Dataset: Transparent Exopolymer Particles (TEP) CTD Bottle Measurements HRS2204

This cruise visited eight stations on the Northeastern U.S. Continental Shelf. Latitudes and longitudes provided per sample in the data, but general station descriptions are below.

• Station 1 - Station 3: Georges Bank near the Gulf of Maine. Approximate location was 41.7 N, 68 W. Samples acquired from 0 m to 25 m depths.
• Station 4: The Great South Channel near the Gulf of Maine. Approximate location was 41.6 N, 69 W. Samples acquired from 0 m to 150 m depths.
• Station 5: Only one CTD profile was taken before this station was aborted due to weather. No data acquired. Station location was 40.8 N, 70.5 W.
• Station 6: Off the coast of Martha's Vineyard. Approximate location was 41.3 N, 70.5 W. Samples acquired from 0 m to 10 m depths.
• Station 7: At the mouth of the Sakonnet River near Newport, Rhode Island. Approximate location was 41.5 N, 71.2 W. Samples acquired from 0 m to 10 m depths.
• Station 8: Hudson Canyon near New York. Approximate location was 39.5 N, 72.3 W. Samples acquired from 0 m to 200 m depths.

Seawater samples between 500 and 2000 ml were vacuum filtered through a 0.45 micron polycarbonate membrane filter. Filter retentate was then stained with Alcian Blue solution. The Alcian Blue solution was made to a concentration of 400 mg/L by mixing dye powder with ultrapure water that was acidified to pH 2.5 with glacial acetic acid. After mixing, the stain was filtered through a 0.22 micron polycarbonate membrane to remove undissolved powder. Stained filters were frozen in Falcon tubes at -20 C for the remainder of the cruise and returned to the lab on dry ice for analysis. In the lab, TEP samples were extracted in 6ml 80% sulfuric acid solution for 2 hrs. The absorbance of this solution was then measured with a spectrophotometer at 787 nm. Concentration of TEP was converted from absorbance to microgram equivalent of Xanthan Gum through a calibration curve. Calibration was conducted following the procedure of Bittar, et al. (2018). A 5-point calibration was performed using dilutions of Xanthan Gum solution with concentrations of 9.37, 18.75, 37.50, 56.25, and 75 micrograms per ml in 1 mL polypropylene tubes. 0.5 ml of the Alcian Blue solution was added to these tubes, which were then mixed for 1 min through manual agitation. These stained aliquots were then poured onto filtration towers and filtered through 0.45 micron polycarbonate filters. The filter retentate was then extracted using the 80% sulfuric acid wash for spectrophotometric quantification. Filters were soaked in the solution for 2-20 hrs with regular agitation. The spectrophotometer (Agilent 8453) was first blanked with ultrapure water prior to measurements. 6 mL of extraction solution was read using 1.0 cm polystyrene disposable cuvettes (Fisher-Scientific).