Everglades phosphorus limits on the right track, but more...( DURHAM N.C. State and federal stand...)

DURHAM, N.C. State and federal standards for phosphorus releases into the Everglades seem sufficient to protect the huge wetlands resident plants and animals from damage, but pollutant levels still reach double or triple safe levels near some of the Everglades outer edges.

A six-year study led by Duke University scientists tracked how various phosphorus levels affected natural communities in two research sites inside the Everglades.

In an Oct. 24, 2007 report in the online edition of the research journal Environmental Science and Technology, the studys authors conclude that current standards protect the wetland. But they warn high phosphorus levels persist in the outer edges of the Everglades despite the construction of nearly 40,000 acres of storm water treatment areas to reduce the harmful effects of nutrient runoff from development and agriculture.

"Theyve made significant strides in reducing the amount of phosphorus input," said Curtis Richardson, a professor of resource ecology at Dukes Nicholas School of the Environment and Earth Sciences and the studys first author. "But a lot of work remains to be done to meet the criteria that they set."

Phosphorus is the key ingredient in fertilizers applied by the agribusinesses and housing subdivisions that have spread in an arc around the Everglades. It is carried in rainwater runoff into the wetlands, where scientists suspect it can harm organisms even in very small doses.

In response to this threat, regulators have begun massive efforts to reduce phosphorus levels by impounding and treating flood waters and encouraging best management practices on upstream farmlands.

Florida and U.S. Environmental Protection Agency guidelines limit phosphorus levels to 10 micrograms (millionths of a gram) per liter of water over a five-year period. Peaks as high as 15 micrograms over a years time are allowed at individual measuring sites.

In a study supported by th
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