Geology topics

Lisa L. Robbins

Publications and source records attributed to Lisa L. Robbins.

At least 19 recordsLinked to original sources

USGS2017

Regional acidification trends in Florida shellfish estuaries: A 20+ year look at pH, oxygen, temperature, and salinity

Increasing global CO 2 and local land use changes coupled with increased nutrient pollution are threatening estuaries worldwide. Local changes of estuarine chemistry have been documented, but regional associations and trends comparing multiple estuaries latitudinally have not been evaluated. Rapid climate change has impacted the annual and decadal chemical trends in estuaries, with local ecosystem processes enhancing or mitigating the responses. Here, we compare pH, dissolved oxygen, temperature, and salinity data from 10 Florida shellfish estuaries and hundreds of shellfish bed stations. Over 80,000 measurements, spanning from 1980 to 2008, taken on Atlantic Ocean and West Florida coast showed significant regional trends of consistent pH decreases in 8 out of the 10 estuaries, with an average rate of decrease on the Gulf of Mexico side estuaries of Florida of 7.3 × 10 −4 pH units year −1 , and average decrease on the Atlantic Coast estuaries of 5.0 × 10 −4 pH units year −1 . The rates are approximately 2–3.4 times slower than observed in pH decreases associated with ocean acidification in the Atlantic and Pacific. Other significant trends observed include decreasing dissolved oxygen in 9 out of the 10 estuaries, increasing salinity in 6 out of the 10, and temperature increases in 3 out of the 10 estuaries. The data provide a synoptic regional view of Florida estuary trends which reflect the complexity of changing climate and coastal ocean acidification superimposed on local conditions. These data provide context for understanding, and interpreting the past and predicting future of regional water quality health of shellfish and other organisms of commercial and ecological significance along Florida’s coasts.

Estuaries and Coasts↗

USGS2017

Historical patterns of acidification and increasing CO2 flux associated with Florida springs

Florida has one of the highest concentrations of springs in the world, with many discharging into rivers and predominantly into eastern Gulf of Mexico coast, and they likely influence the hydrochemistry of these adjacent waters; however, temporal and spatial trends have not been well studied. We present over 20 yr of hydrochemical, seasonally sampled data to identify temporal and spatial trends of pH, alkalinity, partial pressure of carbon dioxide (pCO 2 ), and CO 2 flux from five first-order-magnitude (springs that discharge greater than 2.83 m 3 s −1 ) coastal spring groups fed by the Floridan Aquifer System that ultimately discharge into the Gulf of Mexico. All spring groups had pCO 2 levels (averages 3174.3–6773.2 μatm) that were much higher than atmospheric levels of CO 2 and demonstrated statistically significant temporal decreases in pH and increases in CO 2 flux, pCO 2 , and alkalinity. Total carbon flux emissions increased from each of the spring groups by between 3.48 × 10 7 and 2.856 × 10 8 kg C yr −1 over the time period. By 2013 the Springs Groups in total emitted more than 1.1739 × 10 9 kg C yr −1 . Increases in alkalinity and pCO 2 varied from 90.9 to 347.6 μmol kg −1 and 1262.3 to 2666.7 μatm, respectively. Coastal data show higher CO 2 evasion than the open Gulf of Mexico, which suggests spring water influences nearshore waters. The results of this study have important implications for spring water quality, dissolution of the Florida carbonate platform, and identification of the effect and partitioning of carbon fluxes to and within coastal and marine ecosystems.

Florida↗

USGS2017

Optical and biochemical properties of a southwest Florida whiting event

“Whiting” in oceanography is a term used to describe a sharply defined patch of water that contains high levels of suspended, fine-grained calcium carbonate (CaCO 3 ). Whitings have been reported in many oceanic and lake environments, and recently have been reported in southwest Florida coastal waters. Here, field and laboratory measurements were used to study optical, biological, and chemical properties of whiting waters off southwest Florida. No significant difference was found in chlorophyll a concentrations between whiting and outside waters (non-whiting water), but average particle backscattering coefficients in whiting waters were double those in outside waters, and remote sensing reflectance in whiting waters was higher at all wavelengths (400–700 nm). While other potential causes cannot be completely ruled out, particle composition and biochemical differences between sampled whiting water, contiguous water, and outside water indicate a biologically precipitated mode of whiting formation. Taxonomic examination of marine phytoplankton samples collected during a whiting event revealed a community dominated by autotrophic picoplankton and a small (<10 μm), centric diatom species, identified as Thalassiosira sp. through the use of scanning electron microscopy. Amorphous to fully formed crystals of CaCO 3 were observed along the girdle bands of Thalassiosira sp. cells and autotrophic picoplankton cells. Although carbonate parameters differed from whiting and contiguous to outside water, more sampling is needed to determine if these results are statistically significant.

Florida↗

USGS2016

Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ω calcite = 95.7; Ω aragonite = 68.5; Ω vaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10 −17 J to 3.85 × 10 −20 J, which increases the nuclei formation rate from highly improbable (<<1.0 nuclei cm −3 s −1 ) to instantaneous (8.60 × 10 25 nuclei cm −3 s −1 ). The proposed model for homogenous nucleation of calcium carbonate in seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC) that is currently not accounted for in global carbon budgets and carbonate sediment diagenesis models.

Frontiers in Microbiology↗

USGS2016

Sources, distributions and dynamics of dissolved organic matter in the Canada and Makarov Basins

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L −1 ), CDOM absorption ( a 325 : 0.32 ± 0.07 m −1 ) and CDOM-derived lignin phenols (3 ± 0.4 nmol L −1 ), and high spectral slope values ( S 275–295 : 31.7 ± 2.3 μm −1 ), indicating minor terrigenous inputs and evidence of photochemical alteration in the Beaufort Gyre. By contrast, surface waters of the Makarov Basin had elevated DOC (108 ± 9 μmol L −1 ) and lignin phenol concentrations (15 ± 3 nmol L −1 ), high a 325 values (1.36 ± 0.18 m −1 ), and low S 275–295 values (22.8 ± 0.8 μm −1 ), indicating pronounced Siberian river inputs associated with the Transpolar Drift and minor photochemical alteration. Observations near the Mendeleev Plain suggested limited interactions of the Transpolar Drift with Canada Basin waters, a scenario favoring export of Arctic DOM to the North Atlantic. The influence of sea-ice melt on DOM was region-dependent, resulting in an increase (Beaufort Sea), a decrease (Bering-Chukchi Seas), and negligible change (deep basins) in surface DOC concentrations and a 325 values. Halocline structures differed between basins, but the Canada Basin upper halocline and Makarov Basin halocline were comparable in their average DOC (65–70 μmol L −1 ) and lignin phenol concentrations (3–4 nmol L −1 ) and S 275–295 values (22.9–23.7 μm −1 ). Deep-water DOC concentrations decreased by 6–8 μmol L −1 with increasing depth, water mass age, nutrient concentrations, and apparent oxygen utilization. Maximal estimates of DOC degradation rates (0.036–0.039 μmol L −1 yr −1 ) in the deep Arctic were lower than those in other ocean basins, possibly due to low water temperatures. DOC concentrations in bottom waters (>2500 m; 46 ± 2 μmol L −1 ) of the Canada and Makarov Basins were slightly lower than those reported for deep waters of the Eurasian Basin and Nordic Seas. Elevated a 325 values (by 10–20%) were observed near the seafloor, indicating biological activity in Arctic basin sediments.

Frontiers in Marine Science↗

USGS2016

Interpreting the role of pH on stable isotopes in large benthic foraminifera

Large benthic foraminifera (LBF) are prolific producers of calcium carbonate sediments in shallow, tropical environments that are being influenced by ocean acidification (OA). Two LBF species, Amphistegina gibbosa (Order Rotaliida) with low-Mg calcite tests and Archaias angulatus (Order Miliolida) with high-Mg calcite tests, were studied to assess the effects of pH 7.6 on oxygen and carbon isotopic fractionation between test calcite and ambient seawater. The δ 18 O and δ 13 C values of terminal chambers and of whole adult tests of both species after 6 weeks were not significantly different between pH treatments of 8.0 and 7.6. However, tests of juveniles produced during the 6-week treatments showed significant differences between δ 18 O and δ 13 C values from control (pH 8.0) when compared with the treatment (pH 7.6) for both species. Although each individual's growth was photographed and measured, difficulty in distinguishing and manually extracting newly precipitated calcite from adult specimens likely confounded any differences in isotopic signals. However, juvenile specimens that resulted from asexual reproduction that occurred during the experiments did not contain old carbonate that could confound the new isotopic signals. These data reveal a potential bias in the design of OA experiments if only adults are used to investigate changes in test chemistries. Furthermore, the results reaffirm that different calcification mechanisms in these two foraminiferal orders control the fractionation of stable isotopes in the tests and will reflect decreasing pH in seawater somewhat differently. .

ICES Journal of Marine Science↗

USGS2016

Remote estimation of surface pCO2 on the West Florida Shelf

Surface p CO 2 data from the West Florida Shelf (WFS) have been collected during 25 cruise surveys between 2003 and 2012. The data were scaled up using remote sensing measurements of surface water properties in order to provide a more nearly synoptic map of p CO 2 spatial distributions and describe their temporal variations. This investigation involved extensive tests of various model forms through parsimony and Principal Component Analysis, which led to the development of a multi-variable empirical surface p CO 2 model based on concurrent MODIS (Moderate Resolution Imaging Spectroradiometer) estimates of surface chlorophyll a concentrations (CHL, mg m −3 ), diffuse light attenuation at 490 nm (Kd_Lee, m −1 ), and sea surface temperature (SST, °C). Validation using an independent dataset showed a p CO 2 Root Mean Square Error (RMSE) of <12 µatm and a 0.88 coefficient of determination (R 2 ) for measured and model-predicted p CO 2 ranging from 300 to 550 µatm. The model was more sensitive to SST than to CHL and Kd_Lee, with a 1 °C change in SST leading to a ~16 µatm change in the predicted p CO 2 . Application of the model to the entire WFS MODIS time series between 2002 and 2014 showed clear seasonality, with maxima (~450 µatm) in summer and minima (~350 µatm) in winter. The seasonality was positively correlated to SST (high in summer and low in winter) and negatively correlated to CHL and Kd_Lee (high in winter and low in summer). Inter-annual variations of p CO 2 were consistent with inter-annual variations of SST, CHL, and Kd_Lee. These results suggest that surface water p CO 2 of the WFS can be estimated, with known uncertainties, from remote sensing. However, while the general approach of empirical regression may work for waters from other areas of the Gulf of Mexico, model coefficients need to be empirically determined in a similar fashion.

Continental Shelf Research↗

USGS2016

Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO 2 are causing acidification of the world's oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and p CO 2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36-8.28), aragonite saturation state (0.65-5.63), and calculated pCO2 (195-2537 μatm) were significant. When sampled on a daily basis the range in pH (7.70-8.06), aragonite saturation state (1.86-3.85), and calculated p CO 2 (379-1019 μatm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

Marine and Freshwater Research↗

USGS2016

A multi-decade record of high-quality fCO2 data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)

The Surface Ocean CO 2 Atlas (SOCAT) is a synthesis of quality-controlled f CO 2 (fugacity of carbon dioxide) values for the global surface oceans and coastal seas with regular updates. Version 3 of SOCAT has 14.7 million f CO 2 values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million f CO 2 values relative to version 2 and extends the record from 2011 to 2014. Version 3 also significantly increases the data availability for 2005 to 2013. SOCAT has an average of approximately 1.2 million surface water f CO 2 values per year for the years 2006 to 2012. Quality and documentation of the data has improved. A new feature is the data set quality control (QC) flag of E for data from alternative sensors and platforms. The accuracy of surface water f CO 2 has been defined for all data set QC flags. Automated range checking has been carried out for all data sets during their upload into SOCAT. The upgrade of the interactive Data Set Viewer (previously known as the Cruise Data Viewer) allows better interrogation of the SOCAT data collection and rapid creation of high-quality figures for scientific presentations. Automated data upload has been launched for version 4 and will enable more frequent SOCAT releases in the future. High-profile scientific applications of SOCAT include quantification of the ocean sink for atmospheric carbon dioxide and its long-term variation, detection of ocean acidification, as well as evaluation of coupled-climate and ocean-only biogeochemical models. Users of SOCAT data products are urged to acknowledge the contribution of data providers, as stated in the SOCAT Fair Data Use Statement. This ESSD (Earth System Science Data) “living data” publication documents the methods and data sets used for the assembly of this new version of the SOCAT data collection and compares these with those used for earlier versions of the data collection (Pfeil et al., 2013; Sabine et al., 2013; Bakker et al., 2014).

Earth System Science Data↗

USGS2015

Response of the Miliolid Archaias angulatus to simulated ocean acidification

A common, but not universal, effect of ocean acidification on benthic foraminifera is a reduction in the growth rate. The miliolid Archaias angulatus is a high-Mg (>4 mole% MgCO 3 ), symbiont-bearing, soritid benthic foraminifer that contributes to Caribbean reef carbonate sediments. A laboratory culture study assessed the effects of reduced pH on the growth of A. angulatus . We observed a statistically significant 50% reduction in the growth rate (p < 0.01), calculated from changes in maximum diameter, from 160 μm/28 days in the pH 8.0/pCO 2 air 480 ppm control group to 80 μm/28 days at a treatment level of pH 7.6/pCO 2 air 1328 ppm. Additionally, pseudopore area, δ 18 O values, and Mg/Ca ratio all increased, albeit slightly in the latter two variables. The reduction in growth rate indicates that under a high-CO 2 setting, future A. angulatus populations will consist of smaller adults. A model using the results of this study estimates that at pH 7.6 A. angulatus carbonate production in the South Florida reef tract and Florida Bay decreases by 85%, from 0.27 Mt/yr to 0.04 Mt/yr, over an area of 9,000 km 2 .

Journal of Foraminiferal Research↗

USGS2015

Getting ocean acidification on decision makers' to-do lists: dissecting the process through case studies

Much of the detailed, incremental knowledge being generated by current scientific research on ocean acidification (OA) does not directly address the needs of decision makers, who are asking broad questions such as: Where will OA harm marine resources next? When will this happen? Who will be affected? And how much will it cost? In this review, we use a series of mainly US-based case studies to explore the needs of local to international-scale groups that are making decisions to address OA concerns. Decisions concerning OA have been made most naturally and easily when information needs were clearly defined and closely aligned with science outputs and initiatives. For decisions requiring more complex information, the process slows dramatically. Decision making about OA is greatly aided (1) when a mixture of specialists participates, including scientists, resource users and managers, and policy and law makers; (2) when goals can be clearly agreed upon at the beginning of the process; (3) when mixed groups of specialists plan and create translational documents explaining the likely outcomes of policy decisions on ecosystems and natural resources; (4) when regional work on OA fits into an existing set of priorities concerning climate or water quality; and (5) when decision making can be reviewed and enhanced.

Oceanography↗

USGS2014

USGS Field Activities 11CEV01 and 11CEV02 on the West Florida Shelf, Gulf of Mexico, in January and February 2011

During January and February 2011 the U.S. Geological Survey (USGS), in cooperation with the University of South Florida (USF), conducted geochemical surveys on the west Florida Shelf. Data collected will allow USGS and USF scientists to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. This work is part of a larger USGS study on Climate and Environmental Variability (CEV). The first cruise was conducted from January 3 – 7 (11CEV01) and the second from February 17 - 27 (11CEV02). To view each cruise's survey lines, please see the Trackline page. Both cruises took place aboard the R/V Weatherbird II , a ship of opportunity led by Dr. Kendra Daly (USF), which departed and returned from Saint Petersburg, Florida. Data collection included sampling of the surface and water column (referred to as station samples) with lab analysis of pH, dissolved inorganic carbon (DIC), and total alkalinity. Augmenting the lab analysis was a continuous flow-through system with a Conductivity-Temperature-Depth (CTD) sensor, which also recorded salinity, and pH. Corroborating the USGS data are the vertical CTD profiles collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence, optical backscatter, and transmissometer. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts.

Florida↗

USGS2014

USGS field activities 11BHM01 and 11BHM02 on the west Florida shelf, Gulf of Mexico, May and June 2011

During May and June 2011 the (USGS), in cooperation with (USF), conducted geochemical surveys on the west Florida Shelf to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. The first cruise was conducted from May 3 to 9 (11BHM01) and the second was from June 25 to 30 (11BHM02). To view each cruise's survey lines, please see the Trackline page. Each cruise took place aboard the Research Vessel (R/V) Weatherbird II, a ship of opportunity led by Dr. Kendra Daly (USF), which departed from and returned to Saint Petersburg, Florida. Data collection included sampling of the surface and water column with lab analysis of pH, dissolved inorganic carbon (DIC) or total carbon dioxide (TCO 2 ), and total alkalinity (TA). lLb analysis was augmented with a continuous flow-through system (referred to as sonde data) with a conductivity-temperature-depth (CTD) sensor, which also recorded salinity and pH. Corroborating the USGS data are the vertical CTD profiles (referred to as station samples) collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence and optical backscatter. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts. Two autonomous flow-through (AFT) instruments recorded pH and CO2 every 3-5 minutes on each cruise (referred to as AFT data).

Florida↗

USGS2014

USGS field activities 11BHM03 and 11BHM04 on the west Florida shelf, Gulf of Mexico, September and November 2011

During September and November 2011 the (USGS), in cooperation with (USF), conducted geochemical surveys on the west Florida Shelf to investigate the effects of climate change on ocean acidification within the northern Gulf of Mexico, specifically, the effect of ocean acidification on marine organisms and habitats. The first cruise was conducted from September 20 to 28 (11BHM03) and the second was from November 2 to 4 (11BHM04). To view each cruise's survey lines, please see the Trackline page. Each cruise took place aboard the Research Vessel (R/V) Weatherbird II, a ship of opportunity led by Dr. Kendra Daly (USF), which departed from and returned to Saint Petersburg, Florida. Data collection included sampling of the surface and water column with lab analysis of pH, dissolved inorganic carbon (DIC) or total carbon dioxide (TCO 2 ), and total alkalinity (TA). lLb analysis was augmented with a continuous flow-through system (referred to as sonde data) with a conductivity-temperature-depth (CTD) sensor, which also recorded salinity and pH. Corroborating the USGS data are the vertical CTD profiles (referred to as station samples) collected by USF. The CTD casts measured continuous vertical profiles of oxygen, chlorophyll fluorescence and optical backscatter. Discrete samples for nutrients, chlorophyll, and particulate organic carbon/nitrogen were also collected during the CTD casts. Two autonomous flow-through (AFT) instruments recorded pH and CO 2 every 3-5 minutes on each cruise (referred to as AFT data).

Florida↗

USGS2014

USGS Arctic Ocean Carbon Cruise 2012: Field Activity L-01-12-AR to collect carbon data in the Arctic Ocean, August-September 2012

From August 25 to September 27, 2012, the United States Coast Guard Cutter (USCGC) Healy was part of an Extended Continental Shelf Project to determine the limits of the extended continental shelf in the Arctic. On a non-interference basis, a USGS ocean acidification team participated on the cruise to collect baseline water data in the Arctic. The collection of data extended from coastal waters near Barrow, Alaska, to 83°2'N., -175°36'W., and southward back to coastal waters near Barrow and on to Dutch Harbor, Alaska. As a consequence, a number of hypotheses were tested and questions asked associated with ocean acidification, including: What is the saturation state for different parts of the basin? What factors drive the saturation state in the different parts of the basin? How does saturation state compare to other regions? How do the carbon fluxes compare in the different parts of the basin? What is the buffering capacity of the water (Revelle factor)? What kind of variability does carbon demonstrate in the Arctic (near shore versus offshore and diurnal)? During the cruise, underway continuous and discrete water samples were collected, and discrete water samples were collected at stations to document the carbonate chemistry of the Arctic waters and quantify the saturation state of seawater with respect to calcium carbonate. These data are critical for providing baseline information in areas where no data have existed prior and will also be used to test existing models and predict future trends.

Arctic Ocean↗

USGS2014

USGS Field Activities 12BHM01, 12BHM02, 12BHM03, 12BHM04, and 12BHM05 on the West Florida Shelf, in February, April, May, June, and August 2012

Atmospheric carbon dioxide (CO 2 ) is absorbed by the ocean’s surface where it combines with seawater to form a weak, naturally occurring acid called carbonic acid (H 2 CO 3 ). Increasing carbon dioxide in the atmosphere results in the absorption of more CO 2 by the ocean and, therefore, increases in the acidity of seawater. This process, known as ocean acidification, has the potential to elicit change in ecosystems and organisms by disrupting biological processes. For example, ocean acidification is a problem for marine organisms such as corals, foraminifera, and algae that precipitate calcium carbonate to form their skeletons and shells (Kleypas and others, 2006). The effects are related to corresponding changes in the carbonate saturation state (Ω), where Ω is the ratio of the ion concentration product (Ca 2+ x CO 3 2- ) to the stoichiometric aragonite solubility product (K*sp) (Langdon and Atkinson, 2005). Because pH and CO 3 2- are strongly interdependent through the inorganic carbon system, the decrease in pH will cause a proportionally greater decrease in CO 3 2- . Globally, ocean acidification is occurring faster than at any time in the last 300 million years (Broeker and others, 1979). Recent evidence indicates that individual oceans are responding at different rates, depending on physical and biological processes. For example in the Arctic Ocean, the rate of saturation state decrease was 2.1 percent per year between 1997 and 2010 (Robbins and others., 2013) in an area as large as Montana, largely because of increases in melt of ice, versus the average rate observed for the Pacific Ocean (0.36 percent per year) (Feely and others, 2012). Unfortunately, comparative data sets over multiyear time frames are often not available because time series baseline carbon information has not been collected in many oceans. Data are needed in subtropical latitudes where carbonate saturation states are already naturally low and fluctuate seasonally. These data will help construct a baseline for the assessment of future changes. As part of the U.S. Geological Survey (USGS) Coastal and Marine Geology Program project "R esponse of Florida Shelf Ecosystems to Climate Change " and in partnership with Kendra Daly, University of South Florida ( USF ), data on surface ocean carbonate chemistry were collected on five cruises along transects on the shallow inner west Florida shelf and northern Gulf of Mexico in 2012. Data from the 2011 cruises were also published (Robbins and others., 2013). The data collected allows the USGS, National Oceanic and Atmospheric Administration ( NOAA ), and USF scientists to map variations in ocean chemistry including carbonate saturation states along designated tracks. The USGS also partners with NOAA and the National Aeronautics and Space Administration ( NASA ) to model air-sea flux as part of a Gulf of Mexico Carbon Synthesis project led by NASA.

Florida↗

USGS2013

Baseline monitoring of the western Arctic Ocean estimates 20% of the Canadian Basin surface waters are undersaturated with respect to aragonite

Marine surface waters are being acidified due to uptake of anthropogenic carbon dioxide, resulting in surface ocean areas of undersaturation with respect to carbonate minerals, including aragonite. In the Arctic Ocean, acidification is expected to occur at an accelerated rate with respect to the global oceans, but a paucity of baseline data has limited our understanding of the extent of Arctic undersaturation and of regional variations in rates and causes. The lack of data has also hindered refinement of models aimed at projecting future trends of ocean acidification. Here, based on more than 34,000 data records collected in 2010 and 2011, we establish a baseline of inorganic carbon data (pH, total alkalinity, dissolved inorganic carbon, partial pressure of carbon dioxide, and aragonite saturation index) for the western Arctic Ocean. This data set documents aragonite undersaturation in ~20% of the surface waters of the combined Canada and Makarov basins, an area characterized by recent acceleration of sea ice loss. Conservative tracer studies using stable oxygen isotopic data from 307 sites show that while the entire surface of this area receives abundant freshwater from meteoric sources, freshwater from sea ice melt is most closely linked to the areas of carbonate mineral undersaturation. These data link the Arctic Ocean’s largest area of aragonite undersaturation to sea ice melt and atmospheric CO 2 absorption in areas of low buffering capacity. Some relatively supersaturated areas can be linked to localized biological activity. Collectively, these observations can be used to project trends of ocean acidification in higher latitude marine surface waters where inorganic carbon chemistry is largely influenced by sea ice meltwater.

PLoS ONE↗

USGS2013

USGS Arctic Ocean carbon cruise 2010: field activity H-03-10-AR to collect carbon data in the Arctic Ocean, August - September 2010

Carbon dioxide (CO 2 ) in the atmosphere is absorbed at the surface of the ocean by reacting with seawater to form carbonic acid, a weak, naturally occurring acid. As atmospheric carbon dioxide increases, the concentration of carbonic acid in seawater also increases, causing a decrease in ocean pH and carbonate mineral saturation states, a process known as ocean acidification. The oceans have absorbed approximately 525 billion tons of carbon dioxide from the atmosphere, or about one-quarter to one-third of the anthropogenic carbon emissions released since the beginning of the Industrial Revolution (Sabine and others, 2004). Global surveys of ocean chemistry have revealed that seawater pH has decreased by about 0.1 units (from a pH of 8.2 to 8.1) since the 1700s due to absorption of carbon dioxide (Caldeira and Wickett, 2003; Orr and others, 2005; Raven and others, 2005). Modeling studies, based on Intergovernmental Panel on Climate Change (IPCC) CO 2 emission scenarios, predict that atmospheric carbon dioxide levels could reach more than 500 parts per million (ppm) by the middle of this century and 800 ppm by the year 2100, causing an additional decrease in surface water pH of 0.3 pH units. Ocean acidification is a global threat and is already having profound and deleterious effects on the geology, biology, chemistry, and socioeconomic resources of coastal and marine habitats (Raven and others, 2005; Ruttiman, 2006). The polar and sub-polar seas have been identified as the bellwethers for global ocean acidification.

Data Series↗