Transforming erosion-prone basin into carbon sink: the role of check dams in regulating carbon cycle in a semi-arid basin.

Operational and embodied emissions in life cycle analysis of Biopolymers in Northeastern United States buildings.

Metagenomic and metatranscriptomic analysis of sulfur-driven autotrophic denitrification coupled with carbon assimilation: roles of sulfur-to-nitrogen ratio and hydraulic retention time.

Long-term observations uncover sustained carbon dioxide emissions from lakes following aquaculture retreat.

Permafrost degradation: A critical driver of aboveground carbon sink loss in China's boreal forests

Understanding where blue carbon habitats occur and how they are affected by human activity contributes to effective management of natural carbon sinks. Here, we compiled geographical data for Sweden to map the distribution of coastal vegetated blue carbon (BC) habitats. The mapping effort focused on well-recognised (salt marshes and seagrass meadows) and emergent BC habitats (other rooted submerged macrophytes and forested wetlands). We also estimated the exposure to anthropogenic pressures on coastal BC habitats based on their proximity to land-based human activities, and subsequently, the portion of these BC habitats that were located within protected areas. The total area of BC habitats was estimated to around 1850 km2, corresponding to ca. 35% of the Swedish coast. Seagrass meadows and other rooted submerged macrophytes were dominating, covering about 1500 km2. Around 22% of the mapped BC habitats were expected to be exposed to high pressures from land-based human activities due to their location, while BC habitats within protected areas were often less exposed. This nationwide assessment of coastal vegetated BC habitats accentuates the need for strengthening conservation prioritisation to maximise the carbon storage potential of BC habitats.

Mangrove forests (MFs) play a crucial role in climate change mitigation due to their capacity to store significant amounts of blue carbon. This study investigates carbon sequestration dynamics in MF sediments, encompassing natural stands (sites BD1 and BD3) and planted stands (sites PN2, PN3, and PN4), focusing on vertical soil profiles up to 1m depth. Results indicate that natural mangroves function as blue carbon hotspots, benefiting from mangrove, terrestrial, and marine organic matter (OM) inputs. In comparison, a 10-year-old plantation (PN2) stored approximately twice the carbon of a 2-year-old plantation (PN4), suggesting that effective carbon sink development requires more than a decade. Sediment cores revealed that BD1 dates back to 1952, whereas PN2 is older, dating to 1919. Fine sand layers at BD3 and PN4 are likely remnants of tropical storm deposits, illustrating how mangroves archive century-scale hydroclimatic events. Microplastic (MP) pollution is emerging as a critical concern, with both natural and planted mangroves accumulating MPs in their sediments. A negative correlation between MPs and total organic carbon (TOC) in natural forests suggests that organic-rich sediments may reduce MP retention through competitive adsorption or enhanced biodegradation-an unprecedented finding requiring further investigation. Overall, this study underscores the importance of mangrove restoration for climate resilience and highlights the necessity of integrating MP pollution into blue carbon management strategies. It advances understanding of plantation effectiveness, sediment carbon stability, and anthropogenic stressors influencing mangrove ecosystems.

Karst carbon sink in a subalpine catchment of Eastern Qinghai-Tibetan Plateau: Influences of anthropogenic and natural factors

Marine ranching, as a pivotal strategy for enhancing the ocean’s carbon sequestration potential, offers significant potential to mitigate nearshore fishery depletion and restore marine ecosystems amid the global carbon neutrality agenda. However, the mechanistic pathways linking sediment total organic carbon (TOC) to various environmental factors in tropical marine ranches remain insufficiently quantified. This study selected the Wuzhizhou Island Marine Ranch in Hainan Province—a representative tropical marine ranch—as the research site. Field investigations and sampling were conducted during the dry (March 2024) and wet (September 2024) seasons to quantify TOC in surface sediments and associated environmental variables. A two-step analytical framework, integrating Principal Component Analysis (PCA) and Generalized Additive Models (GAM), was employed to elucidate the environmental drivers governing the spatiotemporal dynamics of TOC. The results show that the surface sediment TOC at Wuzhizhou Island Marine Ranch exhibits a distinct spatial gradient—Core Reef > Atoll > Control > Estuarine, and a pronounced seasonal pattern with elevated concentrations in the dry season relative to the wet season. The spatiotemporal differentiation of TOC is mainly driven by a gradient (explaining 52.1% of variation) that encompasses processes related to carbon accumulation from terrestrial inputs and primary production, as well as organic matter degradation promoted by nutrients and higher water temperatures. Sediment total nitrogen (TN) emerges as the primary environmental driver of TOC distribution, contributing up to 46.9% of the variance at an extremely significant level (p < 0.001). Furthermore, total phosphorus (TP), pH, and water temperature (WT) have relatively minor influences on the distribution of sedimentary TOC. Our study offers a crucial reference for elucidating the key processes governing the carbon cycle in tropical marine ranches and provides essential theoretical support for optimizing ocean carbon sink strategies in the context of global climate change.

Marine sedimentary black carbon (BC) is conventionally attributed to terrestrial biomass and fossil-fuel combustion. However, persistent imbalances in the marine BC budget suggest unaccounted marine sources. This study identifies and quantifies a novel microbially-derived black carbon (mBC) source in deep-sea cold seeps. High-resolution geochemical analysis of Qiongdongnan Basin sediment cores reveals mBC as a significant component, evidenced by extremely depleted stable carbon isotopes in BC (-37.74‰) and total organic carbon (-55.39‰), linking its formation to anaerobic methane oxidation. During active seepage (2011-2020), mBC constitutes 31-43% of sedimentary BC, with a modern accumulation rate of 1.58-3.36 g m-2 yr-1. Scaling this rate to global cold seep areas, we estimate that cold seeps contribute 0.52-0.79 Tg mBC yr-1 as a previously unrecognized sink, accounting for 4.1-5.9% of the total marine BC burial flux. Multiproxy records show a three-stage seep evolution over the past century, governed by shallow fluid dynamics. Isolating the mBC signal also clarifies combustion-derived BC, validating post-2010 regional emission controls. These findings redefine marine BC source apportionment and reveal an important, long-overlooked carbon sequestration pathway, necessitating revisions to marine carbon cycle models to include mBC as a critical sink and a paleo-methane proxy.

Abstract Hydroclimatic extremes are critical regulators of terrestrial carbon sink dynamics, yet their representation in terrestrial biosphere models remains highly uncertain. Here, we assessed uncertainties in TRENDY v12 model simulations of carbon sink responses to hydroclimatic extremes during 1980–2022 by systematically comparing model outputs across regions, event types, and biomes. Site-level evaluations reveal that the multi-model ensemble mean correctly captures the sign of net biome productivity (NBP) anomalies at approximately 60% of stations; however, while the multi-model ensemble mean generally replicates NBP variations during dry events, its performance degrades during wet events. Spatially, most regions act as anomalous carbon sinks during wet extremes, a pattern that largely reverses during dry events. Despite these general trends, substantial inter-model heterogeneity persists. Inter-model uncertainties are more pronounced under dry events between 30°S and 30°N, while other latitudes exhibit comparable or even greater spreads under wet events. Specifically, inter-model spread is more sensitive to wet anomalies in arid and semi-arid regions, but to drought-induced stress in semi-humid and humid regions. Across biomes, uncertainties are greater for grasslands, savannas, and shrublands during wet events, shifting to forests and croplands during dry events. Finally, we demonstrate that the divergent NBP responses primarily originate from uncertainties in simulating gross primary production (GPP). Our findings highlight the persistent challenges TRENDY models face in capturing ecosystem responses to hydroclimatic extremes, underscoring the urgent need to improve simulation fidelity in a rapidly changing climate.

Climate change poses escalating threats to coastal ecosystems through sea-level rise, intensified storms, and rising ocean acidification, placing global sustainability at risk. Mangrove ecosystems play a critical role in coastal protection, biodiversity conservation, and climate mitigation stabilizing shorelines, filtering pollutants, and acting as major carbon sinks. Sustainable mangrove management offers livelihood opportunities for local communities, such as fishing, shellfish gathering, and beekeeping. Despite their importance, mangroves have experienced significant decline, particularly in countries with extensive coastlines. This paper examines how legal frameworks and policy initiatives address mangrove protection in the United States, Saudi Arabia, and Egypt, with a focus on the role of law in mitigating coastal ecosystem degradation. Using a comparative legal analysis, the paper reviews mangrove-related legislation, regulatory approaches, and national initiatives in these three jurisdictions. The analysis finds that the United States employs more developed legal mechanisms for mangrove protection, including marine protected areas and scientific monitoring, while Saudi Arabia and Egypt rely more heavily on large-scale restoration initiatives and broader environmental laws rather than mangrove-specific legal frameworks. The paper concludes that strengthening targeted legal measures for mangrove protection, informed by comparative legal experience, can enhance coastal ecosystem resilience and support long-term environmental sustainability in regions vulnerable to climate change.

The rapid proliferation of incineration plants has rendered their carbon emissions a substantial contributor to urban carbon emissions. Municipal solid waste classification presents waste-to-energy plants with challenges and opportunities. Monitoring nine Shenzhen incineration plants (2018-2022), we employed Monte Carlo simulations for sensitivity analysis and constructed response surface models to derive quantitative emission reduction pathways. Results indicate the plastic incineration proportion rose to 27.6%, increasing direct emissions and carbon substitution credits from electricity. Reducing plastic by 1% cuts emissions by approximately 17.38 kg CO2-eq/t. Plastic should maintain below 34% considering synergistic effects among dominant emission determinants: plastic composition, grid carbon intensity, and electricity output. Singular interventions targeting plastic reduction or energy efficiency improvements have limited mitigation potential. A comprehensive mitigation scenario combining efficiency improvement, combined heat and power, plastic waste reduction, enhanced recycling, and Bioplastic substitution enables net negative emissions under future low-carbon grids. This study highlights that, systemic transformation from carbon source to carbon sink necessitates coordinated actions across multistakeholder.

Aboveground biomass (AGB) is a key indicator of vegetation productivity and terrestrial carbon stocks; therefore, robust AGB estimation is critical for assessing ecosystem services and carbon cycle research. Previous studies have largely focused on forest and cropland ecosystems. In contrast, roadside vegetation along highways and other linear transport corridors remains comparatively underexplored despite its potentially important role as a carbon sink. Here, we integrate field-measured AGB samples with GF-2 high-resolution satellite imagery to evaluate the suitability of multiple remote-sensing predictors and machine-learning algorithms for estimating AGB in highway roadside vegetation. Six remote-sensing variables were used as predictors, including four vegetation indices (Normalized Difference Vegetation Index (NDVI), Perpendicular Vegetation Index (PVI), Enhanced Vegetation Index (EVI), and Modified Soil-Adjusted Vegetation Index (MSAVI) and two-band ratios (B342 and B12/34). Five regression models-multiple linear regression (MLR), partial least squares regression (PLSR), random forest (RF), support vector regression (SVR), and extreme gradient boosting (XGBoost)-were developed and systematically compared under both single-variable and multi-variable scenarios. Model performance was evaluated using five-fold cross-validation, with the coefficient of determination (R2) and the root mean square error (RMSE) as metrics of evaluation. The results indicate that the RF model under the multi-variable scenario achieved the best overall performance, with a training R2 of 0.83 and a testing RMSE of 0.84 kg·m-2, substantially outperforming the other linear and non-linear models. The optimal RF model was further applied to GF-2 imagery to produce a spatially explicit AGB map for a 32 km highway segment and a 30 m roadside buffer on both sides, yielding an estimated total aboveground biomass of 566.97 t for the corridor. These findings demonstrate that combining high-resolution remote sensing with machine-learning approaches can effectively improve AGB estimation for linear roadside vegetation systems, providing technical support for ecological monitoring, roadside greening management, and carbon accounting for transport infrastructure.

Against the backdrop of global change, frequent and severe droughts pose major threats to ecosystems, and quantifying ecosystem anomalies driven by hydrothermal stress remains challenging. Based on this, we propose a drought-monitoring framework centered on solar-induced chlorophyll fluorescence (SIF) and develop an SIF-based Vegetation Health Index (SHI) to improve monitoring performance. Compared with existing SIF-based drought indices (e.g., TFDI and TSWDI), SHI provides a more direct representation of photosynthetic stress, making it more suitable for elucidating drought-response mechanisms. In addition, we use net ecosystem productivity (NEP) to represent carbon sequestration and apply multiple correlation analyses to investigate NEP responses to drought and their spatiotemporal differentiation across vegetation types. Results indicate an overall wetting trend in the study region during 2001–2024, and SIF-based indices perform better in characterizing drought and vegetation responses. The dominant coupling scale between NEP and drought is annual, with an overall lag of 0–3 months: croplands show the strongest coherence and the shortest lag (0–1 month), grasslands are intermediate, and forests show longer lags (2–5 months) as well as a more persistent response window. This study highlights SHI’s advantages for drought monitoring and carbon sink diagnostics, supporting differentiated drought mitigation and management in NWC.

Climate warming is an important driver influencing soil microbial involvement in carbon cycling. To clarify the responses of carbon-fixing microorganisms in alpine lakeshore wetlands, we conducted a warming experiment using open-top chambers (OTCs) in the Qinghai Lake lakeshore wetland and applied high-throughput sequencing of the cbbM gene. The results indicated that warming significantly increased soil temperature and reduced soil moisture, but had no significant effects on soil pH, total carbon, or total nitrogen content. Despite the stability of community α-diversity, warming markedly reshaped the community composition and significantly elevated the relative abundances of dominant taxa including Ensifer and Hydrogenovibrio. In addition, warming significantly strengthened the assembly process of the cbbM-bearing carbon-fixing microbial community, in which heterogeneous selection played a leading role. Redundancy analysis revealed that soil total nitrogen and pH were major drivers influencing the composition of the microbial community. Notably, despite significant fluctuations in taxonomic composition, the functional profile dominated by sulfur oxidation and phototrophy remained unchanged, indicating strong functional redundancy. Overall, cbbM carbon-fixing microorganisms in alpine lakeshore wetlands effectively buffered environmental disturbances through functional redundancy and maintained stable carbon metabolic functions, providing scientific evidence for the short-term resilience of carbon sink functions in alpine wetlands under climate warming.

Boreal forests are experiencing rapid global warming, which may amplify the impact of temperature on their carbon sink function. However, the factors influencing the sensitivity of the carbon balance to temperature in boreal forests are still not well understood, especially over short timescales. Leveraging the FLUXNET dataset, we calculated the sensitivities of carbon fluxes to temperature anomalies (Ts) across boreal forest (24 sites) on the seasonal scale. Here, a positive Ts value indicates that the carbon flux increases with temperature anomaly, while a negative value suggests the opposite. Results showed that Ts of NEP in early spring was positive for evergreen needleleaf forests but negative for deciduous broadleaved forests. Although Ts of gross ecosystem production (GEP) remained positive, it tended to decrease with increasing temperature and vapour pressure deficit in spring and summer. Associated with this decrease were relatively small changes in Ts of ecosystem respiration (Re), so that Ts of NEP decreased with increasing temperature and vapour pressure deficit in spring and summer. Both Ts of GEP and Re increased with ecosystem productivity (represented by annual GEP) in spring, with Ts of GEP being more sensitive, indicating that carbon sinks in sites with lower productivity tended to negatively respond to higher temperature. Young-aged and low-nutrient forests tended to respond negatively to increasing temperatures. Ecosystem productivity and seasonality played an essential role in regulating Ts of NEP. Our results suggest that significant declines in ecosystem productivity may exacerbate the negative response of NEP to elevated temperatures, further compromising carbon sequestration in boreal forests. This understanding is vital both for improving the predictive accuracy of carbon-climate models and for formulating targeted strategies to bolster resilience in the most vulnerable boreal ecosystems.

To achieve the goal of carbon neutrality, it is necessary to comprehensively and accurately check the regional carbon budget and its evolution characteristics. Accordingly, taking Jiangsu Province as an example, this study constructed a carbon budget accounting system from the perspective of the "natural-human" binary structure. The major anthropogenic carbon emission items, carbon sources/sinks of the ecosystem, and the changes of the carbon storage in Jiangsu Province from 2000 to 2020 were calculated, and the pressure of carbon neutrality was evaluated entirely. The results showed that during 2000-2020, the anthropogenic carbon emissions in Jiangsu Province increased from 54.380 6 to 233.841 9 million tons. Carbon emissions associated with industrial energy consumption consistently dominated, accounting for 61% to 72% of total emissions. Emissions from industrial production processes represented the second-largest source, with a fluctuating upward trend in its proportion. Moreover, 11.25% of the land in Jiangsu Province was transferred, resulting in a reduction of ecosystem carbon storage by 2.638 9 million tons. Although the ecosystems functioned as a carbon sink overall, with an annual average carbon sequestration of 6.63 million tons, this capacity has shown fluctuations and a declining trend in recent years. As a whole, Jiangsu Province had high carbon emissions coupled with relatively low carbon sequestration capacity, with carbon sinks offsetting only approximately 4.17% of anthropogenic emissions during the study period, which demonstrates high pressure on realizing the goal of carbon neutrality.

Emission reduction and remittance enhancement in the agricultural sector are crucial to achieving the dual-carbon goal. Taking the Jiangsu Coastal Economic Belt (JCEB) as the research object, the carbon emission coefficient method and the parameter estimation method are adopted to measure the total carbon emission, carbon sink, and net carbon sink (NCS) of the 20 districts and counties from 2005 to 2023 in JCEB. On this basis, the study further analyzes spatial-temporal characteristics and dynamic evolution trends. The spatio-temporal geographically weighted regression model (GTWR) is used to explore the spatio-temporal heterogeneity and evolutionary pattern of each influencing factor. The results showed that: ① The agricultural NCS (measured by C) in JCEB decreased from 3.12×106 t in 2005 to 1.32×106 t in 2023, showing an overall trend of fluctuating decline. Spatially, the total NCS showed a distribution pattern of "high in the center and low in the north and south, " with most areas being low-carbon surplus areas. ② Among the influencing factors, the intensity of financial support for agriculture (FSA), the grain to economy crop ratio (GER), and agricultural development levels (ADL) had positive driving effects on the agricultural NCS. The positive effects of the first two factors continued to strengthen, while the contribution of the latter showed a "U"-shaped change trend. Fertilizer application intensity (FAI), agricultural machinery use intensity (AMI), and rural residents' income level (RRI) generally inhibited the growth of the agricultural NCS. The inhibitory effects of the first two factors were declining, while the negative effect of the latter decreased with economic growth. ③ The impact direction and intensity of each driving factor on the agricultural NCS in different counties showed significant differences. The impact effects of FSA and FAI were distinctly different in the north and south. The impact effects of GER and ADL showed agglomeration characteristics at the municipal level. In contrast, the influence intensity of AMI and RRI on the agricultural NCS presented an overall pattern of interlaced distribution in the north and south.

As an important indicator for measuring the carbon sequestration capacity of ecosystems，carbon storage is of great significance for alleviating global climate change. By taking advantage of machine learning and ecosystem service models，an integrated analysis framework based on the InVEST-Ridge Regression-PLUS model was constructed to conduct a quantitative analysis of the spatio-temporal evolution characteristics and driving mechanisms of carbon storage in the Yunnan-Guizhou Plateau from 2000 to 2020，and future scenarios were designed to predict the changing trends of regional carbon storage under different land use paths. The results show that：Firstly，from 2000 to 2020，the carbon storage in the Yunnan-Guizhou Plateau generally presented a slow growth trend，and the growth rate continued to decline，showing a distribution pattern of "higher in the south and lower in the north." Secondly，vegetation coverage was a crucial determining factor for carbon storage in this area，and the conversion between different land use types affected the spatial distribution of carbon storage. Thirdly，in the future scenario simulation，the carbon storage under the carbon sink enhancement scenario performed best，effectively verifying the effects of ecological projects such as the conversion of farmland to forest and grassland restoration，providing a scientific basis for the dynamic assessment and optimization of carbon storage in the Yunnan-Guizhou Plateau and similar karst areas.