Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Publications
• Parameters
• Instruments
• Deployments
• Project Information
• Program Information
• Funding

CTD and Niskin sample measurements include silicate, total alkalinity, total dissolved inorganic carbon, pH, and oxygen.

These data are published in: Chu, S. N., Z. Aleck Wang, S. C. Doney, G. L. Lawson, and K. A. Hoering (2016), Changes in anthropogenic carbon storage in the Northeast Pacific in the last decade, J. Geophys. Res. Oceans,121, doi:10.1002/2016JC011775.

Conductivity-Temperature-Depth sensor (CTD, Seabird SBE 911plus) and a SBE43 dissolved oxygen (DO) sensor was used to collect discrete seawater samples for analysis of total dissolved inorganic carbon (DIC), total alkalinity (TA), pH, DO, nutrients (nitrate, phosphate, and silicate), and salinity. Seawater samples were collected for pH, DIC, TA, and nutrients at all 34 stations for all sampling depths. Salinity and DO samples were collected at all stations at every third depth for calibrations of the conductivity and DO sensors on the CTD Rosette. Samples for DO were collected first from the Niskin bottles, followed by pH, DIC/TA (in the same bottle), nutrients, and salinity. Standard protocols were followed for sampling procedures [Dickson et al., 2007]. DIC and TA samples were collected into 250 ml Pyrex borosilicate bottles after being filtered with a 0.45 µm in-line capsule filter (Farrwest Environmental Supply, Texas). Each sample was poisoned with 100 µL of a saturated mercuric chloride solution for preservation [Dickson et al., 2007] and sealed with a ground-glass stopper coated with APIEZON®-L grease and was secured with a rubber band applied to the bottle top.

Dissolved oxygen (DO) samples were collected from CTD Niskin bottles into 150 mL brown glass tincture bottles. Sodium iodide-sodium hydroxide mixture and manganese chloride were added sequentially to the sample immediately after collection and mixed thoroughly. One mL of sulfuric acid was added and mixed into the sample prior to measurement. DO samples were measured after temperature equilibration, within 3 days, on an automated dissolved oxygen titrator developed at Woods Hole Oceanographic Institution [Knapp et al. 1990]. The system is based on the Winkler technique. This method has an accuracy of 1.0 µmol kg-1 and precision of 0.2 µmol kg-1. The titrator was standardized with sodium thiosulfate for each group of analyses, usually about 30 samples. A custom procedure was developed and implemented to detect concentrations of dissolved oxygen < 90 µmol kg-1. In situ temperature was used to calculate potential density in order to convert from mL L-1 to µmol kg-1 for bottle samples. Ideally, the conversion temperature should be the temperature measured at the time of sample drawing, but those were not measured. Bottle values were used to calibrate CTD values.

Salinity samples were collected into 250 mL square cross-sectioned, borosilicate glass bottles and measured on an Autosal Salinometer (Guildline 8400B). PSS-78 salinity was calculated from measured conductivity ratios. Measurements were performed after samples had equilibrated to laboratory temperature, within 3 days after collection. The machine was standardized for each group of analyses, approximately 50 samples. International Association for the Physical Sciences of the Oceans (IAPSO) Standard Seawater Batch P-152 was used for standardization. This method has an accuracy of ±0.003 and precision of ± 0.0002. Bottle analyses were used to calibrate CTD salinity values.

DIC was analyzed using an Apollo SciTech DIC auto-analyzer (Model AS-C3), which uses a nondispersive infrared (NDIR) method. The sample is acidified with a 10% phosphoric acid in 10% sodium chloride solution, and CO2 is purged with high purity nitrogen gas and measured by a LI-COR 7000 infrared analyzer. Certified Reference Material (CRM) from Dr. A. Dickson at Scripps Institution of Oceanography was used to calibrate the DIC auto-analyzer at least once daily. In addition, CRM was measured as a sample every few hours to gauge and correct any potential drift. The precision and accuracy of the instrument was ~ ±2.0 µmol kg-1.

TA was measured with an Apollo SciTech alkalinity auto-titrator (Model AS-ALK2), a Ross combination pH electrode and a pH meter (ORION 3 Star) to perform a modified Gran titration [Wang and Cai, 2004]. The electrode and concentration of hydrochloric acid was calibrated every day. The CRMs were also measured as samples every few hours to correct any potential small drift. The accuracy and precision of the instrument was about ± 2.0 µmol kg-1. 

Seawater pH samples were collected directly into 10 cm cylindrical optical cells via silicone tubing and thermostated to 25.0 ± 0.1°C for at least an hour before measurement. Samples were analyzed using an Agilent 8453 UV-VIS spectrophotometer and meta-cresol purple (m-CP) as the indicator [Dickson et al., 2007]. Sample pH was measured on the total scale. Measurements of pH were corrected for indicator perturbation and indicator impurity [Clayton and Byrne, 1993; Dickson et al., 2007; Liu et al., 2011; Yao et al., 2007]. The average of combined corrections was 0.0026 ± 0.0046. The instrument accuracy and precision was 0.002 and 0.001, respectively. 
The nutrient samples were filtered through 0.2 µm filters, collected into vials that had been cleaned with 10% hydrochloric acid and were immediately frozen after collection. Samples were analyzed at the University of California at Santa Barbara Marine Science Institute. Nutrient data from NH1208 were found to have relatively larger scatter than the previous P17N cruise data. This may be due to storage issues that involved freezing and possible melting of samples. 

PACIFICA recommended adjustments for CLIVAR P17N 2001 are shown below along with deep isopycnal crossover results for NH1208 2012 cruise adjusted to the CLIVAR 2001 PACIFICA-corrected data. These values are listed in the data file as ‘deepcorr’ values. Salinity, DIC, and TA factors are additive, while oxygen and silicate factors are multiplicative. Units for all parameters are in µmol kg-1 except for salinity, which is measured on the practical salinity scale.

Cited References:
Clayton, T. D., and R. H. Byrne (1993), Spectrophotometric seawater pH measurements: total hydrogen ion concentration scale calibration of m-cresol purple and at-sea results, Deep. Res., 40(10), 2115-2129, doi:10.1016/0967-0637(93)90048-8.
Dickson, A., C. Sabine, and J. Christian (2007), Guide to best practices for ocean CO2 measurement, PICES Spec. Publ.,191.
Knapp, George P., Marvel C. Stalcup, and Robert J. Stanley (1990), Automated oxygen titration and salinity determination. Woods Hole Oceanographic Institution.
Liu, X., M. C. Patsavas, and R. H. Byrne (2011), Purification and characterization of meta-cresol purple for spectrophotometric seawater ph measurements, Environ. Sci. Technol., 45(11), 4862-4868, doi:10.1021/es200665d.
Wang, Z. A., and W.-J. Cai (2004), Carbon dioxide degassing and inorganic carbon export from a marsh-dominated estuary (the Duplin River): A marsh CO2 pump, Limnol. Oceanogr., 49(2), 341-354, doi:10.4319/lo.2004.49.2.0341.
Yao, W., X. Liu, and R. H. Byrne (2007), Impurities in indicators used for spectrophotometric seawater pH measurements: Assessment and remedies, Mar. Chem., 107(2), 167-172, doi:10.1016/j.marchem.2007.06.012.

Quality flags: 2-acceptable, 3-questionable, 4-bad, 6-duplicate, 9-missing

BCO-DMO Processing:
- added conventional header with dataset name, PI name, version date
- renamed parameters to BCO-DMO standard
- added instrument column
- replaced -999 with nd (no data)

Modified version of the NSF award abstract:
The impact of ocean acidification on marine ecosystems represents a vital question facing both marine scientists and managers of ocean resources. Thecosome pteropods are a group of calcareous planktonic molluscs widely distributed in coastal and open ocean pelagic ecosystems of the world¡¦s oceans. These animals secrete an aragonite shell, and thus are highly sensitive to ocean acidification due to the water column's changing carbonate chemistry, and particularly the shoaling of the aragonite compensation depth at which seawater becomes corrosive to aragonite. In many regions, however, relatively little is known about the abundance, distribution, vertical migratory behavior, and ecological importance of pteropods. Assessing the likely ecosystem consequences of changes in pteropod dynamics resulting from ocean acidification will require a detailed understanding of pteropod distribution and abundance relative to changing aragonite saturation in the water column.

The primary objective of this project is to quantify the distribution, abundance, species composition, shell condition, and vertical migratory behavior of oceanic thecosome pteropods in the northwest Atlantic and northeast Pacific, and correlate these quantities to hydrography and concurrent measurements of carbonate chemistry, including vertical and horizontal distributions of aragonite saturation. In particular, the project will capitalize on present-day variability in the depth distribution of aragonite saturation levels within and between the Atlantic and Pacific Oceans as a "natural experiment" to address the hypotheses that pteropod vertical distribution, species composition, and abundance vary as the compensation depth becomes shallower. Secondary objectives are to develop acoustic protocols for the remote quantification of pteropod abundance for future integration into ocean acidification monitoring networks, and to characterize carbonate chemistry and nutrients along portions of two WOCE/CLIVAR Repeat Hydrography transects (A20 in the Atlantic and P17N in the Pacific) to identify decadal-scale changes in the carbonate system. These hypotheses and objectives will be addressed through two cruises along survey transects between 35 and 50 degrees North in the northwest Atlantic and northeast Pacific involving a combination of station-work and underway measurements, and a comprehensive array of instruments, including acoustic, optical, towed net, hydrographic, and carbonate chemistry sensors and sampling systems.

This highly inter-disciplinary project, combines expertise in zooplankton ecology, acoustics, and marine chemistry. The proposed work will result in a detailed baseline understanding of variability in the horizontal and vertical distribution, as well as species composition, of thecosome pteropods in the northwest Atlantic and northeast Pacific, making a key contribution to zooplankton ecology generally. In addition, by quantifying the response to current spatial variability within and between the Atlantic and Pacific Oceans, the project will provide important information on the likely response of pteropod distribution to future changes in the vertical distribution of aragonite saturation levels, a necessary component in modeling the impacts of ocean acidification on marine ecosystem function, services, and resources.

Ocean acidification is increasingly appreciated as an urgent societal concern. Thecosome pteropods are key prey for a variety of commercially-exploited fish species, and the improved understanding the PIs seek of pteropod distribution and likely response to changing water column carbonate chemistry will have important implications for our understanding of potential effects of ocean acidification on marine resources.
 

The Ocean Carbon and Biogeochemistry (OCB) program focuses on the ocean's role as a component of the global Earth system, bringing together research in geochemistry, ocean physics, and ecology that inform on and advance our understanding of ocean biogeochemistry. The overall program goals are to promote, plan, and coordinate collaborative, multidisciplinary research opportunities within the U.S. research community and with international partners. Important OCB-related activities currently include: the Ocean Carbon and Climate Change (OCCC) and the North American Carbon Program (NACP); U.S. contributions to IMBER, SOLAS, CARBOOCEAN; and numerous U.S. single-investigator and medium-size research projects funded by U.S. federal agencies including NASA, NOAA, and NSF.

The scientific mission of OCB is to study the evolving role of the ocean in the global carbon cycle, in the face of environmental variability and change through studies of marine biogeochemical cycles and associated ecosystems.

The overarching OCB science themes include improved understanding and prediction of: 1) oceanic uptake and release of atmospheric CO2 and other greenhouse gases and 2) environmental sensitivities of biogeochemical cycles, marine ecosystems, and interactions between the two.

The OCB Research Priorities (updated January 2012) include: ocean acidification; terrestrial/coastal carbon fluxes and exchanges; climate sensitivities of and change in ecosystem structure and associated impacts on biogeochemical cycles; mesopelagic ecological and biogeochemical interactions; benthic-pelagic feedbacks on biogeochemical cycles; ocean carbon uptake and storage; and expanding low-oxygen conditions in the coastal and open oceans.

NSF Climate Research Investment (CRI) activities that were initiated in 2010 are now included under Science, Engineering and Education for Sustainability NSF-Wide Investment (SEES). SEES is a portfolio of activities that highlights NSF's unique role in helping society address the challenge(s) of achieving sustainability. Detailed information about the SEES program is available from NSF (https://www.nsf.gov/funding/pgm_summ.jsp?pims_id=504707).

In recognition of the need for basic research concerning the nature, extent and impact of ocean acidification on oceanic environments in the past, present and future, the goal of the SEES: OA program is to understand (a) the chemistry and physical chemistry of ocean acidification; (b) how ocean acidification interacts with processes at the organismal level; and (c) how the earth system history informs our understanding of the effects of ocean acidification on the present day and future ocean.

Solicitations issued under this program:
NSF 10-530, FY 2010-FY2011
NSF 12-500, FY 2012
NSF 12-600, FY 2013
NSF 13-586, FY 2014
NSF 13-586 was the final solicitation that will be released for this program.

PI Meetings:
1st U.S. Ocean Acidification PI Meeting(March 22-24, 2011, Woods Hole, MA)
2nd U.S. Ocean Acidification PI Meeting(Sept. 18-20, 2013, Washington, DC)
3rd U.S. Ocean Acidification PI Meeting (June 9-11, 2015, Woods Hole, MA – Tentative)

NSF media releases for the Ocean Acidification Program:

Press Release 10-186 NSF Awards Grants to Study Effects of Ocean Acidification

Discovery Blue Mussels "Hang On" Along Rocky Shores: For How Long?

Discovery nsf.gov - National Science Foundation (NSF) Discoveries - Trouble in Paradise: Ocean Acidification This Way Comes - US National Science Foundation (NSF)

Press Release 12-179 nsf.gov - National Science Foundation (NSF) News - Ocean Acidification: Finding New Answers Through National Science Foundation Research Grants - US National Science Foundation (NSF)

Press Release 13-102 World Oceans Month Brings Mixed News for Oysters

Press Release 13-108 nsf.gov - National Science Foundation (NSF) News - Natural Underwater Springs Show How Coral Reefs Respond to Ocean Acidification - US National Science Foundation (NSF)

Press Release 13-148 Ocean acidification: Making new discoveries through National Science Foundation research grants

Press Release 13-148 - Video nsf.gov - News - Video - NSF Ocean Sciences Division Director David Conover answers questions about ocean acidification. - US National Science Foundation (NSF)

Press Release 14-010 nsf.gov - National Science Foundation (NSF) News - Palau's coral reefs surprisingly resistant to ocean acidification - US National Science Foundation (NSF)

Press Release 14-116 nsf.gov - National Science Foundation (NSF) News - Ocean Acidification: NSF awards $11.4 million in new grants to study effects on marine ecosystems - US National Science Foundation (NSF)