Rain falling over Kansas and other farm states contains traces of herbicides that may cause long-term damage to plants, preliminary results of a government study say.
The rain is not harmful to animals or humans, said Donald Goolsby of Denver, one of four U.S. Geological Survey scientists conducting the 18-month study of herbicides in rainwater.
The $350,000 study, which is being conducted at the Lawrence USGS office, is expected to be completed in September.
Michael Pomes, a hydrologist at the USGS office in Lawrence, was the project's manager and developed the method to analyze the samples.
He said emissions from Midwest power plants are causing acid rain in the Northeast. And herbicides found in rainwater are showing up in the New York area, he said.
The scientists evaluated a 23-state region stretching from Kansas to the Canadian border and as far east as Virginia. Sites were tested for traces of 11 herbicides.
Samples in Kansas were taken from the Konza Prairie near Manhattan, Scott County in the southwest and Crawford County in the southeast.
The highest trace amounts were found in Kansas, Nebraska, Iowa, Illinois and Indiana, the study said.
Traces of atrazine and alachlor, two of the most common herbicides used to kill weeds in row crops, such as corn, milo or soybeans, were the most commonly found, the study said.
Farm chemicals applied to fields that are not absorbed into the ground can either vaporize into the air or attach themselves to dust particles blown into the air, later returning to the ground in rainfall, researchers said.
Herbicides applied on fields in the Midwest can travel through the air for hundreds of miles and frequently appear in rainfall along the Canadian border, the study said.
Mike Thurman, a research hydrologist with the USGS in Lawrence and another scientist working on the study, theorized this may explain where acid rain in the Northeast originated.