| 1. |
- Abrahamsson, Katarina, 1957, et al.
(författare)
-
Variations of biochemical parameters along a transect in the Southern Ocean, with special emphasis on volatile halogenated organic compounds
- 2004
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Ingår i: Deep-sea research. Part II, Topical studies in oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2745-2756
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Tidskriftsartikel (refereegranskat)abstract
- A number of parameters of biogeochemical interest were monitored along a north-southerly transect (S 43-S 63degrees) in the Atlantic Sector of the Southern Ocean from the 8th to the 20th of December 1997. Changes in total dissolved inorganic carbon (C-T) and total alkalinity (A(T)) were mostly dependent on temperature and salinity until the ice edge was reached. After this point only a weak correlation was seen between these. Highest mean values of C-T and A(T) were observed in the Winter Ice Edge (WIE) (2195 and 2319 mumol kg(-1), respectively). Lowest mean AT (2277 mumol kg(-1)) was observed in the Sub-Antarctic Front (SAF), whereas lowest mean CT concentration (2068 mumol kg(-1)) was associated with the Sub-Tropical Front (STF). The pH in situ varied between 8.060 and 8.156 where the highest values were observed in the southern part of the Antarctic Polar Front (APF) and in the Summer Ice Edge (SIE) Region. These peaks were associated with areas of high chlorophyll a (chl a) and tribromomethane values. In the other areas the pH in situ was mainly dependent on hydrography. Bacterial abundance decreased more than one order of magnitude when going from north to south. The decrease appeared to be strongly related to water temperature and there were no elevated abundances at frontal zones. Microphytoplankton dominated in the SAF and APF, whereas the nano- and picoplankton dominated outside these regions. Volatile halogenated compounds were found to vary both with regions, and with daylight. For the iodinated compounds, the highest concentrations were found north of the STF. Brominated hydrocarbons had high concentrations in the STF, but elevated concentrations were also found in the APF and SIE regions. No obvious correlation could be found between the occurrence of individual halocarbons and chl a. On some occasions trichloroethene and tribromomethane related to the presence of nano- and microplankton, respectively.
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| 2. |
- Bakker, D. C. E., et al.
(författare)
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A multi-decade record of high-quality fCO(2) data in version 3 of the Surface Ocean CO2 Atlas (SOCAT)
- 2016
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 8:2, s. 383-413
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Tidskriftsartikel (refereegranskat)abstract
- The Surface Ocean CO2 Atlas (SOCAT) is a synthesis of quality-controlled fCO(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 fCO(2) values from 3646 data sets covering the years 1957 to 2014. This latest version has an additional 4.6 million fCO(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 fCO(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 fCO(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).Individual data set files, included in the synthesis product, can be downloaded here: doi:10.1594/PANGAEA.849770. The gridded products are available here: doi: 10.3334/CDIAC/OTG.SOCAT_V3_GRID.
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| 3. |
- Bakker, D. C. E., et al.
(författare)
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An update to the surface ocean CO2 atlas (SOCAT version 2)
- 2014
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Ingår i: Earth System Science Data. - : Copernicus GmbH. - 1866-3508 .- 1866-3516. ; 6:1, s. 69-90
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Tidskriftsartikel (refereegranskat)abstract
- The Surface Ocean CO2 Atlas (SOCAT), an activity of the international marine carbon research community, provides access to synthesis and gridded fCO2 (fugacity of carbon dioxide) products for the surface oceans. Version 2 of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO 2 values) and extended data coverage (from 1968-2007 to 1968-2011). The quality control criteria, while identical in both versions, have been applied more strictly in version 2 than in version 1. The SOCAT website (http://www.socat.info/) has links to quality control comments, metadata, individual data set files, and synthesis and gridded data products. Interactive online tools allow visitors to explore the richness of the data. Applications of SOCAT include process studies, quantification of the ocean carbon sink and its spatial, seasonal, year-to-year and longerterm variation, as well as initialisation or validation of ocean carbon models and coupled climate-carbon models. © Author(s) 2014. CC Attribution 3.0 License.
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| 4. |
- Charrieau, Laurie M., et al.
(författare)
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The effects of multiple stressors on the distribution of coastal benthic foraminifera: A case study from the Skagerrak-Baltic Sea region
- 2018
-
Ingår i: Marine Micropaleontology. - : Elsevier BV. - 0377-8398. ; 139, s. 42-56
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Tidskriftsartikel (refereegranskat)abstract
- Coastal ecosystems are subjected to both large natural variability and increasing anthropogenic impact on environmental parameters such as changes in salinity, temperature, and pH. This study documents the distribution of living benthic foraminifera under the influence of multiple environmental stressors in the Skagerrak-Baltic Sea region. Sediment core tops were studied at five sites along a transect from the Skagerrak to the Baltic Sea, with strong environmental gradients, especially in terms of salinity, pH, calcium carbonate saturation and dissolved oxygen concentration in the bottom water and pore water. We found that living foraminiferal densities and species richness were higher at the Skagerrak station, where the general living conditions were relatively beneficial for Foraminifera, with higher salinity and Ωcalc in the water column and higher pH and oxygen concentration in the bottom and pore water. The most common species reported at each station reflect the differences in the environmental conditions between the stations. The dominant species were Cassidulina laevigata and Hyalinea balthica in the Skagerrak, Stainforthia fusiformis, Nonionella aff. stella and Nonionoides turgida in the Kattegat and N. aff. stella and Nonionellina labradorica in the Öresund. The most adverse conditions, such as low salinity, low Ωcalc, low dissolved oxygen concentrations and low pH, were noted at the Baltic Sea stations, where the calcareous tests of the dominant living taxa Ammonia spp. and Elphidium spp. were partially to completely dissolved, probably due to a combination of different stressors affecting the required energy for biomineralization. Even though Foraminifera are able to live in extremely varying environmental conditions, the present results suggest that the benthic coastal ecosystems in the studied region, which are apparently affected by an increase in the range of environmental variability, will probably be even more influenced by a future increase in anthropogenic impacts, including coastal ocean acidification and deoxygenation.
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| 5. |
- Chierici, Melissa, 1968, et al.
(författare)
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Algorithms to estimate carbon dioxide in the upper subarctic North Atlantic using observations, satellite and ocean analysis data
- 2009
-
Ingår i: Deep-sea research. Part II, Topical studies in oceanography. - : Elsevier BV. - 0967-0645. ; 56, s. 630-639
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Tidskriftsartikel (refereegranskat)abstract
- Observations of the surface-water fugacity of carbon dioxide (fCO2sw) measured during 2005 in the subpolar North Atlantic Ocean (58–62°N, 10–40°W) were used together with in situ ocean data and remotely sensed data to develop algorithms to estimate fCO2sw. Based on multiple regression we found that sea-surface temperature (SST), mixed-layer depth (MLD), and chlorophyll a (chl a) contributed significantly to the fit. Two algorithms were developed for periods depending on the presence of chl a data. The correlation coefficient (r2) and the root-mean-square deviation (rms) for the best fit in the period when chl a was observed (20 March–15 October) were 0.720 and ±10.8 μatm, respectively. The best fit for the algorithm for the period when no chl a was present (16 October–19 March) resulted in a r2 of 0.774 and a rms of ±5.6 μatm. Based on these algorithms we estimated seasonal fields of fCO2sw and the air–sea CO2 flux. The estimated net annual CO2 sink was 0.0058 Gt C yr−1 or 0.6 mol C m−2 yr−1.
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| 6. |
- Chierici, Melissa, 1968, et al.
(författare)
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Biogeochemical evolution of the carbon dioxide system in the waters of long-lived mesoscale eddies in the Northeast Pacific Ocean
- 2005
-
Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 52:7-8, s. 955-974
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Tidskriftsartikel (refereegranskat)abstract
- An anticyclonic eddy, named Haida-2000, formed off the Southern Queen Charlotte Islands early in the year 2000. The eddy subsequently tracked northwest, transporting fresh, warm, and nutrient-rich water into the Northeast Pacific Ocean. Based on total dissolved inorganic carbon (CA total alkalinity (AT), and nutrients from six seasonal cruises between February 2000 and September 2001, we found that the oceanic carbonate system of the Surface waters in the eddy changed significantly. The greatest loss of C-T from the surface waters of Haida-2000 occurred during the first year, between February and June 2000. Based oil a concomitant loss in nitrate (NO3), the large CT loss we observed was likely due to biological production of organic carbon and probably resulted in a large drawdown of atmospheric CO,, as supported by the observed fugacity of carbon dioxide (fCO(2)) in the surface waters. During fall, C-T, fCO(2), and NO3 values increased, probably due to oxidation of organic matter and vertical entrainment Of CT and nutrient-rich water from below with fall mixing. As a result, the surface waters of the eddy were highly oversaturated in CO2 relative to the atmosphere. Another Haida eddy (Haida-2001) had a significantly smaller nitrate drawdown than Haida-2000 during its first spring, but the CT losses were similar in the two eddies. In early summer (mid-June) of the second year, the surface and sub-surface waters in Haida-2000 gained C-T, A(T), and NO3, partly caused by a merging with another 2001 Haida eddy, showing that exchange with surrounding waters took place and was significant at times. The high nitrate/ low chlorophyll (HNLC) surface waters at Ocean Station Papa (OSP), showed less fCO(2) Undersaturation during summer and less total nitrate and CT loss than Haida-2000, indicating that both eddies were larger sinks for carbon lthan HNLC waters. The waters surrounding the eddies generally had concentrations of C-T, A(T), and NO3 that were similar to or slightly higher than the waters of both Haida eddies throughout the study. Also, the sub-surface waters in these eddies showed no significant change in total carbon content, suggesting that at these depths eddies are recycling, not exporting systems. (c) 2005 Elsevier Ltd. All rights reserved.
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| 7. |
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| 8. |
- Chierici, Melissa, 1968, et al.
(författare)
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CaCO3 saturation in the Western Arctic Ocean
- 2009
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Ingår i: Gordon Researcg Conference Polar Marine Science, 15-20 March 2009, Il Ciocco, Italy.
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Konferensbidrag (refereegranskat)
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| 9. |
- Chierici, Melissa, 1968, et al.
(författare)
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Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves
- 2009
-
Ingår i: Biogeosciences. ; 6, s. 2421-2432
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Tidskriftsartikel (refereegranskat)abstract
- In the summer of 2005, we sampled surface water and measured pH and total alkalinity (AT) underway aboard IB Oden along the Northwest Passage from Cape Farewell (South Greenland) to the Chukchi Sea. We investigated the variability of carbonate system parameters, focusing particularly on carbonate concentration [CO32-] and calcium carbonate saturation states, as related to freshwater addition, biological processes and physical upwelling. Measurements on AT, pH at 15 ºC, salinity (S) and sea surface temperature (SST), were used to calculate total dissolved inorganic carbon (CT), [CO32-] and the saturation of aragonite (ΩAr) and calcite (ΩCa) in the surface water. The same parameters were measured in the water column of the Bering Strait. Some surface waters in the Canadian Arctic Archipelago (CAA) and on the Mackenzie shelf (MS) were found to be undersaturated with respect to aragonite (ΩAr < 1). In these areas, surface water was low in AT and CT (< 1500 µmol kg-1) relative to seawater and showed low [CO32-]. The low saturation states were probably due to the likely the effect of dilution due to freshwater addition by sea ice melt (CAA) and river runoff (MS). High AT and CT and low pH, corresponded with the lowest [CO32-], ΩAr and ΩCa, observed near Cape Bathurst and along the South Chukchi Peninsula. This was linked to the physical upwelling of subsurface water with elevated CO2. The highest surface ΩAr and ΩCa of 3.0 and 4.5, respectively, were found on the Chukchi Sea shelf and in the cold water north of Wrangel Island, which is heavily influenced by high CO2 drawdown and lower CT from intense biological production. In the western Bering Strait, the cold and saline Anadyr Current carries water that is enriched in AT and CT from enhanced organic matter remineralization, resulting in the lowest ΩAr (~1.2) of the area.
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| 10. |
- Chierici, Melissa, 1968
(författare)
-
Carbon dioxide in the Arctic Ocean
- 2009
-
Ingår i: Japan Swedish Scientific Association workshop, Japan.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Large areas of the Arctic shelves are largely unknown with regard to the carbon dioxide system and the processes affecting the air/sea CO2 flux. This is mainly due to sparse information and lack of data as a result of large logistical challenges to conduct measurement programs which are related to the ice cover and harsh conditions in the polar oceans. Lack of information is of great concern since predictions and observations show that the polar areas are the most vulnerable region for a climate change such as a warming. Moreover, the Arctic Ocean is also predicted to be the first to become affected by an increase in ocean CO2 such as ocean acidification. However, there are large uncertainties about the direction and magnitude of the feedback processes involved in the marine system and as well as its coupling with atmospheric forcing. Large efforts in measurement programs have to be performed to be able to gain insight and understanding of the processes governing the CO2 system. One major measuring effort was performed during summer 2005 where the first continuous surface water measurements of fugacity of CO2 (fCO2sw), was performed onboard the IB Oden along the Northwest Passage from Cape Farwell (S. Greenland) to the Chukchi Sea. CO2 system parameters were measured with the aim to investigate the importance of sea ice and river runoff on the spatial variability of fCO2 and the saturation state of calcium carbonate (Ω). The variability in these parameters are related to natural occurring features such as freshwater content, sea ice, biological processes and physical upwelling. This study highlights the value of using high-frequency measurements to gain increased insight into the variable and complex conditions, encountered on the shelves in the Arctic Ocean.
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| 11. |
- Chierici, Melissa, 1968, et al.
(författare)
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Evolution of the surface water carbon dioxide in relation to the annual trends in salinity and temperature in the Oyashio region.
- 2006
-
Ingår i: Annual Report, PICES XVth Annual meeting, Yokohama, Japan, 13-22 October 2006.. - 1897176597
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Konferensbidrag (refereegranskat)abstract
- We examined the annual trends in the carbon dioxide system and surface water hydrography in the Oyashio region (145E to 155E, 42N to 48N) during 6-years (1995 to 2001). We use data on partial pressure of carbon dioxide (pCO2) in both surface water and air, as well as data on sea surface temperature and salinity obtained from the Japanese-Canadian joint Volunteer Observing Ship program. The annual trends on seasonally detrended data showed increasing surface water pCO2 at an annual rate of 5.3 µatm yr-1, and the atmospheric pCO2 showed an increase of 2.1 µatm yr-1. We also observed a clear trend towards saltier (0.055 yr-1) and colder (-0.29 C yr-1) surface water conditions which suggested increased mixing of subsurface waters to the surface layer in the end of the 1990’s.
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| 12. |
- Chierici, Melissa, 1968, et al.
(författare)
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Increased net CO2 outgassing in the upwelling region of the southern Bering Sea in a period of variable marine climate between 1995 and 2001
- 2006
-
Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH. ; 111:C08008
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated seasonality and interannual variability of the surface water pCO2 (pCO2sw) and sea-air CO2 fluxes in the upwelling region of the southern Bering Sea (53°N to 55°N, 174°E to 194°E). Data of surface water and atmospheric pCO2, sea surface temperature and salinity were based on automated measurements on board cargo ships for 6 years (1995–2001). We observed a significant interannual trend towards more CO2 supersaturated surface water relative to the atmosphere. From linear regression of seasonally detrended data we obtained an annual pCO2sw increase of 6.5 ± 1.4 μatm yr−1 and 11 ± 1.9 μatm yr−1 in the basin and shelf slope, respectively. This was higher than the observed pCO2air increase (between 0.47 ± 0.28 and 0.96 ± 0.62 μatm yr−1), indicating the importance of other processes than oceanic CO2 uptake from the atmosphere to explain the pCO2sw increase. Sea surface temperature and salinity showed a trend towards cooler and more saline conditions. We estimated large interannual variability of net annual oceanic CO2 outgassing, with low CO2 outgassing in years before 1998 (<1 mol m−2 yr−1), increasing to a maximum of 4.5 mol m−2 yr−1 in 2000. Highest net CO2 outgassing was observed in the relatively cold years of 1999 and 2000, whereas the exceedingly warm year 1997 showed four times lower CO2 flux to the atmosphere. Interestingly, we found close coupling between the net CO2 outgassing and biological production; years with less net CO2 outgassing coincided with high biological CO2 drawdown, especially evident in 1997.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
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| 17. |
- Chierici, Melissa, 1968, et al.
(författare)
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Surface water fCO2 algorithms for the high-latitude Pacific sector of the Southern Ocean
- 2012
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Ingår i: Remote Sensing of Environment. - : Elsevier BV. - 0034-4257. ; 119, s. 184-196
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Tidskriftsartikel (refereegranskat)abstract
- The feasibility of using remotely sensed data jointly with shipboard measurements to estimate the carbon dioxide fugacity in the surface water (fCO2sw) of the Pacific sector of the Southern Polar Ocean (S > 60°S) is evaluated using a data set obtained during austral summer 2006. A comparison between remotely sensed chlorophyll a (chl a) and sea-surface temperature (SST) with in-situ measurements, reveals the largest bias in areas with rapid and large concentration changes such as at the ice edge, the polar front and in the Ross Sea Polynya. The correlation between fCO2sw and SST, chl a, biological productivity estimates and mixed layer depth (MLD) are evaluated, and single and multiple regression methods are used to develop fCO2sw algorithms. Single regressions between the study parameters and fCO2sw show that most of the fCO2sw variability is explained by chl a. The Multi-Parameter Linear regressions were used to create fCO2sw algorithms derived from field measurements, and using solely remote-sensing products. Based on the best fits from the two data sets fCO2sw estimates have a root means square deviation of ± 14 μatm and coefficient of determination of 0.82. The addition of satellite derived estimates of biological productivity in the algorithm does not significantly improve the fit. We use the algorithm with remotely sensed chl a and SST data to produce an fCO2sw map for the entire high-latitude Southern Ocean south of 55°S. We analyze and discuss the seasonal and spatial robustness of the algorithm based on the remotely sensed data and compare with climatologic fCO2sw data.
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| 18. |
- Chierici, Melissa, 1968, et al.
(författare)
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The impact of biogeochemical processes and environmental factors on the calcium carbonate saturation state in the Circumpolar Flaw Lead in the Amundsen Gulf, Arctic Ocean. : Controls on calcium carbonate in the Arctic Ocean
- 2011
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Ingår i: Journal of Geophysical Research-Oceans. - 2156-2202. ; 116:C00G09
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Tidskriftsartikel (refereegranskat)abstract
- We report on measurements across an annual cycle of carbon dioxide system parameters in the polar mixed layer (PML) of the circumpolar flaw lead in the Amundsen Gulf, Arctic Ocean. From these and other properties (nitrate, S, T) of the PML, we found that biological processes (photosynthesis and respiration) accounted for about 50% of the monthly variations in the carbonate ion concentration, [CO32−] and Ω, the saturation state of these waters with respect to calcite (ΩCa) and aragonite (ΩAr). Vertical mixing and salinity changes had equal impacts over the annual cycle. The impact of sea ice meltwater resulted in decreasing Ω values in summer, but most of this change was offset by the Ω increase as a result of CO2 drawdown during biological photosynthesis.
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| 19. |
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| 20. |
- Chierici, Melissa, 1968
(författare)
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Towards an understanding of the biological forcing of CO2 in the Southern Polar Ocean.
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this project was to quantitatively investigate the mechanisms driving the oceanic carbon dioxide system and the CO2 air-sea flux in areas of different characteristics regarding water column stratification, ice cover/extent and freshwater input in the Pacific sector of the Southern Ocean. The biogeochemical transformation of carbon was evaluated from CO2 system data and information on water mass properties in the water column. Another goal was to investigate the large natural variability of the marine carbonate system in the study area, to provide basic information needed to predict the response to future changes in the CaCO3 saturation in the Southern Ocean due to changes in sea ice extent and temperature.
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| 21. |
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| 22. |
- Chierici, Melissa, 1968, et al.
(författare)
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Variability in pH, fCO(2), oxygen and flux of CO2 in the surface water along a transect in the Atlantic sector of the Southern Ocean
- 2004
-
Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2773-2787
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Tidskriftsartikel (refereegranskat)abstract
- Underway sampling and measurements of pH, fCO(2), oxygen and Chlorophyll a (Chl a) were performed in the surface waters from Cape Town (South Africa) to Queen Maud Land (Antarctica) in the Atlantic sector of the Southern Ocean during the austral summer 1997/1998. From direct measurements of these parameters and from calculated fCO(2) the oceanic carbon dioxide system was studied and related to hydrological and biological parameters. fCO(2) was in general undersaturated relative to the atmosphere and showed a large variability with values ranging from 313 to 377 muatm with a mean value of 346 +/- 13 muatm. The undersaturation was more pronounced in areas associated with fronts where high Chl a and high pH in situ values were observed. Using shipboard wind speed data, estimates of the CO2 flux were made along the transect and during three mesoscale surveys on the northward return transect in the area of the Spring Ice Edge (SIE), the Winter Ice Edge (WIE) and in the Antarctic Polar Front (APF). The undersaturation observed during the transect caused the ocean to act as a sink for CO2 with a mean sea-air flux for the entire transect of -3+/-5 mmol m(-2) d(-1) with a large variability between -20 mmol m(-2) d(-1) (oceanic uptake) to 1.3 mmol m(-2) d(-1) (oceanic source). The lowest fCO(2) values (largest oceanic uptake Of COD were found at the southern boundary of the APF at 53degreesS, which coincided with a supersaturation in oxygen and high pH values. Oxygen concentrations were measured from 50degreesS to 63degreesS and varied between 324 and 359 mumol kg(-1) with a mean value of 347 +/- 9 mumol kg(-1). In general only small deviations from equilibrium oxygen saturation were observed (mean value = 99+/-2%). However, in the SIE oxygen was clearly undersaturated, probably an effect of upwelling of oxygen poor deep water which had not yet been compensated for by biological production. Three weeks later, the ice edge had retreated in the SIE region and the Chl a concentration had increased three-fold, suggesting the start of a phytoplankton bloom. This was also seen in the oxygen concentration which had increased and showed supersaturation. This coincided with an increased oceanic uptake of CO2 in the SIE during the mesoscale survey. (C) 2004 Elsevier Ltd. All rights reserved.
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| 23. |
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| 24. |
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| 25. |
- Fransson, Agneta, 1964, et al.
(författare)
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Antarctic sea ice carbon dioxide system and controls
- 2011
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Ingår i: Journal of Geophysical Research–Oceans. - 0148-0227. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- In austral summer, from December 2008 to January 2009, we investigated the sea-ice carbon dioxide (CO2) system and CO2 controls in the Amundsen and Ross Seas, Antarctica. We sampled seawater, brine and sea ice for the measurements of total alkalinity (AT), total inorganic carbon (DIC), pH, inorganic nutrients, particulate organic carbon (POC) and nitrogen (PON), chlorophyll a, pigments, salinity and temperature. Large variability in all measured parameters was observed in time and space due to the complex sea-ice dynamics. We discuss the controls of the sea-ice CO2 system, such as brine rejection, biological processes, calcium carbonate (CaCO3) precipitation/dissolution and CO2 exchange. Most (80 to 90%) of the DIC loss was due to brine rejection, which suggests that the sea ice acted as an efficient DIC sink from 0.8 and 2.6 mol m−2 yr−1 (9.6–31 g C m−2 yr−1). The remaining change in DIC was to a large extent explained by net biological production. The AT:DIC ratio in the sea ice was higher than in the under-ice water (UIW), with ratios reaching 1.7, which indicated CaCO3 precipitation and concomitant DIC loss in the sea ice. Elevated AT:DIC ratios and carbonate concentrations were also observed in the UIW, which reflect the solid CaCO3 rejected from the ice during melt. The potential for uptake of atmospheric CO2 in the mixed layer increased by approximately 56 μatm due to the combined effect of CaCO3 precipitation during ice formation, and ice melt in summer.
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| 26. |
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| 27. |
- Fransson, Agneta, 1964, et al.
(författare)
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CO2 in ice covered seas
- 2007
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Ingår i: Oden Southern Ocean seminar series onboard IB Oden December 2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 28. |
- Fransson, Agneta, 1964, et al.
(författare)
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CO2-system development in young sea ice and CO2 gas exchange at the ice/air interface mediated by brine and frost flowers in Kongsfjorden, Spitsbergen
- 2015
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Ingår i: Annals of Glaciology. - 0260-3055. ; 56:69, s. 245-257
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Tidskriftsartikel (refereegranskat)abstract
- In March and April 2010, we investigated the development of young landfast sea ice in Kongsfjorden, Spitsbergen, Svalbard. We sampled the vertical column, including sea ice, brine, frost flowers and sea water, to determine the CO2 system, nutrients, salinity and bacterial and ice algae production during a 13 day interval of ice growth. Apart from the changes due to salinity and brine rejection, the sea-ice concentrations of total inorganic carbon (C T), total alkalinity (A T), CO2 and carbonate ions (CO3 2–) in melted ice were influenced by dissolution of calcium carbonate (CaCO3) precipitates (25–55 μmol kg–1) and played the largest role in the changes to the CO2 system. The C T values were also influenced by CO2 gas flux, bacterial carbon production and primary production, which had a small impact on the C T. The only exception was the uppermost ice layer. In the top 0.05 m of the ice, there was a CO2 loss of ∼20 μmol kg–1 melted ice (1 mmol m–2) from the ice to the atmosphere. Frost flowers on newly formed sea ice were important in promoting ice–air CO2 gas flux, causing a CO2 loss to the atmosphere of 140–800 μmol kg–1 d–1 melted frost flowers (7–40 mmol m–2 d–1).
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| 29. |
- Fransson, Agneta, 1964, et al.
(författare)
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Comparison of interannual trends in the surface water pCO2, salinity and temperature in the subarctic North Pacific.
- 2006
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Ingår i: Annual Report: PICES XVth Annual meeting, Yokohama, Japan, 13-22 October 2006.. - 1897176597
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Konferensbidrag (refereegranskat)abstract
- We investigated the interannual variability of the partial pressure of surface water carbon dioxide (pCO2), salinity and temperature in the surface water in the Western Subarctic Gyre (WSG), the Alaska Gyre (AG) and the southern Bering Sea for a period of 6 years (1995 to 2001). All areas showed increasing surface water pCO2, with largest annual rate in pCO2sw of 9 µatm yr-1 in the southern Bering Sea. In the WSG, the pCO2 in the surface water increased of about 1.5 µatm yr-1, and in the AG 3.6 µatm yr-1. Sea surface temperature showed a cooling trend in all areas for the studied period and salinity increased in the southern Bering Sea and the WSG. We discuss the importance of different processes and ocean-atmosphere coupling to explain the differences between the areas.
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| 30. |
- Fransson, Agneta, 1964, et al.
(författare)
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Continuous pCO2 measurements under the sea ice in Arctic and Antarctic waters onboard an icebreaker.
- 2007
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Ingår i: IOCCP Report from Surface Ocean Surface CO2 Variability and Vulnerabilities Workshop, 11-14th April 2007, UNESCO-IOCCP, Paris, France.. ; 7
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- High-frequency underway pCO2 measurements were successfully performed in the Arctic Ocean in 2005, and in the Antarctic Southern Ocean in 2006 onboard the Swedish I/B Oden. We traversed in both open water and heavy sea ice conditions. The seawater intake was placed at the bow of the ship at approximately 8 meters depth, which enabled immediate under ice measurements in ice covered areas. In both studies, preliminary data showed rapid changes in the pCO2 and oxygen values in the ice zones, which was related to physical fronts and changing sea-ice conditions. However, the under-ice pCO2 levels differed in the two high-latitude oceans, likely due to different ecosystem dynamics involving ice-algae versus pelagic phytoplankton production. Future participation in expeditions to Antarctic Southern Ocean, and a long-term study in the Arctic Ocean in 2007/2008 will enable us to further investigate the biogeochemical dynamics in both Polar seas.
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| 31. |
- Fransson, Agneta, 1964, et al.
(författare)
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Diurnal variability in the oceanic carbon dioxide system and oxygen in the Southern Ocean surface water
- 2004
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Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2827-2839
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Tidskriftsartikel (refereegranskat)abstract
- During the SWEDARP cruise to the Atlantic sector of the Southern Ocean 1997/1998 six 24-hour stations were occupied in the areas of the Spring Ice Edge (SIE1, SIE2 and SIE3), the Winter Ice Edge (WIE), and the Antarctic Polar Front (APF1 and APF2). Samples were taken at the surface (2 m) every second hour and analyzed for total dissolved inorganic carbon, total alkalinity, pH and dissolved oxygen. By the use of wind speed measurements, calculated fugacity of carbon dioxide, fCO(2), and oxygen concentrations in the surface water, sea-air fluxes of carbon dioxide (CO2) and oxygen were calculated. These fluxes and the diurnal change in the chemical properties are discussed in relation to changes in biological activity. The fluctuations in wind speed showed a larger impact on the variability of the calculated fluxes than the fluctuations in surface water fCO(2) or oxygen saturation. The calculated fluxes and the variability also showed large differences depending on how the wind speed was used, instantaneously or averaged over 24 hours. The calculated sea-air CO2 fluxes using instantaneous wind speed varied between -0.012 and -0.11 mmol m(-2) h(-1) in the SIE1, -0.0073 and -0.30 mmol m(-2) h(-1) in the WIE and -0.043 and -1.65 mmol m(-2) h(-1) in the APF2. The mean values of sea-air CO2 fluxes were calculated to -0.046+/-0.044, -0.10+/-0.094 and -0.52+/-0.64 mmol m(-2) h(-1) for the SIE1, WIE and the APF2, respectively. The mean values of sea-air oxygen fluxes were calculated to 0.072+/-0.073, -0.12+/-0.54 and 1.4+/-1.3 mmol m(-2) h(-1) for the corresponding regions. (C) 2004 Elsevier Ltd. All rights reserved.
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| 32. |
- Fransson, Agneta, 1964, et al.
(författare)
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Impact of sea-ice processes on the carbonate system and ocean acidification at the ice-water interface of the Amundsen Gulf, Arctic Ocean
- 2013
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Ingår i: Journal of Geophysical Research - Oceans. - 0148-0227 .- 2156-2202. ; 118:12, s. 7001-7023
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Tidskriftsartikel (refereegranskat)abstract
- From sea-ice formation in November 2007 to onset of ice melt in May 2008, we studied the carbonate system in first-year Arctic sea ice, focusing on the impact of calcium-carbonate (CaCO3) saturation states of aragonite (ΩAr) and calcite (ΩCa) at the ice-water interface (UIW). Based on total inorganic carbon (CT) and total alkalinity (AT), and derived pH, CO2, carbonate ion ([CO3 2-]) concentrations and Ω, we investigated the major drivers such as brine rejection, CaCO3 precipitation, bacterial respiration, primary production and CO2-gas flux in sea ice, brine, frost flowers and UIW. We estimated large variability in sea-ice CT at the top, mid, and bottom ice. Changes due to CaCO3 and CO2-gas flux had large impact on CT in the whole ice core from March to May, bacterial respiration was important at the bottom ice during all months, and primary production in May. It was evident that the sea-ice processes had large impact on UIW, resulting in a five times larger seasonal amplitude of the carbonate system, relative to the upper 20 m. During ice formation, [CO2] increased by 30 μmol kg-1, [CO3 2-] decreased by 50 μmol kg-1, and the ΩAr decreased by 0.8 in the UIW due to CO2-enriched brine from solid CaCO3. Conversely, during ice melt, [CO3 2-] increased by 90 μmol kg -1 in the UIW, and Ω increased by 1.4 between March and May, likely due to CaCO3 dissolution and primary production. We estimated that increased ice melt would lead to enhanced oceanic uptake of inorganic carbon to the surface layer. Key Points Evidence of impact of sea-ice dynamics on CO2 system at ice-water interface Larger variability of CO 2 system in upper 2 m than upper 20 m from solid CaCO3 Ice melt promote enhanced oceanic CO2 uptake © 2013. American Geophysical Union. All Rights Reserved.
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| 33. |
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| 34. |
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| 35. |
- Fransson, Agneta, 1964, et al.
(författare)
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New insights into the variability of carbon dioxide and oxygen in the surface water along the Northwest Passage, using automated high-frequency instrumentation onboard the icebreaker Oden, summer 2005
- 2005
-
Ingår i: Abstracts for the International Conference on Arctic Planning (ICARP II) conference, Copenhagen, November 2005.
-
Konferensbidrag (refereegranskat)abstract
- In summer 2005, continuous measurements of pCO2 and dissolved oxygen in the surface water were successfully carried out onboard the Swedish icebreaker Oden. Seawater was pumped on-line from the ship’s seawater intake, placed in the bow at a depth of about 8 meters, to an automated pCO2 system and an oxygen sensor. The IB Oden journeyed through the Northwest Passage from Cape Farwell (S. Greenland) to the Bering Strait, and encountered both open water and heavy sea-ice conditions. Using 1-minute readings of pCO2 and oxygen, in addition to sea surface salinity and temperature as well as pCO2 in the air, we gained insight into the magnitude of the spatial variability in these parameters along the cruise track. In shelf seas in high-latitude regions, biogeochemical processes, which affect the carbon dioxide system, are highly dependent on the seasonality in formation and melting of sea ice as well as river runoff. In our study, preliminary data showed rapid changes in the pCO2 and oxygen values, likely related to physical fronts and changing sea-ice conditions. Surface water pCO2 was generally below the atmospheric level in ice-covered areas while in areas with no sea ice the pCO2 was close to or in equilibrium with the atmospheric pCO2. To our knowledge, this is the first underway pCO2 measurements performed in tough sea-ice conditions in the Arctic Ocean.
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| 36. |
- Fransson, Agneta, 1964, et al.
(författare)
-
Oceanic carbonate system in the climatically sensitive Amundsen and Ross Seas, Southern Ocean
- 2009
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Ingår i: 8th International Carbon dioxide conference, 13 to 19th of September 2009, Jena, Germany.
-
Konferensbidrag (refereegranskat)abstract
- During three expeditions (2006, 2007/2008 and 2008/2009) in the Pacific sector of the Southern Ocean in austral summer, the IB Oden acted as research platform in the climatically sensitive oceans of the Amundsen and Ross Seas. Continuous underway measurements of fCO2 and sampling of seawater were performed to study the carbonate system parameters. Along the route, we encountered both open water and heavy pack ice, starting from South Chile, crossing Drake Passage, and continuing through the Amundsen Sea to the Ross Sea. Large variability in fCO2 was observed in different areas and between years, linked to varying sea ice conditions, biological production and physical processes. Sea-air CO2 fluxes were calculated using wind speed data together with measured fCO2 in seawater and air. Total alkalinity (AT) and pH were used together with salinity and sea surface temperature to investigate the effect of CO2 in the surface water. We calculated the carbonate ion concentration [CO32-] and the saturation of aragonite (ΩAr) and calcite (ΩCa) in the surface water and found low [CO32-] and low saturation levels with regard to aragonite (ΩAr < 1.2) at several locations.
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| 37. |
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| 38. |
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| 39. |
- Fransson, Agneta, 1964, et al.
(författare)
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Transformation of carbon and oxygen in the surface layer of the eastern Atlantic sector of the Southern Ocean
- 2004
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Ingår i: Deep-Sea Research Part Ii-Topical Studies in Oceanography. - : Elsevier BV. - 0967-0645. ; 51:22-24, s. 2757-2772
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Tidskriftsartikel (refereegranskat)abstract
- The biogeochemical transformation of carbon, and the exchange of carbon dioxide and oxygen over the sea-air interface were evaluated from measurements of dissolved inorganic carbon, total alkalinity, dissolved oxygen and nitrate in the Atlantic sector of the Southern Ocean. The investigation was carried out. along longitude 6degreesE from December 1997 to January 1998 and was focused on three areas; the Spring Ice Edge (SIE), the Winter Ice Edge (WIE) and the Antarctic Polar Front (APF). The method is based on the assumption that differences between preformed and measured concentration of any property, are attributable to biological processes and sea-air exchange. By correcting the deficit of carbon and excess of oxygen observed in the surface mixed layer for the biological activity, the sea-air exchange of carbon dioxide and oxygen is estimated. In the SIE and the APF, a net release of carbon dioxide to the atmosphere of 0.1 and 0.5 mol m(-2), respectively, was calculated over a time scale of several months (from austral winter to January). In the WIE a net oceanic uptake of carbon dioxide was calculated, with a sea-air exchange of -0.1 mol m(-2). The calculated sea-air exchange of oxygen in the APF indicated an oceanic net release of oxygen to the atmosphere of 1.2 mol m(-2). In the SIE and the WIE the sea-air exchange of oxygen was -0.3 and -1.4 mol m(-2), respectively, from austral winter to January. Averaging the integrated sea-air exchanges indicated that the entire region acted as a weak oceanic source of carbon dioxide, from austral winter to January. The corresponding oxygen sea-air exchange showed a sink. (C) 2004 Elsevier Ltd. All rights reserved.
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| 40. |
- Granfors, Anna, 1978, et al.
(författare)
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Biogenic halocarbons in young Arctic sea ice and frost flowers
- 2013
-
Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 155, s. 124-134
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Tidskriftsartikel (refereegranskat)abstract
- The fate of halocarbons, naturally produced volatile halogenated organic compounds, in young Arctic sea ice was studied to better understand the role of sea ice in halocarbon cycling. In early spring, halocarbons were measured in sea ice frozen in core holes, during 12 days of formation and freezing. In order to understand which factors govern halocarbon concentration and distribution, salinity, temperature and biological parameters were monitored in the growing sea ice. It was found that sea ice participates in the cycling of halocarbons between sea and air. Sea ice concentrations and distributions of these compounds were influenced by production in the ice, where ice-inhabiting microorganisms caused local increases in halocarbon concentrations. Moreover, the halocarbon ice concentration decrease/change with time did not follow ice salinity, suggesting that additional removal processes caused sea ice to be a source of halogens to overlying air. The net production rate of bromoform in the surface of newly frozen ice was estimated to 14 pmol L−1 d−1 and the maximum removal rate was 18 pmol L−1 d−1. In addition frost flowers on newly formed sea ice were identified as contributors of halocarbons to the atmosphere with halocarbon concentrations in the same order of magnitude as in sea ice brine
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| 41. |
- Hjalmarsson, Sofia, 1980, et al.
(författare)
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Carbon dynamics in a productive coastal region—The Skagerrak
- 2010
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963. ; 82:4, s. 245-251
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Tidskriftsartikel (refereegranskat)abstract
- The importance of the coastal seas as areas of CO2 uptake from the atmosphere has gained more attention during recent years. This study utilizes dissolved inorganic carbon and hydrographic data collected in the Skagerrak for 10 months in 2006 to assess the carbon dynamics over the year. The surface water is under-saturated in CO2 relative to the atmosphere during the first half of the year and stays close to equilibrium at least until November. Consequently primary production compensates for the increase in pCO2 caused by the temperature increase from 2 to 10 °C in spring. Integrating the annual air–sea CO2 flux as computed using the Wanninkhof (1992) parameterization gives a net uptake of 1.2 mol m− 2 year− 1 which, if representative for the whole Skagerrak area, equals 3.7 ∙ 1010 mol year− 1 or 0.45 Tg C year− 1. Converting the nitrate consumption in the surface mixed layer from January to May to carbon units through the RKR ratio (Redfield et al., 1963) gives a drawdown of 6 g C m− 2. This number increases by a factor of two if primary productivity also occurs in the waters below the surface mixed layer, i.e. an increase in depth from 10 to 25 m as a seasonal average.We estimated the effect of salinity, biological processes and air–sea CO2 exchange on the monthly DIC change. We found that salinity was one of the major drivers for the DIC change.
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| 42. |
- Lauvset, S. K., et al.
(författare)
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Annual and seasonal fCO(2) and air-sea CO2 fluxes in the Barents Sea
- 2013
-
Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963. ; 113-114, s. 62-74
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Tidskriftsartikel (refereegranskat)abstract
- The Barents Sea is the strongest CO2 sink in the Arctic region, yet estimates of the air-sea CO2 flux in this area show a large span reflecting uncertainty as well as significant variability both seasonally and regionally. Here we use a previously unpublished data set of seawater CO2 fugacity (fCO(2)), and map these data over the western Barents Sea through multivariable linear regressions with SeaWiFS/MODIS remote sensing and TOPAZ model data fields. We find that two algorithms are necessary in order to cover the full seasonal cycle, mainly because not all proxy variables are available for the entire year, and because variability in fCO(2) is driven by different mechanisms in summer and winter. A comprehensive skill assessment indicates that there is a good overall correspondence between observations and predictions. The algorithms are also validated using two independent data sets, with good results. The gridded fCO(2) fields reveal tight links between water mass distribution and fCO(2) in all months, and particularly in winter. The seasonal cycle show peaks in the total air-sea CO2 influx in May and September, caused by respectively biological drawdown of CO2 and low sea ice concentration leaving a large open water area. For 2007 the annual average air-sea CO2 flux is -48 +/- 5 gC m(-2), which is comparable to previous estimates. (C) 2013 Elsevier B.V. All rights reserved.
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| 43. |
- Mattsdotter-Bjørk, My, et al.
(författare)
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Ocean acidification state in western Antarctic surface waters: Controls and interannual variability
- 2014
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 11:1, s. 57-73
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Tidskriftsartikel (refereegranskat)abstract
- During four austral summers (December to January) from 2006 to 2010, we investigated the surface-water carbonate system and its controls in the western Antarctic Ocean. Measurements of total alkalinity (AT), pH and total inorganic carbon (CT) were investigated in combination with high-frequency measurements on sea-surface temperature (SST), salinity and Chl A. In all parameters we found large interannual variability due to differences in sea-ice concentration, physical processes and primary production. The main result from our observations suggests that primary production was the major control on the calcium carbonate saturation state (Ω) in austral summer for all years. This was mainly reflected in the covariance of pH and Chl A. In the sea-ice-covered parts of the study area, pH and Ω were generally low, coinciding with low Chl A concentrations. The lowest pH in situ and lowest aragonite saturation (ΩAr ∼ 1.0) were observed in December 2007 in the coastal Amundsen and Ross seas near marine outflowing glaciers. These low Ω and high pH values were likely influenced by freshwater dilution. Comparing 2007 and 2010, the largest ΩAr difference was found in the eastern Ross Sea, where ΩAr was about 1.2 units lower in 2007 than in 2010. This was mainly explained by differences in Chl A (i.e primary production). In 2010 the surface water along the Ross Sea shelf was the warmest and most saline, indicating upwelling of nutrient and CO2-rich sub-surface water, likely promoting primary production leading to high Ω and pH. Results from multivariate analysis agree with our observations showing that changes in Chl A had the largest influence on the ΩAr variability. The future changes of ΩAr were estimated using reported rates of the oceanic uptake of anthropogenic CO 2, combined with our data on total alkalinity, SST and salinity (summer situation). Our study suggests that the Amundsen Sea will become undersaturated with regard to aragonite about 40 yr sooner than predicted by models. © 2014 Author(s).
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| 44. |
- Olofsson, Malin, et al.
(författare)
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Limited response of a spring bloom community inoculated with filamentous cyanobacteria to elevated temperature and pCO2
- 2019
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Ingår i: Botanica Marina. - : Walter de Gruyter GmbH. - 0006-8055 .- 1437-4323. ; 62:1
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Tidskriftsartikel (refereegranskat)abstract
- Temperature and CO2 levels are projected to increase in the future, with consequences for carbon and nutrient cycling in brackish environments, such as the Baltic Sea. Moreover, filamentous cyanobacteria are predicted to be favored over other phytoplankton groups under these conditions. Under a 12-day outdoor experiment, we examined the effect on a natural phytoplankton spring bloom community of elevated temperature (from 1°C to 4°C) and elevated pCO2 (from 390 to 970 μatm). No effects of elevated pCO2 or temperature were observed on phytoplankton biovolumes, but a significantly higher photosystem II activity was observed at elevated temperature after 9 days. In addition, three species of diazotrophic filamentous cyanobacteria were inoculated to test their competitive capacity under spring bloom conditions. The toxic cyanobacterium Nodularia spumigena exhibited an average specific growth rate of 0.10 d−1 by the end of the experiment, indicating potential prevalence even during wintertime in the Baltic Sea. Generally, none of the inoculated cyanobacteria species were able to outcompete the natural phytoplankton species at temperatures ≤4°C. No direct effects were found on heterotrophic bacteria. This study demonstrates the highly efficient resistance towards short-term (12 days) changes in abiotic factors by the natural Baltic Sea spring bloom community.
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| 45. |
- Olsen, Are, 1972, et al.
(författare)
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Sea-surface CO2 partial pressure in the subpolar North Atlantic
- 2008
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Ingår i: Biogeosciences. ; 5, s. 535-547
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Tidskriftsartikel (refereegranskat)abstract
- We present the first year-long subpolar trans-Atlantic set of surface seawater CO2 fugacity (fCO2sw) data. The data were obtained aboard the MV Nuka Arctica in 2005 and provide a quasi-continuous picture of the fCO2sw variability between Denmark and Greenland. Complementary real-time high-resolution data of surface chlorophyll-a (chl-a) concentrations and mixed layer depth (MLD) estimates have been collocated with the fCO2sw data. Off-shelf fCO2sw data exhibit a pronounced seasonal cycle. In winter, surface waters are saturated to slightly supersaturated over a wide range of temperatures. Through spring and summer, fCO2sw decreases by approximately 60 μatm, due to biological carbon consumption, which is not fully counteracted by the fCO2sw increase due to summer warming. The changes are synchronous with changes in chl-a concentrations and MLD, both of which are exponentially correlated with fCO2sw in off-shelf regions.
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| 46. |
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| 47. |
- Shadwick, Elisabeth, et al.
(författare)
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Seasonal variability of the inorganic C in the Amundsen Gulf.
- 2011
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Ingår i: Limnology and Oceanography. ; 56:1, s. 303-322
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Tidskriftsartikel (refereegranskat)abstract
- During a year-round occupation of Amundsen Gulf in the Canadian Arctic Archipelago dissolved inorganic and organic carbon (DIC, DOC), total alkalinity (TA), partial pressure of CO2 (pCO2) and related parameters were measured over a full annual cycle. A two-box model was used to identify and assess physical, biological, and chemical processes responsible for the seasonal variability of DIC, DOC, TA, and pCO2. Surface waters were undersaturated with respect to atmospheric CO2 throughout the year and constituted a net sink of 1.2 mol C m22 yr21, with ice coverage and ice formation limiting the CO2 uptake during winter. CO2 uptake was largely driven by under ice and open-water biological activity, with high subsequent export of organic matter to the deeper water column. Annual net community production (NCP) was 2.1 mol C m22 yr21. Approximately one-half of the overall NCP during the productive season (4.1 mol C m22 from Apr through Aug) was generated by under-ice algae and amounted to 1.9 mol C m22 over this period. The surface layer was autotrophic, while the overall heterotrophy of the system was fueled by either sedimentary or lateral inputs of organic matter.
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| 48. |
- Shadwick, EH, et al.
(författare)
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Seasonal variability of the inorganic carbon system in the Amundsen Gulf region of the southeastern Beaufort Sea
- 2011
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Ingår i: LIMNOLOGY AND OCEANOGRAPHY. - 0024-3590. ; 56:1, s. 303-322
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract During a year-round occupation of Amundsen Gulf in the Canadian Arctic Archipelago dissolved inorganic and organic carbon (DIC, DOC), total alkalinity (TA), partial pressure of CO2 (pCO2) and related parameters were measured over a full annual cycle. A two-box model was used to identify and assess physical, biological, and chemical processes responsible for the seasonal variability of DIC, DOC, TA, and pCO2. Surface waters were undersaturated with respect to atmospheric CO2 throughout the year and constituted a net sink of 1.2 mol C m22 yr21, with ice coverage and ice formation limiting the CO2 uptake during winter. CO2 uptake was largely driven by under ice and open-water biological activity, with high subsequent export of organic matter to the deeper water column. Annual net community production (NCP) was 2.1 mol C m22 yr21. Approximately one-half of the overall NCP during the productive season (4.1 mol C m22 from Apr through Aug) was generated by under-ice algae and amounted to 1.9 mol C m22 over this period. The surface layer was autotrophic, while the overall heterotrophy of the system was fueled by either sedimentary or lateral inputs of organic matter.
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| 49. |
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| 50. |
- Thomas, H, et al.
(författare)
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Barium and carbon fluxes in the Canadian Arctic Archipelago
- 2011
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Ingår i: Journal of Geophysical Research - Oceans. - 0148-0227 .- 2156-2202. ; 116
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Tidskriftsartikel (refereegranskat)abstract
- The seasonal and spatial variability of dissolved Barium (Ba) in the Amundsen Gulf, southeastern Beaufort Sea, was monitored over a full year from September 2007 to September 2008. Dissolved Ba displays a nutrient-type behavior: the maximum water column concentration is located below the surface layer. The highest Ba concentrations are typically observed at river mouths, the lowest concentrations are found in water masses of Atlantic origin. Barium concentrations decrease eastward through the Canadian Arctic Archipelago. Barite (BaSO4) saturation is reached at the maximum dissolved Ba concentrations in the subsurface layer, whereas the rest of the water column is undersaturated. A three end-member mixing model comprising freshwater from sea-ice melt and rivers, as well as upper halocline water, is used to establish their relative contributions to the Ba concentrations in the upper water column of the Amundsen Gulf. Based on water column and riverine Ba contributions, we assess the depletion of dissolved Ba by formation and sinking of biologically bound Ba (bio-Ba), from which we derive an estimate of the carbon export production. In the upper 50 m of the water column of the Amundsen Gulf, riverine Ba accounts for up to 15% of the available dissolved Ba inventory, of which up to 20% is depleted by bio-Ba formation and export. Since riverine inputs and Ba export occur concurrently, the seasonal variability of dissolved Ba in the upper water column is moderate. Assuming a fixed organic carbon to bio-Ba flux ratio, carbon export out of the surface layer is estimated at 1.8 ± 0.45 mol C m−2 yr−1. Finally, we propose a climatological carbon budget for the Amundsen Gulf based on recent literature data and our findings, the latter bridging the surface and subsurface water carbon cycles.
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