Yellowstone 'super-eruption' less super and more frequent

The Yellowstone "super-volcano" is a little less super but more active than previously studies have shown.

Researchers at Washington State University and the Scottish Universities Environmental Research Centre say the biggest Yellowstone eruption, which created the 2 million year old Huckleberry Ridge deposit, was actually two different eruptions at least 6,000 years apart.

Their results paint a new picture of a more active volcano than previously thought and can help recalibrate the likelihood of another big eruption in the future. Before the researchers split the one eruption into two, it was the fourth largest known to science.

"The Yellowstone volcano's previous behaviour is the best guide of what it will do in the future," says Ben Ellis, co-author and post-doctoral researcher at Washington State University's School of the Environment.

"This research suggests explosive volcanism from Yellowstone is more frequent than previously thought."

The new ages for each Huckleberry Ridge eruption reduce the volume of the first event to 2,200 cubic kilometers, roughly 12 percent less than previously thought. A second eruption of 290 cubic kilometers took place more than 6,000 years later.

That first eruption still deserves to be called "super," as it is one of the largest known to have occurred on Earth and darkened the skies with ash from southern California to the Mississippi River.

By comparison, the 1980 eruption of Mount St. Helens produced 1 cubic kilometer of ash. The larger blast of Oregon's Mount Mazama 6,850 years ago produced 116 cubic kilometers of ash.

The study, funded by the National Science Foundation and published in the June issue of the Quaternary Geochronology, used high-precision argon isotope dating to make the new calculations.

The radioactive decay rate from potassium 40 to argon 40 serves as a "rock clock" for dating samples and has a precision of .2 percent. Darren Mark, co-author and a post-doctoral research fellow at the SUERC, recently helped fine tune the technique and improve it by 1.2 percent, a small-sounding difference that can become huge across geologic time.

"Improved precision for greater temporal resolution is not just about adding another decimal place to a number, says Mark. "It's far more exciting. It's like getting a sharper lens on a camera. It allows us to see the world more clearly."

The project asks the question: Might super-eruptions actually be products of multiple, closely spaced eruptions through time? With improved temporal resolution, in times to come, maybe super-eruptions will be not quite so super.

More information: doi:10.1016/j.quageo.2012.01.006

Provided by Washington State University

Flax And Yellow Flowers Can Produce Bioethanol

Surplus biomass from the production of flax shives, and generated from Brassica carinata, a yellow-flowered plant related to those which engulf fields in spring, can be used to produce bioethanol. This has been suggested by two studies carried out by Spanish and Dutch researchers and published in the journal Renewable and Sustainable Energy Reviews.

"These studies evaluate, from an environmental point of view, the production of bioethanol from two, as yet unexploited sources of biomass: agricultural residue from flax (for the production of paper fibres for animal bedding), and Brassica carinata crops (herbaceous plant with yellow flowers, similar to those which carpet the countryside in spring)", Sara González-García, researcher of the Bioprocesses and Environmental Engineering Group of the University of Santiago de Compostela (USC), explains to SINC.

González-García, along with other researchers from USC, the Autonomous University of Barcelona and the University of Leiden (Holland), has confirmed that if bioethanol is produced from these two types of biomass "both CO2 emissions and fossil fuel consumption will be reduced, meeting two of the objectives established by the European Union to promote biofuels".

These works have analysed the environmental load associated with the different stages of the process: the harvesting of flax or Brassica; the production of ethanol (through enzymatic hydrolysis followed by fermentation and distillation); mixing it with petrol (in varying proportions); and its use in passenger automobiles.

The results of both studies, published in the journal Renewable and Sustainable Energy Reviews, show that the use of ethanol-based fuels can help to mitigate climate change (by reducing greenhouse gases).

However, these fuels also "contribute to acidification, eutrophication, the formation of photochemical oxidants and toxicity (for people and the environment)". According to the experts, these negative effects could be lessened with the use of high-yield crops, as well as through optimisation of agricultural activity and better use of fertilisers.

Which is better: flax or Brassica?
The studies developed by the researchers reveal that flax (which is richer in cellulose) can produce up to 0.3 kg of ethanol for every kg of dry biomass, compared with 0.25kg/kg of Brassica. However, when the whole production cycle is analysed, the yellow-flowered plant offers a greater production of biomass per hectare and has a lesser environmental impact.

The biofuel produced from these two plants is "second generation bioethanol", which is obtained from forest or agricultural residues, or from herbaceous crops, and does not enter into direct competition with agricultural crops intended for animal or human consumption.

The European Union and the International Monetary Fund are promoting the development of these types of biofuels. Spain is the third largest producer of bioethanol in Europe, after France and Germany, although its use still only represents 0.4% of total energy consumption.