[Pollinator] Development May Spread Old Pesticides

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Development May Spread Old Pesticides

February 20, 2006 — By Associated Press


 HANOVER, N.H. — Development of former farmland can disturb pesticides spread 
nearly a century ago and contaminate nearby water sources, according to a 
study by researchers at Dartmouth College.

The findings mean communities may need to take additional precautions when 
the soil at former orchards and farms is disturbed for development or new 
agricultural uses, Carl Renshaw, a professor of earth sciences, said in a news 
release.

The problem is that pesticides spread during the early 1900s contained both 
arsenic and lead, which researchers have found remain in the top 10 inches of 
soil. The study results appear in the January-February issue of the Journal of 
Environmental Quality.

But the study, which focused on two New Hampshire apple orchards where the 
pesticide lead arsenate once was used, found that over time these toxic metal 
change form and become part of the silt and organic matter in the soil.

In that new form, the metals become more susceptible to erosion, which can be 
accelerated by development.

"We continue to learn more about how past agricultural practices are 
affecting our current environment," Renshaw said. "Unlike some pesticides used today, 
metals like arsenic and lead in old pesticides do not degrade over time."

The study found that when disturbed, these metals can make their way into 
nearby surface water. It was unclear whether plants and animals that feed off 
that water are absorbing the metals, Renshaw said.

"While the arsenic and lead in the soils of old orchards is essentially 
immobile as long as the land is not disturbed, our work suggests that the 
development of these lands can inadvertently mobilize these metals toward bodies of 
water," he said.

"Communities in these areas may want to ensure additional precautions are 
taken to control erosion when old orchard lands are disturbed in order to reduce 
the potential for contamination of nearby surface water," Renshaw said.

Source: Associated Press
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