Amount Of Carbon Research Articles

Shocks in the warm neutral medium. II. Origin of neutral carbon at high pressure

Ultraviolet lines of neutral carbon observed in absorption in the local diffuse interstellar medium (ISM) have long revealed that a substantial fraction of the mass of the gas lies at a thermal pressure one to three orders of magnitude above that of the bulk of the ISM. In this paper, we propose that this enigmatic component originates from shocks propagating at intermediate ($V_S > 30$ and high velocities ($V_S in the warm neutral medium (WNM). Shock waves irradiated by the standard interstellar radiation field (ISRF) are modelled using the Paris-Durham shock code designed to follow the dynamical, thermal, and chemical evolutions of shocks with velocities up to 500 Each observed line of sight is decomposed into a high-pressure component and a low-pressure component. The column density of carbon at high pressure is confronted with the model predictions to derive the number of shocks along the line of sight and their total dissipation rate. Phase transition shocks spontaneously lead to the presence of high-pressure gas in the diffuse ISM and are found to naturally produce neutral carbon with excitation conditions and line widths in remarkable agreement with the observations. The amounts of neutral carbon at high pressure detected over a sample of 89 lines of sight imply a dissipation rate of mechanical energy with a median of sim $3 and a dispersion of about a factor of three. This distribution of the dissipation rate weakly depends on the detailed characteristics of shocks as long as they propagate at velocities between 30 and 200 in a medium with a pre-shock density of $ and a transverse magnetic field of $B_0 3$ mu G. We not only show that this solution is consistent with a scenario of shocks driven by supernova remnants (SNRs) but also that this scenario is in fact unavoidable. Any line of sight in the observational sample is bound to intercept SNRs, which are mostly distributed in the spiral arms of the Milky Way and expanding in the diffuse ionised and neutral phases of the Galaxy. Surprisingly, the range of dissipation rate derived here, in events that probably drive turbulence in the WNM, is found to be comparable to the distribution of the kinetic energy transfer rate of the turbulent cascade derived from the observations of CO in the cold neutral medium (CNM). This work reveals a possible direct tracer of the mechanisms by which mechanical energy is injected into the ISM. It also suggests that a still unknown connection exists between the amount of energy dissipated during the injection process in the WNM and that used to feed interstellar turbulence and the turbulent cascade observed in the CNM.

Carbon taxation on high utility transport fuels: An implementation of enviro-economic analysis for the sustainable environment”

The humongous increase in carbon emissions in the past few decades presents an environmental challenge to the scientific community. The current study proposes a method of taxation on high-carbon emission fuels. For this purpose, a comparative enviro-economic analysis is carried out on the three most commonly used fuels (gasoline, Liquefied Petroleum Gas (LPG), and Compressed Natural Gas (CNG)). The speed of the test engine varied from 1800 to 4200 Revolution per Minute (RPM) in increments of 400 RPM. Performance parameters (Brake Power (BP), Brake Thermal Efficiency (BTHE), and Brake Specific Fuel Consumption (BSFC)) were measured using a hydro dynamometer. Emission analysis, including Carbon Dioxide (CO2), Carbon Monoxide (CO), Unburned Hydrocarbons (HC), and Nitrogen Oxide (NOx), was conducted using the TESTO 350 analyzer. The application of Weibull distribution with a 95 % confidence interval, on emission data, explained the adequacy of the data. Among test fuels, CNG emerged as an environment-friendly fuel with an emission reduction of 16, 42, and 43 percent for CO2, CO, and HC in comparison to gasoline. Also, BTHE and BSFC of CNG were better than other alternatives. Moreover, the carbon penalty for CNG fuel showed a price reduction of 32 and 20.8 percent in comparison to gasoline and LPG respectively. The study provides a novel approach to assess the environmental impact of fuels by economic analysis based on emitted carbon quantity. In addition, this very idea is novel in promoting the Sustainable Development Goals (SDG) of the United Nations (UN) through carbon taxation.

O-175 Ethical practices and policies for ART carbon reduction

Abstract Background The carbon emissions of global health care activities make up 4-5% of total world emissions, placing the health care industry on par with the food sector. Health care contributes to climate change and climate change health hazards. Safe amounts of carbon in the atmosphere have been exceeded—in part because of medical lifestyles in the industrialized world. A significant proportion of health care carbon comes from pharmaceuticals and clinical services in the developed world, including reproductive technologies. Since 1978, approximately 12 million babies have been born through IVF alone. Problem statement Reproductive technologies have an exceptional impact on the environment as they 1. expend carbon in the medical process, 2. increase population growth in mostly high-carbon countries, 3. impact earth’s carrying capacity, and 4. create a carbon legacy. This would not necessarily be ethically problematic, but in a climate crisis carbon emissions must be reduced in all areas of life. Objectives This presentation by an ethicist (PhD) will: 1. Highlight aspects of environmental ethics for reproductive technologies 2. Offer practices and policies to make reproductive technologies more sustainable. Takeaways • Prevention of infertility fits within basic health care. • Carbon emissions from reproductive technologies can be reduced by life cycle assessments (LCA) of the procedures and components. • Clinical evidence can inform ethical policies to reduce the number and kind of reproductive technologies, thereby lowering fertility industry carbon emissions. • New scientific and technological developments in reproduction must consider sustainability proactively, not reactively, thus putting ethics in the pipeline of reproductive medicine. Further Reading Bhopal A, and Norheim O. Priority setting and net zero healthcare: how much health can a tonne of carbon buy?. BMJ 2021; 375:e067199. Pichler, P.-P. et al., “International Comparison of Health Care Carbon Footprints,” Environmental Research Letters 14, no. 6 (2019): 064004. Richie, Cristina. Environmental Ethics and Medical Reproduction (Oxford University Press, 2024.

Photosynthate transfer from an autotrophic orchid to conspecific heterotrophic protocorms through a common mycorrhizal network.

The minute 'dust seeds' of some terrestrial orchids preferentially germinate and develop as mycoheterotrophic protocorms near conspecific adult plants. Here we test the hypothesis that mycorrhizal mycelial connections provide a direct pathway for transfer of recent photosynthate from conspecific green orchids to achlorophyllous protocorms. Mycelial networks of Ceratobasidium cornigerum connecting green Dactylorhiza fuchsii plants with developing achlorophyllous protocorms of the same species were established on oatmeal or water agar before the shoots of green plants were exposed to 14CO2. After incubation for 48 h, the pattern of distribution of fixed carbon was visualised in intact entire autotrophic/protocorm systems using digital autoradiography and quantified in protocorms by liquid scintillation counting. Both methods of analysis revealed accumulation of 14C above background levels in protocorms, confirming that autotrophic plants supply carbon to juveniles via common mycorrhizal networks. Despite some accumulation of plant-fixed carbon in the fungal mycelium grown on oatmeal agar, a greater amount of carbon was transferred to protocorms growing on water agar, indicating that the polarity of transfer may be influenced by sink strength. We suggest this transfer pathway may contribute significantly to the pattern and processes determining localised orchid establishment in nature, and that 'parental nurture' via common mycelial networks may be involved in these processes.

Soil carbon offset markets are not a just climate solution

There is growing interest in enhancing soil carbon sequestration (SCS) as a climate mitigation strategy, including neutralizing atmospheric emissions from fossil‐fuel combustion through the development of soil carbon offset markets. Several studies have focused on refining estimates of the magnitude of potential SCS or on developing methods for soil carbon quantification in markets. We call on scientists and policy makers to resist assimilating soils into carbon offset markets due to not only fundamental flaws in the logic of these markets to reach climate neutrality but also environmental justice concerns. Here, we first highlight how carbon offset markets rely on an inappropriate substitution of inert fossil carbon with dynamic stocks of soil carbon. We then note the failure of these markets to account for intersecting anthropogenic perturbations to the carbon cycle, including the soil carbon debt and ongoing agricultural emissions. Next, we invite scientists to consider soil functions beyond productivity and profitability. Finally, we describe and support historical opposition to offset markets by environmental justice advocates. We encourage scientists to consider how their research and communications can promote diverse soil functions and just climate‐change mitigation.

The effects of thinning on carbon and nutrient fluxes input into forest floor via litterfall in black pine afforestation sites.

As a component of the biogeochemical cycle, litterfall contributes carbon and nutrients to forest ecosystems by transferring organic material to mineral soil. Litterfall therefore serves as an important indicator for soil fertility and ecosystem health. This study aimed to determine the impact of different levels of thinning (light, moderate, and heavy) on litterfall quantity (needles, branches, bark, cones, and miscellaneous parts) and on the amount of carbon and nutrients entering the ecosystem in black pine afforestation areas. Three levels of low thinning, namely light, moderate, and heavy thinning (15%, 25%, and 35% of breast height area, respectively), were applied as treatments. Additionally, a control plot was included in the experiment. Litterfall samples were collected four times per year (once per season) from 12 treatment plots for three years. In the laboratory, dry weight measurements and analyses of carbon and macro-micro nutrient elements (N, P, K, Ca, Mg, S, Na, Fe, Cu, Zn, and Mn) were performed on litterfall samples taken from the field. Differences between treatments in terms of litterfall and the amount of carbon and nutrient elements entering the ecosystem were evaluated through variance analysis and the Duncan test. According to the findings, the quantity of litterfall input into the forest floor was highest in the control treatment, at 6,543kgha-1year-1 and lowest in the heavy treatment, at 4,378kgha-1year-1, showing a significant variation in litterfall quantity. The input of C to the soil ranged between 2,233kgha-1year-1 and 3,347kgha-1year-1 depending on thinning treatment. Although thinning treatment reduced C input to the soil, there was no significant difference among treatments. This also applied to nutrient elements such as N, P, K, Mg, and S. Needles constituted the majority of litterfall components (60%) and had the highest C density among all components, at 51.2%. The weighted carbon ratio for litterfall was calculated at 50.8%. Considering carbon-focused planning, performing moderate thinning interventions in the study area or similar pine-afforested areas may be a suitable option for maintaining the sustainability and health of the forest.

Accurate Quantification of 0–30 cm Soil Organic Carbon in Croplands over the Continental United States Using Machine Learning

Increases in organic carbon within agricultural soils are widely recognized as a “negative emission” that removes CO2 from the atmosphere. Accurate quantification of soil organic carbon (SOC) to a certain depth in the spatial domain is critical for the effective implementation of improved land management practices in croplands. Currently, there is a lack of understanding regarding what depth strategy should be used to estimate SOC at 0–30 cm when sample datasets come from multiple depths. Furthermore, few studies have examined depth strategies for mapping SOC at the agricultural management level (i.e., field level), opting instead for point-based analysis. Here, three types of approaches with different depth strategies were evaluated for their ability to quantify 0–30 cm SOC content based on soil samples from 0–5 (surface), 5–30 (subsurface), and 0–30 cm (full column). These approaches involved the generalized additive model and machine learning techniques, i.e., artificial neural networks, random forest, and XGBoost. The soil samples used for the model evaluation and selection consisted of the newly collected samples in 2020–2022 and the Rapid Carbon Assessment (RaCA) legacy samples collected in 2010–2011. Environmental covariates corresponding to these SOC measurements were used in model training, including long-term physical climate, short-term weather, topographic and edaphic, and remotely sensed variables. Among the models evaluated in this study, the XGB regression model with a full column depth assignment strategy yielded the best prediction performance for 0–30 cm SOC content, with an r2 (squared Pearson correlation coefficient) of 0.48, an RMSE (root mean square error) of 0.29%, an ME (mean error) of 0.06%, an MAE of 0.25%, and an MEC (modeling efficiency coefficient) of 0.36 at the pixel level and an r2 of 0.64, an RMSE of 0.32%, an ME of −0.20%, an MAE of 0.28%, and an MEC of 0.48 at the field level. This study highlights that machine learning models with a full column depth strategy should be used to quantify 0–30 cm SOC content in agricultural soils over the continental United States (CONUS).

Glacial troughs as centres of organic carbon accumulation on the Norwegian continental margin

The role of continental margin sediments in the carbon cycle and the associated management potential for climate mitigation are currently poorly understood. Previous work has indicated that margin sediments store significant amounts of organic carbon, but few studies have quantified the rates at which organic carbon is accumulated. Here, we use machine learning to make spatial predictions of the organic carbon stocks and accumulation rates of sediments on the Norwegian continental margin. We show that surface sediments (upper 10 cm) store 814 Tg and accumulate 6 Tg yr−1 of organic carbon. Shelf-incised glacial troughs account for 39% of the stocks and 48% of the accumulation, with the main accumulation hotspot located in the Skagerrak. Continental margin sediments accumulate organic carbon at scales much larger than vegetated coastal ecosystems in Norway because of their larger extent. Future studies should explore to what extent management interventions could increase accumulation rates, e.g., by minimising anthropogenic disturbance of seafloor sediments.

Does carbon reduction and sequestration conflict with food security in rural China?-What, why and how?

Based on panel data of 31 provinces in rural China from 1997 to 2020, this manuscript first applies a carbon reduction and sequestration (CRS) model from the perspective of agricultural carbon emissions and agricultural carbon sinks. We then construct a food security evaluation system to examine the four dimensions of quantity, quality, ecological and economic security. Finally, the study uses a spatial Durbin model to empirically analyze the impact of CRS on food security and the moderating effect of fiscal decentralization. The relevant results: First, from 1997 to 2020, carbon emissions rose from 221.9794 million tons (1997) to 251.1368 million tons (2020), representing an increase of 13.14 %. The total amount of carbon sinks increased from 518.259 million tons (1997) to 758.887 million tons (2020); an increase of 46.43 %. CRS exhibited a fluctuating downward trend, falling from 0.98 (1997) to 0.90 (2020). However, food security showed an increasing trend, rising 0.12 (1997) to 0.32 (2020), with an average annual growth rate of 6.94 %. Second, in the short term, national CRS has had a significantly negative impact on food security, whereas the long term the result is exactly the opposite. In terms of control variables, planting structure, openness to the world, and economic development have significantly positive impact on food security, and urbanization, technological progress, and environmental regulation have significantly negative impact on food security. Regional heterogeneity is evident in the three functional attribute areas. Third, fiscal decentralization can enhance the negative impact of CRS on food security in the short term and weaken the positive impact of CRS on food security in the long term. Similarly, some regional heterogeneity is found among different regions.

Effect of Depositional Environment and Climate on Organic Matter Enrichment in Sediments of the Upper Miocene—Pliocene Kampungbaru Formation, Lower Kutai Basin, Indonesia

The Upper Miocene–Pliocene Kampungbaru Formation crops out in the easternmost part of the Lower Kutai Basin, Indonesia. The sedimentological analysis of seven outcrops was carried out, and a total of twenty-five samples from these outcrops was analyzed for bulk geochemistry, organic petrography, and bulk and clay mineralogy to assess the effect of the climate and depositional environment on organic matter enrichment. The Kampungbaru Formation consists of interbedded sandstone, siltstone, claystone, and thick coal beds, which were classified into eleven lithofacies. Subsequently, seven facies associations were identified, namely the fluvial-dominated distributary channel, sheet-like sandstone, tide-influenced distributary channel, mouth bar, crevasse splay, delta plain, and delta front. The coal facies generally have a high amount of total organic carbon (TOC, 5.1–16.9; avg. 10.11 wt.%), and non-coal layers range from 0.03 to 4.22 wt.% (avg. 1.54 wt.%). The dominant maceral is vitrinite, while liptinite occurs only rarely in the samples. Organic matter is inferred to have originated from terrestrial plants growing in mangrove swamps. Identified clay minerals include varying proportions of kaolinite, illite, chlorite, and mixed layer illite/smectite (I/S). Kaolinite, which commonly constitutes up to 30% of the clay volume, indicates intensive chemical weathering during a warm and humid climate. In accordance with the Köppen climate classification, the paleoclimate during the deposition of the Kampungbaru Formation is classified as type Af, which is a tropical rainforest. Tropical climate was favorable for the growth of higher plants and deposition of organic matter under anoxic conditions and led to higher amounts of TOC in the Kampungbaru Formation.

Unravelling CH4 and N2O dynamics in tidal wetlands using natural abundance isotopes and functional genes

Tidal wetlands are one of the major sources of CH4 and N2O in natural systems to the atmosphere; yet we still lack insights into the impact of their biogeochemical dynamics on the emissions of these greenhouse gases (GHGs). Here, we investigated the CH4 and N2O sources in four tidal wetlands ranging from freshwater to polyhaline with a focus on their production pathways. By using natural abundance isotopes and functional marker genes, we found that salinity level, sediment moisture content, quantity and quality of organic carbon (OC) and nutrients were major drivers of the wetland CH4 and N2O emissions. As the salinity levels decreased in the tidal wetlands, both the labile nature and concentration of nutrients and OC increased. These conditions favored methanogenesis as indicated in the abundance and expression of mcrA and the CH4 emissions from the freshwater wetland. Conversely, higher salinity depressed organic matter decomposition rates and microbial activities, causing much lower CH4 production in the saline wetlands. Isotope mapping revealed that denitrification contributed mainly to wetland N2O emissions (80–90%), reflected in the strong expression of denitrifier marker genes nirS, nirK, and nosZ and low nosZ:nir ratio. Nitrification played an important role in wetland N2O emissions at high NH4+ and low salinity levels. This condition was the case in the freshwater wetland – the strongest N2O emitter – where we found the highest NH4+ concentrations and the most abundant and expressed nitrifier marker genes amoA AOA and amoA AOB. Methanogen and denitrifier marker genes were more abundant and expressed at the surface layer compared to the subsurface layer, implying the presence of methane and denitrification paradoxes in the tidal wetlands. This study paves a way for the coupling of isotope and functional gene analyses to deeply explore GHG formation pathways and responsible microbial activities in dynamic wetland systems.

High-efficiency remediation of Hg and Cd co-contaminated paddy soils by Fe–Mn oxide modified biochar and its microbial community responses

Fe–Mn oxide modified biochar (FMBC) was produced to explore its potential for remediation of Hg–Cd contaminated paddy soils. The results showed that the application of FMBC decreased the contents of bioavailable Hg and Cd by 41.49–81.85% and 19.47–33.02% in contrast to CK, while the amount of labile organic carbon (C) fractions and C-pool management index (CPMI) was increased under BC and FMBC treated soils, indicating the enhancement of soil C storage and nutrient cycling function. Dry weight of different parts of Oryza sativa L. was enhanced after the addition of BC and FMBC, and the contents of Fe and Mn in root iron–manganese plaques (IMP) were 1.46–2.06 and 6.72–19.35 times higher than those of the control groups. Hg and Cd contents in brown rice under the FMBC treatments were significantly reduced by 18.32–71.16% and 59.52–72.11% compared with the control. FMBC addition altered the composition and metabolism function of soil bacterial communities, especially increasing the abundance of keystone phyla, including Firmicutes, Proteobacteria and Actinobacteria. Partial least squares path modelling (PLSPM) revealed that the contents of Na2S2O3–Hg, DTPA–Cd and IMP were the key indicators affecting Hg and Cd accumulation in rice grains. These results demonstrate the simultaneous value of FMBC in remediation of Hg and Cd combined pollution and restoring soil fertility and biological productivity.Graphical

Boosting the Electrochemical Performance of Primary and Secondary Lithium Batteries with Mn-Doped All-Fluoride Cathodes.

Transition metal fluorides are potentially high specific energy cathode materials of next-generation lithium batteries, and strategies to address their low conductivity typically involve a large amount of carbon coating, which reduces the specific energy of the electrode. In this study, MnyFe1-yF3@CFx was generated by the all-fluoride strategy, converting most of the carbon in MnyFe1-yF3@C into electrochemical active CFx through a controllable NF3 gas phase fluorination method, while still retaining a tightly bound graphite layer to provide initial conductivity, which greatly improved the energy density of the composite. This synergistic effect of nonfluorinated residual carbon (∼11%) and Mn doping ensures the electrochemical kinetics of the composite. The loading mass of the active substance had been increased to 86%. The theoretical and actual discharge capacity of MnyFe1-yF3@CFx composite was up to 765 mAh g-1 (pure FeF3 is 712 mAh g-1) and 728 mAh g-1, respectively. The discharge capacity at the high-voltage (3.0 V) platform was more than three times higher than that of the non-Mn-doped composite (FeF3@CFx).

Spatial, Temporal, and Interspecific Differences in Composition of Stable Isotopes in Fishes in Maryland Coastal Bays

Carbon (δ13C) and nitrogen (δ15N) isotopes were used to evaluate spatial, temporal, and interspecific differences in trophic relationships of four fish species (Paralichthys dentatus, Anchoa mitchilli, Leiostomus xanthurus, and Bairdiella chrysoura) in Maryland’s coastal bays. The δ13C values for all species were more enriched in 2017 than in 2018, a year of higher-than-average rainfall that likely caused higher amounts of terrestrial carbon to enter the estuary. There were significant differences among species in the δ13C values, with L. xanthurus being the least depleted (−17.2‰ in 2017; −18.8‰ in 2018). Spatially, the δ13C values of the species, particularly P. dentatus and B. chrysoura, were more depleted in the northern bays, which have a higher nutrient content and receive more freshwater inflow directly from tributaries, than the southern bays. The observed δ13C values (−19.5 ± 0.2‰ to –17.2 ± 0.3‰), however, indicate that marine phytoplankton was the primary carbon source of the fishes. Overall, A. mitchilli was the most enriched in δ15N (13.0‰), and L. xanthurus was the most depleted (10.2‰). δ15N was more enriched in fish from the more human-impacted northern bays than in fish from the southern bays, though this might also have stemmed from the differences in the diet composition of the species in the northern and southern bays. A. mitchilli had the highest trophic level, while L. xanthurus and P. dentatus had the lowest trophic levels. Niche breadth was widest in L. xanthurus compared to the other fish species, suggesting a higher variability in diets among L. xanthurus individuals, leading to specialized diets. There was a high niche overlap between B. chrysoura, A. mitchilli, and L. xanthurus, which indicates they fed on similar prey resources.

Transformation and Sequestration of Total Organic Carbon in Black Soil under Different Fertilization Regimes with Straw Carbon Inputs

In the context of the carbon peak and carbon-neutral era, it is crucial to effectively utilize maize straw as a resource for achieving carbon (C) sequestration and emission reduction in rural agriculture. Maize straw carbon undergoes two processes after being added to the soil: mineralization (decomposition) and humification (synthesis) by soil animals and microorganisms. These processes contribute to the reintegration of carbon into the agroecosystem’s carbon cycle. However, understanding of the transformation and stabilization of straw carbon, as well as the differences in C fixation capacity in soils with various fertilization treatments in black soils, remains limited. This study aims to quantify the relationship between straw carbon input and organic carbon sequestration in various fertilization treatments of black soil. Based on a long-term positional fertilization trial (45 years) in black soil, 13C-labeled maize straw (1.5 g in 120 g of dry soil) was applied and combined with an in situ incubation method using carborundum tubes. Throughout the 360-day trial, we observed the influence of fertilization on soil total organic C levels, organic carbon δ13C values, maize straw addition rate, and straw C fixation capacity. The decomposition of straw was most prominent during the initial 60 days of the incubation period, followed by a gradual decrease in the rate of decomposition. Compared with day 0, the SOC δ13C value and straw C residue rate were highest in the no-fertilization treatment (CK) after 360 days of incubation. The amount of organic carbon transformed and fixed in the soil was significantly higher in the organic fertilizer treatment (M) compared to other treatments, highlighting the stronger decomposition, transformation, and carbon fixation capacity of straw carbon in the M treatment. Moreover, the highest carbon storage of 43.23 Mg·ha−1 was observed in the M fertilization treatment after 360 days, which was significantly different from other treatments (p < 0.05). The study demonstrates that soil with low fertility exhibits increased sequestration potential for straw carbon. Additionally, organic fertilizer input would increase soil organic carbon storage and facilitate straw carbon conversion.

The limited effect of deforestation on stabilized subsoil organic carbon in a subtropical catchment

Abstract. Predicting the quantity of soil organic carbon (SOC) requires understanding how different factors control the amount of SOC. Land use has a major influence on the function of the soil as a carbon sink, as shown by substantial organic carbon (OC) losses from the soil upon deforestation. However, predicting the degree to which land use change affects the OC content in soils and the depth down to which this occurs requires context-specific information related to, for example, climate, geochemistry, and land use history. In this study, 266 samples from forests and agricultural fields were collected from 94 soil profiles down to 300 cm depth in a subtropical region (Arvorezinha, southern Brazil) to study the impact of land use on the amount of stabilized OC along the soil profile. We found that the stabilized OC content was not affected by land use below a depth of 90 cm. Along the soil profile, the amount of stabilized OC was predominantly controlled by land use and depth in addition to the silt and clay content and aluminium ion concentrations. Below 100 cm, none of the soil profiles reached a concentration of stabilized OC above 50 % of the stabilized OC saturation point (i.e. the maximum OC concentration that can physically be stabilized in these soils). Based on these results, we argue that it is unlikely that deeper soil layers can serve as an OC sink over a timescale relevant to global climate change due to the limited OC input in these deeper layers. Furthermore, we found that the soil weathering degree was not a relevant control on the amount of stabilized OC in our profiles because of the high weathering degree of the studied soils. It is therefore suggested that, while the soil weathering degree might be an effective controlling factor of OC stabilization over a large spatial scale, it is not an informative measure for this process at regional and local scales (with similar climate, bedrock, and weathering history) in highly weathered soils.

Biocalcification of Sandy Gypseous Soil by Bacillus Pasteurii

Microbial-induced carbon precipitation (MICP) is one of the most recent treatment methods for soil stabilization. The present work employs this technique in improving the collapsing behavior of sandy gypseous soil with 35% gypsum content under one-dimensional loading to 100 kPa and leaching conditions. A bacterial strain, Bacillus pasteurii was used for this purpose. A set of collapse tests was performed inside a modified oedometer on specimens, prepared with 25% bacterial solution and 0, 0.25M, 0.5M, or 1M cementation solution molarities, cured to 7, 14, or 21 days. The results indicated that the bacterium was able to produce a considerable amount of calcium carbonate ranging from 3% to 15%. This carbonate was also observed by microscopic imaging of the specimens at the interparticle contacts and also on the surfaces of soil grains. Consequently, the soil gained additional bonding and the voids became smaller. Therefore, the soil became more resistant to water flow and leaching, where the treated specimen maintained nearly the same permeability with the progression of leaching, unlike the untreated specimen which showed a 7-fold increase over the same water flow condition. Over the examined load, the MICP treatment provided almost no change in the strains caused by external loading, unlike the wetting strains which exhibited a considerable reduction of 11% to 80%. The results of leaching strains appeared to be sensitive to the rate of flow and the cementation solution molarity

Influence of Laser Energy on the Structural and Optical Properties of Sn Nanoparticles produced with Laser-Induced Plasma

This study aimed to investigate the structure and optical properties of Sn nanostructures. Thin tin (Sn) films were deposited on glass substrates using the pulsed laser deposition method. Nd:YAG laser with fundamental wavelengths of 532 nm and 1064 nm was used to create Sn nanostructures with varying energies of 400 mJ to 700 mJ and the same frequency of 6 Hz. The tin powder was compressed into a disc with a one-centimetre diameter to serve as a sample. The X-ray diffraction (XRD) pattern showed a crystalline structure with several Sn nanostructures peaks at various energies (400–700 mJ). The results revealed a crystalline size of 65.90 nm and 86.55 nm at 700 mJ, while the size was 40.19 nm and 17.19 at 400 mJ for the given wavelengths (532nm and 1064 nm), respectively. The appearance of Sn nanostructures and the aggregation of, particularly in the form of cauliflower, were revealed in Field emission scanning electron microscopy (FE-SEM) images. The results of the dispersive energy X-ray spectroscopy (EDS) analysis showed that various amounts of tin, carbon, and oxygen were present. Additionally, the optical characteristics were investigated of each film using absorbance spectra, which covered a range of wavelengths from 190 to 1100 nm. As the laser power increased, the band gap energy values in the optical properties decreased, falling into the ranges of 3.06 to 1.65 eV and 3.22 to 1.82 eV at 1064nm and 532nm, respectively.

Habitat quality evaluation and pattern simulation of coastal salt marsh wetlands

Coastal salt marsh wetlands not only sequester a large amount of organic carbon, mitigating the effect of climate change, but also nurture rich wetland resources and diverse ecological environments. In this study, habitat pattern and quality of the Jiangsu Yancheng Wetland Rare Birds National Nature Reserve were studied. The evolution of habitat patterns was analyzed using the U-Net model and Sentinel-2 data. The habitat quality was evaluated using the InVEST model, while the future habitat pattern in 2027 under different scenarios were simulated using the PLUS model. Our results showed that, during 2017–2022, the Suaeda salsa habitat showed a net decrease in area of 2077.61 ha, while Spartina alterniflora and Phragmites australis habitats manifested a net increase in different degrees. The overall habitat pattern was characterized by fragmentation decline and regularization enhancement. The habitat quality decreased from 0.75 to 0.72, mainly due to the loss of the S. salsa habitat and the expansion of the P. australis habitat. The simulation results indicated that, the habitat quality is expected to further decline to 0.71 under the natural development scenario, and 390.27 ha of S. salsa habitat will convert to P. australis. While in government control scenario, the habitat quality is expected to improve to 0.78, which was 0.07 higher than that in natural development scenario, and S. salsa habitat can be restored well. This study provides a scientific basis for the protection of suitable habitats for waterfowl and is crucial for the ecological conservation and management planning of nature reserves and coastal salt marsh wetlands.

Greenhouse gas fluxes of different land uses in mangrove ecosystem of East Kalimantan, Indonesia

BackgroundMangrove ecosystems exhibit significant carbon storage and sequestration. Its capacity to store and sequester significant amounts of carbon makes this ecosystem very important for climate change mitigation. Indonesia, owing to the largest mangrove cover in the world, has approximately 3.14 PgC stored in the mangroves, or about 33% of all carbon stored in coastal ecosystems globally. Unfortunately, our comprehensive understanding of carbon flux is hampered by the incomplete repertoire of field measurement data, especially from mangrove ecosystem-rich regions such as Indonesia and Asia Pacific. This study fills the gap in greenhouse gases (GHGs) flux studies in mangrove ecosystems in Indonesia by quantifying the soil CO2 and CH4 fluxes for different land use types in mangrove ecosystems, i.e., secondary mangrove (SM), restored mangrove (RM), pond embankment (PE) and active aquaculture pond (AP). Environmental parameters such as soil pore salinity, soil pore water pH, soil temperature, air temperature, air humidity and rainfall are also measured.ResultsGHG fluxes characteristics varied between land use types and ecological conditions. Secondary mangrove and exposed pond embankment are potential GHG flux sources (68.9 ± 7.0 and 58.5 ± 6.2 MgCO2e ha− 1 yr− 1, respectively). Aquaculture pond exhibits the lowest GHG fluxes among other land use types due to constant inundation that serve as a barrier for the release of GHG fluxes to the atmosphere. We found weak relationships between soil CO2 and CH4 fluxes and environmental parameters.ConclusionsThe data and information on GHG fluxes from different land use types in the mangrove ecosystem will be of importance to accurately assess the potential of the mangrove ecosystem to sequester and emit GHGs. This will support the GHG emission reduction target and strategy that had been set up by the Indonesian Government in its Nationally Determined Contributions (NDC) and Indonesia’s 2030 Forest and Other Land Use (FOLU) Net Sink.