HR: 11:50h
AN: H42A-06    [Abstracts]
TI: Presence of Fungicides Used to Control Asian Soybean Rust in Streams in Agricultural Areas in the United States
AU: * Sandstrom, M W
EM: sandstro@usgs.gov
AF: US Geological Survey, PO Box 25046, MS 407, Denver, CO 80225-0046, United States
AU: Battaglin, W A
EM: wbattagl@usgs.gov
AF: US Geological Survey, PO Box 25046, MS 415, Denver, CO 80225-0046, United States
AB: Concentrations of 11 fungicides were measured in stream samples during 2 years in agricultural areas in the United States that grow predominantly corn and soybean. The fungicides are registered for control of Asian Soybean Rust (ASR), which entered the United States in 2004. Many of these fungicides were registered under an emergency exemption because evaluation of environmental risks related to their widespread use on soybeans had not been completed. Some of these fungicides are considered moderately to highly toxic to fish and aquatic invertebrates. We developed a solid-phase extraction and gas chromatography/mass spectrometry method for determining the fungicides at low concentrations (ng/L). Stream samples were collected 2 to 4 times at study areas during the late spring through fall season when fungicides are applied. Six fungicides registered for control of ASR (Phakospora pachyrhizi) in 2005 were measured in streams in Alabama, Georgia, North Carolina, South Carolina, and Mississippi during August-November, 2005. One or more fungicides were detected in 8 of the 12 streams sampled. Azoxystrobin, pyraclostrobin, propiconazole, tebuconazole, and myclobutanil were found in at least one of the 40 samples collected, while chlorothalonil was not found. Azoxystrobin was detected most frequently, in 35 percent of the samples. In 2006, five additional fungicides registered for use in control of ASR were included in the analytical method. One or more of the fungicides (azoxystrobin, pyraclostrobin, trifloxystrobin, metconazole, propiconazole, tebuconazole, tetraconazole, myclobutanil) were detected in 12 of the 16 streams sampled from areas in the South and Midwest during May-September, 2006. Azoxystrobin was detected most frequently (40 percent of the samples) and the highest concentration was 1.1 μg/L in a small predominantly cotton and soybean watershed. The highest concentrations of azoxystrobin were measured prior to the spread of ASR in 2006, and the detections in streams might be related to use on other crops. Concentrations of the fungicides measured were about 100 times lower than aquatic toxicity levels. These results show that ASR fungicides were found in streams before extensive spread of ASR in the United States.
DE: 0496 Water quality
DE: 1803 Anthropogenic effects (4802, 4902)
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2007 Joint Assembly