ABSTRACT
Pesticide application is widespread in South Florida. After application, pesticides can reach the surrounding aquatic system through aerial deposition, field runoff, and groundwater discharge, raising concerns regarding risks to the environment. In this study, the occurrence and distribution of 17 organonitrogen pesticides (ONPs) was performed in surface waters within the Everglades National Park (ENP), Biscayne National Park (BNP) and Big Cypress National Preserve (BICY). Atrazine and metolachlor were the most frequently detected compounds in surface water. The highest level of herbicides was observed at the Tamiami Trail (TT) and the S178 structure, both areas suffering strong anthropogenic impacts. Although the seasonal pesticide distribution showed the highest levels following months after pesticide use, the high average concentration at TT in the dry season suggests potential of run-off. In order to evaluate the areas of potential contamination and which herbicides represent a major risk to the aquatic environment, a contamination index was developed based on the 85th percentile of the concentrations. Even though the observed levels are not expected to be toxic or cause any ecological impacts, its important to monitor these herbicides in the aquatic system, especially atrazine, due to its teratogenic effects in animals.
