Figure 1: Location map showing the study area, sampling-site locations, and tracklines where continuous resistivity profiling (CRP) data were collected.

Figure 2: Bloom of Cladophora sp. macroalgae in Nauset Marsh, Cape Cod National Seashore, June 13, 2004. Photo by Marcus C. Waldron, USGS MA-RI Water Science Center.

Figure 4: 3D view created using Fledermaus software showing onshore topography and offshore resistivity values from the 2004 CRP survey lines collected closest to the shore in the Atlantic Ocean. Resistivity values are in ohm-m.

Figure 5: Flow diagram of the steps involved in processing CRP data.

Figure 6: Oblique aerial view of Salt Pond and Nauset Marsh (Salt Pond Bay) facing toward the southeast. Salt Pond Visitor Center, Cape Cod National Seashore, is visible in the lower left corner, and U.S. Route 6 can be seen in the lower right corner. Photo by Barbara Dougan, National Park Service, Cape Cod, Massachusetts.

Figure 7: The USGS ATV-mounted drilling rig used to advance an electrical conductance probe and piezometers for ground-water sampling was operated from a contract barge platform, shown here on a mudflat in Nauset Marsh during low tide. Photo by John Bratton, USGS Woods Hole Science Center.

Figure 8: Geoprobe System's Direct Image Electrical Conductivity equipment including slide hammer, probe, probe rod, probe cable, power source, and field computer. Photo by Timothy McCobb, USGS MA-RI Water Science Center.

Figure 9: Operating the EC field computer at Salt Pond, Cape Cod, MA. Photo by John Bratton, USGS Woods Hole Science Center.

Figure 10: Electrical conductance profiles from each of the probe locations indicated in Figure 3. The Y-axis is the depth below the surface in meters, with the X-axis representing the electrical conductance in mS/m (millisiemens per meter). Click on the image for a larger version of the plot.

Figure 12a: Profiles of concentrations of nitrogen species (ammonium [NH₄⁺, measured as NH₃], nitrate/nitrite [NO₃^-/NO₂^-], and total dissolved nitrogen [TDN]) in ground water for samples collected from piezometers (see Figure 3 for locations). Profiles are plotted in order from the northernmost (left) to southernmost (right).

Figure 12b: Profiles of concentrations of phosphorus species (phosphate [PO₄^3-] and total dissolved phosphorus [TDP]) in ground water for samples collected from piezometers (see Figure 3 for locations). Profiles are plotted in order from northernmost (left) to southernmost (right).

Figure 13: The contract boat used for collecting vibracores is shown here prior to launching at the Salt Pond boat ramp. The boat was equipped with a frame for supporting coring tubes and vibrations apparatus, as well as a moon pool that allowed coring to be done through the hull of the boat beneath the frame. Photo by Dann Blackwood, USGS Woods Hole Science Center.

Figure 14: Vibracores were returned to shore immediately after collection, split, and described as shown here. Photo by Dann Blackwood, USGS Woods Hole Science Center.