DOC storage in Arctic seas: The role of continental shelves

Walsh, John J.

doi:10.1029/ce049p0203

Cited by 11 publications

(5 citation statements)

References 84 publications

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“…Rho, 2000). Estimates of summer productivity may be compared with the 2–6 g C m −2 day −1 reported during the spring diatom blooms in 1980 and 1981 (Walsh, 1995), during which the maximum chlorophyll concentration in the region was 750 mg Chl a m −2 (Whitledge and Walsh, 1986), or about seven times the maximum reported here. In 1997, the low primary productivity rates observed may seem paradoxical in light of the large area covered by the bloom.…”

Section: Discussionmentioning

confidence: 76%

Anomalous conditions in the south‐eastern Bering Sea, 1997: nutrients, phytoplankton and zooplankton

Stockwell

Whitledge

Zeeman

et al. 2001

Fisheries Oceanography

116

114

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Anomalies in the regional weather over the south‐eastern Bering Sea during spring and summer of 1997 resulted in significant differences in nutrient availability, phytoplankton species composition, and zooplankton abundance over the continental shelf as compared with measurements in the 1980s. Calm winds and the reduction of cloud cover in spring and summer produced a very shallow mixed layer in which nitrate and silicate were depleted after an April diatom bloom. High submarine light levels allowed subsequent phytoplankton growth below the pycnocline and eventual depletion of nitrate from the water column to depths of 70 m or more. Thus, total new production during 1997 may have exceeded that of previous years when nitrate was not depleted below the pycnocline. A bloom of the coccolithophorid, Emiliania huxleyi, was observed in early July in the warm, nutrient‐depleted waters over the middle and inner shelf. Emiliania huxleyi concentrations reached 4.5 × 106 cells L–1 by September, and the bloom persisted through the autumn. There was evidence for increased abundance of some species of copepods in 1997 as compared with data from the middle domain in June 1981. The abundance of adult and juvenile euphausiids in 1997 was statistically similar to values measured in 1980 and 1981. However, near‐surface swarms were rarely observed on the inner shelf in August–September 1997. Lack of euphausiid availability in the upper water column may partially explain the August–September mass mortality of planktivorous short‐tailed shearwaters (Puffinus tenuirostris) observed on the inner shelf.

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Section: Discussionmentioning

confidence: 76%

Anomalous conditions in the south‐eastern Bering Sea, 1997: nutrients, phytoplankton and zooplankton

Stockwell

Whitledge

Zeeman

et al. 2001

Fisheries Oceanography

116

114

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“…Associated with the upper halocline is a prominent nutrient maximum [ Jones and Anderson , 1986] due to sea ice formation [ Aagaard et al , 1981; Melling and Lewis , 1982] and interactions with sediments [ Moore et al , 1983] on the shelves. Since these processes could be sources of DOM, a transport of organic matter into the halocline layer from the shelves to the arctic basin could be expected [ Walsh , 1995; Walsh et al , 1997].…”

Section: Introductionmentioning

confidence: 99%

Colored dissolved organic matter dynamics across the shelf‐basin interface in the western Arctic Ocean

Guéguen¹,

Guo²,

Yamamoto‐Kawai³

et al. 2007

J. Geophys. Res.

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Spatial variations in the concentration and nature of colored dissolved organic matter (CDOM) in the western Arctic Ocean were examined by three‐dimensional excitation/emission matrix (3‐D EEM) spectroscopy. CDOM profiles showed distinctive features well correlated with hydrographic characteristics. CDOM fluorescence was particularly high at depths between 40 and 200 m (up to 3 fluorescence units (Fl.U.)) in both Chukchi Sea and Beaufort Sea transects. Penetration of the high CDOM signal, formed on the shelves, into the Canada Basin was confined to the upper halocline layer (salinity of ∼33.1). This layer had distinctive 3‐D EEM fingerprints in fluorescence spectra, showing a marked terrestrial humic signature. The presence of CDOM in the halocline layer likely resulted from two main processes: the brine rejection during sea ice formation and transport across the sediment‐water interface during early diagenesis. Despite the high primary productivity in the Chukchi shelf, CDOM contribution from in situ production seemed to have little influence on the overall CDOM distributions in the study area.

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“…Increasing population in coastal regions, sea level rise and changes in freshwater inputs are leading to dramatic shifts in estuarine and coastal system biogeochemical balances. Organic matter (OM), both dissolved organic carbon (DOC) and particulate organic carbon (POC) flows from terrestrially loaded freshwaters as either a relatively refractory pool that will be further exported and as labile substrates that will be completely remineralized to CO 2 or partially remineralized to join the refractory pool (Walsh, 1995). In addition to DOC and POC, river waters and surface runoff carry ample nutrients that can stimulate in situ productivity, adding to the total OM pool.…”

mentioning

confidence: 99%

Organic carbon patterns and budgets in the Long Island Sound estuary

Vlahos

Whitney

2017

Limnology & Oceanography

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A multi‐year observational time series was evaluated across the 150 km central axis of the U.S. east coast's Long Island Sound (LIS) estuary, in three distinct regions. Fluxes were calculated at the boundaries of the regions using observations coupled to a hydrodynamic model and applied to a mass balance to assess organic carbon (OC) export from LIS. For all years, during stratified summer periods, LIS was a net exporter of OC to the continental shelf. LIS annual net carbon export however, varied with river flow. The heterotrophic or autotrophic nature of LIS also shifted inter‐annually. During the mass balance analysis period (2009–2012), LIS ranged between net OC import from the continental shelf and heterotrophy in the lowest river flow year (2012) and net export of OC and autotrophy in the highest flow year (2011). Analysis suggests that LIS switches from net OC import to export when the annual river inputs exceed 19 km3 yr−1. Applying these thresholds to the annual river flow record suggests that net import occurred in 15% of the last 20 years and that LIS usually is a net exporter of OC (85%). Annually averaged LIS carbon export values based on river flow conditions over the last 20 yr are estimated at 56 ± 64 × 106 kg yr−1. Analysis also suggests that LIS shifts from net heterotrophic to net autotrophic when annual river flow exceeds 26 km3 yr−1 (35% of the last 20 yr). Net heterotrophic conditions are most common, representing 65% of the last 20 yr.

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DOC storage in Arctic seas: The role of continental shelves

Cited by 11 publications

References 84 publications

Anomalous conditions in the south‐eastern Bering Sea, 1997: nutrients, phytoplankton and zooplankton

Anomalous conditions in the south‐eastern Bering Sea, 1997: nutrients, phytoplankton and zooplankton

Colored dissolved organic matter dynamics across the shelf‐basin interface in the western Arctic Ocean

Organic carbon patterns and budgets in the Long Island Sound estuary

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