Sampling Procedures: 
Three to six transects were taken at each site depending on the visual differences in the sediment’s saturation levels. The first transect at each site was taken at the shoreline with the most saturated transect first and decreasing saturation as the distance from the shoreline increased. Each transect contained three undisturbed surface sediment samples, 1.5 meters apart, in a line parallel to the shore. Samples were collected using an ESS Core N One soil coring device (Environmental Sampling Supply, San Leandro CA, part #LL5035SRNG). 
Sampling dates: September 30, 2022, six transects were taken at each site. December 2, 2022, three transects were collected at site one and four collected at site two. March 27, 2023, three transects were collected at site one and, due to weather conditions and an increase of sinking sand, the shoreline of site two was inaccessible. June 26, 2023, four transects were collected at each site. 


Laboratory Analysis: 
At the lab samples were then stored in a fridge, while not in use, to keep samples stable. The samples were removed from the cores, each disposal coring devices collected approximately 5 g of intact sample and was around 40-65 cm in length. Each sample was separated into a top, middle and bottom layer due to the visual differences of the core and each section was stored in separate, labeled Ziplock bags.
Water content of each layer was determined by drying 0.5 g of sample at 105°C overnight determining the dry weight of the samples using the initial wet weight and the final dry weight. These values were used to determine the water content. 
Total elemental concentration was determined using “Hotblock digestion of Sediments, Sludges, and Soils EPA Method 3050B- Modified for Hotblock Digestion” procedure. Each sample was diluted 1:100, to avoid the high concentration of NaCl to influence the results, and tested levels of metals-ICPMS (Agilent 8900 ICPMSMS).

Data Description: 
- All data are included in the '2022-2023_GSL_AntelopeIsland_Sampling.xlsx' spreadsheet
- Sample collection date: Date samples were collected from the field
- Longitude/Latitude: Location of the transect parallel to the shore. Samples were collected in triplicates along each transect.
- % Wet weight: Determined after drying 0.5 g of sample at 105°C overnight 
- Length of Core section: Reported in milimeters (mm)
- Sample ID: Unique sample ID given for internal Analysis
- Sample Name: Site X TX a/b/c --> Site 1: Bridger Bay; Site 2: White Rock Bay. T1-TN transect numbers from 1 at the shore, and N farthest from the shore; a/b/c given to each sample replicate along each transect
- Conc. [ug/g]: Element concentrations reported on a dry mass basis as micrograms per gram
- MRL: Minimum reporting limit
- MDL: Minimum detection limit
- Color-coding:  Black numbers are quantifiable, Blue are over range (values above the highest standard), Red are below the reporting limit.