Peat porewater chloride concentration profiles in the Everglades during wet/dry cycles from January 1996 to June 1998: field measurements and theoretical analysis

Abstract

Abstract:Water quality is a key aspect of the Everglades Restoration Project, the largest water reclamation and ecosystem management project proposed in the United States. Movement of nutrients and contaminants to and from Everglades peat porewater could have important consequences for Everglades water quality and ecosystem restoration activities. In a study of Everglades porewater, we observed complex, seasonally variable peat porewater chloride concentration profiles at several locations. Analyses and interpretation of these changing peat porewater chloride concentration profiles identifies processes controlling conservative solute movement at the peat-surface water interface, that is, solutes whose transport is minimally affected by chemical and biological reactions. We examine, with an advection-diffusion model, how alternating wet and dry climatic conditions in the Florida Everglades mediate movement of chloride between peat porewater and marsh surface water. Changing surface water-chloride concentrations alter gradients at the interface between peat and overlying water and hence alter chloride flux across that interface. Surface water chloride concentrations at two frequently monitored sites vary with marsh water depth, and a transfer function was developed to describe daily marsh surface water chloride concentration as a function of marsh water depth. Model results demonstrate that porewater chloride concentrations are driven by changing surface water chloride concentrations, and a sensitivity analysis suggests that inclusion of advective transport in the model improves the agreement between the calculated and the observed chloride concentration profiles.

Dynamic hyporheic exchange at intermediate timescales: Testing the relative importance of evapotranspiration and flood pulses

“…During the rewetting flood pulse, ridge and slough velocities differed by 0.06 cm h −1 , with ridge flow direction negative and slough flow direction positive. Optimized vertical velocities were within the range of other instantaneous and long‐term median vertical pore water velocities measured in interior parts of WCA‐2A using seepage meters and Darcy flux calculations and those modeled at sites within WCA‐2A using a different implementation of the ADM [ Reddy et al ., ] (Table ).…”

“…The degree to which this uptake affects inverse solutions of equation depends on background concentrations of the solute. In the Everglades, Cl − background concentrations are 2 orders of magnitude higher than Br − concentrations, so consistent with previous work in the Everglades [ Reddy et al ., ], we selected Cl − as the preferable tracer for the modified ADM. Supporting this decision, Cl − at the study site exhibited expected patterns of evapoconcentration during the seasonal drydown, while Br − did not.…”

River corridor science: Hydrologic exchange and ecological consequences from bedforms to basins

“…Examples of environmental solute tracers include specific conductivity, Cl − or other major ions [ Mulholland , ; Reddy et al ., ; Larsen et al ., ], and water stable isotopes [ Gooseff et al ., ; Böhlke et al ., ; Hunt et al ., ], which are typically used to quantify inflows from various water sources from outside the main channel. They also may help constrain hydrologic exchange fluxes entering or leaving the main channel if, for example, temporal variations in solute tracer concentrations in main channel propagate into off‐channel or subsurface waters.…”

Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

“…Fulvic acid used here was obtained at site F1 (26121 0 35 00 N, 801 22 0 14 00 W) along a 40-mile transect in the Florida Everglades in Water Conservation Area 2A, discharging into Florida Bay and the Atlantic Ocean [14], using procedures and techniques developed in the US Geological Survey over the past 30 years [15]. Dissolved organic matter in surface water at site F1 is from cattail (Typha domingensis) and sawgrass (Cladium jamaicense) aquatic decomposition products [14,[16][17][18].…”

“…Dissolved organic matter in surface water at site F1 is from cattail (Typha domingensis) and sawgrass (Cladium jamaicense) aquatic decomposition products [14,[16][17][18]. FA isolated at site F1, operationally defined as organic material adsorbed by Amberlite R XAD-8 resin at pH¼2 and eluted from the resin with a 0.1 N sodium hydroxide solution, comprises approximately 96 to 97% FA with the balance being HA [16].…”