Carbon Storage Strategies Research Articles

Sustainable Development of ZnO Nanostructure Doping with Water Hyacinth-Derived Activated Carbon for Visible-Light Photocatalysis.

Water hyacinth (Wh) is an aquatic weed considered a nuisance in agricultural and fishing activities. Therefore, this study proposed repurposing this plant into activated carbon (AC). First, the ZnO-AC was precipitated and applied as a photocatalyst for degrading methylene blue. The preliminary photocatalytic test under UV irradiation identified the optimum ZnO-AC photocatalyst to degrade methylene blue (MB). The ZnO-AC photocatalyst recorded the highest degradation rate constant of 11.49 × 10-3 min-1, which was almost two-fold higher than that of ZnO (5.55 × 10-3 min-1). Furthermore, photocatalytic degradation of MB and carbaryl under sunlight irradiation by ZnO-AC demonstrated degradation rate constants of 74.46 × 10-3 min-1 and 8.43 × 10-3 min-1, respectively. To investigate the properties of ZnO-AC, several techniques were performed. ZnO-AC and ZnO exhibited similar results in morphology, crystalline structure, and Raman characteristics. However, ZnO-AC presented smaller pore diameters than those of ZnO, which enlarged pore surface area, and the presence of carbon-related groups implied the presence of AC on ZnO-AC surfaces. This can be attributed to the presence of AC on the ZnO surface, increasing the capture of surrounding toxic molecules and elevating the reaction density. This mechanism is attributed to promoting the degradation of toxic molecules. Therefore, using Wh as a carbon source for the transformation of AC can alternatively solve the problems of aquatic weed management and carbon storage strategies, and the application of AC in ZnO-AC photocatalysts can enhance photocatalysis.

Variations of δ13C in water-soluble compounds during spring phenology of typical tree species in the warm temperate zone

In this study, we examined the regularity of phenological rhythmical change of plant water-soluble compound δ13C (δ13Cwsc) in spring for two typical tree species in the warm temperate zone of China, Pinus tabuliformis and Robinia pseudoacacia. The δ13Cwsc in each organ of those two species in the spring phenological period were measured to explore the relationship between δ13Cwsc and related environmental factors. The results showed that there were significant differences in δ13Cwsc values of each organ between P. tabuliformis and R. pseudoacacia, with higher δ13Cwsc(-25.03‰±0.01‰) in the new shoot of P. tabuliformis. The δ13Cwsc value in the non-photosynthetic organs were 0.83‰-1.8‰ higher than that in the photosynthetic organs, while the δ13Cwsc value in the aboveground part was generally lower than that in the underground part. As spring progressing, different carbon storage strategies were found between two species. When the terminal bud of P. tabuliformis opened, the carbon was obtained from the proximal old leaves. At the beginning of leaf development, photosynthetic products accumulated by old leaves could not meet the growth requirements for new leaves and roots, with 90% of which depending on the carbon reserve in branches and stems. When full leaf having developed, the photosynthetic function of both new and old leaves recovered and the carbon consumed by branches and stems was gradually replenished. For R. pseudoacacia, at the beginning of leaf bud opening and leaf spreading, branches were the main carbon source for new leaves and roots. When leaves were fully unfolded, mature leaves with high capacity of carbon sequestration became the primary carbon source. Results of principal component analysis showed that temperature during observation period, ≥10 ℃ accumulated temperature, sunshine duration and solar radiation were the main factors influencing δ13Cwsc, which could explained 86.3% of the total variation. The δ13Cwsc values of both species was negatively correlated with temperature and relative humidity, but positively correlated with the difference of saturated water pressure, ≥10 ℃ accumulated temperature and sunshine duration. The main environmental factors affecting plant δ13Cwsc varied during the phenological process. Our results could provide a reference for more accurate estimation of spring organ carbon distribution pattern of regional typical tree species, and also a theoretical basis for formulating scientific and reasonable forest management strategy.

Sequestration of solid carbon in concrete: A large-scale enabler of lower-carbon intensity hydrogen from natural gas

Methane pyrolysis is an emerging technology to produce lower-carbon intensity hydrogen at scale, as long as the co-produced solid carbon is permanently captured. Partially replacing Portland cement with pyrolytic carbon would allow the sequestration at a scale that matches the needs of the H2 industry. Our results suggest that compressive strength, the most critical mechanical property, of blended cement could even be improved while the cement manufacture, which contributes to ~ 9% global anthropogenic CO2 emissions, can be decarbonized. A CO2 abatement up to 10% of cement production could be achieved with the inclusion of selected carbon morphologies, without the need of significant capital investment and radical modification of current production processes. The use of solid carbon could have a higher CO2 abatement potential than the incorporation of conventional industrial wastes used in concrete at the same replacement level. With this approach, the concrete industry could become an enabler for manufacturing a lower-carbon intensity hydrogen in a win–win solution.ImpactMethane pyrolysis is an up-scalable technology that produces hydrogen as a lower carbon-intensity energy carrier and industrial feedstock. This technology can attract more investment for lower-carbon intensity hydrogen if co-produced solid carbon (potentially hundreds of million tons per year) has value-added applications. The solid carbon can be permanently stored in concrete, the second most used commodity worldwide. To understand the feasibility of this carbon storage strategy, up to 10 wt% of Portland cement is replaced with disk-like or fibrillar carbon in our study. The incorporation of 5% and 10% fibrillar carbons increase the compressive strength of the cement-based materials by at least 20% and 16%, respectively, while disk-like carbons have little beneficial effects on the compressive strength. Our life-cycle assessment in climate change category results suggest that the 10% cement replacement with the solid carbon can lower ~10% of greenhouse gas emissions of cement production, which is currently the second-largest industrial emitter in the world. The use of solid carbon in concrete can supplement the enormous demand for cement substitute for low-carbon concrete and lower the cost of the low-carbon hydrogen production. This massively available low-cost solid carbon would create numerous new opportunities in concrete research and the industrial applications.

Individual Physiological Adaptations Enable Selected Bacterial Taxa To Prevail during Long-Term Incubations.

Enclosure experiments are frequently used to investigate the impact of changing environmental conditions on microbial assemblages. Yet, how the incubation itself challenges complex bacterial communities is thus far unknown. In this study, metaproteomic profiling, 16S rRNA gene analyses, and cell counts were combined to evaluate bacterial communities derived from marine, mesohaline, and oligohaline conditions after long-term batch incubations. Early in the experiment, the three bacterial communities were highly diverse and differed significantly in their compositions. Manipulation of the enclosures with terrigenous dissolved organic carbon resulted in notable differences compared to the control enclosures at this early phase of the experiment. However, after 55 days, bacterial communities in the manipulated and the control enclosures under marine and mesohaline conditions were all dominated by gammaproteobacterium Spongiibacter In the oligohaline enclosures, actinobacterial cluster I of the hgc group (hgc-I) remained abundant in the late phase of the incubation. Metaproteome analyses suggested that the ability to use outer membrane-based internal energy stores, in addition to the previously described grazing resistance, may enable the gammaproteobacterium Spongiibacter to prevail in long-time incubations. Under oligohaline conditions, the utilization of external recalcitrant carbon appeared to be more important (hgc-I). Enclosure experiments with complex natural microbial communities are important tools to investigate the effects of manipulations. However, species-specific properties, such as individual carbon storage strategies, can cause manipulation-independent effects and need to be considered when interpreting results from enclosures.IMPORTANCE In microbial ecology, enclosure studies are often used to investigate the effect of single environmental factors on complex bacterial communities. However, in addition to the manipulation, unintended effects ("bottle effect") may occur due to the enclosure itself. In this study, we analyzed the bacterial communities that originated from three different salinities of the Baltic Sea, comparing their compositions and physiological activities both at the early stage and after 55 days of incubation. Our results suggested that internal carbon storage strategies impact the success of certain bacterial species, independent of the experimental manipulation. Thus, while enclosure experiments remain valid tools in environmental research, microbial community composition shifts must be critically followed. This investigation of the metaproteome during long-term batch enclosures expanded our current understanding of the so-called "bottle effect," which is well known to occur during enclosure experiments.

Potential for sustainable use of trees in hot arid regions: A case study of Emirati neighborhoods in Abu Dhabi

This paper explores the future of landscapes in arid, coastal regions based on 4 water-energy regimes, using a case study of villa neighborhoods in Abu Dhabi, United Arab Emirates. It examines the potential for the planting of 15 selected tree species for carbon storage under various water-energy regimes to create carbon neutral (or negative) villa neighborhoods. Recent improvements to solar photovoltaic and reverse-osmosis desalination technology have lowered the carbon emissions for water production by over 99% relative to current gas-powered multi-stage flash desalination (0.08 kg CO2/m3 vs.12.8 kg CO2/m3). This allows trees planted in hot, desert climates to utilize treated ocean water while net sequestering between 1.7 and 38.2 kg C/tree/yr depending on species. When planted in existing neighborhood open spaces, we find that net carbon storage rates from trees are significant (15–800%) relative to operational emissions rates for building energy (cooling, lighting, equipment) when households are supplied from 100% renewable energy sources. Thus, as technology advances, landscape design strategies in the region could evolve to maximize planting to sequester carbon while also creating more comfortable outdoor spaces that enhance the livability of neighborhoods. This study provides a first step in identifying the potential for landscape architectural design to employ a tree-based, neighborhood scale, carbon storage strategy in arid regions such as those in the Arabian Peninsula. As nations move towards a carbon-neutral future, it is imperative to develop innovative solutions that address urban sustainability, especially in resource-challenged and extreme climate regions where new urban development is planned.

To spend or to save? Assessing energetic growth-storage tradeoffs in native and invasive woody plants.

Many non-native woody plants invade low-light forest understories but differ from native species in leaf phenology and seasonality of photosynthesis. It is unknown whether such differences in assimilation patterns are due to contrasting strategies of energy allocation. In a group of native and invasive species in Eastern North America, we hypothesized that invaders employ a grow-first strategy, prioritizing allocation to new structural biomass over carbon storage compared to native congeners. We also hypothesized that species producing a single spring leaf flush exhibit a more conservative carbon storage strategy than species with continuous leaf production. We measured sugar and starch concentrations (non-structural carbohydrates; NSCs) in spring and fall in the stems and roots of 39 species of native and non-native shrubs in a common garden, and compared these to patterns of leaf production across species. Native species had higher soluble sugar concentrations than invaders, but invaders tended to store more root starch in spring. We found no difference in leaf production between natives and invaders. Determinate species had more soluble sugars than indeterminate species but had lower root starch. We found no relationship between aboveground productivity and carbon storage. Our results suggest that closely related species with contrasting evolutionary histories have different carbon storage strategies, although not necessarily in relation to their growth potential. The higher soluble sugar concentrations of native species may reflect their evolutionary response to historical disturbances, or different interactions with soil microbes, while increased spring root starch in invaders may support fine root or fruit production.

Are carbohydrate storage strategies of trees traceable by early–latewood carbon isotope differences?

Investigations of stable isotopes in early- and latewood cellulose offer interesting insights to climate-driven adaptations of trees’ carbon storage strategy during different phenological phases. We investigated δ13C isotopic composition in both earlywood and latewood. The origin of the samples is an oak forest (Quercus petraea), situated in Switzerland. A comparison of isotope compositions between early- and latewood can help us to investigate and understand the processes of plant metabolism in more detail. The fact which we found excellent correlations (r 2 = 55 %) between early- and latewood for carbon isotopes strengthens the common knowledge that atmospheric CO2 acts as the major carbon source for latewood but the earlywood strongly depends on the reserves from previous years (r 2 = 68 %), at least for oaks investigated in this study. In addition, that no correlation between late woods (r 2 = 0–5 %) was found, manifests the higher variability of direct assimilates. Furthermore, we examined the impacts of increasing air temperature and CO2 concentration on carbohydrate fluxes in trees and we found remarkable differences between two time periods. In the period ad 1780–1825, the trees intensely used the young reserves while in the period ad 1960–1994, there is no clear preference of them. This suggests that in the latter period, a larger volume of reserves is available and that the new assimilated reserves (previous year) do not play the most important part, mainly due to the very favourable conditions induced by climate change, at the investigated site. In conclusion, a carbon isotope approach on early- and latewood samples is ideal to investigate isotope incorporation pathways of physiological processes. This will augment the interpretation of tree ring isotope records with respect to the assignments of their variations to specific biochemical processes within the tree, i.e. carbon allocation.

The role of silicate surfaces on calcite precipitation kinetics

The aim of this study is to illuminate how calcite precipitation depends on the identity and structure of the growth substrate. Calcite was precipitated at 25°C from supersaturated aqueous solutions in the presence of seeds of either calcite or one of six silicate materials: augite, enstatite, labradorite, olivine, basaltic glass and peridotite rock. Calcite saturation was achieved by mixing a CaCl2-rich aqueous solution with a NaHCO3–Na2CO3 aqueous buffer in mixed-flow reactors containing 0.5–2g of mineral, rock, or glass seeds. This led to an inlet fluid calcite saturation index of 0.6 and a pH equal to 9.1. Although the inlet fluid composition, flow rate, and temperature were identical for all experiments, the onset of calcite precipitation depended on the identity of the seeds present in the reactor. Calcite precipitated instantaneously and at a constant rate in the presence of calcite grains. Calcite precipitated relatively rapidly on labradorite, olivine, enstatite, and peridotite (mainly composed of Mg-olivine) surfaces, but more slowly on augite and basaltic glass. Calcite precipitation rates, however, became independent of substrate identity and mass over time, and all rates approach 10−9.68±0.08mol/s for ∼10day long experiments and 10−9.21±0.2mol/s for ∼70day long experiments. Scanning Electron Microscope images showed olivine, enstatite and peridotite surfaces to be covered extensively with calcite coatings at the end of the experiments. Less calcite was found on labradorite and augite, and the least on basaltic glass. In all cases, calcite precipitation occurs on the mineral, rock or glass surfaces. Calcite precipitation on these surfaces, however, negligibly affects the dissolution rates of the silicate grains. These results support ultramafic and basalt carbonation as a long-term carbon storage strategy, as calcite readily precipitates on the surfaces of minerals contained in these rocks without inhibiting their dissolution.

A synthesis of current knowledge on forests and carbon storage in the United States

Using forests to mitigate climate change has gained much interest in science and policy discussions. We examine the evidence for carbon benefits, environmental and monetary costs, risks and trade-offs for a variety of activities in three general strategies: (1) land use change to increase forest area (afforestation) and avoid deforestation; (2) carbon management in existing forests; and (3) the use of wood as biomass energy, in place of other building materials, or in wood products for carbon storage. We found that many strategies can increase forest sector carbon mitigation above the current 162-256 Tg C/yr, and that many strategies have co-benefits such as biodiversity, water, and economic opportunities. Each strategy also has trade-offs, risks, and uncertainties including possible leakage, permanence, disturbances, and climate change effects. Because approximately 60% of the carbon lost through deforestation and harvesting from 1700 to 1935 has not yet been recovered and because some strategies store carbon in forest products or use biomass energy, the biological potential for forest sector carbon mitigation is large. Several studies suggest that using these strategies could offset as much as 10-20% of current U.S. fossil fuel emissions. To obtain such large offsets in the United States would require a combination of afforesting up to one-third of cropland or pastureland, using the equivalent of about one-half of the gross annual forest growth for biomass energy, or implementing more intensive management to increase forest growth on one-third of forestland. Such large offsets would require substantial trade-offs, such as lower agricultural production and non-carbon ecosystem services from forests. The effectiveness of activities could be diluted by negative leakage effects and increasing disturbance regimes. Because forest carbon loss contributes to increasing climate risk and because climate change may impede regeneration following disturbance, avoiding deforestation and promoting regeneration after disturbance should receive high priority as policy considerations. Policies to encourage programs or projects that influence forest carbon sequestration and offset fossil fuel emissions should also consider major items such as leakage, the cyclical nature of forest growth and regrowth, and the extensive demand for and movement of forest products globally, and other greenhouse gas effects, such as methane and nitrous oxide emissions, and recognize other environmental benefits of forests, such as biodiversity, nutrient management, and watershed protection. Activities that contribute to helping forests adapt to the effects of climate change, and which also complement forest carbon storage strategies, would be prudent.

Bacterial Carbon Storage to Value Added Products

Microorganisms have evolved different systems for storing carbon during times of stress. In the cell’s natural environment, the stored carbon can then be utilized for growth when other nutrients are in better supply. Storage of carbon and other nutrients is ubiquitous throughout the prokaryotic and eukaryotic domains of life. These carbon storage molecules have great industrial importance. They can be useful as value-added products, as either biopolymers or biofuels, and cells are grown in large quantities and these compounds are harvested, usually as a replacement for a petroleum-based product. Nowadays, entire industries have been generated based on the production and utilization of these compounds. We focus on two bacteria that could be considered paradigms of their particular carbon storage strategy: Ralstonia eutropha and Rhodococcus opacus . R. eutropha has been well-studied as a polyhydroxyalkanoate (bioplastic) producer and R. opacus is a model bacterium for high yield triacylglycerol (TAG) production for biofuels. Both species produce carbon storage molecules that can potentially diminish our reliance on fossil-based petroleum. However, in both cases, there are challenges that must be overcome before profitable production schemes are established using these organisms. We explore the previous and current works to address these challenges in this review.

Design of carbon dioxide storage in aquifers

We propose a carbon storage strategy where CO 2 and brine are injected into an aquifer together followed by brine injection alone. This renders 80–95% of the CO 2 immobile in pore-scale (10 s μ m) droplets in the porous rock. Over thousands to billions of years the CO 2 may dissolve or precipitate as carbonate, but it will not migrate upwards and so is effectively sequestered. The CO 2 is trapped during the decades-long lifetime of the injection phase, reducing the need for extensive monitoring for centuries. The method does not rely on impermeable cap rock to contain the CO 2; this is only a secondary containment for the small amount of remaining mobile gas. Furthermore, the favorable mobility ratio between injected and displaced fluids leads to a more uniform sweep of the aquifer leading to a higher storage efficiency than injecting CO 2 alone. This design strategy is demonstrated through the incorporation of a recently developed trapping model into a field-scale streamline-based simulator. The new model includes gas trapping and relative permeability hysteresis and is based on pore-scale modeling results. One-dimensional results are verified through comparison with analytical solutions. Results are then shown for storage in a North Sea aquifer. We design injection to give optimal storage efficiency and to minimize the amount of water injected; for the cases we study, injecting CO 2 with a fractional flow between 85% and 100% followed by a short period of chase brine injection gives the best performance. Sensitivity studies were conducted for different rock wettability and using the Land trapping model. The effectiveness of our proposed strategy is very sensitive to the estimated residual CO 2-phase saturation.

CARBOHYDRATE STORAGE AND LIGHT REQUIREMENTS OF TROPICAL MOIST AND DRY FOREST TREE SPECIES

In many plant communities, there is a negative interspecific correlation between relative growth rates and survival of juveniles. This negative correlation is most likely caused by a trade-off between carbon allocation to growth vs. allocation to defense and storage. Nonstructural carbohydrates (NSC) stored in stems allow plants to overcome periods of stress and should enhance survival. In order to assess how species differ in carbohydrate storage in relation to juvenile light requirements, growth, and survival, we quantified NSC concentrations and pool sizes in sapling stems of 85 woody species in moist semi-evergreen and dry deciduous tropical forests in the rainy season in Bolivia. Moist forest species averaged higher NSC concentrations than dry forest species. Carbohydrate concentrations and pool sizes decreased with the light requirements of juveniles of the species in the moist forest but not in the dry forest. Combined, these results suggest that storage is especially important for species that regenerate in persistently shady habitats, as in the understory of moist evergreen forests. For moist forest species, sapling survival rates increased with NSC concentrations and pool sizes while growth rates declined with the NSC concentrations and pool sizes. No relationships were found for dry forest species. Carbon allocation to storage contributes to the growth-survival trade-off through its positive effect on survival. And, a continuum in carbon storage strategies contributes to a continuum in light requirements among species. The link between storage and light requirements is especially strong in moist evergreen forest where species sort out along a light gradient, but disappears in dry deciduous forest where light is a less limiting resource and species sort out along drought and fire gradients.