scholarly journals A modeling study of temporal and spatial <i>p</i>CO<sub>2</sub> variability on the biologically active and temperature-dominated Scotian Shelf

2021 ◽  
Author(s):  
Krysten Rutherford ◽  
Katja Fennel ◽  
Dariia Atamanchuk ◽  
Douglas Wallace ◽  
Helmuth Thomas
Keyword(s):  
Surface Water ◽  
Coastal Upwelling ◽  
Gulf Of Maine ◽  
Dissolved Inorganic Carbon ◽  
Co2 Flux ◽  
General Assumption ◽  
Biologically Active ◽  
Source Surface ◽  
Scotian Shelf ◽  
Temporal And Spatial

Abstract. Continental shelves are thought to be affected disproportionately by climate change and are a large contributor to global air-sea carbon dioxide (CO2) fluxes. It is often reported that low-latitude shelves tend to act as net sources of CO2 whereas mid- and high-latitude shelves act as net sinks. Here, we combine a high-resolution regional model with surface water time-series and repeat transect observations from the Scotian Shelf, a mid-latitude region in the northwest North Atlantic, to determine what processes are driving the temporal and spatial variability of partial pressure of CO2 (pCO2). In contrast to the global trend, the Scotian Shelf acts as a net source. Surface pCO2 undergoes a strong seasonal cycle associated with both a strong biological drawdown of Dissolved Inorganic Carbon (DIC) in spring, and pronounced effects of temperature, which ranges from 0 °C in the winter to near 20 °C in the summer. Throughout the summer, events with low surface-water pCO2 occur nearshore associated with coastal upwelling. This effect of upwelling on pCO2 is also in contrast to the general assumption that upwelling increases surface pCO2 by delivering DIC-enriched water to the surface. Aside from these localized events, pCO2 is relatively uniform across the shelf. Our model agrees with regional observations, reproduces seasonal patterns of pCO2, and simulates annual outgassing of CO2 from the ocean of +1.9 ± 0.2 mol C m−2 yr−1 for the Scotian Shelf, net neutral CO2 flux of −0.09 ± 0.16 mol C m−2 yr−1 for the Gulf of Maine and uptake by the ocean of −0.88 ± 0.4 mol C m−2 yr−1 for the Grand Banks.

scholarly journals A modelling study of temporal and spatial <i>p</i>CO<sub>2</sub> variability on the biologically active and temperature-dominated Scotian Shelf

2021 ◽  
Vol 18 (23) ◽  
pp. 6271-6286
Author(s):  
Krysten Rutherford ◽  
Katja Fennel ◽  
Dariia Atamanchuk ◽  
Douglas Wallace ◽  
Helmuth Thomas
Keyword(s):  
Surface Water ◽  
Coastal Upwelling ◽  
Gulf Of Maine ◽  
Dissolved Inorganic Carbon ◽  
General Assumption ◽  
Biologically Active ◽  
Source Surface ◽  
Scotian Shelf ◽  
Temporal And Spatial ◽  
Carbon Dioxide Co2

Abstract. Continental shelves are thought to be affected disproportionately by climate change and are a large contributor to global air–sea carbon dioxide (CO2) fluxes. It is often reported that low-latitude shelves tend to act as net sources of CO2, whereas mid- and high-latitude shelves act as net sinks. Here, we combine a high-resolution regional model with surface water time series and repeat transect observations from the Scotian Shelf, a mid-latitude region in the northwest North Atlantic, to determine what processes are driving the temporal and spatial variability of partial pressure of CO2 (pCO2) on a seasonal scale. In contrast to the global trend, the Scotian Shelf acts as a net source. Surface pCO2 undergoes a strong seasonal cycle with an amplitude of ∼ 200–250 µatm. These changes are associated with both a strong biological drawdown of dissolved inorganic carbon (DIC) in spring (corresponding to a decrease in pCO2 of 100–200 µatm) and pronounced effects of temperature, which ranges from 0 ∘C in the winter to near 20 ∘C in the summer, resulting in an increase in pCO2 of ∼ 200–250 µatm. Throughout the summer, events with low surface water pCO2 occur associated with coastal upwelling. This effect of upwelling on pCO2 is also in contrast to the general assumption that upwelling increases surface pCO2 by delivering DIC-enriched water to the surface. Aside from these localized events, pCO2 is relatively uniform across the shelf. Our model agrees with regional observations, reproduces seasonal patterns of pCO2, and simulates annual outgassing of CO2 from the ocean of +1.7±0.2 mol C m−2 yr−1 for the Scotian Shelf, net uptake of CO2 by the ocean of -0.5±0.2 mol C m−2 yr−1 for the Gulf of Maine, and uptake by the ocean of -1.3±0.3 mol C m−2 yr−1 for the Grand Banks.

scholarly journals Distributions of surface water CO<sub>2</sub> and air-sea flux of CO<sub>2</sub> in coastal regions of the Canadian Beaufort Sea in late summer

2008 ◽  
Vol 5 (6) ◽  
pp. 5093-5132 ◽  
Author(s):  
A. Murata ◽  
K. Shimada ◽  
S. Nishino ◽  
M. Itoh
Keyword(s):  
Surface Water ◽  
Dissolved Inorganic Carbon ◽  
High Capacity ◽  
Coastal Region ◽  
Chemical Properties ◽  
Late Summer ◽  
Co2 Flux ◽  
Beaufort Sea ◽  
Atmospheric Co2 ◽  
Co2 Sink

Abstract. To quantify the air-sea flux of CO2 in a high-latitude coastal region, we conducted shipboard observations of atmospheric and surface water partial pressures of CO2 (pCO2) and total dissolved inorganic carbon (TCO2) in the Canadian Beaufort Sea (150° W–127° W; 69° N–73° N) in late summer 2000 and 2002. Surface water pCO2 was lower than atmospheric pCO2 (2000, 361.0 μatm; 2002, 364.7 μatm), and ranged from 250 to 344 μatm. Accordingly, ΔpCO2, which is the driving force of the air-sea exchange of CO2 and is calculated from differences in pCO2 between the sea surface and the overlying air, was generally negative (potential sink for atmospheric CO2), although positive ΔpCO2 values (source) were also found locally. Distributions of surface water pCO2, as well as those of ΔpCO2 and CO2 flux, were controlled mainly by water mixing related to river discharge. The air-sea fluxes of CO2 were −15.0 and −16.8 mmol m−2 d−1 on average in 2000 and 2002, respectively, implying that the area acted as a moderate sink for atmospheric CO2. The air-to-sea net CO2 flux in an extended area of the western Arctic Ocean (411 000 km2) during the ice-free season (=100 days) was calculated as 10.2±7.7 mmol m−2 d−1, equivalent to a regional CO2 sink of 5.0±3.8 Tg C. The estimated buffer factor was 1.5, indicating that the area is a high-capacity CO2 sink. These CO2 flux estimates will need to be revised because they probably include a bias due to the vertical gradients of physical and chemical properties characteristic in the region, which have not yet been adequately considered.

scholarly journals Air-Sea CO<sub>2</sub> fluxes on the Scotian Shelf: seasonal to multi-annual variability

2010 ◽  
Vol 7 (11) ◽  
pp. 3851-3867 ◽  
Author(s):  
E. H. Shadwick ◽  
H. Thomas ◽  
A. Comeau ◽  
S. E. Craig ◽  
C. W. Hunt ◽  
...  
Keyword(s):  
Time Series ◽  
Surface Waters ◽  
Gulf Of Maine ◽  
Co2 Flux ◽  
Sea Surface ◽  
Co2 Fluxes ◽  
Resolution Time ◽  
Scotian Shelf ◽  
Shelf Region ◽  
Annual Scale

Abstract. We develop an algorithm to compute pCO2 in the Scotian Shelf region (NW Atlantic) from satellite-based estimates of chlorophyll-a concentration, sea-surface temperature, and observed wind speed. This algorithm is based on a high-resolution time-series of pCO2 observations from an autonomous mooring. At the mooring location (44.3° N and 63.3° W), the surface waters act as a source of CO2 to the atmosphere over the annual scale, with an outgassing of −1.1 mol C m−2 yr−1 in 2007/2008. A hindcast of air-sea CO2 fluxes from 1999 to 2008 reveals significant variability both spatially and from year to year. Over the decade, the shelf-wide annual air-sea fluxes range from an outgassing of −1.70 mol C m−2 yr−1 in 2002, to −0.02 mol C m−2 yr−1 in 2006. There is a gradient in the air-sea CO2 flux between the northeastern Cabot Strait region which acts as a net sink of CO2 with an annual uptake of 0.50 to 1.00 mol C m−2 yr−1, and the southwestern Gulf of Maine region which acts as a source ranging from −0.80 to −2.50 mol C m−2 yr−1. There is a decline, or a negative trend, in the air-sea pCO2 gradient of 23 μatm over the decade, which can be explained by a cooling of 1.3 °C over the same period. Regional conditions govern spatial, seasonal, and interannual variability on the Scotian Shelf, while multi-annual trends appear to be influenced by larger scale processes.

Seasonal variability of dissolved inorganic carbon and surface water pCO2 in the Scotian Shelf region of the Northwestern Atlantic

2011 ◽  
Vol 124 (1-4) ◽  
pp. 23-37 ◽  
Author(s):  
E.H. Shadwick ◽  
H. Thomas ◽  
K. Azetsu-Scott ◽  
B.J.W. Greenan ◽  
E. Head ◽  
...  
Keyword(s):  
Surface Water ◽  
Seasonal Variability ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Scotian Shelf ◽  
Shelf Region

Sources of Water Contributed to the Bay of Fundy by Surface Circulation

1960 ◽  
Vol 17 (2) ◽  
pp. 181-197 ◽  
Author(s):  
Dean F. Bumpus
Keyword(s):  
Surface Water ◽  
Annual Cycle ◽  
Gulf Of Maine ◽  
Surface Flow ◽  
Bay Of Fundy ◽  
Georges Bank ◽  
Scotian Shelf ◽  
Eastern Side ◽  
Surface Circulation ◽  
Surface Drift

The returns from the 35,000 drift bottles launched in the Gulf of Maine area since 1919 have been analyzed to determine the annual cycle of surface drift. The source of surface flow into the Bay of Fundy expands from a minimum during January in the offing of the eastern side of the bay to a maximum in May which includes most of Georges Bank, the Gulf of Maine and the southwestern Scotian Shelf, then commencing in September gradually contracts toward the minimum.Secular variations in the removal of surface water from the Bay of Fundy, indicative of changes in the Maine eddy, were noted during 1957 and 1958.

scholarly journals Satellite observations reveal high variability and a decreasing trend in CO<sub>2</sub> fluxes on the Scotian Shelf

2010 ◽  
Vol 7 (4) ◽  
pp. 5269-5304
Author(s):  
E. H. Shadwick ◽  
H. Thomas ◽  
A. Comeau ◽  
S. E. Craig ◽  
C. W. Hunt ◽  
...  
Keyword(s):  
North Atlantic ◽  
Surface Waters ◽  
Gulf Of Maine ◽  
Co2 Flux ◽  
Resolution Time ◽  
Scotian Shelf ◽  
The North ◽  
The North Atlantic Oscillation ◽  
Shelf Region ◽  
Annual Scale

Abstract. We develop an algorithm to compute pCO2 in the Scotian Shelf region (NW Atlantic) from satellite-based estimates of chlorophyll-a concentration, sea-surface temperature, and observed wind speed. This algorithm is based on a high-resolution time-series of pCO2 observations from an autonomous mooring. At the mooring location (44.3° N and 63.3° W), the surface waters act as a source of CO2 to the atmosphere over the annual scale, with an outgassing of −1.1 mol C m−2 yr−1 in 2007/2008. A hindcast of air-sea CO2 fluxes from 1999 to 2008 reveals significant variability both spatially and from year to year. Over the decade, the shelf-wide annual air-sea fluxes range from an outgassing of −1.7 mol C m−2 yr−1 in 2002, to −0.02 mol C m−2 yr−1 in 2006. There is a gradient in the air-sea CO2 flux between the northeastern Cabot Strait region which acts as a net sink of CO2 with an annual uptake of 0.5 to 1.0 mol C m−2 yr−1, and the southwestern Gulf of Maine region which acts as a source ranging from −0.8 to −2.5 mol C m−2 yr−1. There is a decline, or a negative trend, in the air-sea pCO2 gradient of 23 μatm over the decade, which can be explained by a cooling of 1.3 °C over the same period. Regional conditions govern spatial, seasonal, and interannual variability on the Scotian Shelf, while multi-annual trends appear linked to the North Atlantic Oscillation.

Coastal Adaptations to the Northern Gulf of Maine and Southern Scotian Shelf

2019 ◽  
pp. 44-80
Author(s):  
Matthew W. Betts ◽  
David W. Black ◽  
Brian Robinson ◽  
Arthur Spiess ◽  
Victor D. Thompson
Keyword(s):  
Surface Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Gulf Of Maine ◽  
Woodland Period ◽  
Late Archaic ◽  
Scotian Shelf ◽  
Near Shore ◽  
Coastal Adaptations ◽  
Cultural Shifts

The northern Gulf of Maine (NGOM) and its watershed have attracted humans for the last 12,500 years (cal BP), and evidence of Palaeoindian marine economies is well established in adjacent regions by ca. 8000 cal BP. Sea level rise (SLR) has obscured understandings of early coastal adaptations, although underwater research and some near-shore sites are providing important insights. The earliest evidence from surviving shell middens dates to ca. 5000 cal BP, and reveals that shellfish collecting and the seasonal exploitation of benthopelagic fish were important throughout the Late Maritime Archaic and Maritime Woodland periods. However, significant economic shifts have occurred. In particular, a Late Archaic focus on marine swordfish hunting was replaced by a dramatic increase in inshore seal hunting in the Maritime Woodland period. After ca. 3100 cal BP, inshore fishing for cod, flounder, sculpin, sturgeon and other species intensified. During the Late Maritime Woodland period, shellfish exploitation declined somewhat and the hunting of small seals, and, in some areas, white-tailed deer, increased sharply. The extent and nature of coastal economies in the NGOM was controlled, in part, by SLR, increasing tidal amplitude, and concomitant changes in surface-water temperatures, in tandem with broad regional cultural shifts.

scholarly journals Hydrochemistry and Dissolved Inorganic Carbon (DIC) Cycling in a Tropical Agricultural River, Mun River Basin, Northeast Thailand

2019 ◽  
Vol 16 (18) ◽  
pp. 3410 ◽  
Author(s):  
Xiaoqiang Li ◽  
Guilin Han ◽  
Man Liu ◽  
Chao Song ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Surface Water ◽  
Carbon Isotope ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Isotope Composition ◽  
Anthropogenic Activities ◽  
Co2 Flux ◽  
Carbon Isotope Composition ◽  
Human Disturbances

Dissolved inorganic carbon isotope composition (δ13CDIC), together with major ion concentrations were measured in the Mun River and its tributaries in March 2018 to constrain the origins and cycling of dissolved inorganic carbon. In the surface water samples, the DIC content ranged from 185 to 5897 μmol/L (average of 1376 μmol/L), and the δ13CDIC of surface water ranged from −19.6‰ to −2.7‰. In spite of the high variability in DIC concentrations and partial pressure of carbon dioxide (pCO2), the δ13CDIC values of the groundwater were relatively consistent, with a mean value of −16.9 ± 1.4‰ (n = 9). Spatial changes occurred in the direction and magnitude of CO2 flux through water-air interface (FCO2). In the dry season, fluxes varied from −6 to 1826 mmol/(m2·d) with an average of 240 mmol/(m2·d). In addition to the dominant control on hydrochemistry and dissolved inorganic carbon isotope composition by the rock weathering, the impacts from anthropogenic activities were also observed in the Mun River, especially higher DIC concentration of waste water from urban activities. These human disturbances may affect the accurate estimate contributions of carbon dioxide from tropical rivers to the atmospheric carbon budgets.

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