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Gold and Amazon Deforestation

Small-scale miners create large-scale devastation, mercury pollution in headwaters

amazon gold mining.jpg
An aerial view of the devastation of small-scale gold mining in the Peruvian Amazon. Credit:

in parts of the Peruvian Amazon has increased six-fold in recent years as small-scale
miners, driven by record gold prices, blast and clear more of the lowland rainforest,
according to a new Duke University-led study.

The study,
published today in the online journal PLoS ONE, combined NASA satellite imagery
spanning six years with economic analyses of gold prices and mercury imports to
document the forces responsible for deforestation in Peru's biologically diverse
Madre de Dios region.

7,000 hectares, or about 15,200 acres, of pristine forest and wetlands were cleared
at two large mining sites between 2003 and 2009, with a dramatic increase in
deforestation occurring in the last three years.

addition to these two large sites, there are many scattered, small but
expanding areas of mining activity across Madre de Dios that are more difficult
to monitor but could develop rapidly like the sites we've tracked over time,"
says Jennifer Swenson, assistant professor of the practice of geospatial
analysis at Duke's Nicholas School of the Environment.

of the deforestation visible in the satellite images has been caused by unregulated,
artisanal mining by miners who are often among the poorest and most
marginalized members of their society.

are small-time miners; there is no big 'Goliath' mining company to blame," Swenson
says.  The miners often lack modern
technology, have limited knowledge of mining's environmental or human health
effects and rarely have safeguards to limit the release of the mercury they use
to process their gold into the air, soil or water.

mining has occurred in the region since the time of the Incas, but the recent
record-setting rise in gold prices, which now exceed $1,400 an ounce, has
shifted its pace into hyperdrive, she says. The mining "is now plainly visible
from space," Swenson says. "At the two sites we studied, Guacamayo
and Colorado-Puquiri, nearly 5,000 acres were cleared in just three years,
between 2006 and 2009, largely outpacing nearby deforestation caused by human

cleared for mining has a different spectral signature on satellite images,
allowing Swenson and her team to differentiate it from deforestation caused by
farming, road-building or other settlement-related activities.

of the gold mined artisanally in Madre de Dios comes from alluvial deposits in the
channels and floodplains of Amazon tributaries.  Miners blast away river banks and clear
floodplain forests to expose potential gold-yielding gravel deposits and use
mercury to process the gold ore.

mercury contaminates local water and soil, and ravages the nervous system of
miners and their families, but the risks extend far beyond the local area, Swenson
says. Small-scale gold mining is the second-largest source of mercury pollution
in the world, behind only the burning of fossil fuels. Mercury from artisanal
mines can travel hundreds of miles in the atmosphere or in surface waters --
eventually settling in sediments and moving up the food chain into fish,
fish-eating wildlife and humans.

all mercury imported to Peru is used for artisanal gold mining and imports have
risen exponentially since 2003, mirroring the rise in gold prices," Swenson
says.  "Given the rate of recent increases,
we project mercury imports will more than double by the end of 2011, to about 500
tons a year."

been difficult for Peru's government to monitor and control all artisanal
mining within its borders, she says, but another approach, worth considering,
may be to be start limiting mercury imports.

Swenson's co-authors were
Catherine Carter of Tetra Tech Inc. in Research Triangle Park, N.C.; Jean-Christophe
Domec of Duke's Nicholas School; and Cesar Delgado of the Environmental Affairs
Office in Lima, Peru. Carter earned a Master of Environmental Management (MEM)
degree from the Nicholas School in 2010. Delgado earned an MEM from the
Nicholas School in 2008.