Conductivity as a tracer of agricultural and urban runoff to delineate water quality impacts in the northern Everglades

Abstract

Agricultural and urban runoff pumped into the perimeter canals of the Arthur R. Marshall Loxahatchee National Wildlife Refuge (Refuge), a 58,320-ha soft-water wetland, has elevated nutrients which impact the Refuge interior marsh. To best manage the Refuge, linkages between inflows to the perimeter canals and environmental conditions within the marsh need to be understood. Conductivity, which typically is high in the canals and lowest at the most interior sites, was used as a surrogate tracer to characterize patterns of constituent transport. The Refuge was initially classified into four zones based upon patterns and variability in conductivity data: Canal Zone; Perimeter Zone (canal to 2.5 km into the interior); Transition Zone (2.5 to 4.5 km from the canal); Interior Zone (>4.5 km from the canal). Conductivity variability declined from the Perimeter to the Interior Zone, with the highest variability in the marsh observed in the Perimeter Zone and the lowest variability observed in the Interior Zone. Analysis of other water quality parameters indicated that conditions in the Perimeter and Transition Zones were different, and more impacted, than in the Interior Zone. In general, there was a positive relationship between structure inflows and canal phosphorus concentrations, including discharges from treatment wetlands and bypasses of untreated water. This classification approach is applicable for stratified sampling designs, resolving spatial bias in water quality models, and in aiding in management decisions about resource allocation.

Surface Water Sulfate Dynamics in the Northern Florida Everglades

“…Sulfate concentrations are observed to decrease along a gradient from the canal to the marsh interior (Gilmour et al, 2007; Harwell et al, 2008), and this spatial gradient is well characterized by our model despite limitations in input data discussed below. Although model spatial resolution is limited, the low bias during most simulation periods demonstrates that the model quantitatively captures the spatial pattern of sulfate concentration (Table 1).…”

“…1). Observations within the canal are available at outflow hydraulic structures, and monitoring data within the Refuge are available from South Florida Water Management District routine monitoring and research (XYZ) sites (McCormick et al, 2000) and the Refuge's Enhanced Monitoring sites (Harwell et al, 2008; Surratt et al, 2008).…”

COMPOSITION OF EXTRACELLULAR POLYMERIC SUBSTANCES FROM PERIPHYTON ASSEMBLAGES IN THE FLORIDA EVERGLADES1

“…Data are collected as a part of long‐term monitoring of marsh health (McCormick et al. 1998, Harwell et al. 2008).…”

Carbon pool trends and dynamics within a subtropical peatland during long-term restoration

“…Furthermore, the correlation of TN, specific conductance and DIC concentration (Table 4) could suggest evidence of a nutrient subsidy stimulated DIC production. Specific conductivity has been used as a tracer of surface water with higher conductivity water representing higher available nutrient canal water penetrating portions of the marsh while lower specific conductivity water represents interior marsh surface water with relatively low nutrient concentrations (Harwell et al 2008; Surratt et al 2008). The correlation of TN and DIC could be linked to the productivity of periphyton and blue-green algae which fix atmospheric nitrogen during metabolism.…”