scholarly journals Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

2017 ◽  
Author(s):  
Jacoba Mol ◽  
Helmuth Thomas ◽  
Paul G. Myers ◽  
Xianmin Hu ◽  
Alfonso Mucci
Keyword(s):  
Sea Ice ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Beaufort Sea ◽  
Total Alkalinity ◽  
The Arctic ◽  
Surface Mixed Layer ◽  
Saturation State ◽  
Carbon Transfer ◽  
Mackenzie Shelf

Abstract. The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries inorganic carbon and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world oceans. Upwelling carries dissolved inorganic carbon (DIC) and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of inorganic carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of inorganic carbon are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf is analyzed and the resulting influence on the carbonate system, including the saturation state of waters with respect to aragonite and pH, is investigated. TA and the oxygen isotope ratio of water (δ18O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air-sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will respond to the aforementioned climate-induced changes.

scholarly journals Inorganic carbon fluxes on the Mackenzie Shelf of the Beaufort Sea

2018 ◽  
Vol 15 (4) ◽  
pp. 1011-1027 ◽  
Author(s):  
Jacoba Mol ◽  
Helmuth Thomas ◽  
Paul G. Myers ◽  
Xianmin Hu ◽  
Alfonso Mucci
Keyword(s):  
Sea Ice ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Beaufort Sea ◽  
Total Alkalinity ◽  
The Arctic ◽  
Surface Mixed Layer ◽  
Carbon Transfer ◽  
Mackenzie Shelf ◽  
Upwelling Event

Abstract. The Mackenzie Shelf in the southeastern Beaufort Sea is a region that has experienced large changes in the past several decades as warming, sea-ice loss, and increased river discharge have altered carbon cycling. Upwelling and downwelling events are common on the shelf, caused by strong, fluctuating along-shore winds, resulting in cross-shelf Ekman transport, and an alternating estuarine and anti-estuarine circulation. Downwelling carries dissolved inorganic carbon (DIC) and other remineralization products off the shelf and into the deep basin for possible long-term storage in the world's oceans. Upwelling carries DIC and nutrient-rich waters from the Pacific-origin upper halocline layer (UHL) onto the shelf. Profiles of DIC and total alkalinity (TA) taken in August and September of 2014 are used to investigate the cycling of carbon on the Mackenzie Shelf. The along-shore transport of water and the cross-shelf transport of DIC are quantified using velocity field output from a simulation of the Arctic and Northern Hemisphere Atlantic (ANHA4) configuration of the Nucleus of European Modelling of the Ocean (NEMO) framework. A strong upwelling event prior to sampling on the Mackenzie Shelf took place, bringing CO2-rich (elevated pCO2) water from the UHL onto the shelf bottom. The maximum on-shelf DIC flux was estimated at 16.9×103 mol C d−1 m−2 during the event. The maximum on-shelf transport of DIC through the upwelling event was found to be 65±15×10-3 Tg C d−1. TA and the oxygen isotope ratio of water (δ18O-H2O) are used to examine water-mass distributions in the study area and to investigate the influence of Pacific Water, Mackenzie River freshwater, and sea-ice melt on carbon dynamics and air–sea fluxes of carbon dioxide (CO2) in the surface mixed layer. Understanding carbon transfer in this seasonally dynamic environment is key to quantify the importance of Arctic shelf regions to the global carbon cycle and provide a basis for understanding how it will respond to the aforementioned climate-induced changes.

scholarly journals Estimates of ikaite export from sea ice to the underlying seawater in a sea ice–seawater mesocosm

2016 ◽  
Vol 10 (5) ◽  
pp. 2173-2189 ◽  
Author(s):  
Nicolas-Xavier Geilfus ◽  
Ryan J. Galley ◽  
Brent G. T. Else ◽  
Karley Campbell ◽  
Tim Papakyriakou ◽  
...  
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Carbon Dynamics ◽  
Total Alkalinity ◽  
Main Process ◽  
Saturation State ◽  
Ice Growth ◽  
Ice Melt

Abstract. The precipitation of ikaite and its fate within sea ice is still poorly understood. We quantify temporal inorganic carbon dynamics in sea ice from initial formation to its melt in a sea ice–seawater mesocosm pool from 11 to 29 January 2013. Based on measurements of total alkalinity (TA) and total dissolved inorganic carbon (TCO2), the main processes affecting inorganic carbon dynamics within sea ice were ikaite precipitation and CO2 exchange with the atmosphere. In the underlying seawater, the dissolution of ikaite was the main process affecting inorganic carbon dynamics. Sea ice acted as an active layer, releasing CO2 to the atmosphere during the growth phase, taking up CO2 as it melted and exporting both ikaite and TCO2 into the underlying seawater during the whole experiment. Ikaite precipitation of up to 167 µmolkg−1 within sea ice was estimated, while its export and dissolution into the underlying seawater was responsible for a TA increase of 64–66 µmolkg−1 in the water column. The export of TCO2 from sea ice to the water column increased the underlying seawater TCO2 by 43.5 µmolkg−1, suggesting that almost all of the TCO2 that left the sea ice was exported to the underlying seawater. The export of ikaite from the ice to the underlying seawater was associated with brine rejection during sea ice growth, increased vertical connectivity in sea ice due to the upward percolation of seawater and meltwater flushing during sea ice melt. Based on the change in TA in the water column around the onset of sea ice melt, more than half of the total ikaite precipitated in the ice during sea ice growth was still contained in the ice when the sea ice began to melt. Ikaite crystal dissolution in the water column kept the seawater pCO2 undersaturated with respect to the atmosphere in spite of increased salinity, TA and TCO2 associated with sea ice growth. Results indicate that ikaite export from sea ice and its dissolution in the underlying seawater can potentially hamper the effect of oceanic acidification on the aragonite saturation state (Ωaragonite) in fall and in winter in ice-covered areas, at the time when Ωaragonite is smallest.

scholarly journals Impacts of ikaite export from sea ice to the underlying seawater in a sea ice-seawater mesocosm

2016 ◽  
Author(s):  
N.-X Geilfus ◽  
R. J. Galley ◽  
B. G. T. Else ◽  
T. Papakyriakou ◽  
O. Crabeck ◽  
...  
Keyword(s):  
Sea Ice ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Open Water ◽  
Carbon Dynamics ◽  
Co2 Exchange ◽  
Total Alkalinity ◽  
Main Process ◽  
Saturation State ◽  
Ice Growth

Abstract. Ikaite precipitation within sea ice could act as a significant sink for atmospheric CO2. However, the fate of these ikaite crystals is still poorly understood. We quantify temporal inorganic carbon dynamics from initial sea ice formation from open water to its melt during a month-long experiment in a sea ice-seawater mesocosm pool. Within sea ice, ikaite precipitation and CO2 exchange with the atmosphere were the main processes affecting inorganic carbon dynamics, while the dissolution of ikaite was the main process affecting inorganic carbon dynamics in the underlying seawater. Based on the total alkalinity (TA) and total dissolved inorganic carbon (TCO2) within sea ice and seawater, we estimated ikaite precipitated up to 167 ± 3 µmol kg-1 within sea ice; up to 57 % of the ikaite precipitated within sea ice was exported to the underlying seawater where it was dissolved. Ikaite export from the ice to the underlying seawater was associated with brine rejection during sea ice growth, increased sea ice vertical connectivity due to the upward percolation of seawater, and meltwater flushing during sea ice melt. The dissolution of the ikaite crystals in the water column kept the seawater pCO2 undersaturated compared to the atmosphere in spite of increased salinity, TA, and TCO2 associated with sea ice growth. Results indicate that ikaite export from sea ice and its dissolution in the underlying seawater can potentially hamper the effect of oceanic acidification on the aragonite saturation state (Ωaragonite) in fall and winter in ice-covered areas, at the time when Ωaragonite is smallest.

scholarly journals Spatio-temporal variability of the CO<sub>2</sub> system on the Scotian Shelf

2011 ◽  
Vol 8 (6) ◽  
pp. 12013-12050 ◽  
Author(s):  
E. H. Shadwick ◽  
H. Thomas ◽  
A. E. F. Prowe ◽  
E. Horne
Keyword(s):  
Temporal Variability ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Large Fraction ◽  
Monitoring Program ◽  
Total Alkalinity ◽  
Surface Mixed Layer ◽  
Scotian Shelf ◽  
Lawrence Estuary ◽  
Spatio Temporal

Abstract. Relative to their surface areas, coastal oceans and continental shelves host a disproportionately large fraction of ocean productivity. The Scotian Shelf is a biologically productive coastal region of the Northwestern Atlantic Ocean. This subpolar region is influenced by the outflow of the St. Lawrence Estuary system and acts as an annual source for atmospheric CO2. As part of the Atlantic Zone Monitoring Program, dissolved inorganic carbon (DIC), total alkalinity, and surface CO2 partial pressure measurements were made throughout the Scotian Shelf in 2007. A shelf-wide assessment of the spatio-temporal variability of the inorganic carbon system was made relying on observations in April and September. Between these periods, biological production results in a significant drawdown of inorganic nutrients and DIC in the surface mixed-layer, while hydrographic controls also influence seasonal changes in DIC. Net community production (NCP) over the spring and summer seasons was estimated on the basis of inorganic carbon data. We find significant spatial variability in NCP with the largest values in the Southwestern Browns Bank region and a general trend of increasing NCP with distance offshore. A bulk seasonal carbon budget suggests that along-shore and cross-shelf transport may result in the export of subsurface DIC from this region.

scholarly journals CO<sub>2</sub> perturbation experiments: similarities and differences between dissolved inorganic carbon and total alkalinity manipulations

2009 ◽  
Vol 6 (10) ◽  
pp. 2145-2153 ◽  
Author(s):  
K. G. Schulz ◽  
J. Barcelos e Ramos ◽  
R. E. Zeebe ◽  
U. Riebesell
Keyword(s):  
Ocean Acidification ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Calcium Carbonate Precipitation ◽  
Carbonate Chemistry ◽  
Carbonate System ◽  
Experimental Conditions ◽  
Saturation State ◽  
Basic Approaches

Abstract. Increasing atmospheric carbon dioxide (CO2) through human activities and invasion of anthropogenic CO2 into the surface ocean alters the seawater carbonate chemistry, increasing CO2 and bicarbonate (HCO3−) at the expense of carbonate ion (CO32−) concentrations. This redistribution in the dissolved inorganic carbon (DIC) pool decreases pH and carbonate saturation state (Ω). Several components of the carbonate system are considered potential key variables influencing for instance calcium carbonate precipitation in marine calcifiers such as coccolithophores, foraminifera, corals, mollusks and echinoderms. Unravelling the sensitivities of marine organisms and ecosystems to CO2 induced ocean acidification (OA) requires well-controlled experimental setups and accurate carbonate system manipulations. Here we describe and analyse the chemical changes involved in the two basic approaches for carbonate chemistry manipulation, i.e. changing DIC at constant total alkalinity (TA) and changing TA at constant DIC. Furthermore, we briefly introduce several methods to experimentally manipulate DIC and TA. Finally, we examine responses obtained with both approaches using published results for the coccolithophore Emiliania huxleyi. We conclude that under most experimental conditions in the context of ocean acidification DIC and TA manipulations yield similar changes in all parameters of the carbonate system, which implies direct comparability of data obtained with the two basic approaches for CO2 perturbation.

scholarly journals A new global interior ocean mapped climatology: the 1° × 1° GLODAP version 2

2016 ◽  
Author(s):  
Siv K. Lauvset ◽  
Robert M. Key ◽  
Are Olsen ◽  
Steven van Heuven ◽  
Anton Velo ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Mapping Method ◽  
Total Alkalinity ◽  
The Arctic ◽  
Global Ocean ◽  
Information Analysis ◽  
Phosphate Silicate ◽  
Analysis Center ◽  
Standard Pressure

Abstract. We here present the new GLODAP version 2 (GLODAPv2) mapped climatology, which is based on data from all ocean basins up to and including 2013. In contrast to its predecessor, GLODAPv1.1, this climatology also covers the Arctic Ocean and Mediterranean Sea. The quality controlled and internally consistent data product files of GLODAPv2 (Olsen et al., 2015; Key et al., 2015) were used to create global 1° × 1° mapped climatologies of total dissolved inorganic carbon, total alkalinity, and pH using the Data-Interpolating Variational Analysis (DIVA) mapping method. Climatologies were created for 33 standard pressure surfaces. To minimize the risk of translating temporal variability in the input data to spatial variations in the mapped climatologies, layers with pressures of 1000 dbar, or less, were mapped for two different time periods: 1986–1999 and 2000–2013, roughly corresponding to the "WOCE" and "CLIVAR" eras of global ocean surveys. All data from the 1972–2013 period were used in the mapping of pressures higher than 1000 dbar. In addition to the marine CO2 chemistry parameters listed above, nitrate, phosphate, silicate, oxygen, salinity and theta were also mapped using DIVA. For these parameters all data from the full 1972–2013 period were used on all 33 surfaces. The GLODAPv2 global 1° × 1° mapped climatologies, including error fields and ancillary information have been made available at the GLODAPv2 web page at the Carbon Dioxide Information Analysis Center (CDIAC, http://cdiac.ornl.gov/oceans/GLODAPv2/).

scholarly journals Arctic Ocean data in CARINA

2010 ◽  
Vol 2 (1) ◽  
pp. 71-78 ◽  
Author(s):  
S. Jutterström ◽  
L. G. Anderson ◽  
N. R. Bates ◽  
R. Bellerby ◽  
T. Johannessen ◽  
...  
Keyword(s):  
Quality Control ◽  
Arctic Ocean ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
The Arctic ◽  
Data Set ◽  
Secondary Quality ◽  
Multi Linear Regression ◽  
The Individual

Abstract. The paper describes the steps taken for quality controlling chosen parameters within the Arctic Ocean data included in the CARINA data set and checking for offsets between the individual cruises. The evaluated parameters are the inorganic carbon parameters (total dissolved inorganic carbon, total alkalinity and pH), oxygen and nutrients: nitrate, phosphate and silicate. More parameters can be found in the CARINA data product, but were not subject to a secondary quality control. The main method in determining offsets between cruises was regional multi-linear regression, after a first rough basin-wide deep-water estimate of each parameter. Lastly, the results of the secondary quality control are discussed as well as applied adjustments.

scholarly journals GLODAPv2.2019 – an update of GLODAPv2

2019 ◽  
Vol 11 (3) ◽  
pp. 1437-1461 ◽  
Author(s):  
Are Olsen ◽  
Nico Lange ◽  
Robert M. Key ◽  
Toste Tanhua ◽  
Marta Álvarez ◽  
...  
Keyword(s):  
Quality Control ◽  
Water Samples ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
The Arctic ◽  
Global Ocean ◽  
Systematic Evaluation ◽  
Isotopic Tracers ◽  
Data Product

Abstract. The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface to bottom ocean biogeochemical data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of water samples. This update of GLODAPv2, v2.2019, adds data from 116 cruises to the previous version, extending its coverage in time from 2013 to 2017, while also adding some data from prior years. GLODAPv2.2019 includes measurements from more than 1.1 million water samples from the global oceans collected on 840 cruises. The data for the 12 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have undergone extensive quality control, especially systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but updated to WOCE exchange format and (ii) as a merged data product with adjustments applied to minimize bias. These adjustments were derived by comparing the data from the 116 new cruises with the data from the 724 quality-controlled cruises of the GLODAPv2 data product. They correct for errors related to measurement, calibration, and data handling practices, taking into account any known or likely time trends or variations. The compiled and adjusted data product is believed to be consistent to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg−1 in dissolved inorganic carbon, 4 µmol kg−1 in total alkalinity, 0.01–0.02 in pH, and 5 % in the halogenated transient tracers. The compilation also includes data for several other variables, such as isotopic tracers. These were not subjected to bias comparison or adjustments. The original data, their documentation and DOI codes are available in the Ocean Carbon Data System of NOAA NCEI (https://www.nodc.noaa.gov/ocads/oceans/GLODAPv2_2019/, last access: 17 September 2019). This site also provides access to the merged data product, which is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/xnme-wr20 (Olsen et al., 2019). The product files also include significant ancillary and approximated data. These were obtained by interpolation of, or calculation from, measured data. This paper documents the GLODAPv2.2019 methods and provides a broad overview of the secondary quality control procedures and results.

scholarly journals An updated version of the global interior ocean biogeochemical data product, GLODAPv2.2021

2021 ◽  
Vol 13 (12) ◽  
pp. 5565-5589
Author(s):  
Siv K. Lauvset ◽  
Nico Lange ◽  
Toste Tanhua ◽  
Henry C. Bittig ◽  
Are Olsen ◽  
...  
Keyword(s):  
Quality Control ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Data System ◽  
Total Alkalinity ◽  
The Arctic ◽  
Global Ocean ◽  
Isotopic Tracers ◽  
Data Product ◽  
Ocean Carbon

Abstract. The Global Ocean Data Analysis Project (GLODAP) is a synthesis effort providing regular compilations of surface-to-bottom ocean biogeochemical bottle data, with an emphasis on seawater inorganic carbon chemistry and related variables determined through chemical analysis of seawater samples. GLODAPv2.2021 is an update of the previous version, GLODAPv2.2020 (Olsen et al., 2020). The major changes are as follows: data from 43 new cruises were added, data coverage was extended until 2020, all data with missing temperatures were removed, and a digital object identifier (DOI) was included for each cruise in the product files. In addition, a number of minor corrections to GLODAPv2.2020 data were performed. GLODAPv2.2021 includes measurements from more than 1.3 million water samples from the global oceans collected on 989 cruises. The data for the 12 GLODAP core variables (salinity, oxygen, nitrate, silicate, phosphate, dissolved inorganic carbon, total alkalinity, pH, CFC-11, CFC-12, CFC-113, and CCl4) have undergone extensive quality control with a focus on systematic evaluation of bias. The data are available in two formats: (i) as submitted by the data originator but updated to World Ocean Circulation Experiment (WOCE) exchange format and (ii) as a merged data product with adjustments applied to minimize bias. For this annual update, adjustments for the 43 new cruises were derived by comparing those data with the data from the 946 quality controlled cruises in the GLODAPv2.2020 data product using crossover analysis. Comparisons to estimates of nutrients and ocean CO2 chemistry based on empirical algorithms provided additional context for adjustment decisions in this version. The adjustments are intended to remove potential biases from errors related to measurement, calibration, and data handling practices without removing known or likely time trends or variations in the variables evaluated. The compiled and adjusted data product is believed to be consistent with to better than 0.005 in salinity, 1 % in oxygen, 2 % in nitrate, 2 % in silicate, 2 % in phosphate, 4 µmol kg−1 in dissolved inorganic carbon, 4 µmol kg−1 in total alkalinity, 0.01–0.02 in pH (depending on region), and 5 % in the halogenated transient tracers. The other variables included in the compilation, such as isotopic tracers and discrete CO2 fugacity (fCO2), were not subjected to bias comparison or adjustments. The original data, their documentation, and DOI codes are available at the Ocean Carbon Data System of NOAA NCEI (https://www.ncei.noaa.gov/access/ocean-carbon-data-system/oceans/GLODAPv2_2021/, last access: 7 July 2021). This site also provides access to the merged data product, which is provided as a single global file and as four regional ones – the Arctic, Atlantic, Indian, and Pacific oceans – under https://doi.org/10.25921/ttgq-n825 (Lauvset et al., 2021). These bias-adjusted product files also include significant ancillary and approximated data and can be accessed via https://www.glodap.info (last access: 29 June 2021). These were obtained by interpolation of, or calculation from, measured data. This living data update documents the GLODAPv2.2021 methods and provides a broad overview of the secondary quality control procedures and results.

scholarly journals A year in the life of a central California kelp forest: physical and biological insights into biogeochemical variability

2016 ◽  
Author(s):  
David A. Koweek ◽  
Kerry J. Nickols ◽  
Paul R. Leary ◽  
Steve Y. Litvin ◽  
Tom W. Bell ◽  
...  
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Kelp Forest ◽  
Total Alkalinity ◽  
Kelp Forests ◽  
Saturation State ◽  
Central California ◽  
High Co2 ◽  
Spatial Gradients ◽  
Spatially Distributed

Abstract. Kelp forests are among the world's most productive marine ecosystems, yet little is known about their biogeochemistry. This study presents a fourteen-month time series (July 2013–August 2014) of surface and benthic dissolved inorganic carbon and total alkalinity measurements, along with accompanying hydrographic measurements, from six locations within a central California kelp forest. We present ranges and patterns of variability in carbonate chemistry, including pH (7.70–8.33), pCO2 (172–952 µatm), and the aragonite saturation state, ΩAr (0.94–3.91). Surface-to-bottom gradients in CO2 system chemistry were as large as the spatial gradients throughout the bottom of the kelp forest. Dissolved inorganic carbon variability was the main driver of the observed CO2 system variability. The majority of spatial variability in the kelp forest can be explained by advection of cold, dense high CO2 waters into the bottom of the kelp forest, with deeper sites experiencing high CO2 conditions more frequently. Despite the strong imprint of advection on the biogeochemical variability of the kelp forest, surface waters were undersaturated with CO2 in the spring through fall, indicative of the strong role of photosynthesis on biogeochemical variability. We emphasize the importance of spatially distributed measurements for developing a process-based understanding of kelp forest ecosystem function in a changing climate.

Sign in / Sign up

Export Citation Format

Share Document