Friday, August 28, 2009

Attack of the Killer Green Algae

Algae clean-up in France

Toxic green algae, decaying into a black sludge that releases a noxious gas, recently claimed the life of a horse in France and knocked out the horse's rider:
Decaying ulva algae threatens other beaches around France and the world, from the United States to China, experts say. Last year, the Chinese government brought in the army to remove the slimy growths so the Olympic sailing competition could be held.

In Brittany's Cote d'Armor region, conditions are perfect for its spread — sunlight, shallow waters and flat beaches. Chemical and natural fertilizers like pig excrement, loaded with nitrates and phosphorous, have saturated the land, spilling into rivers and the ocean, feeding the algae that then proliferate.

Harmless while in water, the algae form dangerous gases — notably hydrogen sulfide, with its characteristic rotten-egg smell — when they wash up on land and decay. A white crust forms and traps the gases, which are released when stepped on or otherwise disturbed. Over time, putrefied algae turns sand into a black silt muck, sometimes containing pockets of poison gas.

Apparently, the algae has been around for a while. "A man was found dead on the same beach two decades ago, his arm sticking out from a pile of algae." [LAT] Though the recent levels of algae washing up on the shores of Brittany appear to be unprecedented. Environmentalists are pointing to runoffs from pig and poultry farming.