Due to the record-breaking wildfires that occurred in Canada in 2023,unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere.The wildfires had emitted more than 1.3 Pg CO_(2)a...Due to the record-breaking wildfires that occurred in Canada in 2023,unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere.The wildfires had emitted more than 1.3 Pg CO_(2)and 0.14 Pg CO_(2)equivalent of other greenhouse gases(GHG)including CH4 and N_(2)O as of 31 August.The wildfire-related GHG emissions constituted more than doubled Canada’s planned cumulative anthropogenic emissions reductions in 10 years,which represents a significant challenge to climate mitigation efforts.The model simulations showed that the Canadian wildfires impacted not only the local air quality but also that of most areas in the northern hemisphere due to long-range transport,causing severe PM_(2.5)pollution in the northeastern United States and increasing daily mean PM_(2.5)concentration in northwestern China by up to 2μg m-3.The observed maximum daily mean PM_(2.5)concentration in New York City reached 148.3μg m-3,which was their worst air quality in more than 50 years,nearly 10 times that of the air quality guideline(i.e.,15μg m-3)issued by the World Health Organization(WHO).Aside from the direct emissions from forest fires,the peat fires beneath the surface might smolder for several months or even longer and release substantial amounts of CO_(2).The substantial amounts of greenhouse gases from forest and peat fires might contribute to the positive feedback to the climate,potentially accelerating global warming.To better understand the comprehensive environmental effects of wildfires and their interactions with the climate system,more detailed research based on advanced observations and Earth System Models is essential.展开更多
The Lower Cretaceous Manville Group of Upper Mc Murray Formation is one of the main bitumen reservoirs in Athabasca.In this study,the relationship between reservoirs heterogeneity and bitumen geochemical characteristi...The Lower Cretaceous Manville Group of Upper Mc Murray Formation is one of the main bitumen reservoirs in Athabasca.In this study,the relationship between reservoirs heterogeneity and bitumen geochemical characteristics were analyzed through core and microscopic observation,lab analysis,petrophysics and logging data.Based on the sedimentology framework,the formation environment of high-quality oil sand reservoirs and their significance for development were discussed.The results indicate that four types lithofacies were recognized in the Upper Mc Murray Formation based on their depositional characteristics.Each lithofacies reservoirs has unique physical properties,and is subject to varying degrees of degradation,resulting in diversity of bitumen content and geochemical composition.The tidal bar(TB)or tidal channel(TC)facies reservoir have excellent physical properties,which are evaluated as gas or water intervals due to strong degradation.The reservoir of sand bar(SB)facies was evaluated as oil intervals,due to its poor physical properties and weak degradation.The reservoir of mixed flat(MF)facies is composed of sand intercalated with laminated shale,which is evaluated as poor oil intervals due to its poor connectivity.The shale content in oil sand reservoir is very important for the reservoir physical properties and bitumen degradation degree.In the context of regional biodegradation,oil sand reservoirs with good physical properties will suffer from strong degradation,while oil sand reservoirs with relatively poor physical properties are more conducive to the bitumen preservation.展开更多
The Canada Basin is the largest basin in the Arctic Ocean.Its unique physical features have the highest concentration of nutrients being found in the subsurface layer,referred to as the subsurface nutrient maximum lay...The Canada Basin is the largest basin in the Arctic Ocean.Its unique physical features have the highest concentration of nutrients being found in the subsurface layer,referred to as the subsurface nutrient maximum layer(SNM).Under climate change in the Arctic,the SNM is an essential material base for primary productivity.However,long-term trends of nutrient variations and dominant factors related to nutrient levels in the SNM are still unclear.In this study,we analyzed the SNM variations and main influencing factors of the Canada Basin based on the Global Ocean Data Analysis Project Version 2 between 1990 and 2015 and the Chinese Arctic Research Expedition between 2010 and 2016.We found that the nutrient concentrations in the SNM were relatively stable for decades[average concentrations of nitrate,phosphate,and silicate were(13.6±2.4)μmol/L,(1.8±0.2)μmol/L,and(31.5±5.7)μmol/L,respectively].Nutrient reservoirs were dominated by physical processes.Inflow and outflow water of the SNM contributed about 60.4%and-50.2%to the nutrient stocks,respectively,while particle deposition and remineralization in the Canada Basin contributed approximately one-third to the nutrient stocks.Nitrogen fixation and denitrification in the Canada Basin had no substantial impact on nutrient stocks.The overall stabilization of the SNM over the past few decades implied that the SNM would not substantially affect short term primary productivity.Understanding the long-term trends and dominant factors of reservoirs in the SNM will provide useful insights into the changing Canada Basin ecosystem.展开更多
Colombia and Canada are the only jurisdictions in the Americas that have adopted countrywide frameworks on medical assistance in dying(MAiD),also known as physicianassisted death,for terminal and non-terminal illnesse...Colombia and Canada are the only jurisdictions in the Americas that have adopted countrywide frameworks on medical assistance in dying(MAiD),also known as physicianassisted death,for terminal and non-terminal illnesses.Both countries have excluded mental illness as a sole condition from eligibility to date.In this forum article,we adopt the notion of truncated autonomy to critically analyse how individuals with mental illness have been impacted by specific instances of legislative inaction and misdirected action,identified throughout the development of the current legislative frameworks on MAiD in each country.展开更多
The stakeholders'perceptions of forest ecosystem services(FESs)vary among different stakeholder groups.This study,using China's Shennongjia National Park Pilot(SNP)and Canada's Banff National Park(BNP)as c...The stakeholders'perceptions of forest ecosystem services(FESs)vary among different stakeholder groups.This study,using China's Shennongjia National Park Pilot(SNP)and Canada's Banff National Park(BNP)as case studies,identifies and evaluates the preference characteristics of key stakeholders(including farmers,individual operators,government officials,and tourists)toward various FESs.We utilized Q-methodology and semistructured interviews to conduct a sorting of 23 Q-statements regarding FESs,across 7 categories(ranging from−3 to+3),with 24 Q-participants.Stakeholders'preferences toward FESs were categorized into 3 common perspectives:tourism and culture,production and livelihood,and ecological conservation.Different types of stakeholders hold both consensus and divergence regarding their views on FESs.For instance,there was strong consensus on services related to“natural ecotourism and biodiversity conservation”,while stakeholders expressed strong opposition regarding services related to“forest protection”.Furthermore,stakeholders elucidated the reasons behind their preferences for different types of FESs.Overall,our study indicates that besides considering the services provided by forests themselves,policymakers also need to pay attention to the preferences and divergences in needs among stakeholders of national parks.This ensures a more comprehensive fulfillment of diverse societal needs and facilitates the formulation of more effective policies to promote the sustainable management and conservation of national parks.展开更多
This article analyzes Canada’s economic system from a systems thinking perspective.The content includes patterns of public choice(party system and power distribution),organizational framework of decision-making arran...This article analyzes Canada’s economic system from a systems thinking perspective.The content includes patterns of public choice(party system and power distribution),organizational framework of decision-making arrangements,information provision and coordination mechanisms,property rights system,incentive system,and welfare system.Canada’s economic system significantly influences the development of the Canadian economy,and its economic system arrangements hold reference significance for other developed and developing countries.展开更多
基金the National Natural Science Foundation of China(Grant No.92044302)the National Key Research and Development Program(Grant Nos.2020YFA0607801,2022YFE0106500)the National Key Scientific and Technological Infrastructure project“Earth System Numerical Simulation Facility”(EarthLab).
文摘Due to the record-breaking wildfires that occurred in Canada in 2023,unprecedented quantities of air pollutants and greenhouse gases were released into the atmosphere.The wildfires had emitted more than 1.3 Pg CO_(2)and 0.14 Pg CO_(2)equivalent of other greenhouse gases(GHG)including CH4 and N_(2)O as of 31 August.The wildfire-related GHG emissions constituted more than doubled Canada’s planned cumulative anthropogenic emissions reductions in 10 years,which represents a significant challenge to climate mitigation efforts.The model simulations showed that the Canadian wildfires impacted not only the local air quality but also that of most areas in the northern hemisphere due to long-range transport,causing severe PM_(2.5)pollution in the northeastern United States and increasing daily mean PM_(2.5)concentration in northwestern China by up to 2μg m-3.The observed maximum daily mean PM_(2.5)concentration in New York City reached 148.3μg m-3,which was their worst air quality in more than 50 years,nearly 10 times that of the air quality guideline(i.e.,15μg m-3)issued by the World Health Organization(WHO).Aside from the direct emissions from forest fires,the peat fires beneath the surface might smolder for several months or even longer and release substantial amounts of CO_(2).The substantial amounts of greenhouse gases from forest and peat fires might contribute to the positive feedback to the climate,potentially accelerating global warming.To better understand the comprehensive environmental effects of wildfires and their interactions with the climate system,more detailed research based on advanced observations and Earth System Models is essential.
基金sponsored by Major Science and Technology Special Project of CNPC(Grant No.2023ZZ07)。
文摘The Lower Cretaceous Manville Group of Upper Mc Murray Formation is one of the main bitumen reservoirs in Athabasca.In this study,the relationship between reservoirs heterogeneity and bitumen geochemical characteristics were analyzed through core and microscopic observation,lab analysis,petrophysics and logging data.Based on the sedimentology framework,the formation environment of high-quality oil sand reservoirs and their significance for development were discussed.The results indicate that four types lithofacies were recognized in the Upper Mc Murray Formation based on their depositional characteristics.Each lithofacies reservoirs has unique physical properties,and is subject to varying degrees of degradation,resulting in diversity of bitumen content and geochemical composition.The tidal bar(TB)or tidal channel(TC)facies reservoir have excellent physical properties,which are evaluated as gas or water intervals due to strong degradation.The reservoir of sand bar(SB)facies was evaluated as oil intervals,due to its poor physical properties and weak degradation.The reservoir of mixed flat(MF)facies is composed of sand intercalated with laminated shale,which is evaluated as poor oil intervals due to its poor connectivity.The shale content in oil sand reservoir is very important for the reservoir physical properties and bitumen degradation degree.In the context of regional biodegradation,oil sand reservoirs with good physical properties will suffer from strong degradation,while oil sand reservoirs with relatively poor physical properties are more conducive to the bitumen preservation.
基金The National Natural Science Foundation of China under contract No.41941013the National Key R&D Program of China under contract No.2019YFE0120900.
文摘The Canada Basin is the largest basin in the Arctic Ocean.Its unique physical features have the highest concentration of nutrients being found in the subsurface layer,referred to as the subsurface nutrient maximum layer(SNM).Under climate change in the Arctic,the SNM is an essential material base for primary productivity.However,long-term trends of nutrient variations and dominant factors related to nutrient levels in the SNM are still unclear.In this study,we analyzed the SNM variations and main influencing factors of the Canada Basin based on the Global Ocean Data Analysis Project Version 2 between 1990 and 2015 and the Chinese Arctic Research Expedition between 2010 and 2016.We found that the nutrient concentrations in the SNM were relatively stable for decades[average concentrations of nitrate,phosphate,and silicate were(13.6±2.4)μmol/L,(1.8±0.2)μmol/L,and(31.5±5.7)μmol/L,respectively].Nutrient reservoirs were dominated by physical processes.Inflow and outflow water of the SNM contributed about 60.4%and-50.2%to the nutrient stocks,respectively,while particle deposition and remineralization in the Canada Basin contributed approximately one-third to the nutrient stocks.Nitrogen fixation and denitrification in the Canada Basin had no substantial impact on nutrient stocks.The overall stabilization of the SNM over the past few decades implied that the SNM would not substantially affect short term primary productivity.Understanding the long-term trends and dominant factors of reservoirs in the SNM will provide useful insights into the changing Canada Basin ecosystem.
文摘Colombia and Canada are the only jurisdictions in the Americas that have adopted countrywide frameworks on medical assistance in dying(MAiD),also known as physicianassisted death,for terminal and non-terminal illnesses.Both countries have excluded mental illness as a sole condition from eligibility to date.In this forum article,we adopt the notion of truncated autonomy to critically analyse how individuals with mental illness have been impacted by specific instances of legislative inaction and misdirected action,identified throughout the development of the current legislative frameworks on MAiD in each country.
基金supported by the China Scholarship Council(grant no.202206760062)the National Natural Science Foundation of China(grant no.32471863)+2 种基金the Project of Background Resources Survey in Shennongjia National Park(SNJNP2023013)the Open Project Fund of Hubei Provincial Key Laboratory for Conservation Biology of Shennongjia Snubnosed Monkeys(SNJGKL2023013)UBC-APFNet National Park Research(grant no.GR025939)
文摘The stakeholders'perceptions of forest ecosystem services(FESs)vary among different stakeholder groups.This study,using China's Shennongjia National Park Pilot(SNP)and Canada's Banff National Park(BNP)as case studies,identifies and evaluates the preference characteristics of key stakeholders(including farmers,individual operators,government officials,and tourists)toward various FESs.We utilized Q-methodology and semistructured interviews to conduct a sorting of 23 Q-statements regarding FESs,across 7 categories(ranging from−3 to+3),with 24 Q-participants.Stakeholders'preferences toward FESs were categorized into 3 common perspectives:tourism and culture,production and livelihood,and ecological conservation.Different types of stakeholders hold both consensus and divergence regarding their views on FESs.For instance,there was strong consensus on services related to“natural ecotourism and biodiversity conservation”,while stakeholders expressed strong opposition regarding services related to“forest protection”.Furthermore,stakeholders elucidated the reasons behind their preferences for different types of FESs.Overall,our study indicates that besides considering the services provided by forests themselves,policymakers also need to pay attention to the preferences and divergences in needs among stakeholders of national parks.This ensures a more comprehensive fulfillment of diverse societal needs and facilitates the formulation of more effective policies to promote the sustainable management and conservation of national parks.
文摘This article analyzes Canada’s economic system from a systems thinking perspective.The content includes patterns of public choice(party system and power distribution),organizational framework of decision-making arrangements,information provision and coordination mechanisms,property rights system,incentive system,and welfare system.Canada’s economic system significantly influences the development of the Canadian economy,and its economic system arrangements hold reference significance for other developed and developing countries.
