Saturday, November 13, 2010

thirst for water

Back on Nov. 2, Green Inc. blog posted an article describing the amount of sealevel rise that can be attributed to human use of groundwater.  The story summarizes some recent publications that suggest that 25% of the rise in sea level seen is due to pumping groundwater.  The idea is simple - we dig wells, pump out ground water, use that water for agriculture etc., and then it drains eventually into the ocean.  But the magnitude of this effect had not been estimated previously.  Many areas of the world grow food using ground water - and unfortunately we are discovering that this is an unsustainable process, because the groundwater is not being recharged as quickly as we are pumping it out.  Eventually the removal of all that water from the ground will run the tap dry - at least in some areas locally or regionally.  And if the water runs out, and there is no other source, and the food doesn't grow, and there is nothing to eat, .... well it ain't pretty.

Wednesday, November 10, 2010

Rare Earths Indeed

Today the New York Times has an article on Rare-Earths.  No, not planets - elements.  The group of elements known as Rare Earth Elements (REEs), otherwise known as the Lanthanides.  REEs are found way down near the bottom of the periodic table - in that strange extra couple of rows that are usually ignored by people who aren't into chemistry.  Below the REEs are the actinide elements - which include the two highly radioactive elements Uranium & Thorium.

But REEs are extremely useful elements, having many different commercial applications - computer memory chips, superconductors, fiber optics, lasers, and many others.  However, access to REEs has been extremely limited in the past year since China, which mines ~95% of the world's REEs, imposed a ban on exporting these valuable elements.  The article in today's NYTimes is on the discovery that certain nodules at the bottom of the ocean - called manganese nodules - many contain REEs, enough to make them profitable for mining.

Manganese nodules have been known about for decades - they occur as small little balls of rocky material at the ocean floor, roughly the size of a softball.  Access to them, however, is technologically difficult, and mining them for, guess what, manganese, has not been terribly successful financially.  The presence of REEs in these nodules, however, might push them over the top economically.

If these do become economically profitable, it would be a new source for these valuable elements.  However, mining the deep seafloor is costly, not only in dollars, but in potential environmental damage to marine life, and also in terms of international relations.  After all, who owns the seafloor?  Who has the rights to mine it?  These questions will continue to be driven by our thirst for goods.

Friday, November 5, 2010

Drilling for Past Climate in an Arctic Lake

Wired Science from a couple of days ago has a story on drilling in an arctic lake.  Here's my quick synopsis: the lake is at extremely high latitude, above the Arctic circle, and is extremely remote - the nearest town is about 55 miles away.  The lake was formed 3.6 million years ago by a meteorite impact - it is an old crater, now filled with water.  But the drilling in this lake has nothing to do with the meteorite, or some natural resource - the drilling is being done in order to learn more about how Earth's climate has changed in the past ~3 million years.  The lake sediments at the bottom record a near continuous record, giving scientists a fantastic window into understanding how the Earth has warmed and cooled in that time period.   The core collected from the lake sediments also contains at least 10 layers of volcanic ash, erupted over time by a nearby southerly volcano.  The core will be compared to other cores from different areas to understand what can be gleaned from it about Earth's climate.