Location and analyses of sediment samples collected at Marconi Beach, Wellfleet during field activity 2021-022-FA on March 10, 2021 (ver. 2.0, December 2023)

Four samples were collected from the lowest exposed beach at low tide to the base of the bluff along five shore perpendicular profiles. Sand was collected with a small rectangular spade from the upper 2 cm of the beach and placed into a labeled plastic bag for grain-size analysis.

Samples submitted to the sediment analysis laboratory for grain size analysis using the Horiba laser diffraction unit (LA-960) and sieving of the ≥ -2 phi fraction are assigned unique analysis identifiers (ANALYSIS_ID) and divided into batches of no more than 30 samples. Each batch is entered into a Microsoft Excel data entry spreadsheet (LD Worksheet Template_xxxx.xlsx, where xxxx is the identifier CS16, which is assigned to the sample submission) to record the initial and dried sample weights, as well as the sieved coarse fraction weights. Each batch is also entered into macro-enabled Microsoft Excel data entry spreadsheets (GrainSizeWorksheet_LD1-30_xxxx(batch_yy).xlsm or GrainSizeWorksheet_LD31-600_xxxx(batch_yy).xlsm, where xxxx is the identifier assigned to the sample submission, "LD1-30" and "LD31-60" refer to the pre-labeled and weighed glass laser diffraction vials the samples will be run in, 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 20-30 grams of wet sediment are placed in a pre-weighed beaker and the gross weight is recorded. The sample is wet sieved through a 4 mm (No. 5) sieve. If there is any coarse fraction remaining in the sieve the coarse material is oven dried at 100C in a pre-weighed beaker and weighed again when dry. This coarse fraction is dry sieved to determine the individual weights of the -2 to -5 phi fractions, and the weights are recorded in the data entry spreadsheet LD Worksheet Template_xxxx.xlsx. The fine fraction in water is collected in a pre-labeled and weighed glass laser diffraction vial. If there is any coarse fraction remaining in the sieve from wet sieving, this vial is also oven dried at 100C and weighed when dry. If there is no coarse fraction remaining from wet sieving the sample can proceed directly to processing for analyses by the Horiba laser diffraction unit (LA-960).
Fine fractions ready for analysis by the Horiba laser diffraction unit are rehydrated with distilled water if they have been dry. Fifteen (15) ml of pre-mixed 40 g/l sodium hexametaphosphate [(NaPO3)6] are added to each sample. If the height of the fluid in the laser diffraction vial is less than 5 cm more distilled water is added to raise the level to no more than 8 cm in the vial. The samples are gently stirred, covered, and allowed to soak for at least 1 hour (for samples that were not dried) up to 24 hours (for samples that were dried). Soaked vials are 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 appear to be fully disaggregated, they are placed into pre-determined autosampler locations, and are run using the Horiba LA-960 for Windows software to get the fine fraction grain size distributions. The fine fraction distribution data are added to the appropriate data entry spreadsheets (GrainSizeWorksheet_LD1-30_xxxx(batch_yy).xlsm or GrainSizeWorksheet_LD31-600_xxxx(batch_yy).xlsm). The spreadsheet is used to calculate a continuous phi class distribution from the original fractions.

Continuous phi class distribution from the original fractions are transposed to the "results" tab in the macro-enabled Microsoft Excel data entry workbook (GrainSizeWorksheet_LD1-30_xxxx(batch_yy).xlsm or GrainSizeWorksheet_LD31-600_xxxx(batch_yy).xlsm, "LD1-30" and "LD31-60" refer to the pre-labeled and weighed glass laser diffraction vials the samples will be run in, and "batch_yy" refer to the sample batch). Macros in the workbook ("GS_MoM_Arithmetic", "GS_statistics," and "sedimentname") are 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 are copied and pasted into a final Microsoft Excel spreadsheet (xxxx_GS-LD_results.xlsx). The processed data are quality control checked and assigned a quality grade based on the examination of the analytical data. Processed data are released to the submitter and incorporated into the laboratory's database. All raw analytical data generated by the samples are archived in the sediment analysis laboratory.

Version 2.0: 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.

The updated Excel file received from the sediment lab is provided and was renamed to 2021022FA_Marconi_sedsamples_v2.xlsx and then converted to a CSV with the same name. The CSV has data values with the established resolution in the attribute section below, the excel file has significant figures beyond the instrument precision. The CSV file column headers were also edited to be lowercase and modified slightly to facilitate readability and the shapefile conversion because Esri headers do not accept spaces, -, (), or /. The 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 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.
Using ArcPro 3.0.0, the CSV file was converted to a shapefile (2020015FA_truro_sedsamples_v2.shp) within ArcPro using the tool 'XY Table to Point' where the X Field was longitude and the Y Field was latitude. The coordinate system of the input coordinates was set to NAD83[2011]. All attributes from the grain-size analysis CSV are included in the shapefile but the headers only show the first 10 characters due to ArcPro limitations.