Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: CONSERVATION EFFECTS ASSESSMENT IN THE SOUTH GEORGIA LITTLE RIVER Title: Pesticide Use and Transport Pathways Within a Coastal Watershed in Southeastern Puerto Rico

Authors
item Potter, Thomas
item Dieppa, Angel -
item Whitall, David -
item Bosch, David
item Strickland, Timothy
item Vega, Jacqueline -

Submitted to: Proceedings of the Watershed Technology Conference and Workshop, Improving Water Quality and the Environment
Publication Type: Abstract Only
Publication Acceptance Date: August 17, 2009
Publication Date: February 21, 2010
Citation: Potter, T.L., Dieppa, A., Whitall, D., Bosch, D.D., Strickland, T.C., Vega, J. 2010. Pesticide Use and Transport Pathways Within a Coastal Watershed in Southeastern Puerto Rico {abstract}. In: Proceedings of the Watershed Technology, Improving Water Quality and Environment. 21st Century Watershed Technology: Improving Water Quality and the Environment. Universidad EARTH, February 21-24, 2010, Costa Rica.

Technical Abstract: In 2007, studies were begun to quantify impacts of agricultural crop production on coastal water quality within the watershed of the Jobos Bay National Estuarine Research Reserve (JBNERR). The reserve is located on Puerto Rico’s southeastern coast and includes sensitive mangrove, sea-grass meadow, and coral reef habitats. In this report we focus on pesticide use and transport. Starting in March 2008, water samples were collected monthly from 5 stations within Jobos Bay and 12 groundwater monitoring wells installed within a 100-ha farm field adjacent to the Bay. Additionally event-based rainfall sampling was conducted. After extraction and concentration, extracts were analyzed for 35 pesticide active ingredients and degradates. In precipitation, detections were sporadic and at trace levels, <0.010 parts per billion (ppb), indicating that wet deposition is not a significant source of pesticides to the Bay. In well samples, two triazine herbicides, atrazine and ametryn and selected degradates of these compounds were routinely detected in the 0.010 to 1.2 ppb range, suggesting that groundwater discharge could result in low-level pesticide transport to the Bay. Notably pesticide levels in all Bay samples were typically below the analytical detection limit, 0.002 ppb, with the exception of one sample that was collected at the Bay station closest to the farm field approximately 4 days after a tropical storm passed through the region in August 2008. Relatively high atrazine concentration, 0.4 ppb, was observed along with a sharp drop in salinity over the days during the storm. Results indicate that extreme events have the potential to contribute substantial pesticide loads through surface runoff to the Bay. This is being taken into account in the conservation plans designed to maintain and improve water quality within the JBNERR.

Last Modified: 10/24/2014
Footer Content Back to Top of Page