TRANSPORT OF THE HERBICIDE ATRAZINE WITHIN WATERS OF MAMMOTH CAVE NATIONAL PARK

Atrazine (2-chloro-4-ethylamine-6-isopropylamino-S-triazine) is a triazine-class herbicide that is used widely in Kentucky to control broad-leaf and grassy weeds in corn cultivation. It is classified as a Restricted Use Pesticide, and since 1994 has been the subject of a Special Review by the US Environmental Protection Agency to better understand potential human and ecological health effects. The US Environmental Protection Agency’s Maximum Contaminant Level (MCL) for atrazine allowable in treated drinking water is three parts per billion (ppb), and recently attention has been drawn to potential developmental impacts within amphibians at levels up to 30 times lower than the MCL.

Although atrazine is used widely throughout south central Kentucky during the spring application season, Mammoth Cave National Park represents 21,300 hectares where no atrazine is applied. Thus, to the extent atrazine occurs within the park, transport mechanisms are identified. A one day “snapshot” of Park waters was made just after the end of the spring 2003 application season on June 10, 2003, using immunoassay analysis with a detection limit of 0.04 ppb, which includes atrazine and smaller amounts of related triazines. Triazines were found to be nearly ubiquitous. Of 25 samples analyzed, 22 (88%) were positive, and detections were found in all classes of water sampled. Mean levels are reported in parentheses as follows: rainfall collected from depression storage (0.29 ppb), surface streams and rivers (1.32 ppb), major underground rivers (0.92 ppb), regional springs (1.38 ppb), Haney Limestone Springs (0.06 ppb), ponds (0.09 ppb), and other small springs (0.14 ppb).