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Greater Everglades carbon and mercury flux assessments - Everglades National Park and Big Cypress National Preserve

Project Chief: Edwardo Patino
Cooperator: USGS Greater Everglades Priority Ecosystem Science (GEPES) Initiative
Period of Project: October 2012 - Sept 2017

Figure 1. Map of study area

Figure 1. Map of the study area

USGS CFWSC employees collecting water samples

USGS CFWSC employees collecting water samples used to develop surrogate models for carbon and mercury concentrations at S-12D monitoring station along Tamiami Trail.

Problem Statement

Continuous and long-term hydrologic data collected throughout the Everglades ecosystem is essential to the development of restoration strategies and for the evaluation of restoration results. Carbon and mercury are two constituents of interest for Everglades restoration. Even though both carbon and mercury have been extensively studied in the Florida Everglades, there are no long-term (years) records of continuous (daily) concentrations of these constituents. When used as proxies, long-term continuous (time-series) sensor data can be used to estimate carbon and mercury concentrations, helping describe short and long-term variability. Continuous data on carbon concentrations, coupled with concurrent discharge records, can help describe the lateral carbon flux, which when linked to atmospheric carbon flux information, can be used to calculate the carbon budget for selected watersheds within the greater Everglades


The objectives of this study are to

  1. develop and document empirical models to estimate carbon and mercury concentrations and loads at selected locations within the Greater Everglades;
  2. develop carbon budgets in water to describe lateral transport mechanisms at selected areas within the Greater Everglades;
  3. link lateral carbon flux estimates in water with atmospheric carbon flux measurements to calculate total carbon sequestration or export from selected areas within the Greater Everglades (fig. 1).


Data from sensors that measure the fluorescence of dissolved organic matter (FDOM) have been used by Bergamaschi and others (2012) in the coastal Everglades to estimate both dissolved organic carbon (DOC) and mercury concentrations. Laboratory results and sensor data collected for this study will be used in the development of empirical models for estimating DOC, particulate organic carbon (POC), dissolved inorganic carbon (DIC), particulate inorganic carbon (PIC), and total and methyl mercury (dissolved and particulate) concentrations at selected locations within the Greater Everglades.

Collection of continuous sensor data
Sensor data collection at Tamiami Trail Control Structure S-12D, Tamiami Trail at Bridge-105, and Sweetwater Strand at Loop Road includes continuous (15-minunte interval) measurements of water level, discharge, temperature, specific conductance, turbidity, and FDOM.

Collection of synoptic samples
Synoptic sampling at Tamiami Trail Control Structure S-12D include samples for DOC and for particulate and dissolved total and methyl mercury. Synoptic sampling at Tamiami Trail at Bridge-105 and Sweetwater Strand at Loop Road include samples for POC, DOC, PIC and DIC.

Empirical model development
Empirical models will be developed by performing regression analyses between proxies for constituents of interest (measured using continuous sensors) and the constituents of interest (derived as laboratory results from synoptic samples described above).

Load computations
Carbon and mercury loads into Everglades National Park at Control Structure S-12D will be calculated using estimated constituent concentrations and available discharge records for this location. Lateral carbon transport will be determined by the difference between load at the inflow section (Tamiami Trail) and load at the outflow section (Loop Road) of the study area.


Bergamaschi, B.A., Krabbenhoft, D.P., Aiken, G.R., Patino, Eduardo, Rumbold, D.G., and Orem, W.H., 2012, Tidally driven export of dissolved organic carbon, total mercury, and methylmercury from a mangrove-dominated estuary: Environmental Science and Technology, v. 46, no. 3, p. 1371-1378.

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