WASHINGTON, Aug. 20 (UPI) — A U.S. study of a Maryland river that flows into Chesapeake Bay has found worryingly high levels of nitrogen and copper, researchers say.
Water tests in the Choptank River, a major tributary of the bay, registered high levels of both pollutants, a U.S. Department of Agriculture release said Friday.
The study was conducted as part of the Conservation Effects Assessment Project. The project, started in 2004, focuses on the effects of conservation practices and Farm Bill conservation programs on 37 watersheds nationwide, the USDA said.
Sampling the water every two months for three years, the scientists found nitrate concentrations in the river often exceeded levels that can cause algal blooms.
Nitrate concentrations were highest at the headwaters where farming is concentrated, suggesting that agricultural fertilizers are primary sources.
High copper concentrations were found in almost all samples at the lower reaches of the Choptank, but not in the upstream areas, suggesting agriculture is not the primary source.
One possible source for copper could be anti-fouling paint used on boat hulls, experts say.
The levels were high enough to be toxic to clams and other aquatic invertebrates that help feed and filter the bay, the study said.
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