Calcium carbonate saturation states along the West Antarctic Peninsula

2021 ◽  
pp. 1-21
Author(s):  
Elizabeth M. Jones ◽  
Mario Hoppema ◽  
Karel Bakker ◽  
Hein J.W. de Baar
Keyword(s):  
Calcium Carbonate ◽  
Surface Water ◽  
Sea Ice ◽  
Antarctic Peninsula ◽  
Inorganic Carbon ◽  
Total Alkalinity ◽  
The West ◽  
Saturation State ◽  
West Antarctic ◽  
West Antarctic Peninsula

Abstract The waters along the West Antarctic Peninsula (WAP) have experienced warming and increased freshwater inputs from melting sea ice and glaciers in recent decades. Challenges exist in understanding the consequences of these changes on the inorganic carbon system in this ecologically important and highly productive ecosystem. Distributions of dissolved inorganic carbon (CT), total alkalinity (AT) and nutrients revealed key physical, biological and biogeochemical controls of the calcium carbonate saturation state (Ωaragonite) in different water masses across the WAP shelf during the summer. Biological production in spring and summer dominated changes in surface water Ωaragonite (ΔΩaragonite up to +1.39; ~90%) relative to underlying Winter Water. Sea-ice and glacial meltwater constituted a minor source of AT that increased surface water Ωaragonite (ΔΩaragonite up to +0.07; ~13%). Remineralization of organic matter and an influx of carbon-rich brines led to cross-shelf decreases in Ωaragonite in Winter Water and Circumpolar Deep Water. A strong biological carbon pump over the shelf created Ωaragonite oversaturation in surface waters and suppression of Ωaragonite in subsurface waters. Undersaturation of aragonite occurred at < ~1000 m. Ongoing changes along the WAP will impact the biologically driven and meltwater-driven processes that influence the vulnerability of shelf waters to calcium carbonate undersaturation in the future.

scholarly journals Changes in the upper ocean mixed layer and phytoplankton productivity along the West Antarctic Peninsula

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170173 ◽  
Author(s):  
Oscar Schofield ◽  
Michael Brown ◽  
Josh Kohut ◽  
Schuyler Nardelli ◽  
Grace Saba ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Mixed Layer ◽  
Carbon Fixation ◽  
Upper Ocean ◽  
The West ◽  
Phytoplankton Productivity ◽  
West Antarctic ◽  
West Antarctic Peninsula

The West Antarctic Peninsula (WAP) has experienced significant change over the last 50 years. Using a 24 year spatial time series collected by the Palmer Long Term Ecological Research programme, we assessed long-term patterns in the sea ice, upper mixed layer depth (MLD) and phytoplankton productivity. The number of sea ice days steadily declined from the 1980s until a recent reversal that began in 2008. Results show regional differences between the northern and southern regions sampled during regional ship surveys conducted each austral summer. In the southern WAP, upper ocean MLD has shallowed by a factor of 2. Associated with the shallower mixed layer is enhanced phytoplankton carbon fixation. In the north, significant interannual variability resulted in the mixed layer showing no trended change over time and there was no significant increase in the phytoplankton productivity. Associated with the recent increases in sea ice there has been an increase in the photosynthetic efficiency (chlorophyll a -normalized carbon fixation) in the northern and southern regions of the WAP. We hypothesize the increase in sea ice results in increased micronutrient delivery to the continental shelf which in turn leads to enhanced photosynthetic performance. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

Extreme Anomalous Atmospheric Circulation in the West Antarctic Peninsula Region in Austral Spring and Summer 2001/02, and Its Profound Impact on Sea Ice and Biota*

2006 ◽  
Vol 19 (15) ◽  
pp. 3544-3571 ◽  
Author(s):  
Robert A. Massom ◽  
Sharon E. Stammerjohn ◽  
Raymond C. Smith ◽  
Michael J. Pook ◽  
Richard A. Iannuzzi ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Phytoplankton Bloom ◽  
Wide Field ◽  
The West ◽  
Austral Spring ◽  
Sea Ice Extent ◽  
Ice Dynamics ◽  
West Antarctic ◽  
West Antarctic Peninsula

Abstract Exceptional sea ice conditions occurred in the West Antarctic Peninsula (WAP) region from September 2001 to February 2002, resulting from a strongly positive atmospheric pressure anomaly in the South Atlantic coupled with strong negative anomalies in the Bellingshausen–Amundsen and southwest Weddell Seas. This created a strong and persistent north-northwesterly flow of mild and moist air across the WAP. In situ, satellite, and NCEP–NCAR Reanalysis (NNR) data are used to examine the profound and complex impact on regional sea ice, oceanography, and biota. Extensive sea ice melt, leading to an ocean mixed layer freshening and widespread ice surface flooding, snow–ice formation, and phytoplankton growth, coincided with extreme ice deformation and dynamic thickening. Sea ice dynamics were crucial to the development of an unusually early and rapid (short) retreat season (negative ice extent anomaly). Strong winds with a dominant northerly component created an unusually compact marginal ice zone and a major increase in ice thickness by deformation and over-rafting. This led to the atypical persistence of highly compact coastal ice through summer. Ecological effects were both positive and negative, the latter including an impact on the growth rate of larval Antarctic krill and the largest recorded between-season breeding population decrease and lowest reproductive success in a 30-yr Adélie penguin demographic time series. The unusual sea ice and snow cover conditions also contributed to the formation of a major phytoplankton bloom. Unexpectedly, the initial bloom occurred within compact sea ice and could not be detected in Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) ocean color data. This analysis demonstrates that sea ice extent alone is an inadequate descriptor of the regional sea ice state/conditions, from both a climatic and ecological perspective; further information is required on thickness and dynamics/deformation.

scholarly journals Ocean acidification and calcium carbonate saturation states in the coastal zone of the West Antarctic Peninsula

2017 ◽  
Vol 139 ◽  
pp. 181-194 ◽  
Author(s):  
Elizabeth M. Jones ◽  
Mairi Fenton ◽  
Michael P. Meredith ◽  
Nicola M. Clargo ◽  
Sharyn Ossebaar ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Ocean Acidification ◽  
Coastal Zone ◽  
Antarctic Peninsula ◽  
The West ◽  
West Antarctic ◽  
West Antarctic Peninsula

scholarly journals Marine pelagic ecosystems: the West Antarctic Peninsula

2006 ◽  
Vol 362 (1477) ◽  
pp. 67-94 ◽  
Author(s):  
Hugh W Ducklow ◽  
Karen Baker ◽  
Douglas G Martinson ◽  
Langdon B Quetin ◽  
Robin M Ross ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Marine Ecosystem ◽  
Ocean Dynamics ◽  
The West ◽  
Sea Ice Extent ◽  
The Past ◽  
West Antarctic ◽  
West Antarctic Peninsula ◽  
The Antarctic

The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba . Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 2°C increase in the annual mean temperature and a 6°C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.6°C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in ice-dependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate/ecological gradients extending along the WAP and the presence of monitoring systems, field stations and long-term research programmes make the region an invaluable observatory of climate change and marine ecosystem response.

scholarly journals Meteoric water contribution to sea ice formation and its control of the surface water carbonate cycle on the Wandel Sea shelf, northeastern Greenland

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Nicolas-Xavier Geilfus ◽  
Kathleen Munson ◽  
Marcos Lemes ◽  
Feiyue Wang ◽  
Jean-Louis Tison ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Surface Water ◽  
Sea Ice ◽  
Water Column ◽  
Inorganic Carbon ◽  
Meteoric Water ◽  
Ice Cover ◽  
Total Alkalinity ◽  
Carbonate Minerals ◽  
Glacial Meltwater

An influx of glacial meltwater has the ability to alter the properties of marine surface waters and their ability to exchange CO2 through changes to water column stratification and the inorganic carbon system. Here, we report how inputs of meteoric water affect the physical and biogeochemical properties of both the water column and the sea ice cover on the Wandel Sea shelf, northeastern Greenland, during spring 2015. The observed depleted δ18O–H2O in the water column, with surface water values as low as –16.3 ‰, suggests a strong input of meteoric water (i.e., water derived from atmospheric precipitation). Depleted δ18O–H2O observed within sea ice (from –21.5 to –8.0 ‰) reflects its formation from surface water that was already depleted isotopically. In addition, a thick snow cover, as present during the study, promotes the formation of snow ice as well as insulates the ice cover. Within sea ice, the resulting relatively warm temperature and low salinity impedes ikaite formation. However, measurements of total dissolved inorganic carbon and total alkalinity indicate that, in both sea ice and the water column, the dissolution of calcium carbonate was the main process affecting the carbonate system. This finding suggests that inputs of glacial meltwater deliver glacier-derived carbonate minerals to the ocean which become incorporated within the ice structure, increasing calcium carbonate dissolution in the water column in the absence of ikaite precipitation within the sea ice. If widespread in glacial-fed waters, bedrock carbonate minerals could increase CO2 sequestration in glacial catchments despite the weakening of the sea ice carbon pump.

scholarly journals Macronutrient and carbon supply, uptake and cycling across the Antarctic Peninsula shelf during summer

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170168 ◽  
Author(s):  
Sian F. Henley ◽  
Elizabeth M. Jones ◽  
Hugh J. Venables ◽  
Michael P. Meredith ◽  
Yvonne L. Firing ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Inorganic Carbon ◽  
Carbon Sink ◽  
Significant Proportion ◽  
Rapid Change ◽  
The West ◽  
Carbon Supply ◽  
West Antarctic ◽  
Shelf Sediment ◽  
West Antarctic Peninsula

The West Antarctic Peninsula shelf is a region of high seasonal primary production which supports a large and productive food web, where macronutrients and inorganic carbon are sourced primarily from intrusions of warm saline Circumpolar Deep Water. We examined the cross-shelf modification of this water mass during mid-summer 2015 to understand the supply of nutrients and carbon to the productive surface ocean, and their subsequent uptake and cycling. We show that nitrate, phosphate, silicic acid and inorganic carbon are progressively enriched in subsurface waters across the shelf, contrary to cross-shelf reductions in heat, salinity and density. We use nutrient stoichiometric and isotopic approaches to invoke remineralization of organic matter, including nitrification below the euphotic surface layer, and dissolution of biogenic silica in deeper waters and potentially shelf sediment porewaters, as the primary drivers of cross-shelf enrichments. Regenerated nitrate and phosphate account for a significant proportion of the total pools of these nutrients in the upper ocean, with implications for the seasonal carbon sink. Understanding nutrient and carbon dynamics in this region now will inform predictions of future biogeochemical changes in the context of substantial variability and ongoing changes in the physical environment. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

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