Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were c...Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were conducted,followed by fatigue tests,to explore how THM treatment influences the fatigue properties of damaged sandstone.Experimental results indicate that rock fatigue deformation,damage evolution,and failure characteristics are highly sensitive to initial damage caused by coupled THM treatment.Rocks subjected to multiple THM cycles exhibit lower initial irreversible strain,shorter fatigue life,lower critical total dissipated energy,and higher irreversible strain increments,indicating accelerated deterioration.After THM coupling,rock fatigue failure shows complex crack networks,with macroscopic failure modes shifting from shear to tensile failure.Polarized microscopy and acoustic emission analyses reveal that this transition stems from micro-scale transgranular to intergranular fractures.We introduced a fractional order-based damage fatigue model to quantitatively describe the rock viscoelastic parameters after different initial damage treatments.Rock viscoelastic-plastic parameters decrease with increasing coupled THM cycles.Finally,we discussed the feasibility of applying these results to the long-term stability analysis of rock slopes.This study provides unique insights and modeling tools from fully coupled THM experiments to understand the rock fatigue characteristics,offering potential applications for slope stability assessment.展开更多
Soil viruses can greatly influence both microbial catabolism and anabolism.Understanding such influences is crucial for unraveling the fate of soil organic carbon(C).However,previous studies on soil viruses have prima...Soil viruses can greatly influence both microbial catabolism and anabolism.Understanding such influences is crucial for unraveling the fate of soil organic carbon(C).However,previous studies on soil viruses have primarily focused on their role in soil C loss,overlooking their role in C sequestration.In this study,soil viruses and microbes were introduced into sterilized samples of crop and forest soils from typical red and brown soil regions of China to examine the effects of soil viruses on C dynamics,from the perspective of C release and retention.The results showed that the viral effects on soil C emissions varied between soil types.However,they significantly enhanced the accumulation of recalcitrant dissolved and metal-bound organic C,which in turn reinforced the viral effects on C emissions.Furthermore,the accumulation of dissolved and metal-bound organic C was always associated with the microbial utilization of dissolved organic nitrogen(N),highlighting the coupled C and N cycling during the viral shuttle process.Our research demonstrates for the first time the virus-mediated coupling of C and N cycling in soils and the dual role of viruses in soil C release and stabilization,providing a new understanding of virus-driven soil C cycling.展开更多
Eddy Covariance technique(EC) achieves the direct measurement on ecosystem carbon, nitrogen and water fluxes, and it provides scientific data for accurately assessing ecosystem functions in mitigating global climate c...Eddy Covariance technique(EC) achieves the direct measurement on ecosystem carbon, nitrogen and water fluxes, and it provides scientific data for accurately assessing ecosystem functions in mitigating global climate change. This paper briefly reviewed the construction and development of Chinese terrestrial ecosystem flux observation and research network(China FLUX), and systematically introduced the design principle and technology of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation system of China FLUX. In addition, this paper summarized the main progress of China FLUX in the ecosystem carbon, nitrogen and water exchange and environmental controlling mechanisms, the spatial pattern of carbon, nitrogen and water fluxes and biogeographical mechanisms, and the regional terrestrial ecosystem carbon budget assessment. Finally, the prospects and emphases of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation of China FLUX are put forward to provide theoretical references for the development of flux observation and research in China.展开更多
Atmospheric CO_(2)is a key factor governing Earth's habitability,with its concentration and isotopic variations influenced by both deep and shallow carbon cycles.The Neoproterozoic Era was pivotal for Earth's ...Atmospheric CO_(2)is a key factor governing Earth's habitability,with its concentration and isotopic variations influenced by both deep and shallow carbon cycles.The Neoproterozoic Era was pivotal for Earth's habitability evolution and global tectonic reorganization,encompassing the assembly-to-breakup of Rodinia and the formation of Gondwana.During this period,marine carbonateδ^(13)C_(PDB)exhibited repeated positive and negative excursions,with the most pronounced negative shift occurring in the Ediacaran(termed the Shuram Excursion,SE).While conventional models attribute SE to organic matter oxidation(due to its13C-depleted signature),this mechanism faces challenges in explaining associated geological features.Notably,the SE event temporally coincides with peak rifting activity and large-scale carbonatite-alkaline magmatism,suggesting a potential deep carbon cycle contribution.Spatial-temporal-compositional correlations imply that tectonic and magmatic processes may play critical roles in carbonateδ^(13)C excursions,necessitating an Earth system approach integrating deep-shallow carbon cycle.Recent studies propose that Neoproterozoicδ^(13)C excursions could originate from deep carbon recycling,with models highlighting subduction-driven decarbonation and melt recycling during supercontinent cycles.These frameworks offer novel insights into the SE enigma.展开更多
Greenhouse gas(GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today,posing serious risks for ecosystem health.Methane(CH_(4))and nitrous oxide(N_(2)O)are the two most ...Greenhouse gas(GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today,posing serious risks for ecosystem health.Methane(CH_(4))and nitrous oxide(N_(2)O)are the two most important GHGs after carbon dioxide(CO_(2)),but their regional and global budgets are not well known.In this study,we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH_(4)and N_(2)O fluxes as driven by multiple environmental changes,including climate variability,rising atmospheric CO_(2),increasing nitrogen deposition,tropospheric ozone pollution,land use change,and nitrogen fertilizer use.The estimated CH_(4)and N_(2)O emissions from global land ecosystems during 1981-2010 were 144.39±12.90 Tg C/yr(mean 62 SE;1 Tg=1012 g)and 12.52±0.74 Tg N/yr,respectively.Our simulations indicated a significant(P,0.01)annually increasing trend for CH_(4)(0.43±0.06 Tg C/yr)and N_(2)O(0.14±0.02 Tg N/yr)in the study period.CH_(4)and N_(2)O emissions increased significantly in most climatic zones and continents,especially in the tropical regions and Asia.The most rapid increase in CH_(4)emission was found in natural wetlands and rice fields due to increased rice cultivation area and climate warming.N_(2)O emission increased substantially in all the biome types and the largest increase occurred in upland crops due to increasing air temperature and nitrogen fertilizer use.Clearly,the three major GHGs(CH_(4),N_(2)O,and CO_(2))should be simultaneously considered when evaluating if a policy is effective to mitigate climate change.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.42372326)supported by the State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Independent Research Project(Grant No.SKLGP2023Z015)supported by the Sichuan Science and Technology Program(Grant No.2024YFFK0416).
文摘Cold regions often feature complex geological environments where various physical phenomena interact,with a particularly notable thermo-hydro-mechanical(THM)coupling.In this study,fully coupled THM cyclic tests were conducted,followed by fatigue tests,to explore how THM treatment influences the fatigue properties of damaged sandstone.Experimental results indicate that rock fatigue deformation,damage evolution,and failure characteristics are highly sensitive to initial damage caused by coupled THM treatment.Rocks subjected to multiple THM cycles exhibit lower initial irreversible strain,shorter fatigue life,lower critical total dissipated energy,and higher irreversible strain increments,indicating accelerated deterioration.After THM coupling,rock fatigue failure shows complex crack networks,with macroscopic failure modes shifting from shear to tensile failure.Polarized microscopy and acoustic emission analyses reveal that this transition stems from micro-scale transgranular to intergranular fractures.We introduced a fractional order-based damage fatigue model to quantitatively describe the rock viscoelastic parameters after different initial damage treatments.Rock viscoelastic-plastic parameters decrease with increasing coupled THM cycles.Finally,we discussed the feasibility of applying these results to the long-term stability analysis of rock slopes.This study provides unique insights and modeling tools from fully coupled THM experiments to understand the rock fatigue characteristics,offering potential applications for slope stability assessment.
基金supported by the National Key R&D Program of China(No.2024YFD1501801)the Science and Technology Program of Zhejiang Province,China(No.2022C02046)+1 种基金the 111 Project of China(No.B17039)China Agriculture Research System(No.CARS-01).
文摘Soil viruses can greatly influence both microbial catabolism and anabolism.Understanding such influences is crucial for unraveling the fate of soil organic carbon(C).However,previous studies on soil viruses have primarily focused on their role in soil C loss,overlooking their role in C sequestration.In this study,soil viruses and microbes were introduced into sterilized samples of crop and forest soils from typical red and brown soil regions of China to examine the effects of soil viruses on C dynamics,from the perspective of C release and retention.The results showed that the viral effects on soil C emissions varied between soil types.However,they significantly enhanced the accumulation of recalcitrant dissolved and metal-bound organic C,which in turn reinforced the viral effects on C emissions.Furthermore,the accumulation of dissolved and metal-bound organic C was always associated with the microbial utilization of dissolved organic nitrogen(N),highlighting the coupled C and N cycling during the viral shuttle process.Our research demonstrates for the first time the virus-mediated coupling of C and N cycling in soils and the dual role of viruses in soil C release and stabilization,providing a new understanding of virus-driven soil C cycling.
基金Science and Technology Service Network Initiative of CAS,No.KFJ-SW-STS-169National Natural Science Foundation of China,No.31420103917
文摘Eddy Covariance technique(EC) achieves the direct measurement on ecosystem carbon, nitrogen and water fluxes, and it provides scientific data for accurately assessing ecosystem functions in mitigating global climate change. This paper briefly reviewed the construction and development of Chinese terrestrial ecosystem flux observation and research network(China FLUX), and systematically introduced the design principle and technology of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation system of China FLUX. In addition, this paper summarized the main progress of China FLUX in the ecosystem carbon, nitrogen and water exchange and environmental controlling mechanisms, the spatial pattern of carbon, nitrogen and water fluxes and biogeographical mechanisms, and the regional terrestrial ecosystem carbon budget assessment. Finally, the prospects and emphases of the terrestrial ecosystem carbon, nitrogen and water fluxes coordinated observation of China FLUX are put forward to provide theoretical references for the development of flux observation and research in China.
基金Hubei Provincial Natural Science Foundation of China(Grant No.2025AFA005)Key Research&Development Program of China(Grant No.2019YFA0708400)MOST Special Fund from State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR2025-202)for their financial support。
文摘Atmospheric CO_(2)is a key factor governing Earth's habitability,with its concentration and isotopic variations influenced by both deep and shallow carbon cycles.The Neoproterozoic Era was pivotal for Earth's habitability evolution and global tectonic reorganization,encompassing the assembly-to-breakup of Rodinia and the formation of Gondwana.During this period,marine carbonateδ^(13)C_(PDB)exhibited repeated positive and negative excursions,with the most pronounced negative shift occurring in the Ediacaran(termed the Shuram Excursion,SE).While conventional models attribute SE to organic matter oxidation(due to its13C-depleted signature),this mechanism faces challenges in explaining associated geological features.Notably,the SE event temporally coincides with peak rifting activity and large-scale carbonatite-alkaline magmatism,suggesting a potential deep carbon cycle contribution.Spatial-temporal-compositional correlations imply that tectonic and magmatic processes may play critical roles in carbonateδ^(13)C excursions,necessitating an Earth system approach integrating deep-shallow carbon cycle.Recent studies propose that Neoproterozoicδ^(13)C excursions could originate from deep carbon recycling,with models highlighting subduction-driven decarbonation and melt recycling during supercontinent cycles.These frameworks offer novel insights into the SE enigma.
基金This study has been supported by NASA Carbon Monitoring System Program(NNX14AO73G)NASA IDS Program(NNX10AU06G,NNG04GM39C)U.S.National Science Foundation Grants(AGS-1243220,CNS-1059376).
文摘Greenhouse gas(GHG)-induced climate change is among the most pressing sustainability challenges facing humanity today,posing serious risks for ecosystem health.Methane(CH_(4))and nitrous oxide(N_(2)O)are the two most important GHGs after carbon dioxide(CO_(2)),but their regional and global budgets are not well known.In this study,we applied a process-based coupled biogeochemical model to concurrently estimate the magnitude and spatial and temporal patterns of CH_(4)and N_(2)O fluxes as driven by multiple environmental changes,including climate variability,rising atmospheric CO_(2),increasing nitrogen deposition,tropospheric ozone pollution,land use change,and nitrogen fertilizer use.The estimated CH_(4)and N_(2)O emissions from global land ecosystems during 1981-2010 were 144.39±12.90 Tg C/yr(mean 62 SE;1 Tg=1012 g)and 12.52±0.74 Tg N/yr,respectively.Our simulations indicated a significant(P,0.01)annually increasing trend for CH_(4)(0.43±0.06 Tg C/yr)and N_(2)O(0.14±0.02 Tg N/yr)in the study period.CH_(4)and N_(2)O emissions increased significantly in most climatic zones and continents,especially in the tropical regions and Asia.The most rapid increase in CH_(4)emission was found in natural wetlands and rice fields due to increased rice cultivation area and climate warming.N_(2)O emission increased substantially in all the biome types and the largest increase occurred in upland crops due to increasing air temperature and nitrogen fertilizer use.Clearly,the three major GHGs(CH_(4),N_(2)O,and CO_(2))should be simultaneously considered when evaluating if a policy is effective to mitigate climate change.
