The western North Atlantic record of MIS 13 to 10: Changes in primary productivity, organic carbon accumulation and benthic foraminiferal assemblages in sediments from the Blake Outer Ridge (ODP Site 1058)

2010 ◽  
Vol 295 (1-2) ◽  
pp. 89-101 ◽  
Author(s):  
Maria Serena Poli ◽  
Philip A. Meyers ◽  
Robert C. Thunell
Keyword(s):  
Organic Carbon ◽  
North Atlantic ◽  
Primary Productivity ◽  
Carbon Accumulation

scholarly journals Towards an improved organic carbon budget for the western Barents Sea shelf

2014 ◽  
Vol 10 (2) ◽  
pp. 569-587 ◽  
Author(s):  
I. Pathirana ◽  
J. Knies ◽  
M. Felix ◽  
U. Mann
Keyword(s):  
Organic Carbon ◽  
Sea Ice ◽  
Primary Productivity ◽  
Carbon Budget ◽  
Barents Sea ◽  
Carbon Accumulation ◽  
The Arctic ◽  
Sediment Surface ◽  
Organic Facies ◽  
Facies Modelling

Abstract. There is generally a lack of knowledge on how marine organic carbon accumulation is linked to vertical export and primary productivity patterns in the Arctic Ocean. Despite the fact that annual primary production in the Arctic has increased as a consequence of shrinking sea ice, its effect on flux, preservation, and accumulation of organic carbon is still not well understood. In this study, a multi-proxy geochemical and organic-sedimentological approach is coupled with organic facies modelling, focusing on regional calculations of carbon cycling and carbon burial on the western Barents Shelf between northern Scandinavia and Svalbard. OF-Mod 3-D, an organic facies modelling software tool, is used to reconstruct and quantify the marine and terrestrial organic carbon fractions and to make inferences about marine primary productivity changes across the marginal ice zone (MIZ). By calibrating the model against an extensive set of sediment surface samples, we improve the Holocene organic carbon budget for ice-free and seasonally ice-covered areas in the western Barents Sea. The results show that higher organic carbon accumulation rates in the MIZ are best explained by enhanced surface water productivity compared to ice-free regions, implying that shrinking sea ice may reveal a significant effect on the overall organic carbon storage capacity of the western Barents Sea shelf.

scholarly journals A multi-method autonomous assessment of primary productivity and export efficiency in the springtime North Atlantic

2018 ◽  
Author(s):  
Nathan Briggs ◽  
Kristinn Guðmundsson ◽  
Ivona Cetinić ◽  
Eric D'Asaro ◽  
Eric Rehm ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
North Atlantic ◽  
Primary Productivity ◽  
Gross Primary Productivity ◽  
Test Method ◽  
Significant Advance ◽  
Diatom Bloom ◽  
Diel Cycles ◽  
Parameterized Model

Abstract. Fixation of organic carbon by phytoplankton is the foundation of nearly all open-ocean ecosystems and a critical part of the global carbon cycle. But quantification and validation of ocean primary productivity at large scale remains a major challenge, due to limited coverage of ship-based measurements and the difficulty of validating diverse measurement techniques. Accurate primary productivity measurements from autonomous platforms would be highly desirable, due to much greater potential coverage. In pursuit of this goal we estimate gross primary productivity over two months in the springtime North Atlantic from an autonomous Lagrangian float using diel cycles of particulate organic carbon derived from optical beam attenuation. We test method precision and accuracy by comparison against entirely independent estimates from a locally parameterized model based on chlorophyll α and light measurements from the same float. During nutrient replete conditions (80 % of the study period), we obtain strong relative agreement between the independent methods across an order of magnitude of productivities (r2 = 0.97), with slight under-estimation by the diel cycles method (−19 ± 5 %). At the end of the diatom bloom, this relative difference increases to −58 % for a six-day period, likely a response to SiO4 limitation, which is not included in the model. In addition, we estimate gross oxygen productivity from O2 diel cycles and find strong correlation with diel cycles-based gross primary productivity over the entire deployment, providing further qualitative support to both methods. Finally, simultaneous estimates of net community productivity, carbon export and particle size suggest that bloom growth is halted by a combination of reduced productivity due to SiO4 limitation and increased export efficiency due to rapid aggregation. After the diatom bloom, high chlorophyll α normalized productivity indicates that low net growth during this period is due to increased heterotrophic respiration and not nutrient limitation. These findings represent a significant advance in the accuracy and completeness of upper ocean carbon cycle measurements from an autonomous platform.

scholarly journals Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic

2009 ◽  
Vol 6 (5) ◽  
pp. 8923-8960 ◽  
Author(s):  
P. Kähler ◽  
A. Oschlies ◽  
H. Dietze ◽  
W. Koeve
Keyword(s):  
Surface Layer ◽  
Surface Water ◽  
Organic Carbon ◽  
North Atlantic ◽  
Carbon Balance ◽  
Organic Nitrogen ◽  
Carbon Accumulation ◽  
Subsurface Water ◽  
Near Surface ◽  
Carbon And Nitrogen

Abstract. The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production. The shallow export of total organic carbon, predominantly dissolved (DOC), by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m−2 a−1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be autotrophic. Subsurface excess nitrogen (DINxs) regeneration implies the utilization of nitrogen in surface water in addition to new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON) is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m−2 a−1. There is no variation in dissolved organic phosphorus (DOP) in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature. DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the Beta Triangle. There are, however, no comparable processes which can explain the equally enigmatic situation concerning phosphorus supply in this area.

scholarly journals A multi-method autonomous assessment of primary productivity and export efficiency in the springtime North Atlantic

2018 ◽  
Vol 15 (14) ◽  
pp. 4515-4532 ◽  
Author(s):  
Nathan Briggs ◽  
Kristinn Guðmundsson ◽  
Ivona Cetinić ◽  
Eric D'Asaro ◽  
Eric Rehm ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
North Atlantic ◽  
Primary Productivity ◽  
Gross Primary Productivity ◽  
Test Method ◽  
Diel Cycle ◽  
Significant Advance ◽  
Diatom Bloom ◽  
Diel Cycles

Abstract. Fixation of organic carbon by phytoplankton is the foundation of nearly all open-ocean ecosystems and a critical part of the global carbon cycle. But the quantification and validation of ocean primary productivity at large scale remains a major challenge due to limited coverage of ship-based measurements and the difficulty of validating diverse measurement techniques. Accurate primary productivity measurements from autonomous platforms would be highly desirable due to much greater potential coverage. In pursuit of this goal we estimate gross primary productivity over 2 months in the springtime North Atlantic from an autonomous Lagrangian float using diel cycles of particulate organic carbon derived from optical beam attenuation. We test method precision and accuracy by comparison against entirely independent estimates from a locally parameterized model based on chlorophyll a and light measurements from the same float. During nutrient-replete conditions (80 % of the study period), we obtain strong relative agreement between the independent methods across an order of magnitude of productivities (r2=0.97), with slight underestimation by the diel cycle method (−19 ± 5 %). At the end of the diatom bloom, this relative difference increases to −58 % for a 6-day period, likely a response to SiO4 limitation, which is not included in the model. In addition, we estimate gross oxygen productivity from O2 diel cycles and find strong correlation with diel-cycle-based gross primary productivity over the entire deployment, providing further qualitative support for both methods. Finally, simultaneous estimates of net community productivity, carbon export, and particle size suggest that bloom growth is halted by a combination of reduced productivity due to SiO4 limitation and increased export efficiency due to rapid aggregation. After the diatom bloom, high Chl a-normalized productivity indicates that low net growth during this period is due to increased heterotrophic respiration and not nutrient limitation. These findings represent a significant advance in the accuracy and completeness of upper-ocean carbon cycle measurements from an autonomous platform.

scholarly journals Oxygen, carbon, and nutrients in the oligotrophic eastern subtropical North Atlantic

2010 ◽  
Vol 7 (3) ◽  
pp. 1143-1156 ◽  
Author(s):  
P. Kähler ◽  
A. Oschlies ◽  
H. Dietze ◽  
W. Koeve
Keyword(s):  
Surface Layer ◽  
Surface Water ◽  
Organic Carbon ◽  
North Atlantic ◽  
Carbon Balance ◽  
Organic Nitrogen ◽  
Carbon Accumulation ◽  
Subsurface Water ◽  
Near Surface ◽  
Carbon And Nitrogen

Abstract. The Beta Triangle, a region of the oligotrophic subtropical eastern North Atlantic Ocean, is notorious for its enigmatic oxygen, carbon, and nitrogen balances, in which nutrient supply is said to explain only a fraction of production necessary for estimated carbon export. Rates of dissolved organic carbon accumulation and dissolved organic nitrogen utilization in surface water and an assessment of oxygen utilized, organic matter consumed, and nitrate and phosphate regenerated in subsurface water, show that conventional production estimates miss substantial shares of biotic production. The shallow export of total organic carbon, predominantly dissolved (DOC), by subduction is responsible for about 50–70% of apparent oxygen utilization in subsurface water between the base of the surface layer at ca. 140 m and ca. 195 m depth, but it is insignificant below. Additionally, there is an estimated accumulation of 1.0 to 1.75 mol DOC m−2 a−1 in surface water. Including DOC dynamics in its carbon balance reveals the surface of this ultra-oligotrophic part of the ocean to be net autotrophic. Increasing subsurface values of excess nitrogen (DINxs) imply the export of nitrogen from surface water stemming from production not exclusively fuelled by new nitrate supplied from below. Total organic nitrogen (almost exclusively dissolved, DON) is consumed in the surface layer at a rate estimated at 0.13 to 0.23 mol m−2 a−1. There is no variation in dissolved organic phosphorus (DOP) in the same direction. DON utilization thus contributes to the pronounced subsurface DINxs signature. DOC export and accumulation are important in the carbon balance in surface and near-surface water. DON utilization and, probably, N2 fixation contribute significant amounts to the nitrogen supply of surface water. These processes can close part of the enigmatic carbon and nitrogen balances in the Beta Triangle. There are, however, no comparable processes which can explain the equally enigmatic situation concerning phosphorus supply in this area.

scholarly journals Towards an improved organic carbon budget for the Barents Sea shelf, marginal Arctic Ocean

2013 ◽  
Vol 9 (4) ◽  
pp. 4939-4986 ◽  
Author(s):  
I. Pathirana ◽  
J. Knies ◽  
M. Felix ◽  
U. Mann
Keyword(s):  
Organic Carbon ◽  
Primary Productivity ◽  
Barents Sea ◽  
Accumulation Rate ◽  
Regional Distribution ◽  
Carbon Accumulation ◽  
Carbon Fractions ◽  
Organic Facies ◽  
Organic Carbon Fractions ◽  
Facies Modelling

Abstract. There is generally a lack of knowledge on how marine organic carbon accumulation is linked to vertical export and primary productivity patterns. In this study, a multi-proxy geochemical and organic-sedimentological approach is coupled with organic facies modelling focusing on regional calculations of carbon cycling and carbon burial on the western Barents shelf between northern Scandinavia and Svalbard. OF-Mod 3D, an organic facies modelling software tool, is used to reconstruct the marine and terrestrial organic carbon fractions and to make inferences about marine primary productivity in this region. The model is calibrated with an extensive sample dataset and reproduces the present-day regional distribution of the organic carbon fractions well. Based on this new organic facies model, we present regional carbon mass accumulation rate calculations for the western Barents Sea.

scholarly journals 14,000-year Carbon Accumulation Dynamics in a Siberian Lake Reveal Catchment and Lake Productivity Changes

2021 ◽  
Vol 9 ◽  
Author(s):  
Lara Hughes-Allen ◽  
Frédéric Bouchard ◽  
Christine Hatté ◽  
Hanno Meyer ◽  
Lyudmila A. Pestryakova ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Sediment Core ◽  
Primary Productivity ◽  
Carbon Accumulation ◽  
Sedimentation Rates ◽  
Terrestrial Vegetation ◽  
Accumulation Rates ◽  
Lake Productivity ◽  
The Core ◽  
Lake Morphology

A multi-proxy paleolimnological analysis of a sediment core sequence from Lake Malaya Chabyda in Central Yakutia (Eastern Siberia, Russia) was conducted to investigate changes in lake processes, including lake development, sediment and organic carbon accumulation, and changes in primary productivity, within the context of Late Pleistocene and Holocene climate change. Age-depth modeling with 14C indicates that the maximum age of the sediment core is ∼14 cal kBP. Three distinct sedimentary units were identified within the sediment core. Sedimentological and biogeochemical properties in the deepest section of the core (663–584 cm; 14.1–12.3 cal kBP) suggests a lake environment mostly influenced by terrestrial vegetation, where organic carbon accumulation might have been relatively low (average ∼100 g OC m−2 a−1), although much higher than the global modern average. The middle section of the core (584–376 cm; 12.3–9.0 cal kBP) is characterized by higher primary productivity in the lake, much higher sedimentation, and a remarkable increase in OC delivery (average ∼300 g OC m−2 a−1). Conditions in the upper section of the core (<376 cm; < 9.0 cal kBP) suggest high primary productivity in the lake and high OC accumulation rates (average ∼200 g OC m−2 a−1), with stable environmental conditions. The transition from organic-poor and mostly terrestrial vegetation inputs (TOC/TNatomic ratios ∼20) to conditions dominated by aquatic primary productivity (TOC/TNatomic ratios <15) occurs at around 12.3 cal kBP. This resulted in an increase in the sedimentation rate of OC within the lake, illustrated by higher sedimentation rates and very high total OC concentrations (>30%) measured in the upper section of the core. Compact lake morphology and high sedimentation rates likely resulted in this lake acting as a significant OC sink since the Pleistocene-Holocene transition. Sediment accumulation rates declined after ∼8 cal k BP, however total OC concentrations were still notably high. TOC/TNatomic and isotopic data (δ13C) confirm the transition from terrestrial-influenced to aquatic-dominated conditions during the Early Holocene. Since the mid-Holocene, there was likely higher photosynthetic uptake of CO2 by algae, as suggested by heavier (isotopically enriched) δ13C values (>−25‰).

Changes in sediment and organic carbon accumulation in a highly-disturbed ecosystem: The Sacramento-San Joaquin River Delta (California, USA)

2009 ◽  
Vol 59 (4-7) ◽  
pp. 154-163 ◽  
Author(s):  
Elizabeth A. Canuel ◽  
Elizabeth J. Lerberg ◽  
Rebecca M. Dickhut ◽  
Steven A. Kuehl ◽  
Thomas S. Bianchi ◽  
...  
Keyword(s):  
Organic Carbon ◽  
River Delta ◽  
Carbon Accumulation ◽  
San Joaquin River

scholarly journals Organic mulching promotes soil organic carbon accumulation to deep soil layer in an urban plantation forest

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Xiaodan Sun ◽  
Gang Wang ◽  
Qingxu Ma ◽  
Jiahui Liao ◽  
Dong Wang ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Fine Roots ◽  
Soil Layer ◽  
Carbon Accumulation ◽  
Bulk Soil ◽  
Organic Mulch ◽  
The Impact ◽  
Soc Fractions

Abstract Background Soil organic carbon (SOC) is important for soil quality and fertility in forest ecosystems. Labile SOC fractions are sensitive to environmental changes, which reflect the impact of short-term internal and external management measures on the soil carbon pool. Organic mulching (OM) alters the soil environment and promotes plant growth. However, little is known about the responses of SOC fractions in rhizosphere or bulk soil to OM in urban forests and its correlation with carbon composition in plants. Methods A one-year field experiment with four treatments (OM at 0, 5, 10, and 20 cm thicknesses) was conducted in a 15-year-old Ligustrum lucidum plantation. Changes in the SOC fractions in the rhizosphere and bulk soil; the carbon content in the plant fine roots, leaves, and organic mulch; and several soil physicochemical properties were measured. The relationships between SOC fractions and the measured variables were analysed. Results The OM treatments had no significant effect on the SOC fractions, except for the dissolved organic carbon (DOC). OM promoted the movement of SOC to deeper soil because of the increased carbon content in fine roots of subsoil. There were significant correlations between DOC and microbial biomass carbon and SOC and easily oxidised organic carbon. The OM had a greater effect on organic carbon fractions in the bulk soil than in the rhizosphere. The thinnest (5 cm) mulching layers showed the most rapid carbon decomposition over time. The time after OM had the greatest effect on the SOC fractions, followed by soil layer. Conclusions The frequent addition of small amounts of organic mulch increased SOC accumulation in the present study. OM is a potential management model to enhance soil organic matter storage for maintaining urban forest productivity.

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