Carbon uptake by cement in China:Estimation and contribution to carbon neutrality goals

Cement is a widely used construction material globally.Its manufacturing contributes to anthropogenic CO_(2)emissions significantly.However,its alkaline compounds can absorb CO_(2)from the surrounding environment and engage in a carbonation reaction,thereby functioning as a carbon sink.As a major cement producer and consumer,China has an important responsibility to rigorously investigate and accurately account for cement carbon uptake.This study presents a comprehensive analytical model of cement carbon uptake from China,revealing a substantial increase in carbon uptake from 1930 to 2021,peaking at 426.77 Mt CO_(2)(95% Confidence Interval:317.67-874.33 Mt CO_(2))in 2021.The uptake accounts for 8.10% to 45.40% of China’s annual land sink and 2.51% to 4.54% of the global land sink.The cumulative carbon uptake by cement is approximately 7.06 Gt CO_(2)(95%CI:5.22–9.44 Gt CO_(2))during this period,offsetting 50.7% of the total emissions(13.91 Gt CO_(2),95%CI:12.44–17.00 Gt CO_(2))from the cement industry.Notably,cement mortar contributed to most absorption(65.64%).From a life cycle perspective,the service stage of cement materials is the period where the largest CO_(2)sink is formed,accounting for 90.03% of the total.Therefore,the potential for carbon sequestration in cement materials and their waste is enormous.Additionally,the model improves the accuracy of cement carbon accounting,supporting both China and global carbon neutrality assessments.Thus,it is crucial for China to achieve its carbon neutrality goals sooner by prioritizing the environmental benefits of cement materials and wastes,and accelerating the development and commercialization of CO_(2)sequestration technologies for cement and its by-products.

Substantial global carbon uptake by cement carbonation

Subject Code:D03With the support by the National Natural Science Foundation of China and the Chinese Academy of Sciences,the research team led by Prof.Xi Fengming(郗凤明)at the Institute of Applied Ecology,Chinese Academy of Sciences(IAE CAS),uncovered the global carbon uptake by cement materials,which was published in Nature Geoscience(2016,9:880—883).Until recent research,cement material was widely considered as an import carbon source.

Overexpression of IbSnRK1 enhances nitrogen uptake and carbon assimilation in transgenic sweetpotato

Nitrogen is an important nutrient for plant development. Nitrogen and carbon metabolisms are tightly linked to physiological functions in plants. In this study, we found that the IbSnRK1 gene was induced by Ca（NO3）2. Its overexpression enhanced nitrogen uptake and carbon assimilation in transgenic sweetpotato. After Ca（^15NO3）2 treatment, the -（15）N atom excess, -（15）N and total N content and nitrogen uptake efficiency（NUE） were significantly increased in the roots, stems, and leaves of transgenic plants compared with wild type（WT） and empty vector control（VC）. After Ca（NO3）2 treatment, the increased nitrate N content, nitrate reductase（NR） activity, free amino acid content, and soluble protein content were found in the roots or leaves of transgenic plants. The photosynthesis and carbon assimilation were enhanced. These results suggest that the IbSnRK1 gene play a important role in nitrogen uptake and carbon assimilation of sweetpotato. This gene has the potential to be used for improving the yield and quality of sweetpotato.

Carbon fluxes and species diversity in grazed and fenced typical steppe grassland of Inner Mongolia, China

Aim Grasslands are dominant vegetation of China,support outstanding biodiversity and sequester bulk amount of atmospheric CO_(2).These grasslands are highly degraded and fragmented due to remarkable anthropogenic and grazing loads.Chinese Government has made great attempt to restore by grazing exclusion.The relations of carbon fluxes with species composition and diversity in the communities sensitive to grazing by large herbivores are needed to be analysed under the global climate change scenario.The objective of present study was to comprehend the effects of grazing and fencing on the ecosystem structure and function of the typical steppe grassland.Methods To meet the objectives,overgrazed and fenced(since year 2001)sys-tems were selected in typical steppe grassland at the Duolun Restoration Ecology Research Station,Inner Mogolia,China.Within each system,three dominant communities with three replicates were selected.In each replicate community,three 1×1 m plots,were randomly located.Each plot was divided into four 50×50 cm quadrats.A total of 216,50×50 cm quadrats were sampled.From each quadrat,number of individuals and above-ground herbaceous biomass for each species,soil respiration(SR),ecosystem respira-tion(ER),net(NEE)as well as gross(GEE)ecosystem CO_(2) exchanges were recorded in June 2015.Data were well analysed using statistical software.Canonical correspondence analysis showed dif-ferential responses of communities to the structure and function of the typical steppe grassland.Important Findings Across the communities,fencing reduced the soil tempera-ture by 12%and at the same time increased the soil moisture by 44.30%,thus,increased the species richness by 28%,evenness by 21%,above-ground biomass by 19%and plant carbon by 20%.Interestingly,fencing increased NEE by 128%,GEE by 77%,SR by 65%and ER by 39%.Under fencing,species composition partially governed the CO_(2) exchange processes.Conclusions Fencing reduces soil temperature and thereby improves species diversity and more efficient CO_(2) sequestration and long-term and in-depth study is desirable for a better understanding of the relation-ship between species diversity and ecosystem carbon uptake.

Carbon footprint of crop production in Heilongjiang land reclamation area,China

In the context of global warming,agriculture,as the second-largest source of greenhouse gas emissions after industry,had attracted widespread attention from all walks of life to reduce agricultural emissions.The carbon footprint of the planting production system of the Heilongjiang Land Reclamation Area(HLRA),an important commodity grain base in China,was evaluated and analyzed in this paper.On this basis,this paper sought feasible strategies to reduce carbon emissions from two aspects:agronomic practices and cropping structure adjustment,which were particularly crucial to promote the low-carbon and sustainable development of agriculture in HLRA.Therefore,using the accounting methods in IPCC and Low Carbon Development and Guidelines for the Preparation of Provincial Greenhouse Gas Inventories compiled by the Chinese government,relevant data were collected from 2000 to 2017 in HLRA and accounted for the carbon emissions of the planting production system in four aspects:carbon emissions from agricultural inputs,N_(2)O emissions from managed soils,CH_(4) emissions from rice cultivation and straw burning emissions.Then carbon uptake consisted of seeds and straws.Finally,with farmers'incomes were set as the objective function and carbon emissions per unit of gross production value was set as the constraint,this paper simulated and optimized the cropping structure in HLRA.The results showed that there was a“stable-growing-declining”trend in the total carbon emissions and carbon uptake of the planting production system in HLRA,with total carbon emissions of 2.84×10^(10) kg and total carbon uptake of 7.49×10^(10) kg in 2017.In the past 18 years,carbon emissions per unit area and carbon emissions per unit of gross production had both shown a decreasing trend.To achieve further efficiency gains and emission reductions in the planting production system,it was recommended that the local governments strengthen the comprehensive use of straw resources,optimize irrigation and fertilization techniques,and adjust the cropping structure,i.e.,increase the planting area of maize and soybeans and reduce the planting area of rice,and increase subsidies to protect the economic returns of planters.