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nutrient loading at two coastal creeks in Everglades National Park
Nutrient Loading at Two Coastal Creeks in Everglades National ParkFrom the Florida Bay and Adjacent Marine Systems Science Conference, December 11-14, 2005, Duck Key, Florida Coastal discharge, total phosphorus (TP) and total nitrogen (TKN) concentrations are continuously monitored by the U.S. Geological Survey (USGS) at West Highway Creek (N 25° 14' 33", W 80° 26' 50") in northeastern Florida Bay and North River (N 25° 20' 19", W 80° 54' 47") in Whitewater Bay (see Fig. 1). The product of net 3-day discharge and mean 3-day concentration sampling is used to compute TP and TKN loads between the wetlands and bays from October 1, 2003 through September 30, 2004 (WY 2004). Net loading was predominately from the wetlands into the bays (positive loading). The mean TP and TKN loads at West Highway equaled about +2 and +180 pounds per day (lbs/day) respectively, and +6 and +400 lbs/day at North River (see Fig. 2). Regression-defined models were developed that predict TP and TKN loads solely as a function of discharge and time (see Fig. 3). The loading models were built for "gap-filling" so that annual loads could be estimated. At West Highway Creek and North River, the TP and TKN models reproduced about 80% and 90% of the actual load variability, respectively. Annual "gap filled" estimates of TP and TKN loads were about +808 and +68,952 lbs, respectively, at West Highway Creek. The estimates of TP and TKN loads were +2,024 and +138,808 lbs, respectively, at North River for WY 2004. Nutrient loads were predicted using the regression defined models and alternate water-management scenarios, specifically, retention, detention, and doubling of the discharge from the wetlands into the bays (see Fig. 4). The retention scenario captured net discharge greater than +40,000 cubic meters (m3), resembling a case where excess runoff is captured for underground aquifer storage and recovery as part of the Comprehensive Everglades Restoration Plan (CERP). The detention scenario also captured net discharge greater than +40,000 m3, but released the captured water at a later date so the total measured discharge is conserved. Doubling the positive coastal discharge from the wetlands into the bays may resemble flow conditions upon the removal of upstream canals and levees, or construction of bridges that elevate roadways above upstream wetlands. Loading changes were apparent under the alternative water management scenarios; loads were mostly explained by creek discharge. It is important to note that 2004 was a relatively dry water year, therefore further data collection is imperative to capture year-to-year trends and changes due to CERP water management. Data collection began in 2003 and is ongoing. Data is also being collected at Upstream North River.
1 MAP OF STUDY AREA
PICTURES OF INSTRUMENTATION AND CREEKS
2 CONCENTRATIONS AND LOADING OF TOTAL PHOSPHORUS (TP) AND TOTAL NITROGEN (TKN)
3 REGRESSION MODELS USED FOR GAP-FILLING AND WATER-MANAGEMENT SCENARIO TESTING
4 LOADING FROM WATER MANAGEMENT SCENARIOS
SUMMARY OF LOADING SCENARIOS
For More Information: Paul Stumpner
Barclay Shoemaker
Mark Zucker
Related information: SOFIA Project: Coastal Gradients of Flow, Salinity and Nutrients |
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U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 05 September, 2006 @ 07:25 AM (KP)
