VIMS research will provide first year-round record of CO2 levels
Earth's oceans have soaked up about a third of the carbon dioxide added to the atmosphere by humans through use of fossil fuels and other activities. That's good news for those concerned with greenhouse warming, but bad news for the marine life that's sensitive to the increasing acidity extra CO2 brings to ocean waters.
Dr. Elizabeth Shadwick, an assistant professor at William & Mary's Virginia Institute of Marine Science, has now deployed a high-tech mooring beneath the seasonally ice-covered waters around Antarctica to better understand ocean acidification in polar regions, particularly during the poorly studied winter months. Funding for her work comes from the National Science Foundation's Office of Polar Programs.
To date, knowledge of CO2 levels in the Southern Ocean around Antarctica relies almost exclusively on data collected by research vessels and resupply ships during summer's brief window of ice-free water. Shadwick's mooring will extend this record year round, right through the long polar winter.
The mooring, a line anchored to the seafloor in about 1,600 feet of water and held vertically by beach-ball-size floats, terminates about 60 feet below the sea surface, well beneath the scour of winter sea ice. It includes cutting-edge sensors that can measure concentrations of dissolved carbon dioxide every three hours throughout the mooring's six-month deployment. Other sensors will measure pH, temperature, salinity, and dissolved oxygen. All data are stored in waterproof memory cards until the mooring is retrieved.
"The autonomous sensors will allow us to monitor the full annual cycle of carbon dioxide in Antarctica's coastal waters, for the first time," says Shadwick. She and VIMS marine technician Olivia De Meo plan to recover the just-deployed mooring in early May--late autumn in Antarctica--when they will also deploy a second identical mooring to be recovered the following December.
Deployment and retrieval takes place from the U.S. research vessel Laurence M. Gould. Retrieval involves using stored GPS coordinates to relocate the mooring--which is not visible at the surface--then freeing it from its seabed tether by pinging a release mechanism with an acoustic signal. The mooring can then float to the surface, where crewmembers hook it with a grapple and hoist it aboard.
Acidification in the Southern Ocean
Because the Southern Ocean plays such an important role in the global carbon cycle--storing almost half the human-induced emissions that have been taken up by seawater--data from Shadwick's moorings should lead to a better understanding of global climate change and an improved ability to predict its worldwide impacts.
"From observations in places like Hawaii and Bermuda, we know the surface ocean is tracking the increase in atmospheric CO2," says Shadwick. "What's less well understood is whether the polar seas are also tracking this increase, since they are out of contact with the atmosphere for several months each year when ice is present."
Modeling based on shipboard measurements from recent Antarctic summers suggests that rising CO2 concentrations will lead to big trouble for local marine life beginning around 2070--when the resulting decrease in pH may impact animals that form shell or skeletons out of calcium carbonate minerals. Shadwick and other scientists are particularly concerned about impacts to microscopic organisms at the bottom of the polar food web, and how those impacts might ripple up to affect fishes, penguins, seals, and whales.
Understanding the wintertime conditions, says Shadwick, is important because unlike in summer, when photosynthesis by marine algae removes CO2 from the water and enhances pH, in winter CO2 is released through respiration or decay of algal blooms, leading to conditions with naturally low pH.
"Using sparse observations of wintertime conditions," says Shadwick, "our models predict the Southern Ocean will become undersaturated with respect to carbonate by the year 2030--roughly 30 years earlier than projections based on conditions representing an annual average, and up to 70 years earlier than those based on summer observations alone." Carbonate undersaturation means that calcium carbonate minerals are more energetically costly for animals to make; carbonate shells may even begin to dissolve in seawater with low pH.
Shadwick cautions, however, that these projections could change based on a number of feedback mechanisms that remain poorly understood. These include continued warming; freshening due to increased melting of sea ice and land-based glaciers; enhanced biological productivity due to a longer open water season, increased delivery of nutrients, or both; and intrusions of carbon-rich water onto the continental shelf from deeper waters nearby.
To better understand these potential feedbacks, Shadwick and collaborators will analyze the mooring data in light of a whole suite of other biological and physical measurements from surrounding waters. The mooring lies within the study area of the Palmer Antarctic Long-Term Ecological Research program, which--as the name implies--was established to monitor year-to-year and decade-to-decade changes in the ecosystems of the West Antarctic Peninsula near the U.S. Palmer Research Station. PAL-LTER scientists have been collecting data in the area since 1991. Shadwick's project has also been endorsed by the Southern Ocean Observing System (SOOS).
David Malmquist | EurekAlert!
Tiny microenvironments in the ocean hold clues to global nitrogen cycle
23.04.2018 | University of Rochester
Clear as mud: Desiccation cracks help reveal the shape of water on Mars
20.04.2018 | Geological Society of America
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
23.04.2018 | Physics and Astronomy
23.04.2018 | Physics and Astronomy
23.04.2018 | Trade Fair News