Welcome, welcome. Monday is here once again right on schedule. The time has come to gather around and take a well deserved hiatus from all the politics of the day. Science talk is here. New discoveries, new takes on old knowledge, and other bits of news are all available for the perusing in today's information world. Over the fold are selections from the past week from a few of the many excellent science news sites around the world. Today's tidbits include current global warming may reverse Atlantic current as it did 20,000 years ago, how ancient plant and soil fungi turned the earth green, land and water management across the U.S. leads to ecological degradation, how lead gets into urban vegetable gardens, and water flowing through ice sheets accelerates warming. Pull up that comfy chair and sit by the fire. There is plenty of room for everyone. Get ready for one more session of Dr. Possum's science education and entertainment.
Featured Stories
Among the many potential effects of continued global warming is a potential reversal of Atlantic Ocean currents.
The Atlantic Ocean circulation (termed meridional overturning circulation, MOC) is an important component of the climate system. Warm currents, such as the Gulf Stream, transport energy from the tropics to the subpolar North Atlantic and influence regional weather and climate patterns. Once they arrive in the North the currents cool, their waters sink and with them they transfer carbon from the atmosphere to the abyss. These processes are important for climate but the way the Atlantic MOC responds to climate change is not well known yet.
...there was a period when the flow of deep waters in the Atlantic was reversed. This happened when the climate of the North Atlantic region was substantially colder and deep convection was weakened. At that time the balance of seawater density between the North and South Atlantic was shifted in such a way that deep water convection was stronger in the South Polar Ocean
Greening of the earth in ancient times took measures of cooperation between plants and soil fungi which are just now beginning to be understood.
The team studied a thalloid liverwort plant, which is a member of the most ancient group of land plants that still exists and still shares many of the original features of its ancestors. They used controlled-environment growth rooms to simulate a CO2-rich atmosphere, similar to that of the Palaeozoic era when these plants originated. This environment significantly amplified the benefits of the fungi for the plant´s growth and so favoured the early formation of the association between the plant and its fungal partner.
The team found that when the thalloid liverwort was colonised by the fungi, it significantly enhanced photosynthetic carbon uptake, growth and asexual reproduction, factors that had a beneficial impact on plant fitness. The plants grow and reproduce better when colonised by symbiotic fungi because the fungi provide essential soil nutrients. In return, the fungi also benefit by receiving carbon from the plants. The research found that each plant was supporting fungi that had an area of 1-2 times that of a tennis court.
The amount of water flowing in 90 percent of U.S. rivers has been lowered by land and water management in recent years.
Flows are altered by a variety of land- and water-management activities, including reservoirs, diversions, subsurface tile drains, groundwater withdrawals, wastewater inputs, and impervious surfaces, such as parking lots, sidewalks and roads.
"Altered river flows lead to the loss of native fish and invertebrate species whose survival and reproduction are tightly linked to specific flow conditions," said Daren Carlisle, USGS ecologist and lead scientist on this study. "These consequences can also affect water quality, recreational opportunities and the maintenance of sport fish populations."
For example, in streams with severely diminished flow, native trout, a popular sport fish that requires fast-flowing streams with gravel bottoms, are replaced by less desirable non-native species, such as carp. Overall, the USGS study indicated that streams with diminished flow contained aquatic communities that prefer slow moving currents more characteristic of lake or pond habitats.
In spite of all precautions taken by their owners urban vegetable gardens may still get contaminated by lead.
Lead contamination in most cities comes from primarily two sources: leaded gasoline and lead paint. Although both sources have been banned, plenty of that lead remains in urban soils all around the raised bed gardens. Roxbury and Dorchester soils have a lot of lead, but they are not unique.
The main suspects in transporting lead into raised beds are wind and perhaps rain, which splatters the ground and can potentially throw fine particles of contaminated soil into the raised beds.
Melt water flowing through crevices, cracks, and other divides in ice sheets may transport heat to the core and accelerate the effects of warming on the ice.
Several factors contributed to the warming and resulting acceleration of ice flow, including the fact that flowing water into the ice sheets can stay in liquid form even through the winter, slowing seasonal cooling. In addition, warmer ice sheets are more susceptible to increases of water flow, including the basal lubrication of ice that allows ice to flow more readily on bedrock.
A third factor is melt water cascading downward into the ice, which warms the surrounding ice. In this process the water can refreeze, creating additional cracks in the more vulnerable warm ice, according to the study.
Taken together, the interactions between water, temperature, and ice velocity spell even more rapid changes to ice sheets in a changing climate than currently anticipated...
Other Worthy Stories of the Week
The ghostly glow of a dead quasar
How can a cloth clean up toxic waste?
Moving holograms: From science fiction to reality
How some plants spread their seeds: Ready, set, catapult
Moving animals may not be a panacea for habitat loss
9 great invasive species worth admiring Photo gallery.
For even more science news:
General Science Collectors:
Alpha-Galileo
BBC News Science and Environment
Eureka Science News
LiveScience
New Scientist
PhysOrg.com
SciDev.net
Science/AAAS
Science Alert
Science Centric
Science Daily
Scientific American
Space Daily
Blogs:
A Few Things Ill Considered Techie and Science News
Cantauri Dreams space exploration
Coctail Party Physics Physics with a twist.
Deep Sea News marine biology
Laelaps more vertebrate paleontology
List of Geoscience Blogs
ScienceBlogs
Space Review
Techonology Review
Tetrapod Zoologyvertebrate paleontology
Science Insider
Scientific Blogging.
Wired News
Science RSS Feed: Medworm
The Skeptics Guide to the Universe--a combination of hard science and debunking crap
Daily Kos regular series:
Daily Kos University, a regular series by plf515
This Week in Science by DarkSyde
This Week in Space by nellaselim
Overnight News Digest:Science Saturday by Neon Vincent. OND tech Thursday by rfall.
Weekend Science by AKMask
All diaries with the DK GreenRoots Tag.
All diaries with the eKos Tag
NASA picture of the day. For more see the NASA image gallery or the Astronomy Picture of the Day Archive.
NGC3256, NASA, Public Domain