26 Cruise Report, RV ATAIR, Cruise 067I033-1, Bremerhaven – Thybor?n – Aberdeen, 23 Jul – 15 Aug 2024 Captair Flow (Erlab) clean bench with a HEPA air filtration unit. The samples were preserved by adding 500 µL of concentrated souble subboiled HNO3 and stored under dark and cool conditions (4 °C / refrigerated) until analysis in the laboratory (Helmholtz-Zentrum Hereon) lo- cated in Geesthacht. Samples for dissolved mercury species (inorganic mercury (iHg) and methylmercury (MeHg)), as well as nutrients were taken at 70 stations at the surface and bottom from Niskin bottles. Water samples were collected in acid-cleaned 2 L HDPE bottles using silicone tubing and stored cold until filtration. The samples were pressure-filtered through 0.45 ?m acid-cleaned polycarbonate filters into acid-cleaned 1 L glass bottles (Bravo et al., 2018). Filtration was car- ried out in a Captair Flow (Erlab) clean bench with a HEPA air filtration unit. The samples were preserved by adding double subboiled HCl (0.4 % v;v) and stored under dark and cool condi- tions (4 °C / refrigerated) until analysis in the laboratory (Helmholtz-Zentrum Hereon) located in Geesthacht. Water samples for nutrient analysis (NOx, PO4 and SiO4) were pressure filtered through 0.45 ?m acid-cleaned polycarbonate filters and stored frozen (-20 °C) until analysis in the la- boratory (Helmholtz-Zentrum Hereon) located in Geesthacht. In total, 168 samples for nutrient analysis were taken. Samples for lead (Pb) isotope ratio analysis were taken at five stations (#003/GN003A, #004/GN007, #028/GN021/AWZW2, #029/GN022 and #041/GN029) at 10 m water depths in duplicate, using one of the two trace metal clean Go-Flo water samplers. Water samples were collected in acid-cleaned 2 L HDPE bottles, which were conditioned onboard by rinsing three times with sampled seawater. Samples were stored dark and frozen (-18°C) until further prep- aration in the laboratory (Helmholtz-Zentrum Hereon) located in Geesthacht. 5.10 Water sampling with respect to Microplastics Microplastics were sampled from approximately 6 m below the surface using the vessel’s metal-free clean seawater system along 11 different transects (see Table 5.6). The sampling workflow was based on using the Geesthacht Inert MP Fractionator (GIMP). Two filter car- tridges with 300 µm mesh size and 10 µm mesh size were used. Around 1–3 m? of ocean water were filtered per sample. The particulate matter was resuspended using ultrasonication and subsequently transferred onto polytetrafluoroethylene (PTFE) membrane filters (5 ?m pore size) by vacuum filtration. The filters were transferred into 250 mL amber glass bottles and submerged in a mixture of approximately 50 mL MQW, 1 mL hydrochloric acid (HCl; 35 % w:w), and 2 mL sodium dodecyl sulfate (SDS) solution until further analysis in the laboratory (Helmholtz-Zentrum Hereon) located in Geesthacht.