Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have r...Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have received a large amount of exogenous nitrogen （N） input from the adjacent agricultural land because of fertilization. In the present study, the effects of nitrogen additions on seed germination and seedling biomass of Calamagrostis angustifolia in freshwater marsh were tested in a greenhouse study. Seed bank soil was exposed to different N additions （0, 5, 10, 20 and 40 g/m^2） under non-flooded water regime. Results revealed that, low level of N additions （less than 10 g/m^2） did not significantly affect the species richness and seedling density, while the seedling biomass at 5 g/m^2 of N addition was higher than other nutrient conditions. But species richness, seedling emergence and biomass decreased significantly at high level of N additions （20-40 g/m^2）. The responses were species-specific. High level of N additions had negative impacts on seed germination, seedling growth and biomass of dominant species Eleocharis ovata, Calamagrostis angustifolia, duncus effusus in the seed bank. To protect and restore the wetland vegetation community in the Sanjiang plain, fertilization, irrigation and land management strategies will need to be implemented to reduce the nutrient input from the agricultural land to the wetlands.展开更多
The purpose of this study is to investigate total mercury （THg） distribution and its bioaccumulation up the soil-plant-grasshopperspider in the Huludao City, which is polluted seriously by chlor-alkali and zinc smel...The purpose of this study is to investigate total mercury （THg） distribution and its bioaccumulation up the soil-plant-grasshopperspider in the Huludao City, which is polluted seriously by chlor-alkali and zinc smelting industry in Northeast of China. Results indicated that average THg concentrations in soil, plant leaves, grasshopper Locusta migratoria manilensis and Acrida chinensis, and spider were 0.151, 0.119, 0.167 and 0.134 mg/kg, respectively. THg spatial distribution suggested that most of mercury came from the chlor-alkali plant and the two zinc smelteries. The highest mercury concentration was found in the wings among different grasshoppers’ organs. Although spiders are the predatory, THg concentrations in their bodies were not high, and only on the same level as in grasshoppers, which might be due to spiders’ special living habits. In the light of the mercury transportation at every stage of the soil-plant-grasshopper-spider food chain, the bioaccumulation factors were 0.03, 0.79–1.11 and 0.80–1.13 respectively. It suggested that mercury biomagnification up terrestrial food chains was not so large and obvious as it was in the aquatic food chain.展开更多
The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 3...The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.展开更多
Herbaceous marsh is the most widely distributed type of marsh wetland ecosystem,and has important ecological functions such as water conservation,climate regulation,carbon storage and fixation,and sheltering rare spec...Herbaceous marsh is the most widely distributed type of marsh wetland ecosystem,and has important ecological functions such as water conservation,climate regulation,carbon storage and fixation,and sheltering rare species.The carbon sequestration function of herbaceous marsh plays a key role in slowing climate warming and maintaining regional environmental stability.Vegetation biomass is an important index reflecting the carbon sequestration capacity of wetlands.Investigating the biomass of marsh vegetation can provide a scientific basis for estimating the carbon storage and carbon sequestration capacity of marshes.Based on field survey data of aboveground biomass of herbaceous marsh vegetation and the distribution data set of marsh in China,we analyzed the aboveground biomass and its spatial distribution pattern of herbaceous marsh on a national scale for the first time.The results showed that in China the total area of herbaceous marsh was 9.7×10^(4) km^(2),the average density of aboveground biomass of herbaceous marsh vegetation was 227.5±23.0 g C m-2(95%confidence interval,the same below),and the total aboveground biomass was 22.2±2.2 Tg C(1 Tg=1012 g).The aboveground biomass density of herbaceous marsh vegetation is generally low in Northeast China and the Tibetan Plateau,and high in central North China and coastal regions in China.In different marsh distribution regions of China,the average biomass density of herbaceous marsh vegetation from small to large was as follows:temperate humid and semi-humid marsh region(182.3±49.3 g C m^(-2))<Tibetan Plateau marsh region(243.9±26.6 g C m-2)<temperate arid and semi-arid marsh region(300.5±73.2 g C m-2)<subtropical humid marsh region(348.4±59.0 g C m-2)<coastal marsh region(675.4±73.8 g C m-2). Due to the different area of herbaceous marsh, the total aboveground biomass of herbaceous marsh vegetation in different marsh distribution regions was the largest in the temperate humid and semi-humid marsh region(9.6±2.6 Tg C), and was the smallest in the coastal marsh region(1.1±0.1 Tg C). The spatial distribution of aboveground biomass of herbaceous marsh vegetation in China has obvious non-zonality characteristics, but also presents certain zonality in some regions. The aboveground biomass of herbaceous marsh vegetation in the Tibetan Plateau decreased with the increase of altitude. With the aggravation of drought, the aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions and temperate arid and semi-arid regions decreased first and then did not obviously change. The aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions was relatively larger in the regions with higher average annual temperature. The results can provide scientific basis for accurately evaluating the adjustment action of wetland ecosystems on climate, and provide decision support for adaptive management of wetland ecosystems.展开更多
Understanding water dynamics is a prerequisite for the restoration of degraded ecosystems in arid and semiarid regions.In this study,we carried out δD and δ^(18)O analyses of precipitation,unsaturated soil water,ove...Understanding water dynamics is a prerequisite for the restoration of degraded ecosystems in arid and semiarid regions.In this study,we carried out δD and δ^(18)O analyses of precipitation,unsaturated soil water,overland flow,surface runoff,and groundwater samples from a seasonally flooded wetland in the Momoge National Nature Reserve of the Songnen Plain,Northeast China,to identify the water sources and understand the mechanisms of unsaturated soil water movement.Unsaturated soil water content(W/W%)at every 20 cm along with a soil profile(0–100 cm)was collected during the growing season,and the HYDRUS-1D model was used to simulate temporal-spatial variations.The results showed that the local meteoric water line(δD=5.90δ18O-7.34,R2=0.95)had a smaller slope and intercept than the global meteoric water line because of strong evaporation at our study site under semi-arid climate.The groundwater was partly recharged by local precipitation via overland flow and unsaturated soil water infiltration.Unsaturated soil water was sourced from both precipitation and groundwater with variations at different depths.The upper soil layer at 0–15 cm was mainly sourced from limited precipitation,while the groundwater could move up to a 25 cm layer during the dry period.The unsaturated soil water content increased with soil depth in the top 40 cm,decreased at depths of 40 to 80 cm,and increased again at depths of 80 to 100 cm.The HYDRUS-1D model could simulate the unsaturated soil water dynamics well in the upper(0–40 cm)and lower(80–100 cm)sections,but poorly for depths of 40–80 cm due to the upward and downward flow.The bidirectional unsaturated soil water movement highlights the importance of capillary groundwater for wetland plants with similar climatic or hydrogeological conditions.展开更多
文摘Over the past five decades, the natural wetlands in Sanjiang Plain, Northeast China, have been extensively reclaimed for agriculture with a total loss of nearly 80% of the surface area and the undrained marshes have received a large amount of exogenous nitrogen （N） input from the adjacent agricultural land because of fertilization. In the present study, the effects of nitrogen additions on seed germination and seedling biomass of Calamagrostis angustifolia in freshwater marsh were tested in a greenhouse study. Seed bank soil was exposed to different N additions （0, 5, 10, 20 and 40 g/m^2） under non-flooded water regime. Results revealed that, low level of N additions （less than 10 g/m^2） did not significantly affect the species richness and seedling density, while the seedling biomass at 5 g/m^2 of N addition was higher than other nutrient conditions. But species richness, seedling emergence and biomass decreased significantly at high level of N additions （20-40 g/m^2）. The responses were species-specific. High level of N additions had negative impacts on seed germination, seedling growth and biomass of dominant species Eleocharis ovata, Calamagrostis angustifolia, duncus effusus in the seed bank. To protect and restore the wetland vegetation community in the Sanjiang plain, fertilization, irrigation and land management strategies will need to be implemented to reduce the nutrient input from the agricultural land to the wetlands.
基金supported by the National Natural Science Foundation of China (No 40830535, 40803021)
文摘The purpose of this study is to investigate total mercury （THg） distribution and its bioaccumulation up the soil-plant-grasshopperspider in the Huludao City, which is polluted seriously by chlor-alkali and zinc smelting industry in Northeast of China. Results indicated that average THg concentrations in soil, plant leaves, grasshopper Locusta migratoria manilensis and Acrida chinensis, and spider were 0.151, 0.119, 0.167 and 0.134 mg/kg, respectively. THg spatial distribution suggested that most of mercury came from the chlor-alkali plant and the two zinc smelteries. The highest mercury concentration was found in the wings among different grasshoppers’ organs. Although spiders are the predatory, THg concentrations in their bodies were not high, and only on the same level as in grasshoppers, which might be due to spiders’ special living habits. In the light of the mercury transportation at every stage of the soil-plant-grasshopper-spider food chain, the bioaccumulation factors were 0.03, 0.79–1.11 and 0.80–1.13 respectively. It suggested that mercury biomagnification up terrestrial food chains was not so large and obvious as it was in the aquatic food chain.
基金support from diverse funding sources,including the National Key Program for S&T Research and Development of the Ministry of Science and Technology(MOST),Yifang Wang's Science Studio of the Ten Thousand Talents Project,the CAS Key Foreign Cooperation Grant,the National Natural Science Foundation of China(NSFC)Beijing Municipal Science&Technology Commission,the CAS Focused Science Grant,the IHEP Innovation Grant,the CAS Lead Special Training Programthe CAS Center for Excellence in Particle Physics,the CAS International Partnership Program,and the CAS/SAFEA International Partnership Program for Creative Research Teams.
文摘The Circular Electron Positron Collider(CEPC)is a large scientific project initiated and hosted by China,fostered through extensive collaboration with international partners.The complex comprises four accelerators:a 30 GeV Linac,a 1.1 GeV Damping Ring,a Booster capable of achieving energies up to 180 GeV,and a Collider operating at varying energy modes(Z,W,H,and tt).The Linac and Damping Ring are situated on the surface,while the subterranean Booster and Collider are housed in a 100 km circumference underground tunnel,strategically accommodating future expansion with provisions for a potential Super Proton Proton Collider(SPPC).The CEPC primarily serves as a Higgs factory.In its baseline design with synchrotron radiation(SR)power of 30 MW per beam,it can achieve a luminosity of 5×10^(34)cm^(-2)s^(-1)per interaction point(IP),resulting in an integrated luminosity of 13 ab^(-1)for two IPs over a decade,producing 2.6 million Higgs bosons.Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons,facilitating precise measurements of Higgs coupling at sub-percent levels,exceeding the precision expected from the HL-LHC by an order of magnitude.This Technical Design Report(TDR)follows the Preliminary Conceptual Design Report(Pre-CDR,2015)and the Conceptual Design Report(CDR,2018),comprehensively detailing the machine's layout,performance metrics,physical design and analysis,technical systems design,R&D and prototyping efforts,and associated civil engineering aspects.Additionally,it includes a cost estimate and a preliminary construction timeline,establishing a framework for forthcoming engineering design phase and site selection procedures.Construction is anticipated to begin around 2027-2028,pending government approval,with an estimated duration of 8 years.The commencement of experiments and data collection could potentially be initiated in the mid-2030s.
基金supported by the National Science&Technology Fundamental Resources Investigation Program of China(Grant No.2013FY111800)the National Natural Science Foundation of China(Grant Nos.41971065 and U19A2042)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant No.ZDBS-LY7019),the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant No.2019235)。
文摘Herbaceous marsh is the most widely distributed type of marsh wetland ecosystem,and has important ecological functions such as water conservation,climate regulation,carbon storage and fixation,and sheltering rare species.The carbon sequestration function of herbaceous marsh plays a key role in slowing climate warming and maintaining regional environmental stability.Vegetation biomass is an important index reflecting the carbon sequestration capacity of wetlands.Investigating the biomass of marsh vegetation can provide a scientific basis for estimating the carbon storage and carbon sequestration capacity of marshes.Based on field survey data of aboveground biomass of herbaceous marsh vegetation and the distribution data set of marsh in China,we analyzed the aboveground biomass and its spatial distribution pattern of herbaceous marsh on a national scale for the first time.The results showed that in China the total area of herbaceous marsh was 9.7×10^(4) km^(2),the average density of aboveground biomass of herbaceous marsh vegetation was 227.5±23.0 g C m-2(95%confidence interval,the same below),and the total aboveground biomass was 22.2±2.2 Tg C(1 Tg=1012 g).The aboveground biomass density of herbaceous marsh vegetation is generally low in Northeast China and the Tibetan Plateau,and high in central North China and coastal regions in China.In different marsh distribution regions of China,the average biomass density of herbaceous marsh vegetation from small to large was as follows:temperate humid and semi-humid marsh region(182.3±49.3 g C m^(-2))<Tibetan Plateau marsh region(243.9±26.6 g C m-2)<temperate arid and semi-arid marsh region(300.5±73.2 g C m-2)<subtropical humid marsh region(348.4±59.0 g C m-2)<coastal marsh region(675.4±73.8 g C m-2). Due to the different area of herbaceous marsh, the total aboveground biomass of herbaceous marsh vegetation in different marsh distribution regions was the largest in the temperate humid and semi-humid marsh region(9.6±2.6 Tg C), and was the smallest in the coastal marsh region(1.1±0.1 Tg C). The spatial distribution of aboveground biomass of herbaceous marsh vegetation in China has obvious non-zonality characteristics, but also presents certain zonality in some regions. The aboveground biomass of herbaceous marsh vegetation in the Tibetan Plateau decreased with the increase of altitude. With the aggravation of drought, the aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions and temperate arid and semi-arid regions decreased first and then did not obviously change. The aboveground biomass of herbaceous marsh vegetation in temperate humid and semi-humid regions was relatively larger in the regions with higher average annual temperature. The results can provide scientific basis for accurately evaluating the adjustment action of wetland ecosystems on climate, and provide decision support for adaptive management of wetland ecosystems.
基金the National Natural Science Foundation of China(42222102,41971136,42171107,42230516)the Department of Science and Technology of Jilin Province(20230508089RC)the Professional Association of the Alliance of International Science Organizations(ANSO-PA-2020-14).
文摘Understanding water dynamics is a prerequisite for the restoration of degraded ecosystems in arid and semiarid regions.In this study,we carried out δD and δ^(18)O analyses of precipitation,unsaturated soil water,overland flow,surface runoff,and groundwater samples from a seasonally flooded wetland in the Momoge National Nature Reserve of the Songnen Plain,Northeast China,to identify the water sources and understand the mechanisms of unsaturated soil water movement.Unsaturated soil water content(W/W%)at every 20 cm along with a soil profile(0–100 cm)was collected during the growing season,and the HYDRUS-1D model was used to simulate temporal-spatial variations.The results showed that the local meteoric water line(δD=5.90δ18O-7.34,R2=0.95)had a smaller slope and intercept than the global meteoric water line because of strong evaporation at our study site under semi-arid climate.The groundwater was partly recharged by local precipitation via overland flow and unsaturated soil water infiltration.Unsaturated soil water was sourced from both precipitation and groundwater with variations at different depths.The upper soil layer at 0–15 cm was mainly sourced from limited precipitation,while the groundwater could move up to a 25 cm layer during the dry period.The unsaturated soil water content increased with soil depth in the top 40 cm,decreased at depths of 40 to 80 cm,and increased again at depths of 80 to 100 cm.The HYDRUS-1D model could simulate the unsaturated soil water dynamics well in the upper(0–40 cm)and lower(80–100 cm)sections,but poorly for depths of 40–80 cm due to the upward and downward flow.The bidirectional unsaturated soil water movement highlights the importance of capillary groundwater for wetland plants with similar climatic or hydrogeological conditions.
