biogeochemical cycles :: Ocean Carbon & Biogeochemistry

Studying marine ecosystems and biogeochemical cycles in the face of environmental change

Archive for biogeochemical cycles

Blue hole in the South China Sea reveals ancient carbon

Posted by mmaheigan

· Wednesday, July 8th, 2020

Blue holes are unique depositional environments that are formed within carbonate platforms. Due to an enclosed geomorphology that restricts water exchange, blue hole ecosystems are typically characterized by steep biogeochemical gradients and distinctive microbial communities. For the past three decades, studies have described vertical gradients in physical, chemical, and biological parameters that typify blue hole water columns, but their elemental cycles, particularly carbon, remain poorly understood.

Figure 1. Aerial photo of the Yongle Blue Hole in the South China Sea (Credit: P. Yao et al./JGR Biogeosciences)

In July 2016, the Yongle Blue Hole (YBH) was discovered to be the deepest known blue hole on Earth (~300 m). YBH is located in the Xisha Islands of the South China Sea. The unique features and ease of accessibility make YBH an ideal natural laboratory for studying carbon cycling in marine anoxic systems. In a recent study published in JGR Biogeosciences, the authors reported extremely low concentrations of dissolved organic carbon (DOC) (e.g., 22 µM) and very high concentrations of dissolved inorganic carbon (DIC) (e.g., 3,090 µM) in YBH deep waters. Radiocarbon dating revealed that the YBH DOC and DIC were unusually old, yielding ages (6,810 and 8270 years BP, respectively) that are much more typical of open ocean deep water. Based on H₂S and microbial community composition profiles, the authors concluded that sharp redox gradients and a high abundance of sulfur cycling bacteria were likely responsible for much of the DOC consumption in YBH. The unusually low concentrations and old DOC ages in the relatively shallow YBH suggest short-term cycling of recalcitrant DOC in oceanic waters, which has been recognized as a long-term microbial carbon sink in the global ocean. The stoichiometry of DIC and total alkalinity changes suggested that the accumulation of DIC in the deep layer of the YBH was largely derived from both the dissolution of carbonate and OC decomposition through sulfate reduction. However, the role of carbonate dissolution from the walls of the blue hole in affecting the old ages of carbon in this system remain uncertain, yet there appears to no evidence of subterranean freshwater into the bottom waters of the blue hole. In the face of expanding oxygen minimum zones and anthropogenically-induced coastal hypoxia, blue holes such as YBH can provide an accessible natural laboratory in which to study the microbial and biogeochemical features that typify these low-oxygen systems.

Authors:
Peng Yao (Ocean University of China)
Thomas S. Bianchi (University of Florida)
Xuchen Wang (Ocean University of China)
Zuosheng Yang (Ocean University of China)
Zhigang Yu (Ocean University of China)

Physics vs. biology in Southern Ocean nutrient gradients

Posted by mmaheigan

· Tuesday, June 16th, 2020

In the Southern Ocean, surface water silicate (SiO₄) concentrations decline very quickly relative to nitrate concentrations along a northward gradient toward mode water formation regions on the northern edge (Figure 1a, b). These mode waters play a critical role in driving global nutrient concentrations, setting the biogeochemistry of low- and mid-latitude regions around the globe after they upwell further north. To explain this latitudinal surface gradient, most hypotheses have implicated diatoms, which take up and export silicon as well as nitrogen: (1) Diatoms, including highly-silicified species such as Fragilariopsis kerguelensis, are more abundant in the Southern Ocean than elsewhere; (2) Iron limitation, which is prevalent in the Southern Ocean, elevates the Si:N ratio of diatoms; (3) Mass export of empty diatom frustules pumps silicate but not nitrate to deeper waters.

Figure 1: (a) and (b) nitrate and silicate concentrations in surface waters of the Southern Ocean (GLODAPv2_2019 data). (c) Model results of a standard run (black diamonds), a run without biology (red diamonds) and a run without mixing (blue diamonds).

In a recent paper published in Biogeosciences, the authors use an idealized model to explore the relative roles of biological vs. physical processes in driving the observed latitudinal surface nutrient gradients. Over timescales of a few years, removing the effects of biology (no SiO₄uptake or export) from the model elevates silicate concentrations slightly over the entire latitudinal range, but does not remove the strong latitudinal gradient (Figure 1c). However, if the effects of vertical mixing processes such as upwelling and entrainment are removed from the model by eliminating the observed deep [SiO₄] gradient, the observed surface nutrient gradient is greatly altered (Figure 1c). These model results suggest that, over short timescales, physics is more important than biology in driving the observed surface water gradient in SiO₄:NO₃ ratios and forcing silicate depletion of mode waters leaving the Southern Ocean. These findings add to our understanding of Southern Ocean dynamics and the downstream effects on other oceans.

Authors:
P. Demuynck (University of Southampton)
T. Tyrrell (University of Southampton)
A.C. Naveira Garabato (University of Southampton)
C.M. Moore (University of Southampton)
A.P. Martin (National Oceanography Centre)

A Methane-Charged Carbon Pump in Shallow Marine Sediments

Posted by mmaheigan

· Wednesday, June 3rd, 2020

Ocean margins are often characterized by the transport of methane, a potent greenhouse gas, entering from the subsurface and moving towards the seafloor. However, a significant portion of subsurface methane is consumed within shallow sediments via microbial driven anaerobic oxidation of methane (AOM). AOM converts the methane carbon to dissolved inorganic carbon (DIC) and reduces the amount of sulfate that diffuses down from the seafloor towards a sediment interval known as the sulfate-methane transition zone (SMTZ). The SMTZ is where the upward flux of methane encounters the downward diffusive sulfate flux (Figure 1). While the mechanisms of methane production and consumption have been extensively studied, the fate of the DIC that is produced in methane-charged sediments is not well constrained.

In a recent study published in Frontiers in Marine Science, authors used existing reports of methane and sulfate flux values to the SMTZ and synthesized a carbon flow model to quantify the DIC cycling in diffusive methane flux sites globally. They report an annual average of 8.7 Tmol (1 Tmol = 10¹² moles) of DIC entering the diffusive methane-charged shallow marine sediments due to sulfate reduction coupled with AOM and organic matter degradation, as well as DIC input from depth (Figure 1). Approximately 75% (average of 6.5 Tmol year^–1) of this DIC pool flows upward toward the water column, making it a potential contributor to oceanic CO₂and ocean acidification. Further, an average of 1.7 Tmol year^–1DIC precipitates as methane-derived authigenic carbonates. This synthesis emphasizes the importance of the SMTZ, not only as a methane sink but also an important biogeochemical front for global DIC cycling.

Figure 1: A simplified representation of DIC cycling at diffusive methane charged settings.

The study highlights that regions characterized by diffusive methane fluxes can contribute significantly to the oceanic inorganic carbon pool and sedimentary carbonate accumulation. DIC outflux from the methane-charged sediments is comparable to ~20% global riverine DIC flux to oceans. Methane-derived authigenic carbonate precipitation is comparable to ~15% of carbonate accumulation on continental shelves and in pelagic sediments, respectively. These pathways must be included in coastal and geologic carbon models.

Authors:
Sajjad Akam (Texas A&M University-Corpus Christi)
Richard Coffin (Texas A&M University-Corpus Christi)
Hussain Abdulla (Texas A&M University-Corpus Christi)
Timothy Lyons (University of California, Riverside)

An Important Biogeochemical Link between Organic and Inorganic Carbon Cycling: Contributions of Organic Alkalinity

Posted by mmaheigan

· Wednesday, April 8th, 2020

As a part of dissolved organic carbon (DOC), organic acid charge groups can contribute significantly to total alkalinity (TA) in natural waters. Such a contribution is termed as organic alkalinity (OrgAlk). Beyond being part of TA, OrgAlk represents an important biogeochemical linkage between organic and inorganic carbon cycling. In other words, the biogeochemical cycling of organic acid charge groups – i.e. their sources, sinks, and biogeochemical behaviors – directly impacts pH and carbonate speciation, which may ultimately influence air-water CO₂ exchange and inorganic carbon fluxes. However, the effects of OrgAlk is often ignored or treated as a calculation uncertainty in many aquatic CO₂ studies. How we treat and study OrgAlk may need a new paradigm under biogeochemical cycles.

Based on direct titration data of OrgAlk, the authors of a recent study conducted a comprehensive assessment of OrgAlk variability, sources, and characteristics in a sub-estuary of Waquoit Bay (Massachusetts). The sub-estuary is influenced by a salt marsh, groundwater input, and offshore water. Both the salt marsh and groundwater OrgAlk contributed up to 4.3% of the TA across all sampled seasons. Estuarine OrgAlk:DOC ratios varied across space and time, which suggests that their abundances are controlled by different biogeochemical processes. In addition, the study demonstrates the insufficiency of using a fixed proportion of DOC to account for OrgAlk, as well as the challenge of using measured pH, TA, and dissolved inorganic carbon (DIC) to estimate OrgAlk. The effects of OrgAlk in these waters are equivalent to a pH change of ~ 0.03 – 0.26, or a pCO₂ change of ~30–1600 matm. If extrapolating OrgAlk results to other coastal systems ranging from estuaries to continental shelves, OrgAlk would exert a strong control on both carbonate speciation and, ultimately, air-sea CO₂ fluxes. This study provides a new conceptual framework for cycling of OrgAlk species and associated links between DOC and DIC pools in coastal systems (Figure 1).

Figure caption: A conceptual model of organic alkalinity cycling in coastal systems. BioP and ChemP represent in-situ biological production and chemical production of organic acid charge groups, respectively. Alk denotes total alkalinity. Arrows with dashed lines indicate processes that were not studied in the present study. The values in the boxes of pH, pCO₂, and buffer capacity represent the magnitude of OrgAlk effects on pH, pCO₂, and buffer capacity in the range of OrgAlk% in TA observed in this study (0.9 – 4.3%).

Authors
Shuzhen Song (East China Normal University)
Zhaohui Aleck Wang (Woods Hole Oceanographic Institution)
Meagan Eagle Gonneea (U. S. Geological Survey)
Kevin D. Kroeger (U. S. Geological Survey)

Untangling microbial evolution in the oceans: How the interaction of biological and physical timescales determine marine microbial evolutionary strategies

Posted by mmaheigan

· Wednesday, March 11th, 2020

Marine microbes are the engines of global biogeochemical cycling in the oceans. They are responsible for approximately half of all photosynthesis on the planet and drive the ‘biological pump’, which transfers organic carbon from the surface to the deep ocean. As such, it is important to determine how marine microbes will adapt and evolve in response to a changing climate in order to understand and predict how the global carbon cycle may change. However, we still lack a mechanistic understanding of how and how fast microorganisms adapt to stressful and changing environments. This is particularly challenging due to the diversity of organisms that live in the ocean and the dynamic nature of the oceans themselves—microbes are at the whim of ocean currents and so get transported large distances fairly quickly. For the first time, a new study published in PNAS provides a prediction on the controls of microbial evolutionary timescales in the oceans. The authors hypothesize that there is a trade-off for marine microbes between ability to evolve to long-term changes versus respond to shorter term variability. Their results suggest that marine microbes commonly experience conditions that favor a short-term strategy at the cost of long-term adaptation. This trade-off determines evolutionary timescales and provides a foundation for understanding distributions of microbial traits and biogeochemistry.

Illustration of trade-off in evolutionary strategy as a function of environmental variability. Trajectories where individuals perceived high environmental variability (a & b) exhibited low selective pressure for any one environment but allowed for high environmental tracking. Trajectories where individuals perceived a more stable environment (c&d) had high selective pressure for ’new environments’ (high probability of a selective sweep) but these individuals exhibited poor environmental tracking. Panels a and c show trajectories where selective sweeps were highly probable (red), likely (yellow), and had a low probability (grey). Panels b and d show the estimated persistence of non-genetic modifications necessary for environmental tracking, where grey indicates unrealistically long timescales.

Authors:
Nathan G. Walworth (University of Southern California)
Emily J. Zakem (University of Southern California)
John P. Dunne (Geophysical Fluid Dynamics Laboratory, NOAA)
Sinéad Collins (University of Edinburgh)
Naomi M. Levine (University of Southern California)

Diatoms commit iron piracy with stolen bacterial gene

Posted by mmaheigan

· Tuesday, February 4th, 2020

Since diatoms carry out much of the primary production in iron-limited marine environments, constraining the details of how these phytoplankton acquire the iron they need is paramount to our understanding of biogeochemical cycles of iron-depleted high-nutrient low-chlorophyll (HNLC) regions. The proteins involved in this process are largely unknown, but McQuaid et al. (2018) scientists described a carbonate-dependent uptake protein that enables diatoms to access inorganic iron dissolved in seawater. As increasing atmospheric CO₂ results in decreased seawater carbonate ion concentrations, this iron uptake strategy may have an uncertain future. In a recent study published in PNAS, authors used CRISPR technology to characterize a parallel uptake system that requires no carbonate and is therefore not impacted by ocean acidification.

This system targets an organically complexed form of iron (siderophores, molecules that bind and transport iron in microorganisms) that is only produced by co-occurring microbes. Two genes are required to convert siderophores from a potent toxicant to an essential nutrient. One of these (FBP1) is a receptor that was horizontally acquired from siderophore-producing bacteria. The other (FRE2) is a eukaryotic reductase that facilitates the dissociation of Fe-siderophore complexes.

Figure caption: (A) Growth curves of diatom cultures ( • = WT, ◇ = ΔFBP1, ☐ = ΔFRE2) in low iron media. (B) Growth in same media with siderophores added. (C) Diatoms under 1000x magnification, brightfield. (D) mCherry-FBP1. (E) Plastid autofluorescence. (F) YFP-FRE2. (G) Phylogenetic tree of FBP1 and related homologs.

Are diatoms really stealing siderophores from hapless bacteria? The true nature of this interaction is unknown and may at times be mutualistic. For example, when iron availability limits the carbon supply to a microbial community, heterotrophic bacteria may benefit from using siderophores to divert iron to diatom companions. Further work is needed to understand the true ecological basis for this interaction, but these results suggest that as long as diatoms and bacteria co-occur, iron limitation in marine ecosystems will not be exacerbated by ocean acidification.

Authors:
Tyler Coale (Scripps Institution of Oceanography, J.Craig Venter Institute)
Mark Moosburner (Scripps Institution of Oceanography, J.Craig Venter Institute)
Aleš Horák (Biology Centre CAS, Institute of Parasitology, University of South Bohemia)
Miroslav Oborník (Biology Centre CAS, Institute of Parasitology, University of South Bohemia)
Katherine Barbeau (Scripps Institution of Oceanography)
Andrew Allen (Scripps Institution of Oceanography, J.Craig Venter Institute)

Also see joint post on the GEOTRACES website

Biogeochemical controls of surface ocean phosphate

Posted by mmaheigan

· Tuesday, November 12th, 2019

Phosphorus availability is important for phytoplankton growth and more broadly ocean biogeochemical cycles. However, phosphate concentration is often below the analytical detection limit of the standard auto-analyzer technique. Thus, we know little about geographic phosphate variation across most low latitude regions. To address this issue, a global collaboration of scientists conducted a study published in Science Advances on combined phosphate measurements using high-sensitivity methods that yielded a detailed map of surface phosphate (Figure 1).

Figure 1: Fine-scale global variation of surface phosphate. Surface phosphate measured using high-sensitivity techniques revealed previously unrecognized low latitude differences in phosphate drawdown.

The study’s new globally expansive phosphate data set revealed previously unrecognized low-phosphate areas, including large regions of the Pacific Ocean—really low phosphate in the western North Pacific and to a lesser extent in the South Pacific. Although atmospheric iron input and nitrogen fixation are commonly described as regulators of surface phosphate, this study shows that shifts in the elemental stoichiometry (N:P:Fe) of the vertical nutrient supply play an additional role. Previous studies and climate models have suggested that the availability of phosphate is a first-order driver of ocean biogeochemical changes. Interestingly, this study suggests that marine ecosystems are more resilient to phosphate stress than previously thought. These findings underscore the importance of accurately quantifying nutrients at low concentrations for understanding the regulation of ocean ecosystem processes and biogeochemistry now and under future climate conditions.

And the data are of course available in BCO-DMO!

Authors:
Adam C. Martiny (University of California, Irvine)
Michael W. Lomas (Bigelow Laboratory for Ocean Sciences)
Weiwei Fu (University of California, Irvine)
Philip W. Boyd (University of Tasmania)
Yuh-ling L. Chen (National Sun Yat-sen University)
Gregory A. Cutter (Old Dominion University)
Michael J. Ellwood (Australian National University)
Ken Furuya (The University of Tokyo)
Fuminori Hashihama (Tokyo University of Marine Science and Technology)
Jota Kanda (Tokyo University of Marine Science and Technology)
David M. Karl (University of Hawaii)
Taketoshi Kodama (Japan Fisheries Research and Education Agency)
Qian P. Li (Chinese Academy of Sciences)
Jian Ma (Xiamen University)
Thierry Moutin (Université de Toulon)
E. Malcolm S. Woodward (Plymouth Marine Laboratory)
J. Keith Moore (University of California, Irvine)

Dramatic Increase in Chlorophyll-a Concentrations in Response to Spring Asian Dust Events in the Western North Pacific

Posted by mmaheigan

· Tuesday, October 23rd, 2018

According to Martin’s iron hypothesis, input of aeolian dust into the ocean environment temporarily relieves iron limitation that suppresses primary productivity. Asian dust events that originate in the Taklimakan and Gobi Deserts occur primarily in the spring and represent the second largest global source of dust to the oceans. The western North Pacific, where productivity is co-limited by nitrogen and iron, is located directly downwind of these source regions and is therefore an ideal location for determining the response of open water primary productivity to these dust input events.

Figure 1. Daily aerosol index values (black squares) and chlorophyll-a concentrations (mg m-3, circles) during the spring (a) 2010 (weak dust event), (b) 1998 (strong dust event) in the western North Pacific. Color scale represents difference between mixed layer depth (MLD) and isolume depth (Z0.054) that indicates conditions for typical spring blooms; water column structures of MLD and isolume were identical in the spring of 1998 and 2010. Dramatic increases in chlorophyll-a (pink shading, maximum of 5.3 mg m-3) occurred in spring 1998 with a lag time of ~10 days after the strong dust event (aerosol index >2.5) on approximately April 20 compared to constant chlorophyll-a values (<2 mg m-3) in the spring of 2010.

A recent study in Geophysical Research Letters included an analysis of the spatial dynamics of spring Asian dust events, from the source regions to the western North Pacific, and their impacts on ocean primary productivity from 1998 to 2014 (except for 2002–2004) using long-term satellite observations (daily aerosol index data and chlorophyll-a). Geographical aerosol index distributions revealed three different transport pathways supported by the westerly wind system: 1) Dust moving predominantly over the Siberian continent (>50°N); 2) Dust passing across the northern East/Japan Sea (40°N‒50°N); and 3) Dust moving over the entire East/Japan Sea (35°N‒55°N). The authors observed that strong dust events could increase ocean primary productivity by more than 70% (>2-fold increase in chlorophyll-a concentrations, Figure 1) compared to weak/non-dust conditions. This result suggests that spring Asian dust events, though episodic, may play a significant role in driving the biological pump, thus sequestering atmospheric CO₂ in the western North Pacific.

Another recent study reported that anthropogenic nitrogen deposition in the western North Pacific has significantly increased over the last three decades (i.e. relieving nitrogen limitation), whereas this study indicated a recent decreasing trend in the frequency of spring Asian dust events (i.e. enhancing iron limitation). Further investigation is required to fully understand the effects of contrasting behavior of iron (i.e., decreasing trend) and nitrogen (i.e., increasing trend) inputs on the ocean primary productivity in the western North Pacific, paying attention on how the marine ecosystem and biogeochemistry will respond to the changes.

Authors:
Joo-Eun Yoon (Incheon National University)
Il-Nam Kim (Incheon National University)
Alison M. Macdonald (Woods Hole Oceanographic Institution)

Shipboard LiDAR: A powerful tool for measuring the distribution and composition of particles in the ocean

Posted by mmaheigan

· Tuesday, October 23rd, 2018

Despite major advances in ocean observing capabilities, characterizing the vertical distribution of materials in the ocean with high spatial resolution remains challenging. Light Detection and Ranging (LiDAR), a technique that relies on measurement of the “time-of-flight” of a backscattered laser pulse to determine the range to a scattering object, could potentially fill this critical gap in our sampling capabilities by providing remote estimates of the vertical distribution of optical properties and suspended particles in the ocean.

A recent article in Remote Sensing of Environment details the development of a portable shipboard LiDAR and its capabilities for extending high-frequency measurements of scattering particles into the vertical dimension. The authors deployed the experimental system (shown in Figure 1a) during research cruises off the coast of Virginia and during a passenger ferry crossing of the Gulf of Maine (associated with the Gulf of Maine North Atlantic Time Series program-GNATS). Remote measurements of LiDAR signal attenuation corresponded well with simultaneous in situ measurements of water column optical properties and proxies for the concentration of suspended particles. Interestingly, the researchers also observed that the extent to which the return signal was depolarized (also known as the LiDAR depolarization ratio) may provide information regarding the composition of particles within the scattering volume. This is evidenced by the strong relationship between the depolarization ratio and the backscattering ratio, an indicator of the bulk composition (mineral vs. organic) of the particles within a scattering medium (Figure 1b).

Figure 1. a) LiDAR system deployed to look through a chock at the bow of the M/V Nova Star. b) Relationship between the LiDAR linear depolarization ratio (ρ) and coincident measurements of the particulate backscattering ratio (b_bp/b_p). The black line represents a least-squares exponential fit to the data.

As LiDAR technology becomes increasingly rugged, compact, and inexpensive, the regular deployment of oceanographic LiDAR on a variety of sampling platforms will become an increasingly practical method for characterizing the vertical and horizontal distribution of particles in the ocean. This has the potential to greatly improve our ability to investigate the role of particles in physical and biogeochemical oceanographic processes, especially when sampling constraints limit observations to the surface ocean.

Authors:
Brian L. Collister (Old Dominion University)
Richard C. Zimmerman (Old Dominion University)
Charles I. Sukenik (Old Dominion University
Victoria J. Hill (Old Dominion University)
William M. Balch (Bigelow Laboratory for Ocean Sciences)

Improved method to identify and reduce uncertainties in marine carbon cycle predictions

Posted by mmaheigan

· Wednesday, September 26th, 2018

Improved method to identify and reduce uncertainties in marine carbon cycle predictions

How well do contemporary Earth System Models (ESMs) represent the dynamics of the modern day ocean? Often we question the fidelity of biological and chemical processes represented in these ESMs. The fact is representations of biogeochemical processes in models are plagued with some degree of uncertainties; therefore, identifying and reducing such deficiencies could advance ESM development and improve model predictions.

An overview of several models with respect to each of the variables, using absolute (left) and relative (right) scores to determine the degree of uncertainty in relation to referenced datasets.

A recent publication in Atmosphere described the ongoing efforts to develop the International Ocean Model Benchmarking (IOMB) package to evaluate ESM skill sets in simulating marine biogeochemical variables and processes. Model performances were scored based on how well they captured the distribution and variability contained in high-quality observational datasets. The authors highlighted systematic model–data benchmarking as a technique to identify ocean model deficiencies, which could provide a pathway to improving representations of sub-grid-scale parameterizations. They have scaled the absolute score from zero to unity, where the red color tends toward zero to quantify weaknesses in the skill set of a particular model in capturing values from the observational datasets. On the other side of the spectrum, the green color signifies considerable temporal and spatial overlap between the predicted and the observational values. The authors also present the standard score to show the relative scores within two standard deviations from the model mean. The benchmarking package was employed in the published study to assess marine biogeochemical process representations, with a focus on surface ocean concentrations and sea–air fluxes of dimethylsulfide (DMS). The production and emission of natural aerosols remain one of the major limitations in estimating global radiative forcing. Appropriate representation of aerosols in the marine boundary layer (MBL) is essential to reduce uncertainty and provide reliable information on offsets to global warming. Results show that model–data biases increased as DMS enters the MBL, with models over-predicting sea surface concentrations in the productive region of the eastern tropical Pacific by almost a factor of two and the sea–air fluxes by a factor of three. The associated uncertainties with oceanic carbon cycle processes may be additive or antagonistic; in any case, a constructive effort to disentangle the subtleties begins with an objective benchmarking effort, which is focused specifically on marine biogeochemical processes. The tool in development will ensure we satisfy some of the Model Intercomparison Project (MIP) benchmarking needs for the sixth phase of Coupled Model Intercomparison Project (CMIP6).

Authors:
Oluwaseun Ogunro (ORNL)
Scott Elliott (LANL)
Oliver Wingenter (New Mexico Tech)
Clara Deal (University of Alaska)
Weiwei Fu (UC Irvine)
Nathan Collier (ORNL)
Forrest M. Hoffman (ORNL)

Funding for the Ocean Carbon & Biogeochemistry Project Office is provided by the National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA). The OCB Project Office is housed at the Woods Hole Oceanographic Institution.

Archive for biogeochemical cycles

Filter by Keyword