Effect of different rates and modes of artificial upwelling on particle flux and potential POC deep export

2021 ◽  
Author(s):  
Moritz Baumann ◽  
Jan Taucher ◽  
Allanah Joy Paul ◽  
Malte Heinemann ◽  
Mari Vanharanta ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Organic Matter ◽  
Deep Water ◽  
Open Water ◽  
Carbon Export ◽  
Export Flux ◽  
Surface Ocean ◽  
Sequestration Potential ◽  
Sinking Velocities ◽  
Removal Technique

<p>To counteract climate change, measures to actively remove carbon dioxide from the atmosphere are required, since the reduction of global CO<sub>2</sub> emissions alone will not suffice to meet the 1.5 °C goal of the Paris agreement. Artificial upwelling in the ocean has been discussed as one such carbon dioxide removal technique, by fueling primary production in the surface ocean with nutrient-rich deep water and thereby potentially enhancing downward fluxes of organic matter and carbon sequestration. In this study we tested the effect of different rates and modes of artificial upwelling on carbon export and its potential attenuation with depth in a five-week mesocosm experiment in the subtropical Northeast Atlantic. We fertilized oligotrophic surface waters with different amounts of deep water in a pulsed (deep water fertilization once at the beginning) and a continuous manner (deep water fertilization every four days) and measured the resulting export flux as well as sinking velocities and respiration rates of sinking particles. Based on this, we applied a simple one-dimensional model to calculate flux attenuation. We found that the export flux more than doubled when fertilizing with deep water, while the C:N ratios of produced organic matter increased from values around Redfield (6.6) to ~8-13. The pulsed form of upwelling resulted in a single export event, while the continuous mode led to a persistently elevated export flux. Particle sinking velocity and remineralization rates were highly variable over time and showed differences between upwelling modes. We stress the importance of experiments with a prolonged application of artificial upwelling and studies including real world open water application to validate the CO<sub>2</sub> sequestration potential of artificial upwelling.</p>

Sensitivity of Benthic Foraminifera to Carbon Flux in the Western Tropical Pacific Ocean

2020 ◽  
Vol 50 (2) ◽  
pp. 235-247 ◽  
Author(s):  
Katharina Billups ◽  
Patricia P. B. Eichler ◽  
Helenice Vital
Keyword(s):  
Organic Matter ◽  
Carbon Flux ◽  
Warm Pool ◽  
Carbon Export ◽  
Export Flux ◽  
Core Species ◽  
Pacific Warm Pool ◽  
Species Abundances ◽  
International Ocean Discovery Program ◽  
Organic Matter Input

ABSTRACT We investigated benthic foraminiferal species as tracers for carbon export flux in the Indo-Pacific warm pool (International Ocean Discovery Program Expedition 363). In core tops, the distribution of lower bathyal and upper abyssal species can be separated into two distinct groups. Foraminifera belonging to the high carbon flux (>3.5 g C m−2 year−1), ‘warm’ (>3.5°C) group are Bolivina robusta, Bulimina aculeata, Globobulimina pacifica, Hoeglundina elegans, Laticarinina pauperata, and Cibicidoides pachyderma. The lower carbon flux, ‘cold’ group includes Oridorsalis umbontus, Uvigerina bifurcata, and Planulina wuellerstorfi. An index based on the percent ‘warm’ assemblage with respect to the total ‘warm’ plus ‘cold’ species in core-top samples correlates significantly with carbon flux (r = 0.91, P = 0.0007) and modern bottom water temperatures (r = 0.94, P = 0.0002). When applied to down-core species abundances based on core catchers spanning the late Miocene through Pleistocene, we observed that sites from the northwestern Australian margin show marked changes in the ‘warm’ index, suggesting a large paleoenvironmental signal in this dynamic region. At Papua New Guinea, down-core abundances of the ‘warm’ group are highest (>80%), consistent with high organic matter input via the Sepik River. At the deeper of the two sites, down-slope movement in this tectonically unstable region may have contributed to organic matter input. At Manus Basin, the ‘warm’ species abundances are also relatively high and covary with the percent abundance of Uvigerina proboscidea, providing further evidence for the use of this index as a tracer for carbon flux. Overall, this study contributes evidence for the relationship between benthic foraminiferal assemblages and carbon export flux in the Indo-Pacific warm pool, suggesting that the ‘warm’ index can be used as a tracer for paleoproductivity.

scholarly journals 210Po/210Pb Disequilibria and Its Estimate of Particulate Organic Carbon Export Around Prydz Bay, Antarctica

2021 ◽  
Vol 8 ◽  
Author(s):  
Huina Hu ◽  
Xiao Liu ◽  
Chunyan Ren ◽  
Renming Jia ◽  
Yusheng Qiu ◽  
...  
Keyword(s):  
Organic Matter ◽  
Water Column ◽  
Deep Water ◽  
Austral Summer ◽  
Euphotic Zone ◽  
Prydz Bay ◽  
Carbon Export ◽  
Activity Concentrations ◽  
Particle Scavenging ◽  
Solid Liquid

Due to the remoteness and difficulty of sampling, the 210Po and 210Pb data are scarce in the Southern Ocean. Here, the activity concentrations of 210Po and 210Pb around Prydz Bay in austral summer were determined to understand their spatial variation and evaluate the dynamics of particle organic matter (POM). The activity concentrations of dissolved 210Po (D210Po) and 210Pb (D210Pb) range from 0.47 to 3.20 Bq⋅m–3 and from 1.15 to 2.97 Bq⋅m–3, respectively, with the lower values in the shelf. The particulate 210Po (P210Po) and 210Pb (P210Pb) are lower in the open ocean and increase to the coastal waters, among which the circumpolar deep water (CDW) is the lowest. The activity concentration of total 210Pb (T210Pb) ranges from 1.26 Bq⋅m–3 to 3.16 Bq⋅m–3, with a higher value in CDW, which is ascribed to radiogenic production from 226Ra and subsequent lateral transport. Occasionally a high value of T210Po occurs in deep water (>3.00 Bq⋅m–3), which may be caused by the remineralization of POM. The disequilibria between T210Po and T210Pb appears throughout the water column at most stations. The average T210Po/T210Pb)A.R. in the euphotic zone is 0.66, reflecting the effect of strong particle scavenging. There is a good positive correlation between the solid-liquid ratio of 210Po and POC, while 210Pb does not, indicating that particulate organic matter regulates the biogeochemical cycle of 210Po around Prydz Bay. Based on the 210Po/210Pb disequilibria, the export flux of POC in the water column is estimated to be 0.8–31.9 mmol m–2 d–1, with the higher values in the shelf.

Origin and Preservation Conditions of Organic Matter in the Mozambique Channel: Evidence for Widespread Oxidation Processes in the Deep-Water Domains

2021 ◽  
pp. 106589
Author(s):  
Martina Torelli ◽  
Anne Battani ◽  
Daniel Pillot ◽  
Eric Kohler ◽  
Joel Lopes De Azevedo ◽  
...  
Keyword(s):  
Organic Matter ◽  
Deep Water ◽  
Oxidation Processes ◽  
Mozambique Channel ◽  
Preservation Conditions

scholarly journals Traces of sunlight in the organic matter biogeochemistry of two shallow subarctic lakes

2021 ◽  
Author(s):  
Marttiina V. Rantala ◽  
Carsten Meyer-Jacob ◽  
E. Henriikka Kivilä ◽  
Tomi P. Luoto ◽  
Antti. E. K. Ojala ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Lake Sediments ◽  
Lake Water ◽  
Human Impacts ◽  
Global Environmental Change ◽  
Carbon Export ◽  
Subarctic Lakes ◽  
Carbon Regulation ◽  
In Situ Experiments

AbstractGlobal environmental change alters the production, terrestrial export, and photodegradation of organic carbon in northern lakes. Sedimentary biogeochemical records can provide a unique means to understand the nature of these changes over long time scales, where observational data fall short. We deployed in situ experiments on two shallow subarctic lakes with contrasting light regimes; a clear tundra lake and a dark woodland lake, to first investigate the photochemical transformation of carbon and nitrogen elemental (C/N ratio) and isotope (δ13C, δ15N) composition in lake water particulate organic matter (POM) for downcore inferences. We then explored elemental, isotopic, and spectral (inferred lake water total organic carbon [TOC] and sediment chlorophyll a [CHLa]) fingerprints in the lake sediments to trace changes in aquatic production, terrestrial inputs and photodegradation before and after profound human impacts on the global carbon cycle prompted by industrialization. POM pool in both lakes displayed tentative evidence of UV photoreactivity, reflected as increasing δ13C and decreasing C/N values. Through time, the tundra lake sediments traced subtle shifts in primary production, while the woodland lake carried signals of changing terrestrial contributions, indicating shifts in terrestrial carbon export but possibly also photodegradation rates. Under global human impact, both lakes irrespective of their distinct carbon regimes displayed evidence of increased productivity but no conspicuous signs of increased terrestrial influence. Overall, sediment biogeochemistry can integrate a wealth of information on carbon regulation in northern lakes, while our results also point to the importance of considering the entire spectrum of photobiogeochemical fingerprints in sedimentary studies.

scholarly journals Particle export fluxes to the oxygen minimum zone of the eastern tropical North Atlantic

2017 ◽  
Vol 14 (7) ◽  
pp. 1825-1838 ◽  
Author(s):  
Anja Engel ◽  
Hannes Wagner ◽  
Frédéric A. C. Le Moigne ◽  
Samuel T. Wilson
Keyword(s):  
Organic Matter ◽  
North Atlantic ◽  
Organic Phosphorus ◽  
Euphotic Zone ◽  
Carbon Export ◽  
Organic Matter Quality ◽  
B Values ◽  
Chl A ◽  
Tropical North Atlantic ◽  
Particle Export

Abstract. In the ocean, sinking of particulate organic matter (POM) drives carbon export from the euphotic zone and supplies nutrition to mesopelagic communities, the feeding and degradation activities of which in turn lead to export flux attenuation. Oxygen (O2) minimum zones (OMZs) with suboxic water layers (< 5 µmol O2 kg−1) show a lower carbon flux attenuation compared to well-oxygenated waters (> 100 µmol O2 kg−1), supposedly due to reduced heterotrophic activity. This study focuses on sinking particle fluxes through hypoxic mesopelagic waters (< 60 µmol O2 kg−1); these represent  ∼  100 times more ocean volume globally compared to suboxic waters, but they have less been studied. Particle export fluxes and attenuation coefficients were determined in the eastern tropical North Atlantic (ETNA) using two surface-tethered drifting sediment trap arrays with seven trapping depths located between 100 and 600 m. Data on particulate matter fluxes were fitted to the normalized power function Fz =  F100 (z∕100)−b, with F100 being the flux at a depth (z) of 100 m and b being the attenuation coefficient. Higher b values suggest stronger flux attenuation and are influenced by factors such as faster degradation at higher temperatures. In this study, b values of organic carbon fluxes varied between 0.74 and 0.80 and were in the intermediate range of previous reports, but lower than expected from seawater temperatures within the upper 500 m. During this study, highest b values were determined for fluxes of particulate hydrolyzable amino acids (PHAA), followed by particulate organic phosphorus (POP), nitrogen (PN), carbon (POC), chlorophyll a (Chl a) and transparent exopolymer particles (TEP), pointing to a sequential degradation of organic matter components during sinking. Our study suggests that in addition to O2 concentration, organic matter composition co-determines transfer efficiency through the mesopelagic. The magnitude of future carbon export fluxes may therefore also depend on how organic matter quality in the surface ocean changes under influence of warming, acidification and enhanced stratification.

Separation of Methane from Shuttle Tanker Vents Gases by Adsorption on a Polyurethane/Zeolite Membrane

2017 ◽  
Vol 733 ◽  
pp. 42-46
Author(s):  
Habiba Shehu ◽  
Edidiong Okon ◽  
Edward Gobina
Keyword(s):  
Carbon Dioxide ◽  
Physical Properties ◽  
Crude Oil ◽  
Deep Water ◽  
Separation Factor ◽  
Gas Permeation ◽  
Zeolite Membrane ◽  
Alumina Support ◽  
Molar Flux

Shuttle tankers are becoming more widely used in deep water installations as a means of transporting crude oil to storage plants and refineries. The emissions of hydrocarbon vapours arise mainly during loading and offloading operations. Experiments have been carried out on the use of polyurethane/zeolite membrane on an alumina support for the separation of methane from carbon dioxide and oxygen. The physical properties of the membrane were investigated by FTIR. Single gas permeation tests with methane, propane, oxygen and carbon dioxide at a temperature of 293 K and pressure ranging from 0.1 to 1.0 x 10-5 Pa were carried out. The molar flux of the gases through the membrane was in the range of 3 x 10-2 to 1 x 10-1 molm-2s-1. The highest separation factor of CH4/CO2 and CH4/O2 and CH4/C3H8 was determined to be 1.7, 1.7 and 1.6 respectively.

scholarly journals Surface ocean carbon dioxide during the Atlantic Meridional Transect (1995–2013); evidence of ocean acidification

2017 ◽  
Vol 158 ◽  
pp. 65-75 ◽  
Author(s):  
Vassilis Kitidis ◽  
Ian Brown ◽  
Nicholas Hardman-Mountford ◽  
Nathalie Lefèvre
Keyword(s):  
Carbon Dioxide ◽  
Ocean Acidification ◽  
Surface Ocean ◽  
Ocean Carbon
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