What’s Up, (re)Dox? Hydrologic modeling of Arsenic contamination in Boca Raton, Florida

Authors: D.S. Monty Watson*, Florida Atlantic University, April A Watson*, Lynn University
Topics: Water Resources and Hydrology, Geographic Information Science and Systems, Environmental Science
Keywords: Arsenic, groundwater, hydrology, modeling, GIS, contaminant, hydrogeology
Session Type: Poster
Day: 4/5/2019
Start / End Time: 3:05 PM / 4:45 PM
Room: Lincoln 2, Marriott, Exhibition Level
Presentation File: Download


Arsenic is a naturally-occurring metallic element that has been used by humans for thousands of years as a pesticide. It is the primary contaminant of concern at the Ocean Breeze Maintenance Area site, at the larger former Ocean Breeze Golf Club in Boca Raton, Florida. Initial sampling showed Arsenic in groundwater; however, though alleged, dumping by vandals was later shown to be unlikely based on the persistent, moderate concentrations and depth of impacted groundwater (8-12 feet below land surface), and without intervening soil impacts. Despite this, elevated concentrations of Arsenic have been detected in on-site monitor wells since 2011. Why did Arsenic concentrations increase after the onset of monitoring, despite the apparent absence of source material? We attempted to solve this problem by constructing a hydrologic model of the Ocean Breeze site, to determine first the flow of the water in the area and the source of the Arsenic contamination. Our results revealed a plume of Arsenic contaminated water in the direction of the natural groundwater flow, which is important as no upgradient source has been identified in another monitor well, or in surface water or sediment in a nearby pond. Likewise, no natural source of Arsenic had been determined. Sampling and monitoring at this site has determined that contamination does not appear to be the result of golf course operations or illegal dumping. Further study is ongoing at this time, focusing on the potential for oxygenation of buried, native sediments to release the Arsenic observed in monitor well samples.

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