Jian Ren

Published marine sediment chronologies from the subarctic North Pacific differ in calibration curves, reservoir corrections, input selection, and modelling conventions, complicating comparisons among palaeoceanographic records. We present a chronology framework for 17 cores from the Bering Sea, Gulf of Alaska, Sea of Okhotsk, and open subarctic North Pacific. The main inventory contains 19 core or segment records: 16 Marine20–rbacon reconstructions, two separately identified legacy calendar-age models, and one segment without a chronology. The 18 canonical age-model tables provide posterior median ages and pointwise 95 % intervals on a standardized 201-depth grid. Users can assign these ages to depth-registered proxy measurements from the same cores after verifying depth-scale correspondence; the framework cannot date a new core without its own chronological constraints. The archive preserves 555 chronology-control rows with their provenance, material roles, and admission decisions. The 18 verified formal model-input files contain 285 rows representing 282 dated-depth clusters or legacy calendar-age nodes. Twenty-eight constraints misassigned to surface chronology during an earlier stage of this compilation are retained with their material-role and exclusion records, allowing users to inspect or revise the admission decisions. The primary precision descriptor is the median width of the pointwise 95 % posterior age interval within each dated interval. Among 14 inventory rows assigned a derived convenience bin, this statistic ranges from 677 to 2765 yr, with a median of approximately 1100 yr. Sampling diagnostics are reported at all evaluation depths. Independent reruns of four preselected records changed this continuous statistic by at most 6.64 yr, although one boundary-adjacent record crossed a derived-bin boundary. Posterior precision is conditional on calibration, the reservoir correction and its adopted date-level uncertainty, input representation, and the modelling protocol; it does not establish absolute chronological accuracy. The adopted reservoir corrections are based on modern observations, whereas deglacial reservoir histories remain incompletely constrained. The release combines age tables, audited inputs, cluster definitions, diagnostics, per-record JSON/CSV packages, source references, and implementation records to support reuse and alternative chronological modelling. Executed model inputs are preserved, but recovery of the full source-to-prepared transformation chain is incomplete. The data are deposited at PANGAEA under https://doi.pangaea.de/10.1594/PANGAEA.996868.

Pulsed particulate organic carbon export plays a vital role in sustaining Arctic marine ecosystems and the biological pump. Wintertime particulate organic carbon export in ice-covered Arctic waters is generally considered negligible due to light-limited local primary production. However, using time-series sediment-trap samples, we observe a high wintertime particulate organic carbon flux lasting over three months at the ice-covered Northwind Abyssal Plain in the High Arctic. We examine its drivers and implications for zooplankton. Here, we show that elevated particulate organic carbon fluxes during winter coincide with increased fecal-pellet carbon and zooplankton swimmer fluxes. Fecal-pellet evidence and nitrogen isotope values indicate that the wintertime carbon export represents a potential food source for zooplankton during the dark season. This wintertime carbon flux is consistent with lateral input, plausibly sourced from shelf and slope regions. Our results demonstrate that such wintertime carbon export provides an important food source for overwintering zooplankton, highlighting its ecological role in ice-covered Arctic ecosystems.

The silica cycle is intimately coupled with marine food-web dynamics, biogeochemical transformations, and the efficiency of the biological carbon pump (BCP). To elucidate the factors controlling biogenic silica (bSiO2) flux and its role in carbon export, we conducted a year-long (August 2008–September 2009) sediment-trap deployment on the Northwind Ridge in the western Arctic Ocean. BSiO2 fluxes exhibited a pronounced seasonal signal, closely paralleling those of particulate organic carbon (POC) and diatoms, with mean fluxes in 2009 tripling those of 2008. This interannual disparity was primarily driven by the interplay of seasonal sea-ice retreat, oligotrophic Beaufort Gyre influence, and nutrient-rich Pacific Water Inflow. Diatoms—particularly heavily silicified Chaetoceros resting spores (CRS)—dominated bSiO2 flux, and CRS fluxes correlated significantly with both bSiO2 and POC, underscoring their role as a critical carbon vector. The mean bSiO2 flux (0.120 mol Si m-2 yr-1) approximated the global average but substantially exceeded those of the Atlantic and Pacific warm pools, while remaining lower than in the Southern Ocean or Bering Sea. Notably, particle export efficiency within the euphotic zone reached 18.9%, surpassing the global mean and those of many productive regions, thus highlighting the high BCP efficiency in this basin. Molar Si/Cinorg and Corg/Cinorg ratios consistently exceeded unity, classifying the Chukchi Sea as a Silica Ocean, wherein diatom-dominated export—facilitated by bSiO2 ballasting—exerts primary control on deep-ocean carbon sequestration. These findings provide critical baseline constraints for projecting how ongoing Arctic warming and shifting circulation may reshape regional biogeochemistry and carbon cycling.

To investigate the migration and transformation of black carbon (BC) under rapid Arctic changes, we systematically quantified its abundance, distribution and particulate (PBC) flux in the Chukchi Shelf and Borderland, western Arctic Ocean. The average sedimentary BC concentration was 1.29 mg g ⁻¹ , with spatial distributions controlled primarily by distance from the coast, water column stratification, and seafloor bathymetry. In the Chukchi Borderland, the mean PBC sinking fluxes reached 0.40 mg m ⁻² d ⁻¹ , exhibiting pronounced seasonal variability, with fluxes during the melting season quadrupling those observed during periods of ice formation. Stable carbon isotopic signatures (δ ¹³ C _BC ) revealed a tripartite BC source mixture throughout the study area: modern biomass combustion, pyrogenic fossil fuel combustion, and petrogenic (coastal erosion) inputs. Finally, we estimated annual BC fluxes of 61 and 655 Gg in the Chukchi Borderland and Central Arctic Ocean, respectively. These findings establish BC as an essential component of the Arctic carbon sink.

Data report: gas hydrate assessment in Baffin Bay at IODP Expedition 400 drill sites

The on-going global warming is causing rapid changes in the carbon cycle of the Arctic. Yet the response of the Arctic to these environmental changes are not fully understood. In this study, we investigate bulk organic parameters (TOC, TN, δ¹³C_org, δ¹⁵N, C/N) and terrestrial n-alkanes (TERR-alkanes) from 19 surface sediments and 5 ²¹⁰Pb-dated sediment cores covering up to the last three centuries from the Chukchi Sea. Downcore profiles indicate increasing OC since the beginning of the Industrial Era in all cores. They also show higher TOC and TN values in southern Chukchi Sea cores coincident with decreasing δ¹³C_org indicating an increasing contribution of terrestrial OC that is confirmed by TERR-alkanes. Comparison with regional paleo-records and instrumental data emphasize the key role of air temperature and sea ice cover on the OC cycle and vegetation of the surrounding landmasses.

The on-going global warming is causing rapid changes in the carbon cycle of the Arctic. Yet the response of the Arctic to these environmental changes are not fully understood. In this study, we investigate bulk organic parameters (TOC, TN, δ¹³C_org, δ¹⁵N, C/N) and terrestrial n-alkanes (TERR-alkanes) from 19 surface sediments and 5 ²¹⁰Pb-dated sediment cores covering up to the last three centuries from the Chukchi Sea. Downcore profiles indicate increasing OC since the beginning of the Industrial Era in all cores. They also show higher TOC and TN values in southern Chukchi Sea cores coincident with decreasing δ¹³C_org indicating an increasing contribution of terrestrial OC that is confirmed by TERR-alkanes. Comparison with regional paleo-records and instrumental data emphasize the key role of air temperature and sea ice cover on the OC cycle and vegetation of the surrounding landmasses.

The on-going global warming is causing rapid changes in the carbon cycle of the Arctic. Yet the response of the Arctic to these environmental changes are not fully understood. In this study, we investigate bulk organic parameters (TOC, TN, δ¹³C_org, δ¹⁵N, C/N) and terrestrial n-alkanes (TERR-alkanes) from 19 surface sediments and 5 ²¹⁰Pb-dated sediment cores covering up to the last three centuries from the Chukchi Sea. Downcore profiles indicate increasing OC since the beginning of the Industrial Era in all cores. They also show higher TOC and TN values in southern Chukchi Sea cores coincident with decreasing δ¹³C_org indicating an increasing contribution of terrestrial OC that is confirmed by TERR-alkanes. Comparison with regional paleo-records and instrumental data emphasize the key role of air temperature and sea ice cover on the OC cycle and vegetation of the surrounding landmasses.