Radon-222 and Physical Water Column Parameter Data Concerning Submarine Groundwater Discharge Along the Western Margin of Indian River Lagoon, East-Central Florida-September 2016 to July 2017

Indian River Lagoon (IRL) is one of the most biologically diverse estuarine systems in the continental United States, stretching 200 kilometers (km) along the Atlantic coast of central Florida. The width of the lagoon varies between 0.5-9.0 km and is characterized by shallow, brackish waters with significant human development along both shores.

Scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center, working in collaboration with the St. Johns River Water Management District, mapped surface water radon-222 (radon-in-water) and basic physical water column properties (for example, salinity and temperature) to investigate submarine groundwater discharge at two locations, Eau Gallie North and Riverwalk Park, along the western shore of IRL. Eau Gallie North is near the central section of IRL. Riverwalk Park is approximately 20 km north of the Eau Gallie site. At each study site, the radon mapping surveys were performed over seven north-south shore parallel transects (EA-EG and RA-RG, respectively), situated between 75-1000 meters offshore, and approximately 1.5 km in length. Each transect was mapped three times in an alternating north-south direction. Surface water was continuously pumped on-board into an air-water exchanger; dissolved radon-222 was purged from the water into a gaseous phase inside the exchanger. Radon-222 in the exchanger was continuously pumped into and measured by commercially available radon-in-air detectors (RAD7, Durridge, Inc). In situ surface water temperature and salinity, as well as the water temperature in the exchanger, were also measured. Radon-in-air measurements were corrected to radon-in-water activities using the temperature-salinity dependent air-water partitioning coefficient (Schubert and others, 2012). Starting in September 2016, surveys were conducted bimonthly along the same transects to determine seasonal and temporal variability of radon-222. This data release contains the raw radon-222 data, physical water column data, Esri GIS data files and data distribution maps of the radon-222 activity and surface water salinity collected from September 2016 through July 2017.

Note: This data release was versioned on March 12, 2018. Please see the Suggested Citation section for details.