Carbon Sequestration Efficiency Research Articles

Climate Change 2022 Mitigation of Climate Change: Urban System

The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR6) assesses literature on the scientific, technological, environmental, economic, and social aspects of mitigation of climate change. The IPCC-AR6 integrates factors of developments in the UN Framework Convention on Climate Change (UNFCCC) process. It includes the Kyoto Protocol and the Paris Agreement, and the UN 2030 Agenda for Sustainable Development including the Sustainable Development Goals (SDGs). This paper reviews the urban system and its pathways in transition to the net zero emissions. The key messages of urban mitigation in the IPCC-AR6 are presented. It is found that the urban green and blue infrastructure can contribute to climate resilience through carbon sequestration, emissions reduction, and energy and material efficiency. It also contributes multiple co-benefits. To achieve urban transformational changes, it requires climate finance and engagement of multiple scales of governance. This includes governments and non-state actors. A knowledge gap to achieve net-zero-emissions cities is highlighted, and a case study of climate resilient development in Thailand’s building sectors towards a low carbon society is discussed.

Human-caused increases in organic carbon burial in plateau lakes: The response to warming effect

The patterns of organic carbon sequestration in lakes, along with their temporal dynamics, have profound implications for assessing the strength of terrestrial carbon sinks and the global carbon budget. The complexity of fluctuations in organic carbon burial in freshwater lake basins, along with the intricate interactions among various controlling factors over time, remains challenging to comprehend. By utilizing data on the organic carbon burial of sedimentary cores from twelve plateau lakes in a gradient of urbanization, this study employed a rigorous methodology to quantify the factors and origins that contribute to lacustrine carbon sequestration. The findings indicate that the rate of Total Organic Carbon (TOC) accumulation in lakes in highly urbanized areas has significantly surpassed that in areas with minimal urbanization since 1985. This trend of divergence has persisted for more than four decades. During the period from 1958 to 2008, soil nutrient characteristics (29.576 %) and human impact (16.684 %) were the major factors regulating the organic carbon burial in plateau lakes. Human pressures indirectly impact carbon sequestration through earth-surface processes in the lake basin, causing carbon burial to lag behind environmental indicators (e.g., δ13C and C/N) by approximately 5 years. Meanwhile, the carbon sequestration efficiency of plateau lakes shows a positive feedback to climatic warming with intensified urbanization, primarily regulated through the impacts on lake basin environments. The results will further enhance our understanding of the response of the lake ecosystem carbon cycle to anthropogenic influences.

Investigations on carbon-sequestration optimization of recycled coarse-aggregate and its effects on concrete performances

Recycled coarse-aggregate (RCA) derived from waste concrete can be re-used for concrete preparation, which is now limited due to its drawbacks such as micro-cracks, high-porosity, and reduced concrete strengths. To remedy these deficiencies, carbon-sequestration was employed to enhance RCA and the conditions were optimized, including the temperature (20 °C–40 °C), pressure (0.1 MPa–0.3 MPa), time (5 h–24 h) and initial water content (25%–75 %). There parameters were optimized based on the orthogonal test with scheme L9(34), which was evaluated based on RCA carbon-sequestration amount as well as its properties. With the optimized parameters, RCA was enhanced as CRCA. Both RCA and CRCA were utilized to fully replace natural coarse-aggregate (NCA) in concrete and concrete basic performances were investigated systematically, including strengths, shrinkage and medium transport properties. The results show that the effects of carbon-sequestration time and initial water-content of aggregate on the carbon-sequestration efficiency of RCA are the most significant. The optimized parameters were 30 °C temperature, 0.3 MPa pressure, 24 h time and 25 % initial water content with the maximum amount of carbon-sequestration at 8.42 %. The carbon-sequestration reduced the width of the recycled aggregate interfacial transition zone (ITZ) in concrete, increased the microhardness of ITZ and mortar, and decreased the porosity of CRCA. The CRCA elevated the compressive strength, splitting tensile strength and flexural strength of the concrete (28d) by 13.5 %, 8.5 % and 7.4 %, respectively. The drying shrinkage at 28d of RCA-concrete was decreased by 12.0 % when RCA was replaced with CRCA, however with the CRCA value still 16.2 % higher than that of NCA-concrete. Moreover, CRCA can decrease the medium transport coefficients of water, chloride, and gas in concrete when compared with the RCA-concrete while they are still greater than those of NCA-concrete.

Enhancing the Startup Rate of Microbial Methanogenic Systems through the Synergy of β-lactam Antibiotics and Electrolytic Cells.

The slow startup and suboptimal efficiency of microbial carbon sequestration and methane-production systems have not been fully resolved despite their contribution to sustainable energy production and the reduction of greenhouse gas emissions. These systems often grapple with persistent hurdles, including interference from miscellaneous bacteria and the slow enrichment of methanogens. To address these issues, this paper examines the synergistic effect of coupling β-lactam antibiotics with an electrolytic cell on the methanogenic process. The results indicated that β-lactam antibiotics exhibited inhibitory effects on Campylobacteria and Alphaproteobacteria (two types of miscellaneous bacteria), reducing their relative abundance by 53.03% and 87.78%, respectively. Nevertheless, it also resulted in a decrease in hydrogenogens and hindered the CO2 reduction pathway. When coupled with an electrolytic cell, sufficient electrons were supplied for CO2 reduction to compensate for the hydrogen deficiency, effectively mitigating the side effects of antibiotics. Consequently, a substantial improvement in methane production was observed, reaching 0.57 mL·L-1·d-1, exemplifying a remarkable 6.3-fold increase over the control group. This discovery reinforces the efficiency of methanogen enrichment and enhances methane-production levels.

Влияние микробиологических препаратов и внесения азота на процессы, связанные с секвестрацией органического углерода в чернозёме типичном слабоэродированном

Organic carbon sequestration is a present-day topical issue. The effect of a biological preparation based on Trichoderma viride and a biological preparation based on Pseudomonas aureofacieens, used to treat shredded by-products of crops before embedding them in the soil, and applied N10 kg PPN per 1 ton of by-products (N) was studied. The research was carried out in 2018–2020 in FSBSI “Kursk FARC” in a stationary field experiment with biopreparations (Kursk Region, Medvensky District, village of Panino) in a typical slightly eroded chernozem soil in a grain crop rotation link (spring barley – buckwheat – fodder beans). It was found that the use of biological preparations separately or together with N contributed to the soil sequestration of carbon in the topsoil, significant accumulation of humus carbon reserves was 2.2 and 2.4 times higher than that in the control, and the application of only N10 kg PPN with 1 ton of plant residues ensured the preservation of humus carbon reserves. Carbon reserves in the by-products, crop and root residues of the cultivated crops in the topsoil when using biological preparations were higher than those in the control. A direct high relationship was revealed between the average amount of carbon dioxide released from the soil during the vegetation of fodder beans and the amount of carbon from their by-products, crop and root residues entering the soil layers of 0–10 cm and 0–20 cm, correlation coefficients were 0.87 and 0.80. The efficiency of soil carbon sequestration in the topsoil when using biological preparations separately or together with nitrogen exceeded that of the control, respectively 2.0 and 2.1 times, and of shredded by-products with N10 PPN per 1 ton only 1.5 times.

Development and carbon accumulation dynamics of a minerotrophic fen during the last millennium, northeast China

Peatlands are terrestrial ecosystems with high carbon sequestration efficiency, providing critical feedback on climate change. It is crucial to understand how peatland development and carbon accumulation respond to various factors to reveal the future direction of carbon reservoirs under changing climatic conditions. To assess the impact of climate and hydrological conditions on the development and carbon accumulation of peatlands, 15 peat core samples were analyzed to examine the processes of lateral expansion in the Dongfanghong (DFH) peatland, a minerotrophic fen located in the Changbai Mountains of northeast China. Accelerator Mass Spectrometry 14C, total organic carbon, dry bulk density, testate amoebae, δ13C of α-cellulose in Carex spp. and plant macrofossil analyses were conducted on a high-resolution peat core. The proxies were used to calculate carbon accumulation rate (CAR) and reconstruct water table depth as well as surface moisture and vegetation development of the DFH peatland. Our findings indicated that the DFH peatland was initiated at 1011 cal. CE and experienced paludification during the last millennium. The expansion of the DFH peatland was primarily determined by hydrological conditions rather than climatic factors such as total solar irradiance and regional temperature. The rapid expansion between 1500 and 1700 cal. CE was likely resulted from relatively low precipitation and a decrease in water table/surface moisture. CAR generally correlated with total solar irradiance, regional temperature, and precipitation, suggesting that climate may be crucial for CAR in DFH peatlands over multi-centennial timescales. However, the increased CAR under relatively dry conditions suggested that the CAR were regulated by hydrological conditions over a centennial timescale. This study highlighted the important roles of climate and hydrological conditions in the lateral expansion and CAR of the peatland in minerotrophic fen and that there may be a threshold for hydrology during the process of peatland development and carbon accumulation.

The effect of carbonation pressure on microbial assisted steel slag-based carbon sequestration material

This study investigates the factors influencing the application of microbial-induced carbonate deposition in the in-situ mineral carbonation process. Carbon-negative building materials are achieved by using steel slag powder as a carbon sequestering cementitious material and employing bacteria producing carbonic anhydrase to enhance the fixation rate of carbon dioxide (CO2). The primary focus is on understanding how different CO2 pressures affect the performance and carbon sequestration efficiency of this process. Our findings reveal that microbial-assisted steel slag exhibits promising potential as an effective carbon sequestration material. Increasing carbonation pressure accelerates the mineralization reaction of steel slag, and the optimal carbonation efficiency has been achieved at a pressure of 0.3 MPa with a carbon sequestration efficiency of up to 16.65%. However, excessively high pressures, such as 0.4 MPa, lead to overly dense specimen surfaces, hindering internal carbonation and reducing specimen strength. The analysis from MIP (mercury intrusion porosimetry) and SEM (Scanning Electron Microscopy) confirms that the products formed by carbonation fill the pores with diameters around 1 μm and significantly increase the fractal dimensions of seepage pores and transition pores. Carbon emission and benefit analysis indicate that carbon-negative materials can be produced under optimal CO2 conditions. In conclusion, this study reveals the intricate relationship between carbonation pressure, sustainability, and efficiency in microbial-assisted in situ mineral carbonation processes.

Estimation of the ecological carbon sink potential of using urban underground Space: A case study in Chengdu City, China

Urban carbon sinks from plant photosynthesis in urban blue-green spaces (BGSs) effectively sequester CO2 and achieve carbon neutrality. Building urban facilities underground saves land for the development of urban BGSs. Development and utilization of urban underground space (UUS) is increasing rapidly in most advanced cities globally, many of which are located in China. This study combined the planting design strategy of urban BGS and the vegetation carbon sequestration efficiency estimation method to quantitatively assess the ecological carbon sink potential of the use of UUS. Three types of BGSs: partly open green space (GPO), closed green space (GC), and partly open blue space (BPO), were first constructed based on their practicability in the city, and a planting strategy was designed for urban BGSs accordingly. Secondly, a model for the conversion of UUS development intensity into surface space to achieve ecological carbon sinks under three scenarios of UUS development intensity (low, medium, and high intensity) was constructed. Thirdly, methods for the calculation of carbon sequestration by GPO, GC, and BPO, were established based on the land-use carbon emission model. The developed method was finally validated through a case study in the Tianfu New District Directly Administered Area of Chengdu in Sichuan Province, China. The results of the study in Chengdu show that the higher the intensity of the use of UUS, the greater the proportion of carbon sink contribution to the CO2 emissions of the building industry for the planned population, and a maximum of 7% of carbon emissions absorbed from the building industry for the planned population was achieved. These findings serve as a reference for assessing the use of UUS to achieve urban carbon neutrality in other cities.

Spatio-Temporal Relationship between Land Use Carbon Emissions and Ecosystem Service Value in Guanzhong, China

In the context of escalating global concerns for “carbon neutrality and peak carbon” and the urgent need for ecological conservation, deciphering the spatiotemporal interactions between carbon emissions and the ecosystem service value (ESV) in relation to land use changes becomes critically significant. Identifying areas to bolster ecosystem services and curtail carbon emissions, especially within the Guanzhong urban agglomeration, is crucial for advancing sustainable and low-carbon regional development. The study focuses on the urban agglomeration of Guanzhong, using land use and socio-economic data from three periods between 2010 and 2020. Methods such as grid analysis and bivariate spatial autocorrelation models are employed to explore the temporal and spatial evolution characteristics and interaction patterns of carbon emissions and ESV in relation to land use. The findings reveal: (1) during 2010–2020, the Guanzhong urban agglomeration experienced varied transitions in land use types, marked by a significant net decrease in arable land and net increases in grasslands and urban construction areas. (2) The ESV in the Guanzhong urban agglomeration witnessed a consistent rise, exhibiting a spatial distribution pattern with higher values in the southwest and lower in the northeast. Among the categorized ecosystem service functions, services related to hydrological and climate regulation stood out. (3) The Guanzhong urban agglomeration observed an average annual growth rate of 5.03% in carbon emissions due to land use, with a spatial trend that was higher in the center and tapered towards the periphery. Predominant carbon sources included arable lands and urban construction areas, while forests accounted for 94% of carbon sequestration. (4) A pronounced negative correlation between the ESV and carbon emissions was discerned in Guanzhong. Regions with a stronger correlation were primarily centered in Guanzhong, notably around Xi’an and Baoji. The results emphasize the pivotal role of the primary sector’s qualitative development in harmonizing the ESV and carbon emission dynamics in the Guanzhong urban agglomeration. This research provides valuable insights for optimizing land resource management, aligned with the rural revitalization strategy, streamlining carbon dynamics, bolstering ESV, augmenting carbon sequestration efficiency, and guiding ecological spatial planning.

Particulate organic carbon export fluxes across the Seychelles-Chagos thermocline ridge in the western Indian Ocean using 234Th as a tracer

We investigated the export flux of particulate organic carbon (POC) using 234Th as a tracer in the western Indian Ocean along 60°E and 67°E transects in 2017 and 2018. The Seychelles-Chagos Thermocline Ridge (SCTR), where production is relatively high due to nutrient replenishment by upwelling of subsurface water, was observed at 3°S – 12°S in 2017 and 4°S – 13°S both 60°E and 67°E in 2018. POC fluxes in 2017 showed no differences between the SCTR and non-SCTR regions. However, in 2018, the POC fluxes in the SCTR regions (8.52 ± 7.89 mmol C m–2 d–1) were one order of magnitude higher than those observed in the non-SCTR regions (0.63 ± 0.07 mmol C m–2 d–1), which appeared to be related to the strong upwelling of subsurface water. These POC fluxes were comparable to those observed under bloom conditions, and thus, are important for estimating the efficiency of carbon sequestration in the ocean.

Sustainable upcycling of artificial lightweight cold-bonded aggregates (ALCBAs) designed by biochar and concrete slurry waste (CSW) into porous carbons materials for CO2 sequestration

CSW (Concrete Slurry Waste) is a hazardous solid waste due to its high alkalinity, and traditional landfill disposal wastes a lot of land. To effectively recycle CSW, this project applied it, ordinary Portland cement (OPC), and Biochar (BC) into designing artificial lightweight cold-bonded aggregates (ALCBAs) by disc granulation. A new test device for evaluating the amount of carbon absorption in ALCBAs was designed and ALCBAs adding ultra-high volume of CSW (CSW-ALCBAs) with BC dosage of 0%, 5%, 10%, and 15% were designed, respectively. The compressive strength, water absorption rate, carbon-sequestration efficiency, pores, hydration phase, and ecological properties of CSW-ALCBAs were also investigated under standard, carbonation, and sealing curing conditions. The results showed that CSW-ALCBAs had obvious carbon-sequestration potential, and the maximum carbon absorption was 18.2 wt% at 15% BC dopsage and the minimum carbon absorption was 16.2 wt% at 5% BC doping. Also, the carbon absorption of CSW-ALCBAs increases with the rise in BC dosage. Besides, the compressive strength in standard and sealed curing conditions peaked at 5% BC dosage, about 2.76 MPa, and then decreased rapidly with increasing BC dosage, and the compressive strength drops to 1.86 MPa at 15% BC dosage. Carbonization condition can improve the mechnaical and physical properties of CSW-ALCBAs with water absorption rate in the range of 6%− 13%, and the maximum compressive strength was about 6.18 MPa. And the compressive strength with the lowest and highest increasing rate in the groups under 28-d carbonized condition were in groups B5 and B10, where the compressive strength increased by 56% and 215%, respectively. Additionally, the total porosity of CSW-ALCBAs is in 13%− 23%, and the BC can provide abundant harmless pores (<50 nm) and store sufficient water. The BC could result in the internal curing effect, and the hydration products such as CH, CC, C-S-H, and AFt could be clearly observed. The choice of 5% BC doping for developing green CSW-ALCBAs is very promising. Overall, this study provides a novel method for the production of carbon-negative aggregates, which not only helps to address the recycling of massive CSW, but also opens up new channels for CSW recycling and CO2 sequestration. Meanwhile, compared with the previous reports about the recycling of CSW has been explored in various ways of utilization and curing regimes, this project explores its potential for carbon capture and investigates the changes in various properties of CSW-ALCBAs after carbonization.

Accelerated integrated watershed management enhances agricultural carbon sequestration and water use efficiency in an endorheic basin

With the continuous promotion of integrated river basin management (IRBM) in endorheic watersheds, the oasis surface processes have undergone significant changes. However, these underlying surface characteristics have not been well integrated into models for simulating carbon-water flux thus far. In this work, a regional SWAT-TECO model was constructed by coupling the modified TECO simulator with irrigation, film mulching, and soil hydraulic redistribution processes within the SWAT framework. The results indicated that the carbon sequestration and water use efficiency (WUE) showed an increasing trend after IRBM implementation in Heihe endorheic basin. WUE was projected to improve under future climate change and can be further enhanced by a maximum of 6.37 % through improving irrigation water use efficiency by 20 %, maintaining existing planting scale, increasing film mulching by 20 %, and reducing fertilizer application by 10 %. These findings can guide the formulation of high-water efficiency agricultural management strategies in global endorheic basins.

An intellectual gap in root research on major crops of the Canadian Prairies

Prairie cropping systems face several challenges, including high input costs and climate change. Research to address these challenges has focused on above-ground agronomic parameters while completely ignoring the role roots play below ground. The objectives of this review study are to (i) synthesize past root studies carried out in the Canadian Prairies, (ii) provide a context for prairie root research, and (iii) identify gaps for future research. This review reports that root architectural traits of major crops have been assessed under field and greenhouse conditions in soil, artificial media, and a mixture of both soil and media, mostly under natural/well-watered and drought conditions. Several root traits have been compared for major crops grown with respect to moisture levels and nutrient uptake. A dearth of research exists on the complex relationship between root traits, soil microbiome, nutrient uptake, carbon sequestration, and photosynthetic efficiency. No studies were found relating root traits, fertilizer placement, and nitrogen and water use efficiencies, carbon sequestration, soil microbiome dynamics, and common root diseases. This review also reports that more research and funding are needed to exploit the benefits that root research will bring to further sustainability goals and ensure food security in the Canadian Prairies.

Temporal and Spatial Changes and Trend Predictions of Forest Carbon Sequestration Efficiency in China Based on the Carbon Neutrality Goal

Forestry’s high-quality development is crucial for China’s sustainable ecological, economic, and social progress. To elevate the efficiency of carbon sequestration in forestry, continuously improve the increment of carbon sinks, and contribute to achieving carbon neutrality, it is crucial to accurately assess the level of carbon sequestration efficiency in China’s forestry and explore its long-term evolution trend. In this paper, a super-efficiency SBM model, which combines the SBM model with the super-efficiency method and considers the relaxation variables, was selected to evaluate the forestry carbon sequestration efficiency of 31 provinces in China; likewise, the temporal development features of the efficacy of Chinese forests in sequestering carbon were examined using the nuclear density estimation method. Secondly, the study constructed traditional and spatial Markov probability transfer matrices to further explore the spatiotemporal evolution of carbon sequestration efficiency within Chinese forestry. Finally, combined with the Markov chain infinite distribution matrix, the future trajectory of carbon sequestration efficiency in China’s forestry was scientifically forecasted. The findings indicate that: (1) The average carbon sequestration efficiency of forestry in China showed a stable increase with fluctuations and reached the optimal state in 2018. The carbon sequestration efficiency level of various forest regions was always portrayed as southwest forest region &gt; southern forest region &gt; northeast forest region &gt; northern forest region. From 2003 to 2018, there were significant differences in forestry carbon sequestration efficiency among provinces. The distribution of forestry carbon sequestration efficiency exhibited a “three-pillar” distribution pattern with Xizang, Zhejiang, and Heilongjiang as the core, and the marginal regions continuously promoted the carbon sequestration efficiency to the inland. (2) The type of transfer of forestry carbon sequestration efficiency in China is stable, and it is difficult to achieve cross-stage transfer in the short term. Moreover, the forestry carbon sequestration efficiency of each province tended to converge to a high (low) level over time, showing a “bimodal distribution” of low efficiency and high efficiency, indicating the existence of the obvious “club convergence phenomenon”. (3) Forecasting from a long-term evolution trend perspective, the outlook for the future evolution of forestry carbon sequestration efficiency in China is optimistic, and the overall trend was concentrated in the high-value area. Therefore, future forestry development in China should contemplate both internal structure optimization and coordinated regional development. Attention should be placed on forestry carbon sequestration’s role while considering the distinctive endowments of each region and developing reasonable, differentiated, and collaborative forestry management strategies.

Research progress on biomass ash carbon capture and storage

Carbon capture and storage (CCS) technology is an important way to slow down the continuous increase in atmospheric CO2 concentration and to achieve the dual carbon target. Carbon capture and storage through biomass ash is a secure, permanent, and environment friendly way. To better understand the characteristics of biomass ash carbon capture and storage, we summarized progresses on biomass ash carbon capture and storage, clarified the mechanisms of biomass ash carbon sequestration, analyzed the influencing factors, and explored its applications in various domains. The capacity of CCS by biomass ash mainly derived from alkaline earth metal oxides of CaO and MgO. The actual carbon sequestration efficiency is affected by factors such as biomass source, chemical composition, temperature, humidity, pressure, and CO2 concentration. However, the underlying mechanism is unclear. The CCS capacity of biomass ash significantly impacts its potential applications in building materials reuse, soil quality improvement, and adsorbents carbon capture and storage absorbent preparation. Long-term research is critically needed. For future studies, we should strengthen the research on the carbonization efficiency of biomass ash from multiple sources, establish a database related to the impact of biomass ash carbonization, build a methodological system to promote scientific management of biomass ash, develop biomass ash carbon capture and storage technologies, and quantitatively assess its role in carbon sequestration.

The Effect of Long-Term Farmyard Manure and Mineral Fertilizer Application on the Increase in Soil Organic Matter Quality of Cambisols

Soil organic matter (SOM) quantity and quality are important factors that significantly influence soil fertility. SOM quality indicators change throughout time. In this study, long—term field experiments (22–50 years in duration) on a Cambisol at four sites in the Czech Republic were selected. Seven crops were successively rotated in the sequence: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were investigated, including an unfertilized treatment, farmyard manure, and various combinations of farmyard manure and mineral fertilization. A total of 40 t ha−1 of farmyard manure was applied to the early potato and potato crops. Combining organic and mineral fertilizers increased soil organic matter quality and quantity over unfertilized or organic only treatment. The highest intensity of mineral fertilizers in our trials elevated the mean of carbon sequestration efficiency to 45.6% in comparison to pure manure treatment which reached only 22.9% efficiency. A strong correlation was established between the total glomalin content and soil organic matter carbon, fulvic acid, humic acid, carbon hot water extraction, potential wettability index (PWI), and aromaticity index. The PWI was also strongly correlated with these indicators. The E4/E6 ratio indicator was shown to be a much less sensitive method for reflecting the change in soil organic matter quality.

Inhibition mechanism and biological recycling utilization of microalgae culture aging solution

During the process of recovering microalgae culture media, the culture media will age and inhibit the growth of microalgae. When the culture media was reused for the third time, the maximum biomass of Spirulina platensis FACHB-439 was only 56.13% of the fresh culture media. But the inhibitors in the aging solution are not known. In this study, the growth inhibition mechanism of Spirulina platensis aging solution was clarified through the identification of target organic matter by cyclic culture experiment and ion chromatography. The results showed that the growth inhibitors in the aging solution were polysaccharides, mainly including fucose and rhamnose. Further reverse addition experiments confirmed that polysaccharide inhibitors would increase with the increase of repeated use of the culture media. By inhibiting the synthesis of photosynthetic pigments in microalgae, they could cause oxidative damage and membrane peroxidation of microalgae cells, resulting in stress on the growth of microalgae. At the same time, this study established a purification method for reusing aging solution of heterologous microalgae (Chlorella sp. L166) to obtain high lipid and high carbohydrate biomass energy. The results showed that the biomass of Chlorella sp. L166 in the first circulating aging solution of S.platensis FACHB-439 increased by 25%, the carbon utilization rate reached 21.36%, the lipid content per cell increased by 1.61 times, and the carbohydrate content increased by 86.71%. This work is helpful to solve the problem that aging of culture media inhibits carbon sequestration efficiency and biomass yield of microalgae in large-scale production of microalgae. And the results of this study have achieved high utilization rate of water resource for large-scale cultivation of microalgae, which is conducive to realize the scale development of microalgae biotechnology.

Physical Mechanisms Driving Enhanced Carbon Sequestration by the Biological Pump Under Climate Warming

AbstractAs ocean Carbon Dioxide Removal techniques are being considered, it is critical that they be evaluated against our scientific understanding of the global biological carbon pump. In a recent paper Nowicki et al. (2022, https://doi.org/10.1029/2021GB007083) provide an innovative and comprehensive breakdown of the different mechanistic pathways of carbon sequestration through the present‐day biological pump but then speculate that “These results suggest that ocean carbon storage will weaken as the oceans stratify and the subtropical gyres expand due to anthropogenic climate change.” Essentially, the authors combine their steady state result that oligotrophic subtropical gyres have lower residence times than other areas with the climate change result of these areas increasing under climate warming and extrapolate—assuming “all else is equal”—that the overall ocean will suffer a reduction in carbon sequestration efficiency. Expressing global changes in carbon sequestered by the ocean's biological pump as the summation of local changes in the sequestered carbon, timescale of return to the surface, and biogeographical area, I discuss how all three terms are tightly coupled, and summarize decades of climate change modeling consistently indicating that the global scale physical sequestration response is an increase ‐ in opposition of what one would infer from changes in subtropical area alone.

Farmland Carbon and Water Exchange and Its Response to Environmental Factors in Arid Northwest China

Carbon neutrality is an important target in China’s efforts to combat the climate crisis. The implementation of carbon neutrality requires high crop yields in farmland ecosystems of arid regions. However, the responses of farmland ecosystems to environmental changes and their effects on the conversion and intensity of carbon sources/sinks within farmlands in arid regions remain unclear, which limits carbon sequestration. In this study, we used a set of eddy covariance systems to observe carbon and water fluxes in cotton and spring maize, two typical crops in arid regions of Northern Xinjiang in China. The carbon and water exchange and water use efficiency (WUE) of cotton and spring maize were evaluated over the entire growth cycle with respect to changes in the environment. Our results show that the carbon sequestration capacity of farmland ecosystems in arid regions is undeniable and is strongly influenced by the growth and development of plants. Spring maize, as a representative of C4 plants, exhibited a 58.4% higher carbon sequestration efficiency than cotton, a C3 plant, and they both reached their carbon sequestration efficiency peak in July. Throughout the growth period, temperature, net surface radiation, and saturated vapor pressure differences (VPD) significantly affected the carbon sequestration capacity and WUE of both crops. Optimal temperatures can maximize the carbon sequestration efficiency of cotton and spring maize; for cotton, they are 20–25 °C, and for spring maize, they are 22–27 °C, respectively. In addition, it is recommended that spring maize be harvested at the end of July when it meets the harvesting standards for silage feed and achieves the maximum carbon sequestration. Afterward, winter crops should be planted to maximize the yield and improve the carbon sequestration capacity of farmlands.

Long-Term Application of Manure and Different Mineral Fertilization in Relation to the Soil Organic Matter Quality of Luvisols

Long-term field experiments were conducted on luvisol at five sites in the Czech Republic (42–48-year duration). The average total organic carbon content in the soil varied between 9.0 and 14.0 g kg−1. In these trials, seven crops were rotated in the following order: clover, winter wheat, early potato, winter wheat, spring barley, potato, and spring barley with interseeded clover. Five treatments were studied: unfertilized treatment (Con), farmyard manure (F), and combinations of farmyard manure with three mineral fertilization levels (F+M1, F+M2, F+M3). Plant residues were not incorporated into the soil. An amount of 40 t ha−1 of farmyard manure fresh matter was applied twice during crop rotation. Intensive mineral fertilizer (F+M3) increased the average value of the carbon sequestration efficiency (CSE) by 12.9% and up to 26.3%. Combining organic and mineral fertilizers at moderate and higher intensities increased the soil organic matter quantity and quality compared to the unfertilized or manure treatment. Data on the glomalin content can be used to study the organic matter quality. We determined a strong correlation between the total glomalin content and the soil organic matter carbon, fulvic acid content, humic acid content, extractable carbon content, and dissolved organic carbon content, as well as the potential wettability index and aromaticity index.