Ocean nourishment sequestering carbon dioxide in the deep ocean

Our small planet is now vulnerable to the cumulative effects of our normal activities. There are two specific grand challenges associated with sustainability that are worth our attention—the global carbon cycle and the global nitrogen cycle. Human beings are disrupting the carbon cycle by releasing carbon, dug out of coalmines and oil fields, into the atmosphere. Mainly due to human beings’ activities, the concentration of carbon dioxide in the atmosphere has increased by more than 30% over the last 250 years, with an annual increase of about 0.5%. Two-thirds of the rise has occurred during the past 50 years. Fossil fuel accounts for 85% of the world’s energy system, and has been the principle agent of interference with the natural cycle for carbon. Such a disrupted carbon cycle, with a high carbon dioxide concentration, is posing tremendous challenges, including wide-spread global warming, rising sea level, significant threats to human health, more frequent extreme weather, and harmful disrupted ecological systems, and so on. Unless there is a change, the world will see much higher concentration of carbon dioxide, and it is thus a must for the world to redesign its energy system to become much less dependent on fossil fuels and less harmful to the carbon cycle. Besides the carbon cycle, the nitrogen cycle is another fundamental feature of life on the planet. The nitrogen cycle is also being disrupted by human beings. Organisms on this planet require nitrogen to survive, but the nitrogen in the atmosphere must be modified to be useful. The nitrogen needed by life is produced by “nitrogen-fixing bacteria” that break the triple bond of atmospheric nitrogen (N2, or N≡N) and produce “available” nitrogen. Only a few bacteria can act as “nitrogen-fixing bacteria.” Additional nitrogen fixation is accomplished by lightning. However, for the past hundred years, human beings have been able to produce available nitrogen from atmospheric nitrogen industrially, using the Haber-Bosch process. The most important product, globally, is nitrogen fertilizer, which has enabled a great expansion of the world’s food supply. The world is now more and more dependent on fertilizers to fix nitrogen. And now, more nitrogen is fixed in fertilizer factories than by the bacteria of the world. Another new source of available nitrogen comes from combustion of fossil fuels, which produces nitrogen oxides (“NOx,” which subsumes NO, NO2, N2O5, and other oxides of nitrogen). Significant increases in NOx emissions could occur over the next several decades due to both population growth and per capita increases in fossil-fuel use, although there are many technologies that can reduce NOx emissions. The extra nitrogen fixation today will seriously affect many environment systems—changing the balance of species, producing unwanted biological growth (eutrophication) in aqueous systems, and increasing the emissions of nitrous oxide (N2O, a greenhouse gas) to the atmosphere. International attention to the nitrogen cycle has gradually increased and focuses on the complexity of human alteration of the nitrogen cycle. Coordinated management of the nitrogen and carbon cycles is desirable. Engineering can provide remedies to disrupted ecosystems and has managed to achieve partial successes. There are many reasons to be optimistic that much can be accomplished, the world still has a terribly inefficient system for using carbon and nitrogen, and there is so much room to improve our energy system, food system, and agricultural system. The word “smart” is a key word to describe what engineers can contribute—smart buildings, appliances, infrastructure, vehicles, and food systems, with a core aim to achieve better efficiency. In order to achieve that, we can use a carbon price and a nitrogen price to promote efficient use. Also, we have an enormous amount of global infrastructure still to build, especially in the developing world (Table 1). Crucially, young scientists and engineers now find the challenges of carbon and nitrogen management exciting. As a main engineering method to protect the carbon cycle, carbon dioxide can be captured at a coal plant, then compressed and sent into porous rocks deep below ground. Someday all coal plants may separate the burning of coal from the emission of carbon dioxide. The already existing network of carbon dioxide pipelines in the USA shows that such a route for a low-carbon future

Our knowledge about the global carbon cycle can be made more robust by making use of the condition of mass continuity, distributions of tracers and interactions with the the nutrient cycles. Glimpses of the historical development of our knowledge Carbon is the basic element of life. All organic compounds in nature contain carbon and the carbon dioxide in the atmosphere is the source of the carbon that plants assimilate in the process of photosynthesis. An understanding of the global carbon cycle is of basic importance in studies of human-induced climate change, not only because of the need to determine expected changes of atmospheric carbon dioxide concentrations due to human emission, but because natural changes of the carbon cycle may also have influenced the climate in the past. The detection of the fundamental chemical and biochemical processes of relevance in this context is a most important part of the development of chemistry during the eighteenth century and the first decades of the nineteenth century. Joseph Black (1754) is credited with the discovery of carbon dioxide gas. Its real nature was, however, not very well understood until Carl W. Scheele in Sweden and Joseph Priestley in England identified ‘fire air’ (i.e. oxygen) a few decades later and the French chemist Lavoisier correctly interpreted the concepts of fire and combustion. When carbon burns, carbon dioxide is formed. It was not realised until well into the nineteenth century that carbon dioxide, like oxygen and nitrogen, is a permanent constituent of the air and that it is a source of carbon for plants. However, it was not then possible to measure the amount present in the atmosphere.

Plastics in blue carbon ecosystems: a call for global cooperation on climate change goals

<strong class="journal-contentHeaderColor">Abstract.</strong> High-mountain ecosystems are experiencing acute effects of climate change, most visibly through glacier recession and the greening of the terrestrial environment. The streams draining these landscapes are affected by these shifts, integrating hydrologic, geologic, and biological signals across the catchment. We examined the organic and inorganic carbon dynamics of streams in four Alpine catchments in Switzerland to assess how glacier loss and vegetation expansion are affecting the carbon cycle of these high mountain ecosystems. We find that organic carbon concentration and fluorescence properties associated with humic-like compounds increase with vegetation cover within a catchment, demonstrating the increasing importance of allochthonous carbon sources following glacier retreat. Meanwhile, streams transitioned from carbon dioxide sinks to sources with decreasing glacier coverage and increased vegetation coverage, with chemical weathering and soil respiration likely determining the balance. Periods of sink behavior were also observed in non-glaciated streams, indicating geochemical consumption of carbon dioxide may be more common in high-mountain, minimally vegetated catchments than previously described. Together, these results demonstrate the dramatic shifts in carbon dynamics of alpine streams following glacier recession, with significant changes to both the organic and inorganic carbon cycles. The clear link between the terrestrial and aquatic zones further emphasizes the coupled dynamics with which all hydrologic and biogeochemical changes in these ecosystems should be considered, including the role of mountain streams in the global carbon cycle.

The advanced process‐based model, National Integrated Catchment‐based Eco‐hydrology (NICE)‐BGC, which incorporates the whole process of carbon cycling in land, was modified to include the feedback between soil organic content and overland carbon fluxes. It is a crucial and difficult task to evaluate the balance of the terrestrial carbon budget including the effect of inland water robustly. To accomplish this purpose, NICE‐BGC was applied to quantify the global biogeochemical carbon cycle closely associated with the complex hydrological cycle during the 36 years between 1980 and 2015. The model demonstrated that the inter‐annual variations of carbon cycle have been greatly affected by the extreme weather patterns. In particular, spatial distribution of temporal trends in riverine carbon fluxes and their relation to soil organic carbon (SOC) were analysed between different biomes and major river basins. Although there was a positive relationship between SOC and riverine flux of dissolved organic carbon and particulate organic carbon in the northern boreal region, it is difficult to see this relation in other regions. Further, the evaluation of potential controlling factors of temporal trends in SOC and fluvial carbon exports was also helpful to quantify the inter‐annual variation or temporal trend caused by the various effects. SOC was more influenced by temperature variations, whereas riverine carbon exports were mainly determined by precipitation variations. Finally, net land flux including inland water (−1.49 ± 0.50 PgC/year) showed a slight decrease in the carbon sink in comparison with previous values (−2.33 ± 0.50 PgC/year). These results help to distinguish the carbon cycle in different river basins and to re‐evaluate carbon cycle change explicitly including the effect of inland water because this effect has been so far implicitly included within the range of uncertainty in the Earth's global carbon cycle comprising land, oceans, and atmosphere.

Chapter 2 - Importance and roles of soil respiration

The ocean is a vast carbon sink and mediates global carbon cycling, essential for mitigating climate change. The deep-sea pelagic and subseafloor environments represent the largest microbial habitats on Earth and are key sites for organic matter remineralization and storage in the biosphere. Moreover, diverse unique and extreme habitats, e.g. seamounts, trenches, cold seeps and hydrothermal vents exist in the deep sea, developing special and active microbial communities and metabolic processes that significantly impact global carbon cycling. It is therefore important to understand the diversity, activity and metabolism of deep-sea microorganisms, particularly their mechanisms for utilization and transformation of organic matter, and the environmental factors affecting these processes. The main aim of this Research Topic is to collect recent work focusing on the diversity and metabolic activities of microorganisms in different deep-sea habitats, in order to understand the microorganisms that drive carbon cycling in the deep ocean.Marine sediments harbor diverse physicochemical properties that regulate the assemblages of microorganisms. However, it is unclear how variations in sediment

Simultaneous assimilation of SMOS soil moisture and atmospheric CO2 in-situ observations to constrain the global terrestrial carbon cycle

Plastic pollution can both chemically and physically impede marine biota. But it can also provide novel substrates for colonization, and its leachate might stimulate phytoplankton growth. Plastic contains carbon, which is released into the environment upon breakdown. All of these mechanisms have been proposed to contribute global impacts on open ocean carbon cycling and climate from ubiquitous plastic pollution. Laboratory studies produce compelling data showing both stimulation and inhibition of primary producers and disruption of predatory lifecycles at individual scale, but global carbon cycle impacts remain mostly unquantified. Preliminary modelling estimates ecosystem alterations and direct carbon release due to plastic pollution will remain vastly less disruptive to global carbon cycling than the direct damage wrought by fossil fuel carbon emissions. But when considered by mass, carbon in the form of bulky, persistent plastic particles may be disproportionally more influential on biogeochemical cycling than carbon as a gas in the atmosphere or as a dissolved component of seawater. Thus, future research should pay particular attention to the optical and other physical effects of marine plastic pollution on Earth system and ecological function, and resulting impacts on oxygen and nutrient cycling. Improved understanding of the breakdown of plastics in the marine environment should also be considered high-priority, as any potential perturbation of biological carbon cycling by plastic pollution is climate-relevant on centennial timescales and longer.

Effects of fuel and forest conservation on future levels of atmospheric carbon dioxide

Turf and surf

This work is devoted to experimental research of the extraction of triterpene saponins from Aralia mandshurica and Panax ginseng using the supercritical extraction process. Triterpene saponins of Aralia mandshurica and Panax ginseng are polar compounds. Therefore, the supercritical extraction process was carried out in a supercritical carbon dioxide using a co-solvent – an aqueous solution of ethanol. A technique for carrying out the supercritical extraction process is described and a schematic diagram of a supercritical extraction apparatus proprietary design with an extractor volume of 22 ml is presented. The kinetic curves of the yield of extract are presented. This work is considering methods of intensification of the supercritical extraction process: optimization of operational conditions, superposition of fields. Optimization of operational conditions was carried out in the temperature range of 40 to 50 °С and pressures range of 120 to 200 bar. The phenomenon of retrogradation was noted when the temperature of the supercritical extraction process from Panax ginseng changed. The influence of the method of supplying supercritical carbon dioxide (constant supply throughout the process and pulse supply) was studied. The pulsed supply made it possible to significantly reduce the consumption of carbon dioxide – by 59.5% relative to the experiment with a constant consumption of carbon dioxide. The study of the effect of ultrasonic exposure (the method of superimposing fields) on the intensity of the supercritical extraction process was carried out. The usage of ultrasound led to an increase in the yield of extract. The largest amount of extract from Aralia mandshurica and Panax ginseng was obtained at 50 °С and 200 bar with the usage of ultrasonic exposure and at a constant supply of carbon dioxide (500 g/h) throughout the process. For citation: Khudeev I.I., Lebedeva E.S., Artemiev A.I., Kazeev I.V., Menshutina N.V. Intensification of supercritical extraction of triterpene saponins from Aralia mandshurica and Panax ginseng. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 3. P. 108-118. DOI: 10.6060/ivkkt.20236603.6737.

The deep sea is the largest biome on earth, but one of the least studied despite its critical role in global carbon cycling and climate buffering. Deep-sea organisms largely rely on particulate organic matter from the surface ocean for energy – these organisms in turn play critical roles in energy transport, transformation, storage, and sequestration of carbon. Within the deep sea, submarine canyons are amongst the most complex and dynamic environments in our oceans, where varied morphology, powerful currents, and variable nutrient conditions influence the distribution of species and transport of organic material throughout the water column and the seafloor. Significant habitat heterogeneity provides ideal substrates for cold-water corals, making submarine canyons of interest to conservation and management. However, how these and other topographic features in the deep ocean influence energy flow and trophic pathways is poorly known. Thus, submarine canyons serve as model systems to track variability in organic material flux and consequential utilization and assimilation by the benthos. In this study, we used an extensive stable isotope dataset to examine food-web structure in Baltimore and Norfolk submarine canyons and compared them to their adjacent slopes located along the U.S. Atlantic margin. Linear models were used to construct geospatially-explicit consumer isoscapes that predicted variation in carbon and nitrogen isotopes across the canyon-slope seascape, providing a predictive map from which to test hypotheses on the distribution and flow of energy resources, relevant to understanding whole community function. Communities were composed of isotopically diverse feeding groups with photosynthetically-derived organic carbon providing the basal food resource. Canyon communities were distinct from the slope, with canyon consumers significantly 13C-depleted, indicating a greater supply and/or utilization of fresh organic matter compared to the slope. Isoscapes for benthic and suspension feeders were distinct, possibly due to the consumption of different quality organic matter sources (fresh = suspension feeders, old = benthic feeders), each with distinct isotope composition. To our knowledge, our modeled isoscapes represent the first spatially extensive isotopic maps of deep-sea consumers, providing insights into regional-scale variation in stable carbon and nitrogen isotopes for different consumer groups. They provide a baseline for tracking climate-change induced fluctuations in the quality and availability of surface primary production and the consequential impact to benthic communities, which play critical roles in carbon cycling in our world’s oceans.

Small headwater streams are recognized for intense outgassing to the atmosphere of climate‐relevant carbon dioxide (CO2) and methane (CH4). Though these headwaters are markedly oversaturated for both CO2 and CH4, the origins and controls over the fate of these two carbon‐gases are still poorly constrained, especially for the stronger greenhouse gas CH4. Here, by measuring stream‐based production of CO2 and CH4, concurrently with their rates of outgassing to the atmosphere, we identify distinct biophysical control mechanisms for each gas. We show that while CO2 is largely imported from the catchment in proportion to discharge, CO2 outgassing can be modulated by in‐stream metabolism to offset outgassing by up to 30% in spring and summer. In contrast, CH4 shows a non‐linear response to seasonal changes in discharge and is predominantly produced in the streambed in relation to sediment type. Further, once released from the streambed, outgassing of CH4 at the surface and flow‐driven dilution occur far more rapidly than biological methane oxidation and CH4 leaves the water largely unaltered by biology. Incorporating the intense carbon cycling of headwater streams into the global carbon cycle will require distinct parameterizations for each carbon gas in Earth system models.

The recent publication of the summary for policy makers by Working Group I of the Intergovernmental Panel on Climate Change (IPCC) [1] has injected a renewed sense of urgency to address climate change. It is therefore timely to review the notion of preventing 'dangerous anthropogenic interference with the climate system' as put forward in the United Nations Framework Convention on Climate Change (UNFCCC). The article by Danny Harvey in this issue [2] offers a fresh perspective by rephrasing the concept of 'dangerous interference' as a problem of risk assessment. As Harvey points out, identification of 'dangerous interference' does not require us to know with certainty that future climate change will be dangerous—an impossible task given that our knowledge about future climate change includes uncertainty. Rather, it requires the assertion that interference would lead to a significant probability of dangerous climate change beyond some risk tolerance, and therefore would pose an unacceptable risk.