scholarly journals Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Tellus B ◽  
2010 ◽  
Vol 62 (5) ◽  
pp. 621-635 ◽  
Author(s):  
Elizabeth Jones ◽  
Dorothee Bakker ◽  
Hugh Venables ◽  
Michael Whitehouse ◽  
Rebecc Korb ◽  
...  
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Carbonate Chemistry ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Rapid Changes ◽  
Water Carbonate

Rapid changes in surface water carbonate chemistry during Antarctic sea ice melt

Tellus B ◽  
2010 ◽  
Vol 62 (5) ◽  
Author(s):  
Elizabeth M. Jones ◽  
Dorothee C. E. Bakker ◽  
Hugh J. Venables ◽  
Michael J. Whitehouse ◽  
Rebecca E. Korb ◽  
...  
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Carbonate Chemistry ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Rapid Changes ◽  
Water Carbonate

scholarly journals Ocean acidification state in western Antarctic surface waters: drivers and interannual variability

2013 ◽  
Vol 10 (5) ◽  
pp. 7879-7916 ◽  
Author(s):  
M. Mattsdotter Björk ◽  
A. Fransson ◽  
M. Chierici
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Interannual Variability ◽  
Chlorophyll A ◽  
Total Alkalinity ◽  
Full Description ◽  
Carbonate System ◽  
Amundsen Sea ◽  
Water Carbonate

Abstract. Each December during four years from 2006 to 2010, the surface water carbonate system was measured and investigated in the Amundsen Sea and Ross Sea, western Antarctica as part of the Oden Southern Ocean expeditions (OSO). The I/B Oden started in Punta Arenas in Chile and sailed southwest, passing through different regimes such as, the marginal/seasonal ice zone, fronts, coastal shelves, and polynyas. Discrete surface water was sampled underway for analysis of total alkalinity (AT), total dissolved inorganic carbon (CT) and pH. Two of these parameters were used together with sea-surface temperature (SST), and salinity to obtain a full description of the surface water carbonate system, including pH in situ and calcium carbonate saturation state of aragonite (ΩAr) and calcite (ΩCa). Multivariate analysis was used to investigate interannual variability and the major controls (sea-ice concentration, SST, salinity and chlorophyll a) on the variability in the carbonate system and Ω. This analysis showed that SST and chlorophyll a were the major drivers of the Ω variability in both the Amundsen and Ross seas. In 2007, the sea-ice edge was located further south and the area of the open polynya was relatively small compared to 2010. We found the lowest pH in situ (7.932) and Ω = 1 values in the sea-ice zone and in the coastal Amundsen Sea, nearby marine out flowing glaciers. In 2010, the sea-ice coverage was the largest and the areas of the open polynyas were the largest for the whole period. This year we found the lowest salinity and AT, coinciding with highest chl a. This implies that the highest ΩAr in 2010 was likely an effect of biological CO2 drawdown, which out-competed the dilution of carbonate ion concentration due to large melt water volumes. We predict and discuss future Ω values, using our data and reported rates of oceanic uptake of anthropogenic CO2, suggesting that the Amundsen Sea will become undersaturated with regard to aragonite about 20 yr sooner than predicted by models.

scholarly journals Variability in Antarctic sea ice from 1998-2017

2018 ◽  
Author(s):  
Zhankai Wu ◽  
Xingdong Wang
Keyword(s):  
Sea Ice ◽  
First Year ◽  
Concentration Data ◽  
Sea Ice Concentration ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Ice Concentration ◽  
The Antarctic ◽  
Melt Duration ◽  
Multiyear Ice

This study was based on the daily sea ice concentration data from the National Snow and Ice Data Center (Cooperative Institute for Research in Environmental Sciences, Boulder, CO, USA) from 1998 to 2017. The Antarctic sea ice was analysed from the total sea ice area (SIA), first year ice area, first year ice melt duration, and multiyear ice area. On a temporal scale, the changes in sea ice parameters were studied over the whole 20 years and for two 10-year periods. The results showed that the total SIA increased by 0.0083×106 km2 yr-1 (+2.07% dec-1) between 1998 and 2017. However, the total SIA in the two 10-year periods showed opposite trends, in which the total SIA increased by 0.026×106 km2 yr-1 between 1998 and 2007 and decreased by 0.0707×106 km2 yr-1 from 2008 to 2017. The first year ice area increased by 0.0059×106 km2 yr-1 and the melt duration decreased by 0.0908 days yr-1 between 1998 and 2017. The multiyear ice area increased by 0.0154×106 km2 yr-1 from 1998 to 2017, and the increase in the last 10 years was about 12.1% more than that in the first 10 years. On a spatial scale, the Entire Antarctica was divided into two areas, namely West Antarctica (WA) and East Antarctica (EA), according to the spatial change rate of sea ice concentration. The results showed that WA had clear warming in recent years; the total sea ice and multiyear ice areas showed a decreasing trend; multiyear ice area sharply decreased and reached the lowest value in 2017, and accounted for only about 10.1% of the 20-year average. However, the total SIA and multiyear ice area all showed an increased trend in EA, in which the multiyear ice area increased by 0.0478×106 km2 yr-1. Therefore, Antarctic sea ice presented an increasing trend, but there were different trends in WA and EA. Different sea ice parameters in WA and EA showed an opposite trend from 1998 to 2007. However, the total SIA, first year ice area, and multiyear ice area all showed a decreasing trend from 2008-2017, especially the total sea ice and first year ice, which changed almost the same in 2014-2017. In summary, although the Antarctic sea ice has increased slightly over time, it has shown a decreasing trend in recent years.

scholarly journals Low <i>p</i>CO<sub>2</sub> under sea-ice melt in the Canada Basin of the western Arctic Ocean

2017 ◽  
Author(s):  
Naohiro Kosugi ◽  
Daisuke Sasano ◽  
Masao Ishii ◽  
Shigeto Nishino ◽  
Hiroshi Uchida ◽  
...  
Keyword(s):  
Surface Water ◽  
Sea Ice ◽  
Partial Pressure ◽  
Arctic Ocean ◽  
Canada Basin ◽  
Western Arctic Ocean ◽  
Co2 Partial Pressure ◽  
Ice Melt ◽  
Low Co2 ◽  
Western Arctic

Abstract. In September 2013, we observed an expanse of surface water with low CO2 partial pressure (pCO2sea) (

scholarly journals Sea-ice melt CO<sub>2</sub>–carbonate chemistry in the western Arctic Ocean: meltwater contributions to air–sea CO<sub>2</sub> gas exchange, mixed-layer properties and rates of net community production under sea ice

2014 ◽  
Vol 11 (23) ◽  
pp. 6769-6789 ◽  
Author(s):  
N. R. Bates ◽  
R. Garley ◽  
K. E. Frey ◽  
K. L. Shake ◽  
J. T. Mathis
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Mixed Layer ◽  
Pond Water ◽  
Carbonate Chemistry ◽  
Western Arctic Ocean ◽  
Ice Melt ◽  
Melt Pond ◽  
Melt Ponds ◽  
Western Arctic

Abstract. The carbon dioxide (CO2)-carbonate chemistry of sea-ice melt and co-located, contemporaneous seawater has rarely been studied in sea-ice-covered oceans. Here, we describe the CO2–carbonate chemistry of sea-ice melt (both above sea-ice as "melt ponds" and below sea-ice as "interface waters") and mixed-layer properties in the western Arctic Ocean in the early summer of 2010 and 2011. At 19 stations, the salinity (∼0.5 to <6.5), dissolved inorganic carbon (DIC; ∼20 to <550 μmol kg−1) and total alkalinity (TA; ∼30 to <500 μmol kg−1) of above-ice melt pond water was low compared to the co-located underlying mixed layer. The partial pressure of CO2 (pCO2) in these melt ponds was highly variable (∼<10 to >1500 μatm) with the majority of melt ponds acting as potentially strong sources of CO2 to the atmosphere. The pH of melt pond waters was also highly variable ranging from mildly acidic (6.1 to 7) to slightly more alkaline than underlying seawater (>8.2 to 10.8). All of the observed melt ponds had very low (<0.1) saturation states (Ω) for calcium carbonate (CaCO3) minerals such as aragonite (Ωaragonite). Our data suggest that sea-ice generated alkaline or acidic type melt pond water. This melt water chemistry dictates whether the ponds are sources of CO2 to the atmosphere or CO2 sinks. Below-ice interface water CO2–carbonate chemistry data also indicated substantial generation of alkalinity, presumably owing to dissolution of CaCO3 in sea-ice. The interface waters generally had lower pCO2 and higher pH/Ωaragonite than the co-located mixed layer beneath. Sea-ice melt thus contributed to the suppression of mixed-layer pCO2, thereby enhancing the surface ocean's capacity to uptake CO2 from the atmosphere. Our observations contribute to growing evidence that sea-ice CO2–carbonate chemistry is highly variable and its contribution to the complex factors that influence the balance of CO2 sinks and sources (and thereby ocean acidification) is difficult to predict in an era of rapid warming and sea-ice loss in the Arctic Ocean.

scholarly journals Southern Ocean Biogeochemical Argo detect under-ice phytoplankton growth before sea ice retreat

2021 ◽  
Vol 18 (1) ◽  
pp. 25-38
Author(s):  
Mark Hague ◽  
Marcello Vichi
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Light Adaptation ◽  
Ice Cover ◽  
Data Sampling ◽  
Argo Data ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Ice Retreat ◽  
Ice Edge

Abstract. The seasonality of sea ice in the Southern Ocean has profound effects on the life cycle (phenology) of phytoplankton residing under the ice. The current literature investigating this relationship is primarily based on remote sensing, which often lacks data for half of the year or more. One prominent hypothesis holds that, following ice retreat in spring, buoyant meltwaters enhance available irradiance, triggering a bloom which follows the ice edge. However, an analysis of Biogeochemical Argo (BGC-Argo) data sampling under Antarctic sea ice suggests that this is not necessarily the case. Rather than precipitating rapid accumulation, we show that meltwaters enhance growth in an already highly active phytoplankton population. Blooms observed in the wake of the receding ice edge can then be understood as the emergence of a growth process that started earlier under sea ice. Indeed, we estimate that growth initiation occurs, on average, 4–5 weeks before ice retreat, typically starting in August and September. Novel techniques using on-board data to detect the timing of ice melt were used. Furthermore, such growth is shown to occur under conditions of substantial ice cover (>90 % satellite ice concentration) and deep mixed layers (>100 m), conditions previously thought to be inimical to growth. This led to the development of several box model experiments (with varying vertical depth) in which we sought to investigate the mechanisms responsible for such early growth. The results of these experiments suggest that a combination of higher light transfer (penetration) through sea ice cover and extreme low light adaptation by phytoplankton can account for the observed phenology.

scholarly journals Controls on surface water carbonate chemistry along North American ocean margins

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei-Jun Cai ◽  
Yuan-Yuan Xu ◽  
Richard A. Feely ◽  
Rik Wanninkhof ◽  
Bror Jönsson ◽  
...  
Keyword(s):  
Surface Water ◽  
North American ◽  
Carbonate Chemistry ◽  
Water Carbonate

scholarly journals Southern Ocean BGC-Argo Detect Under Ice Phytoplankton Growth Before Sea Ice Retreat

2020 ◽  
Author(s):  
Mark Hague ◽  
Marcello Vichi
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Light Adaptation ◽  
Data Sampling ◽  
Argo Data ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Highly Active ◽  
Ice Retreat ◽  
Ice Edge

Abstract. The seasonality of sea ice in the Southern Ocean has profound effects on the life cycle (phenology) of phytoplankton residing under the ice. The current literature investigating this relationship is primarily based on remote sensing, which often lacks data for half the year or more. One prominent hypothesis holds that following ice retreat in spring, buoyant melt waters enhance irradiance levels, triggering a bloom which follows the ice edge. However, an analysis of BGC-Argo data sampling under Antarctic sea ice suggests that this is not necessarily the case. Rather than precipitating rapid accumulation, we show that melt waters enhance growth in an already highly active phytoplankton population. Blooms observed in the wake of the receding ice edge can then be understood as the emergence of a growth process that started earlier under sea ice. Indeed, we estimate that growth initiation occurs, on average, 4–5 weeks before ice retreat, typically starting in August and September. Novel techniques using on-board data to detect the timing of ice melt were used. Furthermore, such growth is shown to occur under conditions of substantial ice cover (> 90 % satellite ice concentration) and deep mixed layers (> 100 m), conditions previously thought to be inimical to growth. This led to the development of several 0D model experiments in which we sought to investigate the mechanisms responsible for such early growth. The results of theses experiments suggest that a combination of higher light transfer (penetration) through sea ice and extreme low light adaptation by phytoplankton can account for the observed phenology.

Microzooplankton composition in the winter sea ice of the Weddell Sea

2017 ◽  
Vol 29 (4) ◽  
pp. 299-310 ◽  
Author(s):  
Marina Monti-Birkenmeier ◽  
Tommaso Diociaiuti ◽  
Serena Fonda Umani ◽  
Bettina Meyer
Keyword(s):  
Sea Ice ◽  
Ice Cores ◽  
Complete Loss ◽  
Weddell Sea ◽  
Late Winter ◽  
Ice Melt ◽  
Antarctic Sea Ice ◽  
Carbon Biomass ◽  
The Antarctic ◽  
Carbon Concentrations

AbstractSympagic microzooplankton were studied during late winter in the northern Weddell Sea for diversity, abundance and carbon biomass. Ice cores were collected on an ice floe along three dive transects and seawater was taken from under the ice through the central dive hole from which all transects were connected. The areal and vertical microzooplankton distributions in the ice and water were compared. Abundance (max. 1300 ind. l-1) and biomass (max. 28.2 µg C l-1) were high in the ice cores and low in the water below the sea ice (max. 19 ind. l-1, 0.15 µg C l-1, respectively). The highest abundances were observed in the bottom 10 cm of the ice cores. The microzooplankton community within the sea ice comprised mainly aloricate ciliates, foraminifers and micrometazoans. In winter, microzooplankton represent an important fraction of the sympagic community in the Antarctic sea ice. They can potentially control microalgal production and contribute to particulate organic carbon concentrations when released into the water column during the ice melt in spring. Continued reduction of the sea ice may undermine the roles of microzooplankton, leading to a reduction or complete loss of diversity, abundance and biomass of these sympagic protists.

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