INORGANIC CARBON AND ACIDIFICATION DYNAMICS IN WESTERN GULF OF MAINE SURFACE WATERS.J. Salisbury, D. Vandemark, C. Hunt, S. Shellito (Univ. of New Hampshire)W. R. McGillis (Columbia Univ./LDEO)C. L. Sabine (NOAA/PMEL)

Atmospheric carbon dioxide record from Mauna Loa for 1958-2000by C.D. Keeling and T.P. Whorfhttp://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htmAverage for year 2000 = 369.4ppm

OutlineOur place and our observation kitBackground on CO2 and acid variability and western GOMIdeas on variability from our data setCoastal acidificationConclusions and questions

Our Science Questions

Is the Gulf of Maine a source or sink of atmospheric CO2?What are the space/time variability and mechanistic controls of surface pCO2 and subsequent acidification?Can we apply CO2 and O2 data to support monitoring/prediction of lower trophic status via net ecosystem metabolism estimates?

Climate and the Integrated Ocean Observing System( First of the Seven IOOS Societal Goals )

1. Improve predictions of climate change and weather and their effects on coastal communities and the nation

UNH COOAstudy regionwithin NERACOOS

Suite of variables:Optical propertiesPhytoplankton pigments (HPLC)Zooplankton biomass and speciesNutrients and oxygenInorganic and organic carbon (pCO2, DIC, TA, pH, DOC)TemperatureSalinityTwo monthly cruises since 2004 1) cross-shore out to Wilkinson Basin and 2) along-shore up into the Kennebec River.

COOA monthly Gulf of Maine ecosystem observations 2004 - now, Phys/Bio/ChemFast-rate pCO2 equilibratorProfilers for IOPs , AOPs, and CTDInfrared pCO2 gas analyzer UNH R/V Gulf Challenger Underway pCO2, oxygen, IOPs, NO3 and CTD

http://www.cooa.unh.edu

Some background: CO2 Reactions with water

CO2 (air)

-------------------------------------------------- Sea Surface ----

CO2 + H2O H2CO3 H+ + HCO3- 2H+ + CO3=

CaCO3 (solid)Add Ca++K*1K*2Note: DIC or CO2 is the sum of CO2(aq), HCO3- and CO32-

In simple terms, is a measure of the product of the concentrations of CO32- and Ca2+ ions relative to the amount of aragonite that can be dissolved at a given temperature, salinity and pressure.

Aragonite saturation state:

CO2 gas flux at air-sea interfaceTypical parameterization -flux (mmolC/m2/hr) = * k * (pCO2) = gas solubility; known quantity f(T,S)k = gas transfer coefficient; an unknown at sea and empirically related to wind speed (U) pCO2 = pCO2atmosphere pCO2aqueouspCO2 = partial pressure of CO2 gas

~387 Atm

Main variables affecting temporal variability of DIC, and air-sea exchange in W. Gulf of Maine

The role of river discharge?Influence spring stratification and impart resistance to mixingoften has a different temperature signaturePotential subsides of nutrients, DOC, acid and deficits of DIC and alkalinity

Observed variability relevant to CO2.

Salinity, temperature and f-chlorophyll GOMOOS Buoy B

Seasonal to interannual pCO2 and air-sea variations

Interesting cases: Do they affect the annual budget?Effect of discharge on the onset and persistence of two spring blooms? (2004 and 2005)

Turbulent interruption of a spring bloom (2006)

Timing of the fall turnover could be a significant factor influencing the annual CO2 flux (2007).

Salinity and f-chlorophyll at GOMOOS Buoy BSurface f-chlorophyllInflection 2/13/05, SST ~2.0CPersistence 155 days?Inflection 3/05/04, SST ~3.0CPersistence 115 daysSalinityCase1. Blooms of different duration (2004-2005)

Salisbury et al., 2008

Salisbury et al., 2008

Biologically mediated DIC and air-sea flux

Salisbury et al., 2008

Case 2: Patriots Day Storm (2006)A serious interruption of the spring bloom

Start of mixing > 20mEvidence for storm induced mixing of shallow and deep DIC pools

Coastal acid dynamics

Joe Salisbury, Mark Green, Doug Vandemark, Chris HuntIts not just and air-sea issue

Most soils are acidic

Decaying plant material

Weathering of minerals

Atmospheric deposition

Simulation:

Hold SST at median SST (16.1 C)

Subtract result from original image

Simulation:

Hold pCO2 at the mean atmospheric value (384uatm)

Subtract result from original image

Simulation:

Hold TA at the 90th prctile

Subtract result from original image

Saturation state can be very low within River Plumes

Periodic acidification in the Gulf of Maine:

Soft shelled clam calcification

Closing remarksOperational Salinity model Huijie Xue (UMO)

Important stuff I didnt cover very wellPAR (effect of clouds)Distribution of PAR in the water (effects of attenuation) Community dynamicse.g. Phaeocystis has a C:N of 30 (Mykelstad, 1988)

Some conclusions/ questionsSeveral week-to-month (event scale) processes impart lots of interannual variability.W. Gulf is a an overall air-sea source of CO2 but with interannual variability that can swing to a sink (annual flux numbers - unimpressive)Seasonal pCO2 cycle has large swings from spring drawdown to winter ventilation but we are near carbon neutral over the yearFreshwater mixing and biology affect

Some questions

Why arent we a big sink for atmospheric CO2?

What role does freshwater play in carbon and acid dynamics?

What role do storms play?

data collection acknowledgments - a regional and local effort UNH WB transect PIs:J. CampbellR. MorrisonJ. SalisburyD. VandemarkJ. Runge (GMRI)A. Bucklin (Uconn)UNH/COOA measurement crew:P. Pelletier, B. Soares, D. BrewittC. ManningR. JonesC. HuntT. GregoryM. NovakS. Shellitoand many more

Read titleA collaborative observational effort amongst the coauthors, is primarily funded by NOAA/CSC under the IOOS start up efforts, and is undertaken by the UNH coastal ocean observation program under Janet Campbell. As I hope youll see the work involves many others and as such illustrates the promise of ocean observing systems to support multiple uses

A MULTI-YEAR SURVEY OF SURFACE LAYER CARBON DIOXIDE DYNAMICS IN THE GULF OF MAINEAbstract:The Gulf of Maine represents a coastal ecosystem with a dynamic carbon cycle attributed to strong tidal mixing, seasonal stratification, cross shelf exchange, and land-ocean export. An ongoing shipboard program, started in 2004, is providing a new data set for ocean surface layer pCO2 to address questions surrounding the impacts of biology and land-ocean interaction on the ocean carbon cycle and greenhouse gas exchange. Surface layer pCO2 and dissolved oxygen (DO) data are being collected alongside ancillary biological, physical, and chemical data from underway, discrete sample, and profiling systems. The program is complemented with an autonomous pCO2 buoy measurement system, two gulf-wide R/V Oceanus surveys in fall 2006 and 2007, and the summer 2007 NOAA Gulf of Mexico and East Coast Carbon Cruise. We will present data showing strong seasonal and shorter time scale pCO2 and DO signatures and evaluation of their covariance with riverine input and biological productivity. The composite data set provides a wealth of new spatial and temporal information for future modeling and observing system design efforts related to monitoring carbon dynamics in the coastal zone.

Slides to add/amend:Add the CO2 gas flux from brown center or elsewhereGrab the climate talk ppt and look it overGet the 4 year average sink source for each station and whole thing with stdev Sink or Source?At the very beginning of the time series Revelle and Suess had the foresight to understand human influence on the climate system. Where do the coastal oceans fit into that experiment?No information about decadal or longer term changes. Defer to Andy and other Black Bears.Quantification of fluxes is work in progress. Motivation (1)These are big overarching questions that can be answered with varying levels of uncertainty as we will discuss. As for IOOS, we just wish to point out that while climate is in the IOOS charter, little attention is paid to measurement of climate-related variables such as CO2 to date and we are trying to push in this direction for both the IOOS and ORION efforts. We want IOOS to get involved in collecting these data!I want to get back to the cruise data a bit more with a couple quick slides.Idea was that much of these data were not available with autonomous systems but needed to evaluate and monitor ecosystem dynamics Western Gulf of Maine gives us access to a region with significant land-ocean interaction in spring-to-summer snowmelt and watershed runoffThis talk will focus on WB dataWhat we measure - just wish to point out the equilibrator and the Infrared gas analyzer for now - we are stripping CO2 our of the surface water and measuring its partial pressure.

Monthly sampling since April 2004 of Western Gulf of Maine out to depth of 300 m.Note DIC dynamics and saturation state should be related. As more CO2 enters the water, the equilibrium is shifted from Now the proportions of the various species in seawater is a function of pH, pressure and most importantly, temperature.From a couple of slides ago, we had CO2, bicarb and carbonate. If we start with 2100 umol kg at a salinity of 31 a,d cool the water, carbonate and CO2 both go down.This somewhat important in GOM waters that are strongly influenced by river water. Note the proportion of CO2 dramatically increases as pH drops. As pH goes down H+ acid concentration goes up and Speaking of exchange across the sea surface, (I.e. source or sink of atmospheric C, if more goes in than comes out, its a sink) Each curve has leverage to affect interannual variabilityWind speed - facilitates CO2 transfer, energy for mixing (high in winter and low in summer)Temperature, affects P-R dynamics (especially R) and shifts carbonate equilibrium to lower CO2.NCP potential biological pump. NPP generally larger in spring than in fall. Respiration is higher during higher primary biomass and warmer temperatures

Here we invoke the role of discharge as a buoyant subsidy influencing stratification.NPP - obviously. A lot written on the causes of NPPDo not speak of the role of solar radiationLets look at some data from our region. Next 2 slides show variability in the vicinity of the little box.. This is from GOMOOS Buoy B. Poor mans proxis for mixing (T&S), potential for air-sea exchange , productivity and biomassPositive is a source to the atmosphere and negative values are a sink. For a hyperactive system in terms of productivity and wind speed, these are fairly unimpressive values and the same magnitude as the Mid altlantic bight (mol C m2 y-1)Get back to our biggest question for marginal shelf CO2 budgets - sink or source?

As you can see - Can events that last a week or two make a difference?Poor mans proxies for stratification and onset and duration of bloom. 2005 was very wet, stratification was early and evidently the bloom kicked in in early Feb.Pretty busy - but to provide an example on what hourly sampling across a suite of variables is helping us to do - sort out controls in greater detail..Not sure the degree to which this interruption affects overall carbon dynamics of the bloom. Even if a bloom grinds to a halt for a couple of weeks, the nutrients are presumable still there, so it continues. But the community changes and that may be a driver.

When you get a deep mix you bring up higher DIC waters. So resistance to mixing is a very important factor in air-sea exchange. For example from an air-sea exchange viewpoint it would not matter too much if you had just experienced an intense fall bloom with low CO2 in the surface waters.A couple of points:Fisheries -in a protein-starved worldRecreation multibillion dollar industry non-monetary benefitsWildlife - Heterogeneity Supports bio DiversityTransportation import, export and delivery of goods dependent on navigatatable watersWaste Processing - consider the service of coastal waters waste remineralization of organic wasteCostanza Although this analysis is controversial, it underscores the importance of relative value of coastal watersIt is either extremely efficient at recycling C, or there are significant allochtronous sourcesIt is either extremely efficient at recycling C, or there are significant allochtronous sourcesIt is either extremely efficient at recycling C, or there are significant allochtronous sourcesNote interannual variability. Mostly a negative signalTalk about scales of processes (River flow and delivery, phytoplankton dynamics seasonality)3 hourly model Note temporal scales Tidal (biggest tides in the world) weekly-monthly, seasonal. If we had time to let it run, youd see interannualSpatial scales, imagine the complexity and note that freshwater is important. We could show tons of data from 4+ years of measurements, but the model says it best.NPP - obviously. A lot written on the causes of NPPDo not speak of the role of solar radiationI will try to cover what we are measuring and some motivation for it where I wish to highlight the need for long-term coastal ecosystem observations across a suite of variables in order to generate the data needed to support the desired climate and ecosystem modeling. Moreover, as you will likely here in this and other talks, the Gulf of Maine region has a rich history of observations across different disciplines, productive fisheries, and as elsewhere, is experiencing some extreme climate events in this decade.

The data we will show provides a first extended look across time in CO2 dynamics on the east coast of the US and I will discuss the annual and interannual signal we observed. And finally I hope to get to some examples of what an regional observing system can start to provide to help better understand the controls on carbon cycling in coastal waters.It is either extremely efficient at recycling C, or there are significant allochtronous sources