DOI: 10.1594/pangaea.950656
title: Transparent exopolymer particles (TEP), coomassie stainable particles (CSP) and Surfactants measurements from the central artic

description: As part of the MOCCHA 2018 campaign onboard I/B Oden, Sea surface microlayer (SML) and underlying water (ULW) samples were taken from an open lead system in the central arctic. Sampling occurred during the autumn freeze-up from 18.08.18 - 08.09.18. Latitude ranged from 88.7644-89.5474 degrees and longitude ranged from -129.5000 - 47.998700 degrees as the ice pack moved over time. Sea surface microlayer samples were collected using the glass plate technique (Harvey and Burzell, 1972, doi:10.4319/lo.1972.17.1.0156) via rotating glass disks equipped to a catamaran and underlying water samples were collected from 1 meter depth. Seven variables were sampled for; transparent exopolymer particles (TEP), coomassie stainable particles (CSP), surfactants, chlorophyll a, particulate organic carbon (POC), particulate organic nitrogen (PON) and particulate organic phosphorous (POP). Replicate concentrations of TEP and CSP are presented here in micrograms per liter using the spectrophotometric method (Passow and Alldredge, 1995, doi:10.4319/lo.1995.40.7.1326) and thus referenced to xanthan gum and bovine serum albumin standards respectively. TEP was measured by filtering seawater (25-225 ml), in triplicates, onto 0.2 µm polycarbonate filters under low vacuum (&lt; 100 mm Hg). After filtration, samples were stained with Alcian Blue solution (0.02 g alcian blue in 100mL of acetic acid solution of pH 2.5) for 5 s. Filters are pre-soaked in 1M HCL solution to reduce background staining of filters. Samples were placed in Eppendorf tubes and stored at −18°C until processing back in the home laboratory (within 6 months). In the laboratory, Alcian Blue stain was extracted for 2 h in 80% sulfuric acid, with gentle agitation applied to reduce bubble formation, and analysed using a spectrophotometer (VWR UV-1600PC, precision of 1 ± 0.2% T) following (Passow and Alldredge, 1995). The stock solution of Alcian blue was calibrated using the xanthan gum (Carl Roth) standard according to Passow and Alldredge (1995). A calibration of the Alcian Blue stain was run directly before the cruise and had a calibration factor of 163 µg XG eq. A–1, where eq. refers to equivalents and A is absorbance and detection limits ranged from 0.049 to 1.089 absorbance units. Triplicate blanks (empty filters stained with Alcian Blue) were also prepared with every 3 sets (9 filters) of filtered samples. TEP values are reported as the average of analytical triplicates in units of µg XG eq. L–1. Recent calibration issues noted by Bittar et al. (2018) were not observed in our studies, and thus their new method was not required. CSP was measured by filtering seawater, in triplicates, onto 0.2 µm polycarbonate filters under low vacuum (&lt; 100 mm Hg) and staining with CBB-G 250 solution (0.04% in filtered seawater solution with a pH of 7.4) for 30 s. Filters were stored at −18°C until processing back in the home laboratory (within 6 months). In the laboratory, stained filters were placed in glass vials with 10 ml of extraction solution (3% SDS in 50% isopropyl alcohol) and gently agitated for 2 hours. Sonication as suggested by Cisternas-Novoa et al. (2014) always resulted in deterioration and consequential contamination by filters, thus only continuous gentle agitation was applied and showed to be sufficient in extracting the stain from the filters into the solution. Extracted stain was then analysed using a spectrophotometer (VWR UV-1600PC, precision of 1 ± 0.2% T) and were determined relative to a bovine serum albumin standard and expressed in units of µg BSA eq. L–1 after Cisternas-Novoa et al. (2014). The calibration of CBB solution (conducted just prior to the cruise) gave a calibration factor of 220 µg BSA eq. A–1, and detection limits ranged from 0.059 to 0.199 absorbance units. Triplicate blanks (empty filters stained with CBB) were also prepared with every 3 sets (9 filters) of filtered samples. CSP values are reported as the average of analytical triplicates in units of µg BSA eq. L-1.