Hydrocosm

A TEXT POST

Russian seafloor methane emissions of “a scale not seen before.”

This is the first time that we’ve found continuous, powerful and impressive seeping structures, more than 1,000 metres in diameter. It’s amazing,” Dr Semiletov said, [in reference to the recently observed plumes of methane his team found pouring from the sea floor in the East Siberian Shelf region of northern Russia. “I was most impressed by the sheer scale and high density of the plumes.

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Dr Semiletov’s team published a study in 2010 estimating that the methane emissions from the region are about eight million tonnes a year, but the latest expedition suggests this is a significant underestimate of the phenomenon.

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“In a very small area, less than 10,000 square miles, we have counted more than 100 fountains, or torch-like structures, bubbling through the water column and injected directly into the atmosphere from the seabed,” Dr Semiletov said. “We carried out checks at about 115 stationary points and discovered methane fields of a fantastic scale – I think on a scale not seen before. Some plumes were a kilometre or more wide and the emissions went directly into the atmosphere – the concentration was a hundred times higher than normal.”

The Independent article suggests that the recent increase in East Siberian Shelf methane emissions could be tied to rising sea water temperature and global warming, a link which has recently been called into question.

A PHOTO

While NASA’s Opportunity rover was busy finding strong evidence for water on the Martian surface, another line of evidence was being struck down. Researchers have long suspected that the Nepenthes Mensae, above, was an ancient river delta. The slopes of the gully’s walls suggested that they were formed in the presence of water. But new experiments suggest that, due to Mars’ lower gravity, water wasn’t needed to form the structures as was previously thought.

A pile of sand, gravel, or other granular material takes on a familiar conical shape, with the slope of the pile’s walls coming to rest at the static angle of repose. If the material exceeds this angle, it will trigger an avalanche, tumbling down until it comes to rest at the dynamic angle of repose…

As largely a matter of geometry, grain properties, and internal friction, scientists have assumed these two angles of repose are fixed for a given substance. Observations of the angles of gully walls on Mars, found to be too shallow for the materials involved, have been used to argue that surface water must have played a part, either lubricating landslides or depositing the material directly.

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The authors suggest Mars’ weaker gravity would reduce internal friction for avalanching material and could explain the shallow gully walls [in the Nepenthes Mensae and elsewhere.]

Photo: European Space Agency

Source: Gravity’s effect on landslides: A strike against Martian water

Study: Static and dynamic angles of repose in loose granular materials under reduced gravity

A PHOTO

A Point for Water on Mars.

Last month, researchers used the Microscopic Imager and Alpha Particle X-ray Spectrometer on the rover’s arm and multiple filters of the Panoramic Camera on the rover’s mast to examine the vein, which is informally named “Homestake.” The spectrometer identified plentiful calcium and sulfur, in a ratio pointing to relatively pure calcium sulfate.

Calcium sulfate can exist in many forms, varying by how much water is bound into the minerals’ crystalline structure. The multi-filter data from the camera suggest gypsum, a hydrated calcium sulfate. On Earth, gypsum is used for making drywall and plaster of Paris. Observations from orbit had detected gypsum on Mars previously. A dune field of windblown gypsum on far northern Mars resembles the glistening gypsum dunes in White Sands National Monument in New Mexico

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The Homestake deposit, whether gypsum or another form of calcium sulfate, likely formed from water dissolving calcium out of volcanic rocks. The calcium combined with sulfur that was either leached from the rocks or introduced as volcanic gas, and it was deposited as calcium sulfate into an underground fracture that later became exposed at the surface.

Source: NASA Mars Rover Finds Mineral Vein Deposited by Water

A TEXT POST

Elevated water contamination found in poor Californian neighbourhoods

Access to safe drinking water is an emerging problem in [the United States]… Water systems in the San Joaquin Valley [central California] that serve higher proportions of minority residents, or that serve areas where residents are not homeowners, have higher levels of contaminants.

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The team found that increased nitrogen levels were associated with communities with a higher percentage of Latino residents and a decreased percentage of homeowners. The trend was not statistically significant for the overall data set, but was significant when the team looked just at small water systems that served 200 people or fewer. The researchers also found that arsenic concentration decreased by 0.27 microgram per liter for every 1 percent increase in home ownership, a relationship that was significant for all community water systems as well as small ones.

Full Story: Got Arsenic? Social Disparities in Drinking Water Quality, GeoSpace

A QUOTE

Israel’s national water company signed a financing agreement to build a desalination plant, which officials said could allow drought-ridden Israel to export water to its neighbors upon completion in 2013.

A PHOTO

Scientists working with the British Antarctic Survey’s BEDMAP Consortium put together an incredibly detailed map of the Antarctic continent’s surface—the land under the ice. The map updates the original BEDMAP map which was put together in 2000. The BBC’s Jonathan Amos writes,

The map is a fascinating perspective but it is more than just a pretty picture - it represents critical knowledge in the quest to understand how Antarctica might respond to a warming world.

Scientists are currently reporting significant changes at the margins of the continent, with increasing volumes of ice now being lost to the ocean, raising global sea levels. The type of information contained in BEDMAP will help researchers forecast the pace of future events.

Photo: Bedmap Consortium / British Antarctic Survey

A PHOTO

Last year, scientists lead by Natalia Shakhova and Igor Semiletov from the University of Alaska and the Russian Academy of Sciences announced that vast stores of methane, thought to be locked away in permafrost-hardened terrain under the East Siberian Sea, were leaking. The study, published in Science, found that “80 percent of the deep water and greater than half of surface water had methane levels more than eight times that of normal seawater,” according to the accompanying press release.

The authors worried that the subsurface permafrost, stirred by recent global warming, was losing its grip, letting the methane escape. The logical extension was that further warming could spur larger emissions—a powerful feedback cycle.

However, a recent study in the Journal of Geophysical Research argued that while Shakhova and Semiletov’s observations were right, the tie to modern warming was wrong.

Records of seafloor water temperature showing a 2.1°C rise since 1985, coupled with recent observations of methane emissions from the sea bed, have led some scientists to speculate that the rising temperatures have thawed some of the subsurface permafrost, liberating the trapped methane. The connection is compelling, but an investigation by Dmitrenko et al. (2011) into the sensitivity of permafrost to rising temperatures suggests the two observations are not connected.

Using a permafrost model forced with paleoclimate data to analyze changes in the depth of frozen bottom sediments, the authors found that roughly 1 m of the subsurface permafrost thawed in the past 25 years, adding to the 25 m of already thawed soil. Forecasting the expected future permafrost thaw, the authors found that even under the most extreme climatic scenario tested this thawed soil growth will not exceed 10 m by 2100 nor 50 m by the turn of the next millennium.

The authors note that the bulk of the methane stores in the east Siberian shelf are trapped roughly 200 m below the seafloor, indicating that the recent methane emissions observations were likely not connected to the modest modern permafrost thaw.

Photo: Google Maps

Full Story: Siberian shelf methane emissions not tied to modern warming

Study: Recent changes in shelf hydrography in the Siberian Arctic: Potential for subsea permafrost instability, Journal of Geophysical Research - Oceans

A PHOTO

The river swirls away, white-crested and silt-laden, racing to the nearby border with Pakistan. But there the Baglihar dam [seen above] is a source of bitterness. Pakistanis cite it as typical of an intensifying Indian threat to their existence, a conspiracy to divert, withhold or misuse precious water that is rightfully theirs. Officials in Islamabad and diplomats abroad are primed to grumble about it. Pakistan’s most powerful man, the head of the armed forces, General Ashfaq Kayani, cites water to justify his “India-centric” military stance.

Others take it further. “Water is the latest battle cry for jihadis,” says B.G. Verghese, an Indian writer. “They shout that water must flow, or blood must flow.” Lashkar-e-Taiba, a Pakistani terror group, likes to threaten to blow up India’s dams. Last year a Pakistani extremist, Abdur Rehman Makki, told a rally that if India were to “block Pakistan’s waters, we will let loose a river of blood.”

The Full Story: Unquenchable Thirst: A growing rivalry between India, Pakistan and China over the region’s great rivers may be threatening South Asia’s peace, The Economist

Photo: Vinayak Razdan

A VIDEO

This week the National Oceanic and Atmospheric Administration released an annual update to their Arctic Report Card. The report gives an overview of the state of Arctic dynamics, with an emphasis on sea ice, temperature, marine life, and Arctic vegetation. The most intriguing statement seems to be that,

the Arctic Ocean climate has reached a new state, with characteristics different than those observed previously.

If the Arctic has indeed reached a fundamentally new state of climate dynamics, that would be incredibly important as it’s likely that, from here on out, no aspect of the system will act the way we expect.

NOAA also released a short video with some of the report’s highlights (above).

Full report pdf

A PHOTO

Swirling rafts of algae paint the ocean in vivid greens and blues, a natural painting—lamentably temporary. While their presence is aesthetically pleasing, phytoplankton blooms make drastic changes to water chemistry. Microbes feeding on the sudden abundance of tiny phytoplankton cause a decrease in dissolved oxygen levels. Outbreaks of algae are normally driven by a large influx of cold, deep, nutrient rich water drawn up to the surface waters, but they can also be triggered by the flow of nutrient-bearing runoff from agricultural regions as can be seen in the above image of the Mississippi River’s mouth draining into the Gulf of Mexico.

New research in the November issue of Nature Geoscience, however, shows that the consequences of fertilizer-induced algae blooms can reach far beyond temporary oxygen depletion. The spike in microbial activity drives up local dissolved carbon dioxide levels, which in turn break apart into carbonate ions and a hydrogen ions, increasing the ocean’s acidity. The study’s authors found that this effect accounted for a 0.29 drop in pH, adding to the observed 0.11 pH decline due to traditional ocean acidification.

Most importantly, the researchers found that phytoplankton blooms reduce the ability of the ocean waters to buffer changes in pH, a process which would normally keep any sudden variations in acidity in check. This reduced buffering capacity was worth another 0.05 unit drop in pH, meaning that coastal regions under the effect of human-induced phytoplankton blooms experience ocean acidification even more strongly than you’d expect from either process alone—a divergence that will only increase as atmospheric carbon dioxide levels continue to swell.

Photo: NASA SeaWiFS

Study: Acidification of subsurface coastal waters enhanced by eutrophication, Nature Geoscience

Hydrocosm

13th December 2011

Russian seafloor methane emissions of “a scale not seen before.”

12th December 2011

7th December 2011

Elevated water contamination found in poor Californian neighbourhoods

6th December 2011

Israel’s national water company signed a financing agreement to build a desalination plant, which officials said could allow drought-ridden Israel to export water to its neighbors upon completion in 2013.

5th December 2011

4th December 2011

3rd December 2011

2nd December 2011

1st December 2011