Friday, November 25, 2011

Early Pollution

Rio Tinto- "Wine-colored River"
Faced with a constant barrage of stories about EPA, fracking, oil pipelines and salmon swimming upstream against human impact, it is easy to think that pollution is a modern phenomenon.  There is strong evidence of worldwide "industrial" pollution with sulfide and heavy metals extending back 4,800 years.

Barry Yeoman's article The Mines that Built Empires* is a fascinating look at the history of the Rio Tinto mines in Spain.  Mining began in the copper age, dated by a 5,000 year old hammer head, used to extract copper ores such as malichite and azurite.  Subsequently the Phoenicians, Carthaginians, and Romans maintained massive mining operations for lead, silver and copper which peaked between 70 and 160 A.D.
Hammer Head 3000 BCE- Archeology Magazine

Back to the global pollution, ice core studies from Greenland in the 1990's show massive lead pollution during the peak Roman mining period.  The cores found that 70% of the lead had the "chemical signature" of Rio Tinto lead.  Smelting the ore in large furnaces released its heavy sulfide content in the form of sulfur dioxide, a residue which remains with us to this day.  Much like oil, when these ancient deposits are brought to the surface, their chemical components don't sink back from whence they came.

The name Rio Tinto came from the wine colored acidic river which runs through the area.  Originally thought to be due to extensive run off of mining contamination, we now know that the colors are natural and existed long before mining began around 3,000 BCE. reports that the average pH of the river is 2.0 and it carries naturally high concentrations iron, copper, and zinc.  It has even been studied by NASA, exploring the  unique organisms which eat its iron and sulfide which have implications for studies on Mars.

*Archeology Magazine, October, 2010.

1 comment:

  1. Great post. It reminds me of sulfer springs and the build up of yellow deposits from thousands of years of percolating through the earth.