenging by the high levels of carbon dioxide in Earth's atmosphere.
At the Bottom of the Deep Blue Sea
From volcanic peaks to ocean deep, DCO scientists do what it takes to collect precious samples and data sets. The ocean is vast, and the deep ocean remains a largely unexplored frontier. With the help of technologies such as ROV’s and high pressure-withstanding submersibles, scientists are constantly learning more about the intricate relationships between biology and geochemistry at the seafloor.
A number of DCO scientists in the Deep Life and Deep Energy Communities are investigating the links between life and fluid geochemistry at hydrothermal vents. Discovered in 1977, these thriving deep ocean ecosystems have long fascinated scientists. In the absence of energy from sunlight, how can life survive many kilometers deep? What kinds of organisms live here? Are these environments similar to those that gave birth to life four billion years ago? These questions drive researchers like Jill McDermott (University of Toronto, Canada) and Julie Huber (Marine Biological Laboratory at Woods Hole, USA) when they ship out to sea to collect samples at deep ocean vents .
Still deeper yet, within the oceanic sediment and crust, microbial life survives over geologic time. By drilling into the marine subsurface, DCO scientists retrieve cores, long cylinders of sediment and rock harboring signs of deep life. Scientific ocean drilling expeditions are notoriously grueling; scientists spend up to two months at sea working 12-hour shifts day and night. But these cruises often yield groundbreaking insights into the inner workings of Earth. In 2012, DCO’s Kai-Uwe Hinrichs (University of Bremen, Germany) and Fumio Inagaki (Japan Agency for Marine-Earth Science and Technology) led the Integrated Ocean Drilling Program (IODP; now International Ocean Discovery Program) Expedition 337 onboard the scientific riser-drilling vessel Chikyu to drill into the seafloor off the northwestern Pacific coast of Japan. The researchers published their findings in Science, thrilling the scientific community with multidisciplinary data showing life thriving in 20 million-year-old coal beds at ~2.5km below the ocean floor . That they had even drilled to this depth was a massive achievement, a world record in scientific ocean drilling at the time. In the Fall of 2016, DCO scientists will take part in the IODP Expedition 370 to the Nankai Trough subduction zone off Cape Muroto, Japan. The goal of the expedition is to better constrain the temperature limit of life in the deep biosphere, and will utilize the state-of-the-art drilling and analytical facilities of the Chikyu and on-shore laboratories for this challenging deep life mission.
More recently, DCO’s Gretchen Früh-Green (ETH Zurich, Switzerland) and Beth Orcutt (Bigelow Laboratory for Ocean Sciences, USA) led the 47-day IODP Expedition 357 to the Atlantis Massif, an enormous underwater mountain range in the mid-Atlantic ocean. The Atlantis Massif is an exciting location for deep life scientists, with large expanses of actively serpentinizing rock potentially fueling a large deep life ecosystem. Deep Energy scientists are also interested in studying the biotic and abiotic mechanisms for forming methane and other carbon compounds. Preliminary data released in early 2016 suggest that the drill cores collected on this expedition do indeed contain signs of microbial life living in the rock of the Atlantis Massif.
The challenges of studying the deep ocean on Earth pale in comparison to looking for life on extraterrestrial planetary bodies. But that’s just what DCO’s Chris Glein (Southwest Research Institute, USA) is doing. He and his colleagues are studying the ocean worlds of the outer solar system – Saturn’s moons Enceladus and Titan, and Jupiter’s moon Europa – trying to understand whether water-rock interactions taking place beneath their icy crusts could provide sources of chemical energy and building blocks for microbial life. Using data from the Cassini mission, Glein’s work suggests Enceladus’ ocean has a high pH, a hallmark of active serpentinization taking place where liquid water meets the moon’s rocky core .
Continental Exploration Around the World
DCO scientists are no strangers to conducting field expeditions in countless remote and geologically fascinating places on land. While volcanoes are thrilling windows into Earth’s mantle, as discussed above, there are many more clues to Earth’s deep carbon cycle in the crust.
Ophiolites are geological mistakes, where pieces of Earth’s mantle, usually 7 km below the seafloor, are thrust-faulted to Earth’s surface together with the overlying igneous, oceanic crust where we can walk around on them. One of the largest ophiolites is the Semail in Oman. In 2014, DCO was the first group to back a multi-million dollar continental drilling expedition to the Semail. Funded now by several agencies, including the International Continental Drilling Project (ICDP), the Oman Drilling Project is currently scheduled to commence in late 2016. The scientists involved, led by DCO’s Peter Kelemen (Lamont Doherty Earth Observatory, USA) and Jurg Matter and Damon Teagle (both at the University of Southampton, UK), will take samples by drilling into the ophiolite in several different locations. In an important new partnership with IODP, core logging will take place on the scientific drill ship JOIDES Resolution. The team is investigating processes during formation and alteration of igneous crust at scenic spreading ridges, the extent of natural carbon sequestration in the ophiolite by weathering, and the nature of microbial communities living within the rock itself.
For some DCO scientists, the “drilling” has already been done. Where gold or other resources are mined humans have already carved out a path into Earth’s crust. In the Sudbury and Timmins mines in Canada, DCO’s Barbara Sherwood Lollar (University of Toronto, Canada) has led several expeditions that take her and her team and colleagues 2.4 km underground. They collect samples of ancient water, which in some cases has been trapped in rock fractures for billions of years. Sherwood Lollar and her DCO collaborator Chris Ballentine (University of Oxford, UK) showed in a 2013 paper in Nature in Nature that this ancient water with residence times of over a billion years has been trapped in rock fractures . A second paper in Nature (2014) demonstrated the hydrogen rich nature of these and other fluids globally – transforming our understanding of the habitability of fluid in the deep precambrian rocks of the planet that make up more than 70% of the continental lithosphere . In South Africa, DCO’s DCO's Esta van Heerden (University of the Free State, South Africa), Gaetan Borgonie (Extreme Life Isyensya in Gentbrugge, Belgium), and Tullis Onstott (Princeton University, USA) found not only deep microbes living in mine fracture fluids, but also multicellular eukaryotes, including nematode worms . This body of work is challenging our perception of surface life as the dominant biomass on Earth, and shedding light on the incredible diversity of deep life.
Work by DCO scientists on water rock reactions and serpentinization is revolutionizing origins of life research. Once the purview of chemists and biologists, origins research now integrates a pivotal role for Earth’s mineralogy in life’s beginnings. How life and rocks interact, and have done so for billions of years, has long fascinated DCO’s Executive Director Robert Hazen (Carnegie Institution for Science Geophysical Laboratory, USA). Since the very beginning of life on Earth, minerals and microbes have relied intimately on one another. Indeed, without life Earth’s mineralogical composition would lack its remarkable diversity. In a recent NOVA television documentary for the US channel PBS, “Life’s Rocky Start,” Hazen and other experts in the field take viewers on a tour of Earth through geological time, and explore how life gained a foothold on our planet (the film is available in its entirety for some audiences here).
Integrating Field Sampling Across Disciplines
The incredible community of scientists who have come together under the DCO banner bring a wide range of skills to the table. Several groups are taking advantage of this in the field. In September 2015 the leaders of the second DCO Early Career Scientist Workshop in the Azores decided to pool the expertise of workshop participants and experiment with multi-disciplinary sampling. At a hydrothermal field site in Furnas volcano on São Miguel Island the 45-strong group collected microbiological and geochemical samples, and measured diffuse degassing. At the end of the workshop the samples were shipped to institutions around the world for analysis, and the organizing committee is currently collating all the data for publication.
This small-scale experiment inspired a larger project, currently in the planning stages, also involving a team of DCO early career scientists. Whatever the future of deep carbon science holds, innovative fieldwork is sure to remain a key piece of the puzzle.
The author would like to thank Terry Plank (Lamont Doherty Earth Observatory, USA) for essential feedback while writing this article, and the many scientists in the DCO Community who are conducting this impressive work.
Download Powerpoint slides featuring DCO Field Studies here.