scholarly journals The impact on atmospheric CO<sub>2</sub> of iron fertilization induced changes in the ocean's biological pump

2007 ◽  
Vol 4 (5) ◽  
pp. 3863-3911 ◽  
Author(s):  
X. Jin ◽  
N. Gruber ◽  
H. Frenzel ◽  
S. C. Doney ◽  
J. C. McWilliams
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Light Availability ◽  
Co2 Flux ◽  
Surface Patch ◽  
Biological Pump ◽  
Small Surface ◽  
Uptake Efficiency ◽  
Iron Fertilization ◽  
Basin Scale ◽  
The Impact

Abstract. Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical biogeochemical ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC) removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability) tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

scholarly journals The impact on atmospheric CO<sub>2</sub> of iron fertilization induced changes in the ocean's biological pump

2008 ◽  
Vol 5 (2) ◽  
pp. 385-406 ◽  
Author(s):  
X. Jin ◽  
N. Gruber ◽  
H. Frenzel ◽  
S. C. Doney ◽  
J. C. McWilliams
Keyword(s):  
Dissolved Inorganic Carbon ◽  
Light Availability ◽  
Co2 Flux ◽  
Surface Patch ◽  
Biological Pump ◽  
Small Surface ◽  
Uptake Efficiency ◽  
Iron Fertilization ◽  
Basin Scale ◽  
The Impact

Abstract. Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical/biogeochemical/ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC) removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, integrated over 10 years, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production and export. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability) tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.

scholarly journals Anomalies in the Carbonate System of Red Sea Coastal Habitats

2019 ◽  
Author(s):  
Kimberlee Baldry ◽  
Vincent Saderne ◽  
Daniel C. McCorkle ◽  
James H. Churchill ◽  
Susana Agusti ◽  
...  
Keyword(s):  
Red Sea ◽  
Dissolved Inorganic Carbon ◽  
Total Alkalinity ◽  
Carbonate Precipitation ◽  
Mangrove Forests ◽  
Sedimentary Processes ◽  
Carbonate System ◽  
Seagrass Meadows ◽  
Basin Scale ◽  
The Impact

Abstract. We use observations of dissolved inorganic carbon (DIC) and total alkalinity (TA) to assess the impact of ecosystem metabolic processes on coastal waters of the eastern Red Sea. A simple, single-end-member mixing model is used to account for the influence of mixing with offshore waters and evaporation/precipitation, and to model ecosystem-driven perturbations on the carbonate system chemistry of coral reefs, seagrass meadows and mangrove forests. We find that (1) along-shelf changes in TA and DIC exhibit strong linear trends that are consistent with basin-scale net calcium carbonate precipitation; (2) ecosystem-driven changes in TA and DIC are larger than offshore variations in > 85 % of sampled seagrass meadows and mangrove forests, changes which are influenced by a combination of longer water residence times and community metabolic rates; and (3) the sampled mangrove forests show strong and consistent contributions from both organic respiration and other sedimentary processes (carbonate dissolution and secondary redox processes), while seagrass meadows display more variability in the relative contributions of photosynthesis and other sedimentary processes (carbonate precipitation and oxidative processes).

scholarly journals Defining BGC-Argo-based metrics of ocean health and biogeochemical functioning for the evaluation of global ocean models

2021 ◽  
Author(s):  
Alexandre Mignot ◽  
Hervé Claustre ◽  
Gianpiero Cossarini ◽  
Fabrizio D'Ortenzio ◽  
Elodie Gutknecht ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Dissolved Inorganic Carbon ◽  
Numerical Models ◽  
Co2 Flux ◽  
Global Scale ◽  
Global Ocean ◽  
Argo Floats ◽  
In Situ Data ◽  
Biogeochemical Models ◽  
The Impact

Abstract. Numerical models of ocean biogeochemistry are becoming a major tool to detect and predict the impact of climate change on marine resources and ocean health. Classically, validation of such models relies on comparison with surface quantities from satellite (such as chlorophyll-a concentrations), climatologies, or sparse in situ data (such as cruises observations, and permanent fixed oceanic stations). However, these datasets are not fully suitable to assess how models represent many climate-relevant biogeochemical processes.  These limitations now begin to be overcome with the availability of a large number of vertical profiles of light, pH, oxygen, nitrate, chlorophyll-a concentrations and particulate backscattering acquired by the Biogeochemical-Argo (BGC-Argo) floats network. Additionally, other key biogeochemical variables such as dissolved inorganic carbon and alkalinity, not measured by floats, can be predicted by machine learning-based methods applied to float oxygen concentrations. Here, we demonstrate the use of the global array of BGC-Argo floats for the validation of biogeochemical models at the global scale. We first present 18 key metrics of ocean health and biogeochemical functioning to quantify the success of BGC model simulations. These metrics are associated with the air-sea CO2 flux, the biological carbon pump, oceanic pH, oxygen levels and Oxygen Minimum Zones (OMZs). The metrics are either a depth-averaged quantity or correspond to the depth of a particular feature. We also suggest four diagnostic plots for displaying such metrics.

The Influence of Disintegration of Hard Coal Varieties of Different Metamorphism Grade on the Amount of Sorbed Ethane / Wpływ rozdrobnienia odmian węgla kamiennego o różnym stopniu metamorfizmu na ilości sorbowanego etanu

2013 ◽  
Vol 58 (2) ◽  
pp. 449-463 ◽  
Author(s):  
Mieczysław Żyła ◽  
Agnieszka Dudzińska ◽  
Janusz Cygankiewicz
Keyword(s):  
Sorption Isotherms ◽  
Electron Donors ◽  
Hard Coal ◽  
Coal Surface ◽  
Compact Layer ◽  
Compact Structure ◽  
Small Surface ◽  
Mining Works ◽  
The Impact ◽  
Content Of Oxygen

Ethane constitutes an explosive gas. It most often accompanies methane realizing during exploitation and mining works. In this paper the results of ethane sorption have been discussed on three grain classes of six selected hard coal samples collected from active Polish coalmines. On the basis of obtained results, it has been stated that the tested hard coals prove differentiated sorption power with reference to ethane. Te extreme amount of ethane is sorbed by low carbonized hard coal from “Jaworzno” coalmine. This sort of coal shows great porosity, and great content of oxygen and moisture. The least amount of ethane is sorbed by hard coal from “Sośnica” coalmine. This sort of coal possesses relatively a great deal of ash contents. Together with the process of coal disintegration, the amount of sorbed ethane increases for all tested coal samples. Between tested coals there are three medium carbonized samples collected from “Pniówek”, “Chwałowice” “Zofiówka” coalmines which are characterized by small surface values counted according to model BET from nitrogen sorption isotherms determined at the temperature of 77.5 K. The samples of these three coals prove the highest, from between tested coals, increase of ethane sorption occurring together with their disintegration. These samples disintegrated to 0,063-0,075 mm grain class sorb ethane in the amount corresponding with the sorption quantity of low carbonized coal from “Jaworzno” coalmine in 0.5-0.7 mm grain class. It should be marked that the low carbonized samples collected from “Jaworzno” and Wesoła” coalmines possess large specific surface and great porosity and belong to coal group of “loose” spatial structure. Regarding profusion of sorbed ethane on disintegrated medium carbonized samples from “Pniówek”, “Zofiówka”, “Chwałowice” coalmines it can be supposed that in the process of coal disintegration, breaking their “compact’ structure occurs. Loosened structure of medium carbonized coals results in increasing accessibility of ethane particles to sorption centres both electron donors and electron acceptors which are present on hard coal surface. The surface sorption centre increase may result in formation a compact layer of ethane particles on coal surface. In the formed layer, not only the strengths of vertical binding of ethane particles with the coal surface appear but also the impact of horizontal strengths appears which forms a compact layer of sorbed ethane particles. The surface layer of ethane particles may lead to explosion.

scholarly journals Anthropogenic drought dominates groundwater depletion in Iran

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samaneh Ashraf ◽  
Ali Nazemi ◽  
Amir AghaKouchak
Keyword(s):  
Economic Security ◽  
Groundwater Depletion ◽  
Groundwater Storage ◽  
Rates Of Change ◽  
Level Data ◽  
Basin Scale ◽  
Storage Basin ◽  
Groundwater Reserves ◽  
The Impact ◽  
Hydrological Droughts

AbstractUsing publicly-available average monthly groundwater level data in 478 sub-basins and 30 basins in Iran, we quantify country-wide groundwater depletion in Iran. Natural and anthropogenic elements affecting the dynamics of groundwater storage are taken into account and quantified during the period of 2002–2015. We estimate that the total groundwater depletion in Iran to be ~ 74 km3 during this period with highly localized and variable rates of change at basin and sub-basin scales. The impact of depletion in Iran’s groundwater reserves is already manifested by extreme overdrafts in ~ 77% of Iran’s land area, a growing soil salinity across the entire country, and increasing frequency and extent of land subsidence in Iran’s planes. While meteorological/hydrological droughts act as triggers and intensify the rate of depletion in country-wide groundwater storage, basin-scale groundwater depletions in Iran are mainly caused by extensive human water withdrawals. We warn that continuation of unsustainable groundwater management in Iran can lead to potentially irreversible impacts on land and environment, threatening country’s water, food, socio-economic security.

scholarly journals Can land use changes alter carbon, nitrogen and major ion transport in subtropical brazilian streams?

2007 ◽  
Vol 64 (4) ◽  
pp. 317-324 ◽  
Author(s):  
Daniela Mariano Lopes da Silva ◽  
Jean Pierre Henry Balbaud Ometto ◽  
Gré de Araújo Lobo ◽  
Walter de Paula Lima ◽  
Marcos Augusto Scaranello ◽  
...  
Keyword(s):  
Land Use ◽  
Sugar Cane ◽  
Dissolved Inorganic Carbon ◽  
Comprehensive Evaluation ◽  
Land Use Changes ◽  
Agricultural Practices ◽  
Major Ion ◽  
Se Brazil ◽  
Tropical Watersheds ◽  
The Impact

Several studies in tropical watersheds have evaluated the impact of urbanization and agricultural practices on water quality. In Brazil, savannas (known regionally as Cerrados) represent 23% of the country's surface, representing an important share to the national primary growth product, especially due to intense agriculture. The purpose of this study is to present a comprehensive evaluation, on a yearly basis, of carbon, nitrogen and major ion fluxes in streams crossing areas under different land use (natural vegetation, sugar cane and eucalyptus) in a savanna region of SE Brazil. Eucalyptus and sugar cane alter the transport of the investigated elements in small watersheds. The highest concentration of all parameters (abiotic parameters, ions, dissolved organic carbon DOC - and dissolved inorganic carbon - DIC) were found in Sugar Cane Watersheds (SCW). The observed concentrations of major cations in Eucalyptus Watersheds (EW) (Mg, Ca, K, Na), as well as DIN and DOC, were found frequently to be intermediate values between those of Savanna Watersheds (SW) and SCW, suggesting a moderate impact of eucalyptus plantations on the streamwater. Same trends were found in relation to ion and nutrient fluxes, where the higher values corresponded to SCW. It is suggested that sugar cane plantations might be playing an important role in altering the chemistry of water bodies.

scholarly journals The impact of sedimentary alkalinity release on the water column CO<sub>2</sub> system in the North Sea

2016 ◽  
Vol 13 (3) ◽  
pp. 841-863 ◽  
Author(s):  
H. Brenner ◽  
U. Braeckman ◽  
M. Le Guitton ◽  
F. J. R. Meysman
Keyword(s):  
Coastal Zone ◽  
North Sea ◽  
Dissolved Inorganic Carbon ◽  
Co2 Uptake ◽  
Overlying Water ◽  
Southern North Sea ◽  
The North ◽  
Alkalinity Generation ◽  
The North Sea ◽  
The Impact

Abstract. It has been previously proposed that alkalinity release from sediments can play an important role in the carbonate dynamics on continental shelves, lowering the pCO2 of seawater and hence increasing the CO2 uptake from the atmosphere. To test this hypothesis, sedimentary alkalinity generation was quantified within cohesive and permeable sediments across the North Sea during two cruises in September 2011 (basin-wide) and June 2012 (Dutch coastal zone). Benthic fluxes of oxygen (O2), alkalinity (AT) and dissolved inorganic carbon (DIC) were determined using shipboard closed sediment incubations. Our results show that sediments can form an important source of alkalinity for the overlying water, particularly in the shallow southern North Sea, where high AT and DIC fluxes were recorded in near-shore sediments of the Belgian, Dutch and German coastal zone. In contrast, fluxes of AT and DIC are substantially lower in the deeper, seasonally stratified, northern part of the North Sea. Based on the data collected, we performed a model analysis to constrain the main pathways of alkalinity generation in the sediment, and to quantify how sedimentary alkalinity drives atmospheric CO2 uptake in the southern North Sea. Overall, our results show that sedimentary alkalinity generation should be regarded as a key component in the CO2 dynamics of shallow coastal systems.

scholarly journals Spatial-temporal changes in river runoff and terrestrial ecosystem water retention under 1.5 °C and 2 °C warming scenarios across China

2017 ◽  
Author(s):  
Ran Zhai ◽  
Fulu Tao ◽  
Zhihui Xu
Keyword(s):  
Climate Change ◽  
Interannual Variability ◽  
River Runoff ◽  
Water Retention ◽  
Terrestrial Ecosystem ◽  
Maximum Temperature ◽  
Climate Scenarios ◽  
Warming Scenario ◽  
Basin Scale ◽  
The Impact

Abstract. The Paris Agreement set a long-term temperature goal of holding the global average temperature increase to below 2.0 ℃ above pre-industrial levels, and pursuing efforts to limit this to 1.5 ℃, it is therefore important to understand the impacts of climate change under 1.5 ℃ and 2.0 ℃ warming scenarios for climate adaptation and mitigation. Here, climate scenarios by four Global Circulation Models (GCMs) for the baseline (2006–2015), 1.5 ℃ and 2.0 ℃ warming scenarios (2106–2115) were used to drive the validated Variable Infiltration Capacity (VIC) hydrological model to investigate the impacts of global warming on river runoff and Terrestrial Ecosystem Water Retention (TEWR) in China. The trends in annual mean temperature, precipitation, river runoff and TEWR were analysed at the grid and basin scale. Results showed that there were large uncertainties in climate scenarios from the different GCMs, which led to large uncertainties in the impact assessment. The differences among the four GCMs were larger than differences between the two warming scenarios. The interannual variability of river runoff increased notably in areas where it was projected to increase, and the interannual variability increased notably from 1.5 ℃ warming scenario to 2.0 ℃ warming scenario. By contrast, TEWR would remain relatively stable. Both extreme low and high river runoff would increase under the two warming scenarios in most areas in China, with high river runoff increasing more. And the risk of extreme river runoff events would be higher under 2.0 ℃ warming scenario than under 1.5 ℃ warming scenario in term of both extent and intensity. River runoff was significantly positively correlated to precipitation, while increase in maximum temperature would generally cause river runoff to decrease through increasing evapotranspiration. Likewise, precipitation also played a dominant role in affecting TEWR. Our findings highlight climate change mitigation and adaptation should be taken to reduce the risks of hydrological extreme events.

scholarly journals Joint inverse estimation of fossil fuel and biogenic CO2 fluxes in an urban environment: An observing system simulation experiment to assess the impact of multiple uncertainties

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Kai Wu ◽  
Thomas Lauvaux ◽  
Kenneth J. Davis ◽  
Aijun Deng ◽  
Israel Lopez Coto ◽  
...  
Keyword(s):  
High Resolution ◽  
Urban Environment ◽  
Co2 Emissions ◽  
Fossil Fuel ◽  
Atmospheric Transport ◽  
System Simulation ◽  
Co2 Flux ◽  
Point Sources ◽  
Co2 Fluxes ◽  
The Impact

The Indianapolis Flux Experiment aims to utilize a variety of atmospheric measurements and a high-resolution inversion system to estimate the temporal and spatial variation of anthropogenic greenhouse gas emissions from an urban environment. We present a Bayesian inversion system solving for fossil fuel and biogenic CO2 fluxes over the city of Indianapolis, IN. Both components were described at 1 km resolution to represent point sources and fine-scale structures such as highways in the a priori fluxes. With a series of Observing System Simulation Experiments, we evaluate the sensitivity of inverse flux estimates to various measurement deployment strategies and errors. We also test the impacts of flux error structures, biogenic CO2 fluxes and atmospheric transport errors on estimating fossil fuel CO2 emissions and their uncertainties. The results indicate that high-accuracy and high-precision measurements produce significant improvement in fossil fuel CO2 flux estimates. Systematic measurement errors of 1 ppm produce significantly biased inverse solutions, degrading the accuracy of retrieved emissions by about 1 µmol m–2 s–1 compared to the spatially averaged anthropogenic CO2 emissions of 5 µmol m–2 s–1. The presence of biogenic CO2 fluxes (similar magnitude to the anthropogenic fluxes) limits our ability to correct for random and systematic emission errors. However, assimilating continuous fossil fuel CO2 measurements with 1 ppm random error in addition to total CO2 measurements can partially compensate for the interference from biogenic CO2 fluxes. Moreover, systematic and random flux errors can be further reduced by reducing model-data mismatch errors caused by atmospheric transport uncertainty. Finally, the precision of the inverse flux estimate is highly sensitive to the correlation length scale in the prior emission errors. This work suggests that improved fossil fuel CO2 measurement technology, and better understanding of both prior flux and atmospheric transport errors are essential to improve the accuracy and precision of high-resolution urban CO2 flux estimates.

scholarly journals Resolving ecological feedbacks on the ocean carbon sink in Earth system models

2020 ◽  
Author(s):  
David I. Armstrong McKay ◽  
Sarah E. Cornell ◽  
Katherine Richardson ◽  
Johan Rockström
Keyword(s):  
Climate Change ◽  
Carbon Sink ◽  
Biological Pump ◽  
Earth System ◽  
Temperature Dependent ◽  
System Models ◽  
Plankton Ecology ◽  
Ocean Carbon ◽  
The Impact ◽  
Earth System Models

Abstract. The Earth’s oceans are one of the largest sinks in the Earth system for anthropogenic CO2 emissions, acting as a negative feedback on climate change. Earth system models predict, though, that climate change will lead to a weakening ocean carbon uptake rate as warm water holds less dissolved CO2 and biological productivity declines. However, most Earth system models do not incorporate the impact of warming on bacterial remineralisation and rely on simplified representations of plankton ecology that do not resolve the potential impact of climate change on ecosystem structure or elemental stoichiometry. Here we use a recently-developed extension of the cGEnIE Earth system model (ecoGEnIE) featuring a trait-based scheme for plankton ecology (ECOGEM), and also incorporate cGEnIE's temperature-dependent remineralisation (TDR) scheme. This enables evaluation of the impact of both ecological dynamics and temperature-dependent remineralisation on the soft-tissue biological pump in response to climate change. We find that including TDR strengthens the biological pump relative to default runs due to increased nutrient recycling, while ECOGEM weakens the biological pump by enabling a shift to smaller plankton classes. However, interactions with concurrent ocean acidification cause opposite sign responses for the carbon sink in both cases: TDR leads to a smaller sink relative to default runs whereas ECOGEM leads to a larger sink. Combining TDR and ECOGEM results in a net strengthening of the biological pump and a small net reduction in carbon sink relative to default. These results clearly illustrate the substantial degree to which ecological dynamics and biodiversity modulate the strength of climate-biosphere feedbacks, and demonstrate that Earth system models need to incorporate more ecological complexity in order to resolve carbon sink weakening.

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