An update on the North American Coastal Carbon Synthesis
Raymond Najjar, The Pennsylvania State University, (Presenter)
Presentation Type:Plenary Talk
Session:Science Session 1: NACP Program Highlights and Syntheses
Presentation Time:Mon 11:10 AM(20 minutes)
The CO2 system in the Gulf of Mexico, a synthesis and modeling effort
Leticia Barbero, NOAA, (Presenter)
RikWanninkhof, NOAA/AOML,
Lisa L. Robbins, U.S. Geological Survey,
Wei-Jun Cai, University of Delaware,
Ruoying He, North Carolina State University,
Katja Fennel, Dalhousie University,
Before 2006, very few surface carbon measurements had been made in the Gulf of Mexico either spatially or temporally. However, the unique geographical features of the Gulf make it an important contributor to the total air-sea CO2 flux of the coastal United States. Within the frame of the Gulf of Mexico Coastal Carbon Synthesis effort and the recently funded NASA ROSES “Air-Sea CO2 Flux and Carbon Budget Synthesis and Modeling in the Entire Gulf of Mexico” proposal, work is underway to compile and provide the most comprehensive set of surface ocean carbon measurements available in the region. Here we present data collection and synthesis results and proposed outcomes from the project.
Data has been collected on board of Ships of Opportunity, NOAA research vessels and dedicated cruises. As of December 2014, there are over 400K CO2 fugacity, (fCO2), total alkalinity, pH and Dissolved Inorganic Carbon data points in the Gulf of Mexico.
This extensive dataset provides enough information to produce a monthly air-sea CO2 flux climatology centered on the year 2009 and to analyze seasonal and spatial variability in five Gulf sub-regions, with special attention to the Northern GOM and West Florida shelf. Model derived estimates will be compared with observation estimates to gain a process understanding of the regional controls on the sea-air fluxes.
Presentation Type:Poster
NACP Session:NACP Program Highlights and Syntheses - Poster (Mon 12:00 PM)
NACP Poster Location: 1
From observational studies to regional carbon budgets: a synthesis approach to carbon cycling in estuaries along the U.S. east coast and Gulf of Mexico regions
Maria Herrmann, The Pennsylvania State University, (Presenter)
Raymond G. Najjar, The Pennsylvania State University,
W. Michael Kemp, University of Maryland,
Richard B. Alexander, USGS, National Water Quality Assessment Program,
Elizabeth W. Boyer, The Pennsylvania State University,
Wei-Jun Cai, University of Delaware,
Peter C. Griffith, NASA GSFC / Sigma Space,
Kevin D. Kroeger, USGS, Woods Hole Coastal and Marine Science Center,
S. Leigh McCallister, Virginia Commonwealth University,
Richard A. Smith, USGS, National Water Quality Assessment Program,
Thomas S. Bianchi, University of Florida,
Christopher L. Osburn, North Carolina State University,
Estuarine systems, while accounting for less than 0.5% of global ocean area, are a widespread feature of coastal landscapes and play a significant role in the CO2 exchange between the atmosphere and the hydrosphere and act as a filter between the land and the sea. Globally, estuaries degas between 0.25 and 0.4 Pg C yr-1, comparable to the current estimates of the uptake of atmospheric CO2 by continental shelves and as much as one quarter of the estimated uptake of atmospheric CO2 by the open ocean. Complete carbon budgets for estuaries are critical for a predictive understanding of how these systems will respond to future alterations as a result of human activity and climate change. Such budgets, however, are only available for a few individual estuaries – not on the regional scales relevant to the global carbon cycle, and the existing system-level estimates of estuarine carbon fluxes are severely limited in number, spatial extent, and temporal coverage. Paucity of observational data combined with the inherent heterogeneity of estuarine environments greatly complicate temporal and spatial averaging of the fluxes and construction of regional budgets, thus calling for a systematic method for scaling up local estimates to regional scales. As part of the NACP/OCB Coastal Carbon Synthesis (CCARS) activity, we conducted a synthesis of published system-level carbon flux estimates for the estuaries along the U.S. east coast and Gulf of Mexico regions and scaled-up the assembled data to estimate regional carbon budgets. Empirical models were used to scale up system-level net ecosystem production and burial estimates, whereas organic carbon input from upland sources was taken from a data-constrained statistical water quality model (SPARROW). Net export of organic carbon across the seaward boundary was estimated by difference, assuming steady state. Uncertainties in the budget were estimated by allowing uncertainties in the supporting model relations.
Presentation Type:Poster
NACP Session:NACP Program Highlights and Syntheses - Poster (Mon 12:00 PM)
NACP Poster Location: 5
Carbon Fluxes on the West Florida Shelf
Lisa L. Robbins, U.S. Geological Survey, (Presenter)
Leticia Barbero, NOAA,
RikWanninkhof, NOAA/AOML,
Ruoying He, North Carolina State University,
Wei-Jun Cai, University of Delaware,
Katja Fennel, Dalhousie University,
The Gulf of Mexico is a large semi-enclosed subtropical/tropical sea shared almost equally by the U.S. and Mexico. Knowledge of CO2 fluxes in the Gulf will aid in estimating continental atmospheric CO2 concentrations and carbon export through continental runoff. Large differences between marine atmospheric CO2 impacted by the flux of CO2 from Gulf of Mexico and continental air masses can introduce significant errors into continental CO2 flux calculations by atmospheric inversion methods, particularly at regional scales. Like many of the shelves worldwide, the West Florida Shelf (WFS) is poorly characterized in terms of its air-sea exchange of carbon dioxide and other carbon fluxes.
As part of the Gulf of Mexico Coastal Carbon Synthesis effort and more recently the NASA ROSES “Air-Sea CO2 Flux and Carbon Budget Synthesis and Modeling in the Entire Gulf of Mexico” proposal, we have compiled data from over 39 research cruises over nine years (1996, 2003, 2006-2012) and over 37,527 fCO2, pH, and total alkalinity data records from the WFS. These data demonstrate significant spatial and seasonal variations in surface water fCO2 distributions. The patterns have provided the basis to identify measurable latitudinal, inner to outer shelf, and seasonal changes in coastal and ocean carbon chemistry (pCO2, air-sea flux) and derive carbonate saturation state maps of Florida shelf waters. General trends show higher fCO2 values and larger fluxes of CO2 on the WFS within 50-100 km of shore. While exceptions can be observed in some years, more southerly sites, such as those associated with the Florida Keys for example, show higher fCO2 values and larger CO2 fluxes than more northerly locations which are sinks of CO2. Seasonally, WFS surface water goes from being a source of CO2 in winter months, with an average flux of 0.26 mol/m2month, to a carbon sink in spring months, with an average of -0.071 mol/m2month.
Presentation Type:Poster
NACP Session:NACP Program Highlights and Syntheses - Poster (Mon 12:00 PM)
NACP Poster Location: 8
Florida Coastal Spring: Carbon Sink or Source?
Kira Barrera, U.S. Geological Survey,
Lisa L. Robbins, U.S. Geological Survey, (Presenter)
Inland waters are an integral component in biogeochemical cycles between land, freshwater, coastal zones, ocean, and atmosphere. While the transfer of carbon dioxide from aquatic ecosystems, such as rivers and streams, laterally to the ocean has been documented, only recently has CO2 evasion from inland waters to the atmosphere been included in global carbon budget estimates. Previous United States riverine studies demonstrate supersaturation with respect to atmospheric CO2 levels and estimate a degassing of approximately 97 Tg of carbon annually to the atmosphere, with the potential for upward refinement due to high CO2 levels in small streams omitted from models (Butman and Raymond, 2011). Many Florida rivers and streams are of small magnitude, are spring-fed, and are influenced by groundwater-surface water interactions as well as karst geology. They do not easily fit into existing predictive models for riverine CO2 fluxes.
This study analyzed pCO2, pH, and CO2 flux in the Chassahowitzka Springs Group, a first magnitude spring which discharges to the Gulf of Mexico, with the goal of determining if this system was a source or sink for CO2. Hydrochemical measurements (n=287), seasonally sampled and spanning more than 20 years, were analyzed. Linear regression of pH over the study period indicates a significant decreasing trend (p-value < 0.01, R2= 48.5). Multiple regression analysis was used to explore relationships between hydrochemical parameters. Seasonal variations in pH were significant with highest values occurring in the winter and lowest in the summer, and opposite trend with pCO2 seasonality. Time series analysis of CO2 flux over the study period shows a shift from carbon sink to source and correlates with rising atmospheric CO2 levels.
Presentation Type:Poster
NACP Session:NACP Program Highlights and Syntheses - Poster (Mon 12:00 PM)
NACP Poster Location: 9
Coastal Carbon Synthesis for the Continental Shelf of the North American Pacific Coast (NAPC): Preliminary Results
Samantha Siedlecki, University of Washington, (Presenter)
Simone Alin, NOAA Pacific Marine Environmental Laboratory,
Burke Hales, Oregon State University,
Jeremy Mathis, NOAA - PMEL,
Wiley Evans, University of Alaska Fairbanks,
Michael Stukel, University of Maryland,
Jerome Fiechter, University of California- Santa Cruz,
Curtis Deutsch, University of Washington,
James Kenneth Bishop, UC Berkeley,
Gilberto Gaxiola, Centro de InvestigaciónCientífica y de Educación Superior de Ensenada (CICESE),
Jose Martin Hernandez, UnversidadAutonoma de Baja California (UABC),
Lauren Juranek, Oregon State University,
Miguel Goni, Oregon State University,
GiulianaTuri, ETH Zürich,
Joseph Needoba, Oregon Health & Science University,
Emilio Mayorga, University of Washington,
ZouhairLochkar, ETH Zürich,
Nicolas Gruber, ETH Zürich,
Jens Hartmann, University of Hamburg,
Nils Moosdorf, University of Hamburg,
John Largier, University of California- Davis,
Francisco Chavez, MBARI,
Lihini Indira Aluwihare, Scripps Institution of Oceanography,
Francis Chan, Oregon State University,
Al Devol, University of Washington,
Debby Ianson, Fisheries and Oceans Canada,
Richard Alan Feely, NOAA/PMEL,
The West Coast represents the longest coastline in North America, stretching from Panama all the way northward to the Aleutians. Key advances in the carbon cycling of this margin have been made since the North American Continental Margins report (Hales et al., 2008), notably the convergence of models and observations on air-sea fluxes; more sophisticated coastal carbon cycle models; and increased observational coverage in space and time, allowing for more data synthesis and model-data comparison. The preliminary carbon budget for the Pacific Coast of North America identifies the best-known fluxes as the air-sea exchange of CO2 and terrestrial inputs. The least constrained fluxes are respiration, cross-shelf exchange, and carbon metabolism in estuaries. The coast was divided up into sub-regions based on differences in oceanographic drivers of coastal carbon cycling. Those sub-regions include the Gulf of Alaska, the Central American Isthmus, and the California Current System (CCS), which is further subdivided into northern, central, and southern sectors. Spatial trends were typically consistent among models and observations, but the magnitude of the fluxes varied widely. While more modeling and observational studies exist than are presented here, relevant fluxes for the carbon budget were often unreported. In the long-term, investments in research and monitoring will be needed to better constrain the fluxes of many of the highly variable regions described in this study. In addition to the budget, this synthesis identifies gaps and priorities for future research.
Presentation Type:Poster
NACP Session:NACP Program Highlights and Syntheses - Poster (Mon 12:00 PM)
NACP Poster Location: 11
Contemporary and projected lateral carbon fluxes from North America to Oceans: A process-based modeling study
HanqinTian, Auburn University, (Presenter)
Qichun Yang, Auburn University,
Bowen Zhang, Auburn University,
Jia Yang, Auburn University,
Shufen Pan, Auburn University,
Wei Ren, Auburn University,
Chaoqun Lu, Auburn University,
Bo Tao, Auburn University,
Steven Lohrenz, University of Massachusetts Dartmouth,
Wei-Jun Cai, University of Delaware,
Ruoying He, North Carolina State University,
Marjorie Friedrichs, Virginia Institute of Marine Science,
Raymond Najjar, The Pennsylvania State University,
The magnitude and spatiotemporal patterns of lateral carbon fluxes from land to oceans and the underlying mechanisms responsible for these fluxes are far from certain. Here we applied a process-based land model with explicit representation of carbon processes in stream and rivers (Dynamic Land Ecosystem Model: DLEM 2.0) to examine how changes in climate, land use, management practices, atmospheric CO2, and nitrogen deposition have affected the carbon fluxes from North American continent to Oceans in the past three decades, and further to project potential riverine carbon fluxes under future climate scenarios. For the contemporary period, our simulated results indicated that the mean annual fluxes (mean ± 1 standard deviation) of dissolved organic carbon (DOC) and dissolved inorganic carbon (DIC) over 1980-2005 were 33.02 ± 2.78 Tg C yr-1 and 62.8 ± 6.42 Tg C yr-1, respectively. Terrestrial Carbon export shows substantially spatial and temporal variability. Of the five sub-regions (Arctic coast, Pacific coast, Gulf of Mexico, Atlantic coast, and Great lakes), the Arctic sub-region provide the highest DOC flux (33.1%), whereas the Gulf of Mexico sub-region provided the highest DIC flux (38.4%). For the entire North America, neither DOC nor DIC export demonstrated a long-term trend. However, terrestrial carbon export to the arctic oceans showed increasing trends for both DOC and DIC, whereas DOC and DIC export to the Gulf of Mexico decreased from 1980 to 2005. In addition, we used DLEM in conjunction with future climate scenarios to investigate the potential changes in riverine carbon fluxes in the 21st century.
Presentation Type:Poster
NACP Session:Carbon Observing and Monitoring - Poster (Mon 12:00 PM)
NACP Poster Location: 26
Air-sea CO2 flux monitoring in a coastal region influenced by freshwater: is the CO2 sink changing?
Janet Reimer, University of Delaware, (Presenter)
Wei-Jun Cai, University of Delaware,
Xue Liang, University of Delaware,
Rodrigo Vargas, University of Delaware,
Scott Noakes, University of Georgia,
Xinping Hu, Texas A&M University - Corpus Christi,
Jeremy Mathis, NOAA/PMEL,
Richard Alan Feely, NOAA/PMEL,
Adrienne Sutton, NOAA/PMEL,
Sylvia Musielewicz, NOAA/PMEL,
Chris Sabine, NOAA PMEL,
RikWanninkhof, NOAA/AOML,
Air-sea CO2 fluxes (FCO2) on continental margins influenced by large inputs of freshwater have been identified as part of our knowledge gap in terms of coastal carbon budgets. Low spatio-temporal monitoring coverage has been cited as one of the reasons for this lack of knowledge, as well as the complexities of coastal regions that are heterogeneous. High resolution time series observations are an important tool that allows us to monitor in situ CO2 partial pressure (pCO2) and then calculate FCO2. Further knowledge of the regional source/sink is essential for balancing coastal budgets and the fluxes between ecosystems. CO2 monitoring in the South Atlantic Bight (SAB) at the Gray’s Reef mooring has been nearly continuous since July of 2006. The location of the GR mooring presents an ideal opportunity to study competing effects of freshwater and Gulf Stream influences. Here we present the time series of FCO2, annual net FCO2, and potential synoptic-scale sources that may contribute the variability in the annual source/sink for FCO2. Previously, we found that pCO2, and therefore FCO2, is likely influenced via changes in the terrestrial hydrologic cycle, which is in competition with intrusions from the Gulf Stream. During times when precipitation is increased, dissolved inorganic carbon (DIC) in freshwater (distal respiration) likely dominates FCO2 variability; however, when precipitation is decreased Gulf Stream intrusions may reach closer on shore or Gulf Stream movement may be influenced by hemisphere-scale atmospheric oscillations. Furthermore, we show how temporal limitations may lead to under and overestimations for FCO2, as may have been the case in previous studies, and therefore there is a great need for more continuous monitoring efforts. We determined that annual net FCO2 ranged from approximately -2.0 ± 0.46 to 1.8 ± 0.40 mmol m-2, with the site switching between a source and a sink several times over the course of the time series.
Presentation:2015_Poster_Reimer_31_254.pdf (1000k)
Presentation Type:Poster
NACP Session:Carbon Observing and Monitoring - Poster (Mon 12:00 PM)
NACP Poster Location: 31
Sea surface carbon dioxide at the Georgia time series site (2006-2007): air-sea flux and controlling processes
Liang Xue, University of Delaware, (Presenter)
Wei-Jun Cai, University of Delaware, (Presenter)
Xinping Hu, Texas A&M University - Corpus Christi,
Chris Sabine, NOAA PMEL,
Adrienne Sutton, NOAA PMEL,
Li-Qing Jiang, NOAA,
Janet Reimer, University of Delaware,
Carbon dioxide partial pressure (pCO2) data in surface seawater were continuously collected every three hours using a moored autonomous pCO2 system (MAPCO2), deployed on the Gray’s Reef buoy (Station 41008) offshore Georgia, USA (31.402°N, 80.869°W) from 18 July 2006 through 31 October 2007. Surface water pCO2 (average 373 ± 52 µatm) showed a clear seasonal pattern, undersaturated with respect to the atmosphere in cold months (November-March) and generally oversaturated in warm months (April-October). High temporal resolution observations also revealed important events not captured in previous ship-based observations, such as sporadically occurring biological production-induced pCO2 drawdown during April-June 2007. In addition to a qualitative analysis of the primary drivers of pCO2 variability based on property regressions, we quantified contributions of temperature, air-sea exchange, mixing (horizontal) and biological processes to monthly pCO2 variations using a 1-D diagnostic model. Although temperature played a dominant role in an annual cycle of pCO2, river inputs especially in the wet season, biological respiration in peak summer and biological production during April-June 2007 also influenced seawater pCO2. Sea surface pCO2 was higher in September-October 2007 than in September-October 2006, associated with increased river inputs in fall 2007. On an annual basis, this site was a moderate net atmospheric CO2 sink and was autotrophic as revealed by monthly average net community production (NCP) in the mixed layer, when the bloom in April-May 2007 was included during the calculation. While previous ship-based pCO2 data collected around this buoy generally agreed with the buoy CO2 data on seasonal scales, high resolution buoy observations revealed that the cruise-based surveys under-sampled temporal variability in coastal waters, which could bias the estimation of air-sea CO2 fluxes or annual NCP, and even produce contradictory results.