Summary

Description

Surface water and sediment contamination of the Loxahatchee National Wildlife Refuge Refuge is a management concern given the proximity of both agriculture and urban development to the Refuge. This study was undertaken to determine baseline data for contaminants present in, and entering into, the Cypress Swamp Swamp of the Refuge. The Swamp is a Refuge area outside Water Conservation Area 1 and its bordering perimeter canal. The Swamp directly receives surface water inflow from adjacent agricultural areas. Water and sediment samples were collected from eight locations during the threeyear study 20012004. Surface water grab samples were collected quarterly for determination of pesticide and metal concentrations. Water samples were collected monthly for determination of phosphorous and chloride concentrations. Composite sediment samples were collected annually for determination of pesticide, metal, and PCB contamination. Metal and pesticide concentrations were compared to the state of Floridas surface water quality criteria and sediment quality assessment guideline SQAG values for potential contaminant risks to the Refuges ecosystem resources. Several metals beryllium, copper, iron, mercury, lead, selenium were detected at least once in surface waters at a concentration that exceeded their respective surface water quality criteria. The most commonly detected metal, and the one most likely to lead to aquatic system impacts, was copper. While several pesticides were detected in the surface water, few criteria values exist for pesticides and none existed for those detected in this study. Barium, chromium, copper, mercury, and lead were detected in sediments at concentrations exceeding SQAG values for effects to benthic invertebrates. Copper was detected at a concentration as high as 481 mgkg dw, which exceeded the probable effects concentration and may lead to aquatic system impacts. Average concentrations were considerably less but still exceeded the threshold effects concentration. Most of the organic contaminants detected in sediments were the banned persistent pollutants, DDE and chlordane. Food chain modeling to predict risks to the aquatic community and piscivorous birds from DDE and chlordane predicted adverse effects only for the aquatic community. Total phosphorous concentrations ranged from 55 to 4,469 gL while orthophosphate concentrations ranged from 32 to 3,970 gL. Total chloride concentrations ranged from 13 to 118 mgL. The high phosphorous and copper concentrations along the eastern side of the Swamp, along with detections of current use pesticides in Swamp water, indicate the Swamp was being impacted by inflow of waters from adjacent agricultural areas.