Marine phytoplankton contributes nearly half of the total primary production on Earth through photosynthesis. Parameterizations of algal photosynthesis commonly employed in global biogeochemical simulations generally fail to capture the observed vertical structure of primary production. Here we examined the consequences of decoupling photosynthesis (carbon fixation) and biosynthesis (biomass building)

Organic matter (OM) sulfurization can enhance the preservation and sequestration of carbon in anoxic sediments, and it has been observed in sinking marine particles from marine O2-deficient zones. The magnitude of this effect on carbon burial remains unclear, however, because the transformations that occur when sinking particles encounter sulfidic conditions remain undescribed. Here, we briefly expose

The Pantanal region of Brazil is the largest seasonally flooded tropical grassland and, according to local chamber measurements, a substantial CH4 source. CH4 emissions from wetlands have recently become of heightened interest because global atmospheric 13CH4 data indicate they may contribute to the resumption of atmospheric CH4 growth since 2007. We have regularly measured vertical atmospheric profiles

Continental shelves are important sources of iron (Fe) in the land-dominated Arctic Ocean. To understand the export of Fe from the Arctic to Baffin Bay (BB) and the North Atlantic, we studied the alteration of the Fe signature in waters transiting the Canadian Arctic Archipelago (CAA). During its transit through the CAA, inflowing Arctic Waters from the Canada Basin become enriched in Fe as result

Systematic regional variations in the ratio of nutrient depth gradients of dissolved inorganic carbon (ΔDIC): nitrate (ΔNO3): phosphate (ΔPO4) in the upper layer (300m) of the Pacific Ocean are observed. Regional variations in the ΔDIC/ΔNO3/ΔPO4 are primarily the result of three processes, that is, the C/N/P of organic matter (OM) being exported and subsequently degraded, nitrogen fixation and air-sea

Atmospheric methane (CH4) and its isotopic composition trends over the last decades are explained by various flux scenarios, from tropical wetland emission increases through to reductions in global hydroxyl (OH). In this work we develop a modelling framework to assess the potential usefulness of clumped isotope measurements to distinguish between the main drivers of change in the CH4 burden. We model

Although iron (Fe) is a key regulator of primary production over much of the ocean, many components of the marine iron cycle are poorly constrained, which undermines our understanding of climate change impacts. In recent years, a growing number of studies (often part of GEOTRACES) have used Fe isotopic signatures (δ56Fe) to disentangle different aspects of the marine Fe cycle. Characteristic δ56Fe

The flux of terrigenous organic carbon through estuaries is an important and changing, yet poorly understood, component of the global carbon cycle. Using dissolved organic carbon (DOC) and fluorescence data from thirteen British estuaries draining catchments with highly variable land uses, we show that land use strongly influences the fate of DOC across the land-ocean transition via its influence on

Earth system models are intended to make long-term projections, but they can be evaluated at interannual and seasonal time scales. Although the Community Earth System Model (CESM2) showed improvements in a number of terrestrial carbon cycle benchmarks, relative to its predecessor, our analysis suggests that the interannual variability (IAV) in net terrestrial carbon fluxes did not show similar improvements

Particulate pyrogenic carbon (PyC) transported by rivers and aerosols, and deposited in marine sediments, is an important part of the carbon cycle. The chemical composition of PyC is temperature dependent and levoglucosan is a source-specific burning marker used to trace low-temperature PyC. Levoglucosan associated to particulate material has been shown to be preserved during riverine transport and

The ACT-America Earth Venture mission conducted five airborne campaigns across four seasons from 2016-2019, to study the transport and fluxes of Greenhouse gases across the eastern United States. Unprecedented spatial sampling of atmospheric tracers (CO2, CO, COS) related to biospheric processes offers opportunities to improve our qualitative and quantitative understanding of seasonal and spatial patterns

Increasing mercury isotope ratios from pre-industrial (1510 – 1850) to present-day (1990 – 2014) in lake sediment cores have been suggested to be a global phenomenon. To assess factors leading to spatiotemporal changes, we compiled mercury concentration (THg) and mercury isotope ratios in twenty-two lake sediment cores located at various regions of the world. We find that the positive δ202Hg shifts

Polar marine ecosystems are particularly vulnerable to the effects of climate change. Warming temperatures, freshening seawater, and disruption to sea-ice formation potentially all have cascading effects on food webs. New approaches are needed to better understand spatiotemporal interactions among biogeochemical processes at the base of Southern Ocean food webs. In marine systems, isoscapes (models

Planktonic foraminifera precipitate calcite shells, which after the death of the organisms are exported to the seafloor. Globally, the resulting calcite flux constitutes up to half of the pelagic calcite flux. Given their importance for the marine calcite budget and for the carbonate counter pump, which counteracts the biological pump in terms of oceanic capacity for CO2 uptake, it is crucial to understand

Human alteration of nutrient cycles has caused persistent and widespread degradation of water quality around the globe. In many regions, including Western Europe, elevated nitrate (NO3−) concentration in surface waters contributes to eutrophication and noncompliance with environmental legislation. Discharge, NO3− concentrations and the vulnerability of the aquatic ecosystems to eutrophication often

Gallium exhibits weak metallic properties owing to its proximity to non-metals in the periodic table, yet is volatile in extra-terrestrial bodies and fairly reactive in nature. It has been used extensively to elucidate the Solar System evolution, planet interior differentiation, and terrestrial processes. However, Ga speciation and transformation in various planetary compartments and the dynamics of

Climate change has substantially increased the frequency of extreme droughts in the Amazon basin, generating concern about impacts on the world's largest tropical forest, which contributes about one-seventh of the global vegetation carbon sink. Most research to understand drought impacts has focused on the immediate influences of such events, neglecting post-drought effects on ecosystems recovery.

Aluminum (Al) is delivered to surface ocean waters by aeolian dust, making it a promising tracer to constrain dust deposition rates and the atmospheric supply of trace metal micronutrients. Over recent years, dissolved Al has been mapped along the GEOTRACES transects, providing unparalleled coverage of the world ocean. However, inferring atmospheric input rates from these observations is complicated

Temperate shelf seas are productive areas with the potential to export high quantities of particulate organic carbon (POC), as sinking particles, to the sediments or off-shelf to the open ocean. The amount of carbon which can be exported depends partly on the amount of POC produced and on the remineralization processes occurring on the sinking material. Here, we assessed the relative seasonal importance

The hydrography of the Arctic Seas is being altered by ongoing climate change, with knock-on effects to nutrient dynamics and primary production. As the major pathway of exchange between the Arctic and the Atlantic, the Fram Strait hosts two distinct water masses in the upper water column, northward flowing warm and saline Atlantic Waters in the east, and southward flowing cold and fresh Polar Surface

Internal climate variability plays an important role in the abundance and distribution of phytoplankton in the global ocean. Previous studies using large ensembles of Earth system models (ESMs) have demonstrated their utility in the study of marine phytoplankton variability. These ESM large ensembles simulate the evolution of multiple alternate realities, each with a different phasing of internal climate

Arctic soils are an important reservoir of soil organic carbon (SOC) and their role in determining arctic ecosystem functioning in global carbon budgets requires closer attention. We investigated the coupling of soil properties and SOC stabilization mechanisms in high Arctic terrestrial habitats differing in vegetation cover and organic matter input. We focused on soil physical and chemical properties

No abstract is available for this article.

Withdrawal:“Observations of nutrient supply by mesoscale eddy stirring and diapycnal mixing in the oligotrophic North Atlantic” from the Authors: Carl P. Spingys, Richard G. Williams, Robyn E. Tuerena, Alberto Naveira Garabato, Clément Vic, Alexander Forryan, and Jonathan Sharples, published online on 17 June, 2021 on Wiley Online Library (http://wileyonlinelibrary.com), has been withdrawn by agreement

Ocean phytoplankton play a critical role in the global carbon cycle, contributing ∼50% of global photosynthesis. As planktonic organisms, phytoplankton encounter significant environmental variability as they are advected throughout the ocean. How this variability impacts phytoplankton growth rates and population dynamics remains unclear. Here, we systematically investigated the impact of different

Air-sea exchange of gaseous elemental mercury (Hg0) is not well constrained, even though it is a major component of the global Hg cycle. Lack of Hg0 flux measurements to validate parameterizations of the Hg0 transfer velocity contributes to this uncertainty. We measured the Hg0 flux on the Baltic Sea coast using micrometeorological methods (gradient-based and relaxed eddy accumulation [REA]) and also

Quantifying the anthropogenic fluxes of CO2 is important to understand the evolution of carbon sink capacities, on which the required strength of our mitigation efforts directly depends. For the historical period, the global carbon budget (GCB) can be compiled from observations and model simulations as is done annually in the Global Carbon Project's (GCP) carbon budgets. However, the historical budget

Soil heterotrophic respiration (SHR) is important for carbon-climate feedbacks because of its sensitivity to soil carbon, climatic conditions and nutrient availability. However, available global SHR estimates have either a coarse spatial resolution or rely on simple upscaling formulations. To better quantify the global distribution of SHR and its response to climate variability, we produced a new global

Anthropogenic nitrogen deposition is widely considered to increase CO2 sequestration by land plants on a global scale. Here, we demonstrate that bedrock nitrogen weathering contributes significantly more to nitrogen-carbon interactions than anthropogenic nitrogen deposition. This working hypothesis is based on the introduction of empirical results into a global biogeochemical simulation model over

The total human mobilization of Li from the Earth's crust, >1,000 × 109 g/year, is much larger than Li mobilized by the natural processes of chemical and mechanical weathering (94 and 132 × 109 g/year, respectively), representing a ∼500% perturbation of the global cycle of Li by human activities. The anthropogenic perturbation of the global Li cycle shows enhanced releases to freshwaters from oil-produced

The Canadian Arctic Archipelago (CAA) is vulnerable to climate warming, and with over 300 tidewater glaciers, is a hotspot for enhanced glacial retreat and meltwater runoff to the ocean. In contrast to Greenlandic and Antarctic systems, CAA glaciers and their impact on the marine environment remain largely unexplored. Here, we investigate how CAA glaciers impact nutrient delivery to surface waters

Iron is a key micronutrient controlling phytoplankton growth in vast regions of the global ocean. Despite its importance, uncertainties remain high regarding external iron source fluxes and internal cycling on a global scale. In this study, we used a global dissolved iron data set, including GEOTRACES measurements, to constrain source and scavenging fluxes in the marine iron component of a global ocean

A comprehensive cross-biome assessment of major nitrogen (N) species that includes dissolved organic N (DON) is central to understanding interactions between inorganic nutrients and organic matter in running waters. Here, we synthesize stream water N chemistry across biomes and find that the composition of the dissolved N pool shifts from highly heterogeneous to primarily comprised of inorganic N,

The widespread expansion of the oxygen minimum zone onto shelves has been commonly regarded as a primary cause of benthos extinction in epicratonic sea ecosystems during the Cenomanian–Turonian boundary event (CTBE). However, neither lithology, geochemical proxies, nor micropaleontological data support this hypothesis. Instead, our integrated foraminiferal and dinoflagellate cyst study, corroborated

Ammonia (NH3) and nitrogen oxides (NOx: nitrogen dioxide [NO2] + nitric oxide [NO]) play important roles in atmospheric chemistry. Throughout most of Africa, emissions of these gases are predominantly from soils and biomass burning. Here we use observations of tropospheric NO2 vertical column densities (VCDs) from the Ozone Monitoring Instrument from 2005 through 2017 and atmospheric NH3 VCDs from

Diffuse radiation can increase the light use efficiency for plant photosynthesis. However, the lack of observations limits the explorations of diffuse fertilization effects on the global scale. Here, we bias-correct global hourly diffuse fraction (Kd) from a climate reanalysis using an artificial neural network (ANN) model in combination with site-level observations. Evaluations at independent sites

Upwelling and the biological pump in the Southern Ocean control the amount and stoichiometry of nutrients available for lateral export to lower latitudes, thereby collectively acting as a gatekeeper for the global thermocline nutrient distribution and global ocean productivity. Yet, the exact role played by phytoplankton and its community composition in this gatekeeping has not been well established

No abstract is available for this article.

Nitrogen (N) deposition in Europe and North America decreased in the 1990s, whereas N deposition in China began to decline in the early 2010s. The response of temperate forests to decreasing N deposition implied a delay recovery, but it remains unknown whether recovery in subtropical forests follows a similar trend. Therefore, the effects of decreased N deposition on N leaching were simulated in an

Soil methanotrophy is the only biological process that removes methane (CH4) from the atmosphere. There is good agreement about the size of the global sink but great uncertainty about its interannual variability and regional responses to changes in key environmental drivers. We used the process-based methanotrophy model Methanotrophy Model (MeMo) v1.0 and output from global climate models to simulate

This study presents an assessment of benthic nutrient regeneration and its role for the nutrient budget of the outer Laptev and East Siberian shelf sea. Porewater profiles of the major nutrients dissolved silica (DSi), dissolved inorganic nitrogen (DIN), and dissolved inorganic phosphate (DIP) as well as total dissolved iron (DFe) were evaluated with a one-dimensional reaction transport model to derive

Peatland reservoirs are global hotspots for drinking water provision and are likely to become more important as demand per capita rises and the climate changes. Dissolved organic carbon (DOC) is associated with harmful disinfection byproducts and reduced aesthetic quality, and its removal is the major treatment cost. Littoral zones are known to be disproportionately important for DOC production through

Oceanic dimethyl sulfide (DMS) emissions have been recognized as a biological regulator of climate by contributing to cloud formation. Despite decades of research, the climatic role of DMS remains ambiguous largely because of limited observational evidence for DMS-induced cloud condensation nuclei (CCN) enhancement. Here, we report concurrent measurement of DMS, physiochemical properties of aerosol

The ocean absorbs anthropogenic carbon, slowing atmospheric CO2 increase but driving ocean acidification. Long-term changes in the carbon system are typically assessed from single-point time series or from hydrographic sections spaced by decades. Using higher resolution observations (1–3 year−1) from the Line P time series, we investigate processes modulating trends in the carbon system of the northeast

We present a new approach for quantifying the bioavailability of dissolved iron (dFe) to oceanic phytoplankton. Bioavailability is defined using an uptake rate constant (kin-app) computed by combining data on: i) Fe content of individual in situ phytoplankton cells; ii) concurrently-determined seawater dFe concentrations; and iii) growth rates estimated from the PISCES model. We examined 930 phytoplankton

Biological productivity in the ocean directly influences the partitioning of carbon between the atmosphere and ocean interior. Through this carbon cycle feedback, changing ocean productivity has long been hypothesized as a key pathway for modulating past atmospheric carbon dioxide levels and hence global climate. Because phytoplankton preferentially assimilate the light isotopes of carbon and the major

The North Pacific Ocean is located at the end of the thermohaline circulation of deep water. This study reports on basin-scale full-depth sectional distributions of total dissolvable (td), dissolved (d), and labile particulate (lp) Cd, Ni, Zn, and Cu along three transects: the GEOTRACES transects GP18 (165°E) and GP02 (47°N), and along 160°W. We find that scavenging is an important factor that significantly

As two most important metrics for ocean acidification (OA), both pH and calcium carbonate mineral saturation states (Ω) respond sensitively to anthropogenic carbon dioxide (CO2). However, contrary to intuition, they are often out of phase in the global surface ocean, both spatially and seasonally. For example, during warm seasons, Ω is lowest at high-latitude seas where there are very high pH values

Plants employ a range of strategies to modulate the impact of water stress, including changes to rooting depth and hydraulic conductance (e.g., xylem conductance). However, it is still poorly understood how these strategies vary in relation to climate and land cover types and how they could coordinate globally. Based on daily microwave vegetation optical depth (VOD) from AMSR-E and AMSR2 over 2002–2011

Terrestrial biosphere models (TBMs) play a key role in the detection and attribution of carbon cycle processes at local to global scales and in projections of the coupled carbon-climate system. TBM evaluation commonly involves direct comparison to eddy-covariance flux measurements. We use atmospheric CO2 mole fraction ([CO2]) measured in situ from aircraft and tower, in addition to flux-measurements

No abstract is available for this article.

The receding of the seasonal ice cover in the Arctic due to climate change has been predicted by models to increase climate-active biogenic trace gas emissions, specifically those of dimethylsulfide (DMS). However, insufficient DMS measurements are currently available to either support or refute this hypothesis and to fully understand the various responses of oceanic DMS in a rapidly changing Arctic

As climate-driven El Niño Southern Oscillation (ENSO) events are projected to increase in frequency and severity, much attention has focused on impacts regarding ecosystem productivity and carbon balance in Amazonian rainforests, with comparatively little attention given to carbon dynamics in fluvial ecosystems. In this study, we compared the wet 2012 La Niña period to the following normal hydrologic

Positive 14C gradients have recently been observed within the surface mixed layer of several continental-margin sediments. The best explanation for these positive 14C gradients is the occurrence and rapid degradation of labile organic carbon (LOC) in the upper 5–10 cm of the seabed. Based on a two-component model for sedimentary organic matter (i.e., a planktonic labile component and an older refractory

We study the drivers behind the global atmospheric methane (CH4) increase observed after 2006. Candidate emission and sink scenarios are constructed based on proposed hypotheses in the literature. These scenarios are simulated in the TM5 tracer transport model for 1984–2016 to produce three-dimensional fields of CH4 and δ13C-CH4, which are compared with observations to test the competing hypotheses

Collectively, reservoirs constitute a significant global source of C-based greenhouse gases (GHGs). Yet, global estimates of reservoir carbon dioxide (CO2) and methane (CH4) emissions remain uncertain, varying more than four-fold in recent analyses. Here we present results from a global application of the Greenhouse Gas from Reservoirs (G-res) model wherein we estimate per-area and per-reservoir CO2

Permafrost thaw in northern peatlands alters the ground thermal conditions, moisture, and chemistry that control microbial activity responsible for the production of greenhouse gases (GHGs) like methane from decomposing organic matter. This paper examines interactions between microbial communities, peat chemistry, moisture content, and temperature in the context of degrading palsa fields in the vast

Single and combined fertilization additions are a common tool to assess the interactions between nutrients in a given ecosystem. While such experiments can allow systems to be defined into categories of nutrient interactions, for example, simultaneous co-limitation or single resource response, this categorization may itself be sensitive to way nutrient interactions are mathematically formulated. To

Seagrass meadows rank among the most significant organic carbon (Corg) sinks on earth. We examined the variability in seagrass soil Corg stocks and composition across Australia and identified the main drivers of variability, applying a spatially hierarchical approach that incorporates bioregions and geomorphic settings. Top 30 cm soil Corg stocks were similar across bioregions and geomorphic settings

The North Atlantic Basin is a major sink for atmospheric carbon dioxide (CO2) due in part to the extensive plankton blooms which form there supported by nutrients supplied by the three-dimensional ocean circulation. Hence, changes in ocean circulation and/or stratification may influence primary production and biological carbon export. In this study, we assess this possibility by evaluating inorganic