Birnstiel, Stéphanie; Grelaud, Michaël; E P Teixeira, Carlos; Guilherme, Andreia; Lorenz, Claudia; Vollertsen, Jes; Sobral, Paula; Langer, Gerald; Ziveri, Patrizia: Sample information and microlitter concentration from tropical to temperate regions of the Atlantic Ocean [dataset]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.986741 (dataset in review),

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In: Birnstiel, S et al.: Microlitter distribution from tropical to temperate regions of the Atlantic Ocean during the PYROWIND cruise (April–May 2022) [dataset bundled publication]. PANGAEA, https://doi.pangaea.de/10.1594/PANGAEA.986734 (dataset in review)

Microlitter distribution from tropical to temperate regions of the Atlantic Ocean was assessed using the pump-underway ship intake system. Sampling was performed during the PYROWIND oceanographic campaign in the Atlantic Ocean (April 27th – May 19th 2022), on board of the Spanish R/V Hespérides. The research cruise covered an 8,000-km transect, from Brazil (Salvador) to the Strait of Gibraltar. Subsurface water samples were continuously collected through the pump-underway ship intake system during navigation. The water was collected by a pump (BKMKC.1011, TECNUIM) with a Teflon core located in the keel of the vessel at about 4.5 m deep, with a flow rate of 4 m³/h. The pump-underway system had a tap connection to the wet laboratory, to which the filtering device was connected to a hose. The filtering device consisted of a flowmeter attached to a funnel, which enclosed a 63 μm stainless-steel sieve, in order to avoid airborne contamination. The flow ran 24/7 and was divided into samples of 4.15 ± 1.47 m³ (10 L/min; n = 52). All 52 samples were analyzed for the large fraction (≥ 315 μm) and 15 were analyzed for the small fraction (10–315 μm). Particles were quantified and analyzed using ATR-FTIR (≥ 315 μm) and μFTIR (10–315 μm). The large fraction (≥ 315 μm; n = 52) was analyzed on a stereomicroscope (Leica Z16 APO) equipped with a camera (Canon EOS 650D). The filter was horizontally examined from the top left to the bottom right and every relevant particle was photographed. Each particle was counted and classified according to their type. The chemical analysis was carried out using ATR-FTIR (Agilent 630 Cary ATR-FTIR spectroscopy). The small fraction (10–315 μm; n = 15) was analyzed using μFTIR (Agilent 620 FTIR microscope with a FPA detector and a Cary 670 FTIR spectrometer) and examined with siMPle (open-source software; https://simple-plastics.eu/).

Samples 1, 17, 26, 34 and 45 were used in the OpenDrift model to identify the probable pathways and sources of microlitter.

Empty cells represent the samples/blanks that were not measured for a specific parameter (e.g. since we collected 52 samples in total and only 15 were analyzed for the small fraction [< 315 μm], the remaining 37 samples did not go through the small fraction analysis, which are the ones with empty cells).