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A screening level risk assessment of metal and organic contaminants in the Everglades National Park, Biscayne National Park and Big Cypress National Preserve (South Florida, USA)
Citation:
Carriger, John F. A screening level risk assessment of metal and organic contaminants in the Everglades National Park, Biscayne National Park and Big Cypress National Preserve (South Florida, USA). Presented at The 4th International Conference on Environmental Pollution, Restoration, and Management, Quy Nhon, VIETNAM, March 03 - 07, 2024.
Impact/Purpose:
This presentation will provide information on an ecological risk assessment done with a large data set of contaminant concentrations collected in South Florida, particularly in and adjacent to protected areas such as Everglades National Park. From the database, several metal and organic contaminants were selected for risk evaluation (i.e., DDT, endosulfan, arsenic, chromium, copper, lead, zinc). Metals were examined in sediment and water and organic contaminants were examined in fish tissue, sediment and water. Methods compared existing information on species effects with the measured contaminant concentrations in the environment grouped by regions for Biscayne Bay, Big Cypress, Florida Bay, Taylor Slough, Shark River Slough and boundary regions near urban and agricultural locations and fish species for pesticides. Risk characterization examined exceedances of toxicity values by contaminant exposure benchmark concentrations and ranked environments based on potential risks. Higher freshwater risks were found in ecosystems bordering human communities (e.g., endosulfan and agriculture) and marine regions had the highest risks from copper in Biscayne Bay saltwater sediment, also near urbanized areas. The presentation demonstrates an exploration of contaminant monitoring data and interpreting in terms of existing information on effects from ecotoxicity endpoints.
Description:
South Florida is a subtropical environment with diverse ecological and human communities that rely on a complex water system undergoing the costliest restoration in U.S. history. Pesticide and metal input to the aquatic systems of South Florida can impact the capabilities of maintaining a clean environment for ecological systems, especially for populations and communities that are susceptible to adverse effects from constant or repeated exposures. An ecological risk assessment was conducted using specially collected data to examine and compare risks for diverse regions of the South Florida environment. Compounds selected for the current risk assessment were ones that had sufficient detections, toxicity data, and have been found to be of ecological concern in past risk assessments in South Florida or other recent risk assessments. Metals (arsenic, chromium, copper, lead, zinc) concentrations in water and sediment and pesticide (DDT, endosulfan) concentrations in water, sediment and fish tissue collected from wild specimens were assessed. Methods followed a standard probabilistic ecological risk assessment approach to compare existing ecotoxicological information with measured exposure concentrations grouped by regions for Biscayne Bay, Big Cypress, Florida Bay, Taylor Slough, Shark River Slough and boundary regions near urban and agricultural locations and through use of a multiple substance aggregation used in probabilistic risk assessment. Fish tissue comparisons for DDT and endosulfan were also made on a species basis. Risk characterization found that most of the higher risks were prevalent for sediment, with the exception of DDT, endosulfan and zinc which had higher surface water risks. Higher freshwater risks were found in ecosystems bordering human communities (e.g., endosulfan and agriculture) and marine regions had the highest risks from copper to mollusks and arthropods in Biscayne Bay saltwater sediment. Additional scenarios are examined along with a discussion of limitations. Urban regions with sensitive ecosystems like South Florida would benefit from continual and targeted monitoring with periodic ecological hazard and risk assessments to ensure water quality that is beneficial for both human and ecological systems.