Downward flux of chlorophyll a (Chl a >0.7 µm) and particulate organic carbon (POC) in five stations in the Barents Sea, in three fjords on Svalbard and two fjords in Northern Norway – not-corrected and corrected for contamination by filtered seawater and ambient water Contact information: Ingrid Wiedmann, I.wiedmann@gmx.net, ORCID: 0000-0002-9274-3084 File "Data_Wiedmann_et_al_2026.csv" Columns in the data set: Location Location of sampling; if several locations in one sampling site, specification by station name or sampling month Station Unique station name, including location in abbreviation, station (AS, ArS, M1, M2, M4), sampling month (Sept = September), and sampling year (17: 2017, 18: 2018), deployment duration (longer = L, shorter = S), cylinder treatment (FSW: pre-filled with filtered seawater, FSW), deployment time during day (e.g.15-21: between 15:00 and 21:00 local time), and subsequent sampling on consecutive days (1, 2, 3) Station_ID Unique station ID including also sampling depth Latitude_(N) Latitude of sampling location (°N) Longitude_(E) Longitude of sampling location (°E) Deployment_(Year) Year of trap array deployment Deployment_(Month) Month of trap array deployment Deployment_(Day) Day of trap array deployment Deployment_(Hour) Hour of trap array deployment Deployment_(Minute) Minute of trap array deployment Recovery_(Year) Year of trap array recovery Recovery_(Month) Month of trap array recovery Recovery_(Day) Day of trap array recovery Recovery_(Hour) Hour of trap array recovery Recovery_(Minute) Minute of trap array recovery Deployment_duration_(d^-1) Deployment duration per day (d^-1) Instrument Short-term surface tethered sediment trap with cylinders by KC Denmark DeploymentDepth_(m) Deployment depth of sediment trap (in meter) BottomDepth_(m) Bottom depth (in meter) Chl_a_in_trap_at_Deployment_end(mg_m^-3) Chl a concentration in the trap cylinder at the end of the deployment POC_in_trap_at_Deployment_end(mg_m^-3) POC concentration in the trap cylinder at the end of the deployment AV_Chl_a_flux_(mg_m^2_d^-1;not_corrected) Average downward Chl a flux per square meter per day (mg Chla m^2 d^-1) - not corrected for contamination by ambient water or prefilling with filtered seawater SD_Chl_a_flux_(not_corrected) Standard deviation of the not corrected average downward Chl a flux Correction_Method_Chl_a Correction method for the Chl a downward flux Correction_Chl_a_(mg_m^-3) Correction for Chl a contamination was done using this concentration (mg m^-3) AV_Chl_a_flux_(mg_m^-2_d^-1;corrected) Average downward Chl a flux per square meter per day (mg Chl a m^2 d^-1) - corrected for contamination by ambient water or prefilling with filtered seawater SD_Chl_a_flux_(corrected) Standard deviation of the corrected average downward Chl a flux AV_POC_flux_(mg_m2_d1;not_corrected) Average downward POC flux per square meter per day (mg POC m^2 d^-1) - not corrected for contamination by ambient water or prefilling with filtered seawater SD_POC_flux_(not_corrected) Standard deviation of the not corrected average downward POC flux Correction_Method_POC Correction method for the POC downward flux Correction_POC_(mg_m^-3) Correction for POC contamination was done using this concentration (mg m^-3) AV_POC_flux_(mg_m-2_d-1;corrected) Average downward POC flux per square meter per day (mg POC m^2 d^-1) - corrected for contamination by ambient water or prefilling with filtered seawater SD_POC_flux_(corrected) Standard deviation of the corrected average downward Chl a flux AV_PON_flux_(mg_m^-2_d^-1) Average downward PON flux per square meter per day AV_CN_a:a Average CN ratio of the sinking matter Details on the sampling, the analyses, and how the downward flux corrected: Downward fluxes of chlorophyll a (Chl a) and particulate organic carbon (POC) were determined at five stations in the Barents Sea (BS_AS, BS_ArS, BS_M1, BS_M2, BS_M4), in three fjords on Svalbard (AF: Adventfjorden, HS: Hornsund, VMF: van Mijenfjorden) and two fjords in Northern Norway (BF: Balsfjorden, KF: Kaldfjorden) by short-term surface-tethered trap arrays. The arrays shared the same principal design (gimballed frames attached to a rope with transparent plexiglass sediment trap cylinders, height: 45 cm, inner diameter: 7.2 cm; KC Denmark). In the open Barents Sea, the trap array was free-drifting or moored to drifting sea ice floes (Lagrangian approach), while in narrow fjords (AF, BF, HS, KF) the array was moored to the bottom. In VMF, the array was deployed through a hole in the land-fast sea ice (approximate thickness 40 cm). All sediment trap cylinders were deployed either pre-filled with filtered seawater (FSW, using pre-combusted GF/F filters, 0.7 µm pore size) with additional salt (absolute salinity 5 g kg^-1 greater than ambient seawater salinity) or the cylinders were deployed empty and filled themselves with ambient water at the deployment depth. The downward flux of Chl a and POC was calculated for each deployment either using the Chl a and POC concentration in the cylinder at the end of the deployment (notCorrected flux results). In addition, a corrected flux was calculated to take the contaminations by pre-filling the cylinders with FSW or ambient water into account. As FSW still holds low concentrations of Chl a and POC, we assumed that the pre-filled cylinders contained 75 µg POC L^-1 (Digernes et al., 2025) and 0.1 µg Chl a L^-1 (Knefelkamp et al., 2007) at the start of the deployments (CorrectionMethod: FSW). For empty-deployed trap cylinders, we assumed that the cylinders filled themselves with ambient seawater at the deployment depth and presumed for those that the suspended POC and Chl a concentration at this depth to be in the trap cylinder at the start of the deployment. We corrected for this contamination (CorrectionMethod: ambient).