Sediment sample analysis data from ponds to the beach on North Core Banks, NC in October 2022

Sand was collected with a small spade from the upper 2 cm of the sample site and placed into a labeled plastic bag for grain-size analysis. Samples at each site (New Pond 0, 1, and 3) were taken on a shore-perpendicular profile from the pond or channel edge to the ocean side waterline, targeting changes in topography and visually distinct changes in the sand. Two additional samples were taken using a grab sampler deployed from two kayaks on New Pond 1. Samples were stored in a cooler. The dates of the sample collection are provided in the CSV file, the process data provided here is the last day of collection. A picture was also taken of the surface where the sand was collected with a quarter for scale (see larger work citation SandSnap grain-size data and photos).

The samples were analyzed in the sediment laboratory at the USGS Woods Hole Coastal and Marine Science Center using the HORIBA LA-960 laser diffraction unit and sieving of the ≥ -2 phi fraction. Samples submitted to the sediment laboratory for grain-size analysis were assigned unique analysis identifiers (ANALYSIS_ID). Each batch is entered into a Microsoft Excel data entry spreadsheet (LD Worksheet Template_JO01.xlsx, where JO01 is the identifier assigned to the sample submission) to record the initial and dried sample weights, as well as the sieved coarse fraction weights. Each batch was also entered into macro-enabled Microsoft Excel data entry spreadsheets (GrainSizeWorksheet_LD1-30_JO01(batch_yy).xlsm or GrainSizeWorksheet_LD31-60_JO01(batch_yy).xlsm, where "LD1-30” and “LD31-60” refer to the pre-labeled and weighed glass laser diffraction vials in which the samples will be run, and “batch_yy” refers to the sample batch) to record the measurement data coming from the laser diffraction unit and incorporate the initial, dried, and sieved weights.
About 10-15 grams of wet sediment were placed in a pre-weighed beaker and the gross weight was recorded. The sample was wet sieved through a 4 mm (No. 5) sieve. If there was any coarse fraction remaining in the sieve, the coarse material was oven dried at 100°C in a pre-weighed beaker and weighed again when dry. This coarse fraction was dry sieved to determine the individual weights of the -2 to -5 phi fractions, and the weights were recorded in the data entry spreadsheet LD Worksheet Template_SS05.xlsx. The fine fraction in water was collected in a pre-labeled and weighed glass laser diffraction vial. If there was any coarse fraction remaining in the sieve from wet sieving, this vial was also oven dried at 100°C and weighed when dry. If there was no coarse fraction remaining from wet sieving, the sample proceeded directly to processing for analyses by the HORIBA LA-960 laser diffraction unit.
Fine fractions ready for analysis by the HORIBA laser diffraction unit were rehydrated with distilled water if they had been dry. Fifteen (15) ml of pre-mixed 40 g/l sodium hexametaphosphate [(NaPO3)6] was added to each sample. If the height of the fluid in the laser diffraction vial was less than 5 cm, more distilled water was added to raise the level to no more than 8 cm in the vial. The samples were gently stirred, covered, and allowed to soak for at least 1 hour (for samples that were not dried) or up to 24 hours (for samples that were dried). Soaked vials were placed into an ultrasonic bath and run for 10 minutes at a frequency of 37 Hz with a power level of 100. If the samples appeared to be fully disaggregated, they were placed into pre-determined autosampler locations and were run using the HORIBA LA-960 for Windows software to get the fine fraction grain-size distributions. The fine fraction distribution data was added to the appropriate data entry spreadsheets (GrainSizeWorksheet_LD1-30_JO01(batch_yy).xlsm or GrainSizeWorksheet_LD31-60_JO01(batch_yy).xlsm). The spreadsheet was used to calculate a continuous phi class distribution from the original fractions.

A continuous phi class distribution from the original fractions was transposed to the "results" tab in the macro-enabled Microsoft Excel data entry workbook (GrainSizeWorksheet_LD1-30_JO01(batch_01, batch_02, batch_03, or batch_replicates).xlsm or GrainSizeWorksheet_LD31-60_JO01(batch_01, batch_02, batch_03, or batch_replicates).xlsm. Macros in the workbook (“GS_MoM_Arithmetic,” "GS_statistics," and "sedimentname") were run to calculate grain-size classification and statistical analyses and finish processing the data. Sample, navigation, and field identifiers, along with continuous phi class distribution data, grain-size classification, and statistical analysis results were copied and pasted into the final Microsoft Excel spreadsheet (JO01_GS-LD_results.xlsx). The processed data were quality control checked and assigned a quality grade based on the examination of the analytical data. Processed data were released to the submitter and incorporated into the laboratory's database. All raw analytical data generated by the samples were archived in the sediment analysis laboratory.

Grain size data were reprocessed in September 2023 as part of a corrective action taken after an issue was identified in the Microsoft Excel data processing workbook (version 1.0) used to calculate grain size statistics and phi class distributions from raw data obtained from the Sediment Lab's Horiba LA-960 laser diffraction unit. Data coming from the instrument and weights recorded from sieving were not faulty. An error was found in a formula embedded in the workbook that translates data originally formatted in columns into rows. There are 96 bins of particle size distribution information recorded for each sample run on the instrument. The error resulted in a shifting of data by one bin (the values in bin number one in the column of data coming from the machine were translated into the position for bin number 2 in the corresponding row, and so on). Overall, the resulting data coming from version 1.0 of the processing workbook are affected by a slight shift in grainsize distribution. This error in the formula was corrected in September 2023 and a new version of the workbook (version 2.1) was generated and approved for use in the Sediment Lab. In addition, labeling for the logarithmic d10, d25, d75 and d90 headings was updated. Note the differing order of these values between Logarithmic and Arithmetic Method of Moments statistics. All affected grain size datasets using data from the laser diffraction unit have been reprocessed, reviewed, and prepared for release.

Carbon content loss-on-ignition (CC-LOI) samples data with Sample_ID containing "CC") were taken from samples submitted to the Sediment Laboratory and placed into pre-weighed aluminum dishes. Samples were weighed after drying in oven at 100 degrees Celsius for at least 24 hours. The dry sample was powdered pulverized by hand. Five grams of dry powder were transferred to a pre-weighed ceramic crucible.

Filled crucibles were heated in a muffle furnace for LOI using a modified method outlined by Dean (1974). Crucibles were heated to 550 degrees Celsius for 3 hours, cooled, and weighed. Weight differential after the first heating step is assigned to loss of organic matter.

The updated results from the laser diffraction (JO01_GS-LD_results.xlsx) and loss on ignition (J01_LOI_results.xlsx) are provided but were also saved as CSV files. Files have the FA number and location added to the front of the file name (2022034FA_NCB). The CSV file column headers of the las diffraction data were also edited to be lowercase and modified slightly to facilitate readability. The laser diffraction CSV file does not have the first row of the excel file that labels columns U-AC as “Methods of Moments Statistics – Logarithmic (phi)”, columns AD-AL as “Methods of Moments Statistics – Arithmetic (micrometers)”, and columns AM-BH as “Distribution (phi)”. Modifications to the laser diffraction CSV headers not related to capitalization or changing spaces to underscores include T_DEPTH to T_Depth_cm, B_DEPTH to B_Depth_cm, DATE_COLLECTED to Collection_date, ANALYSIS COMPLETION DATE to Analysis_date, WEIGHT to Weight_g, CLASSIFICATION (SHEPARD) to Classification, MEDIAN (D50) to D50, and QA/QC COMMENTS to Comments. Additional changes include adding _Phi to the headers in columns U-AC, adding _um to the headers in columns AD-AL, and all minus signs were replaced with M.