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Contaminants in City Soil Found Similar to Industrial Sites

Students take soil samples in Cedar Rapids following the 2008 floods (University of Iowa).

Students take soil samples in Cedar Rapids following the 2008 floods (University of Iowa).

Engineers at University of Iowa in Iowa City tested residential soil in nearby Cedar Rapids after the city flooded in 2008 and found industrial pollutants similar to those found at industrial sites. The findings appear in the online issue of the journal Environmental Pollution (paid subscription required), and scheduled to appear in print in the February 2012 issue.

Civil and environmental engineering professor Keri Hornbuckle, who led the research, says the study is one of the first in the U.S. to test residential soil samples for the industrial pollutants polychlorinated biphyenyls (PCBs) and chlordane. The soil samples used in the research were taken in August 2008 about 70 days after record floods in Cedar Rapids that affected a large portion of residential, commercial, and industrial land in the city.

PCBs were widely used as coolants in electrical transformers and in a wide variety of products ranging from waterproofing compounds to paints and pesticides. In the 1970s, PCBs were banned due to their toxicity and persistence in the environment. Chlordane was used to control termites in buildings and as insecticides on lawns and gardens, as well as on corn and other crops, before the EPA banned its use in 1988.

Iowa researchers took 66 soil samples from about four square miles near Cedar Rapids streets. Each sample consisted of about two pounds of soil dug from a five-inch deep site, placed in plastic freezer bags and brought to the university, where they were refrigerated prior to being analyzed.

Nearly all (94%) of the sample sites were located inside the flood area, with researchers focusing on an area south of Cedar Lake and west of the Cedar River. Cedar Lake, which also flooded in 2008, is used as a cooling pond for an electrical power generating station and is known to be contaminated with chlordane and PCBs. The samples were tested for chlordane with gas chromatography and mass spectrometry. The researchers used mass spectrometry to test for PCBs.

The tests showed the presence of both chemical groups in quantities similar to other urban and industrial sites around the world. The measurements were also found to be of the same order of magnitude as the provisional threshold recommended by the U.S. Environmental Protection Agency to perform soil remediation.

Hornbuckle, who grew up in Cedar Rapids, says that residents of this city and others should know that these chemicals are widely present in urban soils. She adds that the source of the PCBs found in Cedar Rapids soils is unknown, but that the presence of chlordane is probably the result of the chemical used in the insecticide to kill termites, with the original contamination occurring more than 30 years ago.

Read more: Mercury Found in Soil Near Central Indiana Coal Power Plants

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