10.1594/PANGAEA.987320Pérez-Rodríguez, MartaMartaPérez-Rodríguez0000-0001-7139-3049Technische Universität BraunschweigBiester, HaraldHaraldBiesterTechnische Universität BraunschweigPANGAEA2026in-situ pumpsMercuryMethylmercuryparticleSouth Sandwich IslandsEvent labelDATE/TIMELATITUDELONGITUDEDEPTH, waterMercuryMethylmercuryCTD/Rosette, trace metal cleanCold vapor atomic fluorescence spectrometer (CV-AFS), Brooks RandSector field inductively coupled plasma mass spectrometer (SF-ICP-MS), Thermo Fisher Scientific, Element XRPS133/1PolarsternGlobal marine biogeochemical cycles of trace elements and their isotopes (GEOTRACES)Tippenhauer, SandraSandraTippenhauer0000-0003-3405-6275Trimborn, ScarlettScarlettTrimborn0000-0003-1434-99272022-10-22T02:01:02/2022-11-09T19:36:26Dataset10.1029/2025GB008767100 data pointstext/tab-separated-valuesCreative Commons Attribution 4.0 InternationalWater samples for total mercury (Hg) and methylmercury (MeHg) were collected in the Southern Ocean between 22 October and 9 November 2022 during the PS133/1 expedition, covering depths from 20 to 7000 m. Sampling was conducted using an ultraclean Titan rosette system (SBE-911Plus, Seabird) equipped with 24 × 12 L Ocean Test Equipment (OTE) bottles and a metal-free winch with a synthetic reinforced Vectran cable. After recovery, the clean CTD rosette was covered with clean plastic caps and transferred by trolley to an ISO Class 5 clean laboratory container. Each bottle was introduced through a clean airlock, rinsed externally with Milli-Q water from the container's integrated water treatment system, and subsampled following GEOTRACES ultraclean protocols. Samples for total Hg were collected unfiltered into pre-cleaned 60 mL glass vials to minimize contamination. Samples for MeHg were collected unfiltered into 250 mL HDPE Nalgene bottles and acidified to 0.4 % v/v with ultrapure trace-metal-grade HCl. Total Hg concentrations were determined using a custom single gold-trap purge and trap system following US EPA Method 1631. Dissolved MeHg concentrations were quantified by gas chromatography coupled to sector field inductively coupled plasma mass spectrometry (GC–SF–ICP–MS) with isotopic dilution calibration.-40.00189-24.94616000000002-56.28945-51.28811Danish National Research Foundationhttps://doi.org/10.13039/501100001732DNRF145Danish Center for Hadal Research, HADALGerman Research Foundationhttps://doi.org/10.13039/501100001659528941462Controls of Primary Production on Southern Ocean Mercury Cycling (COPPSOM)German Research Foundationhttps://doi.org/10.13039/501100001659GPF 20-1_053Island Impact: Understanding the Regional Impact of South Georgia on Southern ACC Biogeochemistry and Ecosystem FunctionGerman Research Foundationhttps://doi.org/10.13039/501100001659GPF 20-2_024South Polar Carbon: Benthic Carbon Mineralization and Preservation in Southern Ocean Bathyal, Abyssal and Hadal Sediments