Sink Enhancement Research Articles

Bedrock regulated climatic controls on the interannual variation of land sink in South-West China karst through soil water availability

South-West China (SWC) is a pivotal region for global greening, recognized as having great carbon sink potential. Multiple evidence underscores the expanding contribution of SWC’s carbon sink to the global carbon sink enhancement. However, our understanding of carbon sink dynamics and the response to climate across bedrock remains limited. In this study, we investigated the divergence in trends in carbon sink across bedrocks, evaluating their respective contributions of bedrocks to the overall carbon sink in SWC. Additionally, we assessed the dominant climatic factors and examined how bedrocks shape the response of carbon sink to climate change. Our results revealed a notable increase in the regional carbon sink, with an average rate of 3.58 TgC/yr from 1981 to 2019. Continuous Carbonate Rocks (CCR) exhibited the highest increased rate of total carbon sequestration (1.57 TgC/yr), surpassing Discontinuous Carbonate Rocks (DCR) by threefold. Non-karst areas contributed the most to both the mean and interannual variations of the overall carbon sink, with CCR exerting the most contribution to the trends. Over time, the contribution of CCR to the overall carbon sink escalated, while the contributions of DCR and non-karst declined. All bedrocks displayed negative correlations between NEP and temperature, with DCR showing higher susceptibility. Non-karst areas experienced adverse impacts from vapor pressure deficit, while CCR benefited from positive soil moisture effects. Our findings implied that bedrock indeed played a critical role in the variations in NEP and the response of NEP to climate change. Bedrock regulated climatic controls on carbon sink through soil water availability as soil water availability is affected by the lithology of basement carbonate. This novel understanding emphasizes the necessity for tailored ecological restoration initiatives that consider the distinctive lithological features of the karst ecosystem, and holds significance for implementing ecologically sound projects in karst regions.

Calixarene-Capped Platinum Nanofluid for Pseudohomogeneous Catalytic Cracking and Heat Sink Enhancement of Ethylcyclohexane

Calixarene-Capped Platinum Nanofluid for Pseudohomogeneous Catalytic Cracking and Heat Sink Enhancement of Ethylcyclohexane

Synchronized slowdown of climate warming and carbon sink enhancement over deciduous broadleaf forests based on FLUXNET analysis

The temperate deciduous broadleaf forests (DBFs) are widely distributed in middle and high latitudes and play vital role in providing ecosystem services and mitigating human induced climate change, however, the responses of the carbon sink of DBFs to recent warming slowdown were not well known at regional scale. Here, we investigated the temporal pattern of carbon sink in DBFs and its drivers based on the eddy covariance carbon flux observations at 15 FLUXNET sites from 1997 to 2014. The annual mean net ecosystem production (NEP) was 272 ± 43 g C m−2 yr−1 during 1997–2005 and it increased to 445 ± 13 g C m−2 yr−1 during 2006–2014, as a result of boosted gross primary production (GPP) and weakened ecosystem respiration, respectively. We found slowdown in trends of temperature and carbon sink enhancement during 2006–2014. The NEP decreased at the rate of −11.9 g C m−2 yr−1 during the warming slowdown period (2006–2014, p < 0.05) compared to a prior strong increased trend during the warming period (1997–2005, 47.6 g C m−2 yr−1, p < 0.05). The mean annual temperature dominated the inter-annual variation of NEP (46.9 %), and it worked together with seasonal water availability to control the NEP changes. The slowdown of peak photosynthesis growth rate and carbon uptake period (CUP) extension may contribute to the NEP reversal during the later period. Our results demonstrated that the carbon uptake potential of temperate DBFs may highly depend on warming trends.

Study the Effect of Silicon Nanofluid on the Heat Transfer Enhancement of Triangular-Shaped Open Microchannel Heat Sinks

Study the Effect of Silicon Nanofluid on the Heat Transfer Enhancement of Triangular-Shaped Open Microchannel Heat Sinks

A review of applied research on low-carbon urban design: based on scientific knowledge mapping.

The construction of low-carbon cities is an essential component of sustainable urban development. However, there is a lack of a comprehensive low-carbon city design and evaluation system that incorporates "carbon sink accounting-remote sensing monitoring-numerical modelling-design and application" in an all-around linkage, multi-scale coupling, and localized effects. This paper utilizes the Citespace tool to evaluate low-carbon city design applications by analyzing literature in the Web of Science (WOS) core collection database. The results reveal that low-carbon cities undergo four stages: "measurement-implementation-regulation - management." The research themes are divided into three core clustering evolutionary pathways: "extension of carbon sink functions," "spatialisation of carbon sink systems," and "full-cycle, full-dimensional decarbonisation." Applications include "Utility studies of multi-scale carbon sink assessments," "Correlation analysis of carbon sink influencing factors," "Predictive characterisation of multiple planning scenarios," and "Spatial planning applications of urban sink enhancement." Future low-carbon city construction should incorporate intelligent algorithm technology in real-time to provide a strong design basis for multi-scale urban spatial design with the features of "high-precision accounting, full-cycle assessment and low-energy concept."

Phosphate in Aqueous Solution Adsorbs on Limestone Surfaces and Promotes Dissolution

The use of large quantities of phosphorus-containing fertilizers has resulted in an increase in phosphorus content in the groundwater system, and phosphorus can be adsorbed on the surface of carbonate rocks, affecting their dissolution process and thus carbon sequestration and sink enhancement in carbonate rocks. Therefore, in this study, limestone was exposed to 2 mg/L and 100 mg/L phosphate solutions for 12 d through static batch adsorption experiments. The hydrochemical results showed that in 100 mg/L phosphate solution, a substitution reaction occurred to produce CaHPO4 precipitate, while the concentration of each ion in 2 mg/L phosphate solution was relatively stable and in dynamic equilibrium; combined with XRD and XPS analyses, the main mechanism of phosphate adsorption may be chemical precipitation, which is preferentially adsorbed to Ca sites on carbonate rocks, and the surface deposits are mainly CaHPO4 and a small amount of Mg2PO4(OH). The FTIR spectra were obtained in the range of 1040 cm−1–1103 cm−1 for observed phosphate vibrations, and the υ3 (asymmetric stretching) mode was more significant in the experimental group with a higher phosphate concentration. Raman spectra located near 149 cm−1 and 275 cm−1 involved Ca2+ or Mg2+ relative translations and vibrations, corroborating the FTIR spectroscopic results; a combination of XRD, XPS, FTIR, and Raman spectra confirmed that phosphate adsorption on limestone may be due to the interaction of electrostatic, chemical precipitation, and ligand exchange mechanisms. In addition, the SEM-EDS results showed that, with the combined effect of the water–rock chemical reaction and physical adsorption, metal–phosphorus phase precipitation was formed on the limestone surface, which promoted the dissolution of limestone and may have an unfavorable effect on the carbon sequestration and sinking of carbonate rocks.

Thermal performance of dual flow slotted fin mini channel heat sink using Al2O3-H2O and TiO2-H2O: a numerical and experimental approach

To overcome the extensive heat generation inside the microprocessors nanofluids have gained importance because of their better thermophysical properties as compared with air and water. This work proposes a two-pronged strategy for thermal performance enhancement of mini channel heat sinks. Firstly, a novel dual flow slotted fin mini channel heat sink flow configuration is proposed. Secondly, a detailed numerical investigation is performed to assess heat transfer enhancement property of Al2O3-H2O and TiO2-H2O nanofluids. Considering the first step, fin spacing, number of slots, slot thickness and slot angle are investigated in detail yielding to the selection of best structural parameters. Two slots per fin of 0.5 mm thickness at an angle of 45° is selected because it provides better thermal performance as compared with water. Further, numerical assessment of nano fluid behavior was carried out at volumetric concentrations of 0.005% and 0.01%. For the case of novel dual flow slotted fin mini channel heat sink, maximum numerical and experimental advantages in all targeted system properties is observed for Al2O3-H2O nano fluid at volumetric concentration of 0.01%, as compared with water. Al2O3-H2O nano fluid provides better thermal performance both numerically and experimentally as compared with TiO2-H2O nanofluids. Increment in the pressure drop is noted with increasing volumetric concentrations.

Relationship between carbon stock and the structure of coniferous and broad-leaved mixed forest in Tianmu Mountains, China.

Taking the coniferous and broad-leaved mixed forest of Tianmu Mountain National Nature Reserve in Zhejiang Province as research object, we divided the tree species into three pairs, including evergreen and deci-duous species, broad-leaved and coniferous species, dominant and non-dominant species, to compare the difference of the individual tree carbon stock of each pair and analyze the diameter distribution pattern and tree height distribution pattern of carbon stocks. The relationship between spatial structure and individual tree carbon stock was analyzed by using spatial structure indicators including V_Hegyi competition index, complete mingling and aggregation index, to reveal the relationship between the structure of coniferous and broad-leaved forests and carbon stocks, and provide a theoretical basis for management of forest carbon sequestration. The results showed that the average individual carbon stock for evergreen and deciduous species, broad-leaved and coniferous species, dominant and non-dominant species were 57.7 and 87.4 kg, 54.6 and 74.7 kg, 67.4 and 48.1 kg, respectively. The individual tree carbon stock of evergreen species was significantly lower than that of deciduous species, the individual tree carbon stock of broad-leaved species was significantly lower than that of coniferous species, and the individual tree carbon stock of dominant tree species was significantly higher than that of non-dominant tree species. The diameter distribution and height distribution of carbon stock of each species group obeyed normal distribution. The V_Hegyi competition index was significantly negatively correlated with individual tree carbon stock, and it was consistent with the power function distribution. Both complete mingling and aggregation index were linearly and positively correlated with individual tree carbon stock. The direction of influence of different spatial structures on the individual tree carbon stock was consistent. The structure of coniferous and broad-leaved mixed forest had a significant impact on individual tree carbon stock. In the management of forest carbon sequestration and sink enhancement, it is necessary to regulate the unreasonable forest structure and promote its succession to the climax community in order to improve forest carbon stock.

Exploring the correlation between waterbodies, green space morphology, and carbon dioxide concentration distributions in an urban waterfront green space: A simulation study based on the carbon cycle

Urban ecological spatial patterns affect the carbon sequestration capacity of green spaces. High-resolution carbon concentration data simulated by Envi-met4.4.5 were obtained in Nanyuan Riverside Green space in Huangpu District, Shanghai. And the correlation among green space morphology factors, microclimatic and bioclimatic factors were explored by Random Forest model. The results showed that the importance of the waterfront distance factor to the carbon sink impact reaches 28.88%, and gradually decreased with the change of distance from water from south to north. The importance of the arboreal area ratio and green biomass reached 15.79% and 12.65% respectively, which was much more important than non-green vegetation space proportion indices. The importance of Cohesion reflecting green patches connectivity was 10.33%. In terms of the internal influencing microclimate factors of green space carbon cycle, relative humidity, air temperature and wind speed, had a more significant influence, with the importance degree of influence being 33.50, 29.02 and 10.29%, respectively. Compared with the influence effect between the factors of the bioclimate, the index of photosynthetically active radiation was greater than the influence of the vapor flux. The study provides a reasonable explanation for the theoretical of coupling carbon sink enhancement of hydrological and green spatial factors.

Recent progress and emerging strategies for carbon peak and carbon neutrality in China

AbstractAs the global climate crisis intensifies, ecosystems, human society and economic activities are significantly affected. Countries around the world have successively put forward the goal of carbon neutrality or zero carbon. At the 75th session of the United Nations General Assembly, the Chinese government explicitly proposed making efforts to reach the goal of Carbon Peak (peak of carbon emissions before 2030) and Carbon Neutrality (Dual Carbon) (carbon neutrality before 2060). In October 2021, the CPC Central Committee and the State Council issued the “Opinions on Fully, Accurately and Comprehensively Implementing the New Development Concepts to Achieve Carbon Peak and Carbon Neutrality” and the Action Plan for Achieving Carbon Peak before 2030, specifying the targets and tasks related to achieving carbon peak and carbon neutrality in China. As the world's largest developing country, the world's largest manufacturer, and a country with the most complete industrial categories, China will face multiple challenges such as climate change, economic transition, and environmental protection, which requires systematic support from policy, economy, technology, and society. How to achieve the goal will be a great challenge to China's sustainable development. The academic community has conducted extensive exploration on the realization of China's carbon peak and carbon neutrality in many fields, such as energy transformation, industrial structure upgrading, transportation carbon reduction, urban planning and construction, carbon sink enhancement, low‐carbon technologies, green finance, and supporting policies. Among them, policy planning and technological innovation are the most important to achieve the goal of carbon peak and carbon neutrality. Second, industrial adjustment and enterprise implementation are also important. Therefore, this review will focus on the development status and prospects of policy support, technological innovation, industrial adjustment, and enterprise implementation for achieving dual carbon goals in China. © 2023 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Enhancing Forest Canopy Height Retrieval: Insights from Integrated GEDI and Landsat Data Analysis

Canopy height is a crucial indicator for assessing the structure and function of the forest ecosystems. It plays a significant role in carbon sequestration, sink enhancement, and promoting green development. This study aimed to evaluate the accuracy of GEDI L2A version 2 data in estimating ground elevation and canopy height by comparing it with airborne laser scanning (ALS) data. Among the six algorithms provided by the GEDI L2A data, algorithm a2 demonstrated higher accuracy than the others in detecting ground elevation and canopy height. Additionally, a relatively strong correlation (R-squared = 0.35) was observed between rh95 for GEDI L2A and RH90 for ALS. To enhance the accuracy of canopy height estimation, this study proposed three backpropagation (BP) neural network inversion models based on GEDI, Landsat 8 OLI, and Landsat 9 OLI-2 data. Multiple sets of relative heights and vegetation indices were extracted from the GEDI and Landsat datasets. The random forest (RF) algorithm was employed to select feature variables with a cumulative importance score of 90% for training the BP neural network inversion models. Validation against RH90 of ALS revealed that the GEDI model outperformed the OLI or OLI-2 data models in terms of accuracy. Moreover, the quality improvement of OLI-2 data relative to OLI data contributed to enhanced inversion accuracy. Overall, the models based on a single dataset exhibited relatively low accuracy. Hence, this study proposed the GEDI and OLI and GEDI and OLI-2 models, which combine the two types of data. The results demonstrated that the combined model integrating GEDI and OLI-2 data exhibited the highest performance. Compared to the weakest OLI data model, the inversion accuracy R-squared improved from 0.38 to 0.74, and the MAE, RMSE, and rRMSE decreased by 1.21 m, 1.81 m, and 8.09%, respectively. These findings offer valuable insights for the remote sensing monitoring of forest sustainability.

Responses of carbon exchange characteristics to meteorological factors, phenology, and extreme events in a rubber plantation of Danzhou, Hainan: evidence based on multi-year data

IntroductionOn Hainan Island, a rubber plantation that occupies a large swath of land plays an important role in the regional carbon budget. However, the carbon exchange of the rubber plantation is poorly understood.MethodsIn this study, using the eddy covariance methods we measured carbon metrics in the rubber plantation for 13 years from 2010 to 2022.ResultsWe clarified that the rubber plantation is a carbon sink and the annual net ecosystem exchange (NEE), ecosystem respiration, and gross primary production were −911.89 ± 135.37, 1,528.04 ± 253.50, and 2,439.93 ± 259.63 gC·m−2·a−1, respectively. Carbon fluxes differed between interannual years; specifically, rainy season fluxes were nearly double dry season fluxes. Radiation explained 46% of the variation for NEE in rainy season, and temperature explained 36% of the variation for NEE in the dry season. LAI explained the highest proportion of the monthly variation in NEE (R2 = 0.72, p &amp;lt; 0.001), indicating that when hydrothermal conditions are sufficient phenology may be the primary factor controlling carbon sequestration of rubber plantation. Due to climate change, there is an increasing probability of extreme climate events, such as typhoons, heat waves, and drought. Thus, we compared NEE before and after such events and results show extreme climate events reduce carbon uptake in the rubber plantation. We found that typhoons reduced NEE to varying degrees on different timescales. Heat waves generally decreased NEE during the day but recovered quickly and increased carbon uptake if there was sufficient precipitation. Drought reduced carbon uptake and continued to decrease even after precipitation.DiscussionEstimating the carbon sink capacity of the rubber plantation and studying the response to regional environmental changes are important for both applied research (carbon sink research and market trading, sink enhancement, and emission reduction, etc.) and basic research (land use change, phenology change, etc.).

Effects of Vegetation Types on Carbon Cycle Functional Genes in Reclaimed Soil from Open Pit Mines in the Loess Plateau

Vegetation restoration can effectively improve the ecological environment of mining areas, enhance the ecological service function, and promote the carbon sequestration and sink increase in the ecosystem. The soil carbon cycle plays an important role in the biogeochemical cycle. The abundance of functional genes can predict the material cycling potential and metabolic characteristics of soil microorganisms. Previous studies on functional microorganisms have mainly focused on large ecosystems such as farmland, forest, and wetland, but relatively little attention has been paid to complex ecosystems with great anthropogenic interference and special functions, such as mines. Clarifying the succession and driving mechanism of functional microorganisms in reclaimed soil under the guidance of vegetation restoration is helpful to fully explore how functional microorganisms change with the change in abiotic and biotic conditions. Therefore, 25 topsoil samples were collected from grassland (GL), brushland (BL), coniferous forests (CF), broadleaf forests (BF), and mixed coniferous and broadleaf forests (MF) in the reclamation area of the Heidaigou open pit waste dump on the Loess Plateau. The absolute abundance of soil carbon cycle functional genes was determined using real-time fluorescence quantitative PCR to explore the effect of vegetation restoration on the abundance of carbon cycle-related functional genes in soil and its internal mechanism. The results showed that:① the effects of different vegetation restoration types on the chemical properties of reclaimed soil and the abundance of functional genes related to the carbon cycle were significantly different (P<0.05). GL and BL showed significantly better accumulation of soil organic carbon, total nitrogen, and nitrate nitrogen (P<0.05) than that in CF. ② The gene abundance of rbcL, acsA, and mct was the highest among all carbon fixation genes. The abundance of functional genes related to carbon cycle in BF soil was higher than that in other types, which was closely related to the high activity of ammonium nitrogen and BG enzymes and the low activity of readily oxidized organic carbon and urease in BF soil. The functional gene abundance of carbon degradation and methane metabolism was positively correlated with ammonium nitrogen and BG enzyme activity and negatively correlated with organic carbon, total nitrogen, readily oxidized organic carbon, nitrate nitrogen, and urease activity (P<0.05). ③ Different vegetation types could directly affect soil BG enzyme activity or affect soil nitrate nitrogen content, thus indirectly affecting BG enzyme activity, in turn manipulating the abundance of functional genes related to the carbon cycle. This study is helpful to understand the effects of different vegetation restoration types on the functional genes related to the carbon cycle in the soil of mining areas on the Loess Plateau and provides a scientific basis for ecological restoration and ecological carbon sequestration and sink enhancement in mining areas.

Impacts and prediction of land use change on ecosystem carbon sequestration in Zhejiang Province, China.

It is crucial to clarify the impact of land use change on ecosystem carbon sequestration service for exploring natural-based carbon neutral solutions. We used InVEST and FLUS models to analyze land use change and its impacts on ecosystem carbon sequestration service in Zhejiang Province from 2000 to 2021, and predict ecosystem carbon sequestration service potential and its economic value of land use pattern in 2035 and 2050 under three scenarios of natural development, ecological protection, and cultivated land protection. The results showed that the area of cultivated land, forest, grassland, and water was continuously reducing and the area of construction land was continuously increasing from 2000 to 2021 in Zhejiang Province. The total amount of ecosystem carbon sequestration service decreased by 29.9658 million t, and the net income of carbon sequestrqtion service was -170.7184 million dollars. The distribution of ecosystem carbon sequestration services showed a spatial pattern of high in the southwest and low in the northeast. In the future, the total amount of ecosystem carbon sequestration services in Zhejiang Province would be the highest under the ecological protection scenario, followed by the cultivated land protection scenario, and the lowest under the natural development scenario. From 2021 to 2035 and 2050, ecosystem carbon sequestration services in Zhejiang Province would increase by 3.2326 million and 4.73 million t respectively under the ecological protection scenario, generating carbon sequestration service benefits of 77.0786 million and 111.8391 million dollars, respectively. Under the cultivated land protection scenario, it would be reduced by 10.1318 million and 16.1611 million t, and the net loss of carbon sequestration service value would be 241.3849 million and 381.9109 million dollars, respectively. Under the natural development scenario, it would be reduced by 11.6490 million and 16.1651 million t, resulting in a net loss of carbon sequestration service value of 277.5393 million and 382.0063 million dollars, respectively. In the context of actively addressing climate change and striving to achieve the goal of carbon neutrality, Zhejiang Province should focus on protecting ecological land such as woodlands, grasslands, and water, expand the scale of ecological land, optimize the spatial structure of ecological land, and continuously enhance carbon sequestration and sink enhancement functions of ecological land.

Thermal analysis and optimization of metal foam PCM-based heat sink for thermal management of electronic devices

Efficient thermal management in electric devices is highly essential for ensuring the reliability and durability of electronics. This study aims to investigate the thermal performance and optimization of metal foam PCM-based heat sink for thermal management units. Different design parameters, such as PCM types (RT31, RT42, and RT55), metal foam porosities (85%, 90%, and 95%), and metal foam materials, are studied to determine heat sink optimal parameters, considering various critical temperatures: 40 °C, 50 °C, 60 °C and 70 °C. The volume-averaged method is used to simulate the heat transfer, phase change, and fluid flow within the heat sink unit. Heat transfer between PCM and metal foam is established using a thermal non-equilibrium model. The results show that the usage of metal foam is conducive to the thermal performance enhancement of heat sinks. Among the three parameters, PCM types show a considerable effect on thermal performance of heat sinks, e.g., the maximum operation time of heat sinks with RT31 is about 5 times that of heat sinks with RT55 for the critical temperature of 40 °C. Among all the cases, heat sinks using RT31 and aluminum foam perform optimally, which can achieve the optimal design of heat sinks.

Spatio-Temporal Pattern, Evolution and Influencing Factors of Forest Carbon Sinks in Zhejiang Province, China

Zhejiang Province, charged with the task of opening “an important window”, should take the lead in the implementation of the national “carbon peak, carbon neutral” strategy. The intention of this study is to start from the intersection of economics and geography, and on the basis of GIS analysis, use the spatial Dubin model to study the spatio-temporal evolution trend, key influencing factors, and spatial spillover effects of forest carbon sequestration in 72 districts and counties of Zhejiang Province from 2000 to 2020, to provide a theoretical and practical reference for how to formulate regional synergistic forest sink enhancement measures and help Zhejiang achieve the goal of carbon neutrality. The conclusions are as follows: (1) From 2000 to 2020, the overall growth of forest carbon sequestration in all regions and counties of Zhejiang Province was relatively high, but the regional differences were large. The concentration center and range moved to the southwest. (2) If the spatial effect is considered, the increase of per capita GDP, road density, and deforestation will reduce the forest carbon sequestration, and the conservation of ecological public welfare forests will have a significant positive relationship with the forest carbon sequestration.

Ecohydrological Insight: Solar Farm Facilitates Carbon Sink Enhancement in Drylands

Ecohydrological Insight: Solar Farm Facilitates Carbon Sink Enhancement in Drylands

Experimental investigation for thermal performance enhancement of various heat sinks using Al2O3 NePCM for cooling of electronic devices

Electronic devices are being used extensively for different applications, where the thermal management of these devices is still a critical challenge due to rapid miniaturization, high heat flux and constantly rising temperature. Phase change materials (PCMs) based thermal management is adopted, but the low thermal conductivity limits their use in temperature-controlled electronic devices. Nano-enhanced phase change materials (NePCMs) can advance the heat transfer rate (HTr), decrease the temperature, and increase the operating time of the electronic device. The present study compares the thermal performances (TP) of three different heat sinks (simple, circular pin finned and copper foam) with NePCM (RT54HC/Al2O3) and varying Al2O3 nanoparticles concentrations (0.15–0.25 wt%) and heat fluxes (0.98–2.94 kW/m2) to optimize the overall device performance. The results show that at a heat flux (HF) of 0.98 kW/m2 and 0.25 wt% of Al2O3 nanoparticles (NPs), the base temperature of simple, circular pin finned and Cu foam heat sink was reduced by 21.3%, 25.03%, and 36.2%, respectively. The Cu foam heat sink (HS) has exceptional TP than the HSs without Cu foam. Accordingly, NePCMs are highly recommended in electronic devices for an optimized thermal management system.

Scoping carbon dioxide removal options for Germany–What is their potential contribution to Net-Zero CO2?

In its latest assessment report the IPCC stresses the need for carbon dioxide removal (CDR) to counterbalance residual emissions to achieve net zero carbon dioxide or greenhouse gas emissions. There are currently a wide variety of CDR measures available. Their potential and feasibility, however, depends on context specific conditions, as among others biophysical site characteristics, or availability of infrastructure and resources. In our study, we selected 13 CDR concepts which we present in the form of exemplary CDR units described in dedicated fact sheets. They cover technical CO2 removal (two concepts of direct air carbon capture), hybrid solutions (six bioenergy with carbon capture technologies) and five options for natural sink enhancement. Our estimates for their CO2 removal potentials in 2050 range from 0.06 to 30 million tons of CO2, depending on the option. Ten of the 13 CDR concepts provide technical removal potentials higher than 1 million tons of CO2 per year. To better understand the potential contribution of analyzed CDR options to reaching net-zero CO2 emissions, we compare our results with the current CO2 emissions and potential residual CO2 emissions in 2050 in Germany. To complement the necessary information on technology-based and hybrid options, we also provide an overview on possible solutions for CO2 storage for Germany. Taking biophysical conditions and infrastructure into account, northern Germany seems a preferable area for deployment of many concepts. However, for their successful implementation further socio-economic analysis, clear regulations, and policy incentives are necessary.

Guizhou Karst Carbon Sink and Sustainability—An Overview

Global warming and climate change are becoming the most popular topics among scientists. In this century, the research focusing on the process and mechanism of the carbon cycle, especially the research of reducing the concentration of atmospheric CO2 (carbon sink and carbon sequestration technology), are the core issues of global change. The karst carbon sink was neglected due to the consideration that it was a geological process with a long timescale. Recently, studies have proven that carbonate rock weathering is a rapid and sensitive process, and the Fifth Climate Change Assessment Report of the United Nations Intergovernmental Panel on Climate Change confirmed this. Guizhou, as the center of karst in China, has the unique advantages of the karst carbon sink, and is the core area of the karst carbon sink. On the basis of summarizing the development and evolution trend of karst carbon sinks, through data collection and field research, the Carbon Neutralization Research Group of Guizhou Institute of Technology has conducted an exploratory investigation on karst carbon sinks in Guizhou Province, and basically identified the mechanism, influencing factors and measurement methods of karst carbon sinks in Guizhou karst areas. The results show that the potential of the karst carbon sink in Guizhou is huge. Vegetation restoration, soil improvement, irrigation with external water and the cultivation of aquatic plants are important ways to increase the karst carbon sink by artificial intervention. A series of achievements have been made in the theory, technology and platform construction of the karst carbon cycle geological survey and carbon sink effect evaluation. It is worth noting that there are still great challenges in karst carbon sink measurement and verification, and in the demonstration of artificial intervention in carbon sequestration and sink enhancement, which need to be continuously tackled and improved in the “14th Five-Year Plan” period and beyond, so as to meet the needs of the carbon neutralization target of geological carbon sink services.