Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transec...Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transect to investigate spatial variability in key nitrogen transformation processes,functional gene abundances,ammonia-oxidizing archaea(AOA)community structures,and key nitrogen transformation regulators.The potential denitrification rates were higher than the nitrification rates in the soil samples,although nitrification may still regulate N2O emissions from tundra soil.The nutrient(total carbon,total organic carbon,total nitrogen,and NH_(4)^(+)-N)contents were important determinants of spatial variability in the potential denitrification rates of soil along the tundra transect.The total sulfurcontent was the main variable controlling potential nitrification processes,probably in association with sulfate-reducing bacteria.The nitrate content was the main variable affecting potential dissimilatory nitrate reduction to ammonium.AOA and ammonia-oxidizing bacteria amoA,nirS,and anammox 16S rRNA genes were found in all of the soil samples.AOA play more important roles than ammonia-oxidizing bacteria in soilnitrification.Anammox bacteria may utilize NO_(2)^(-)produced through nitrification.Phylogenetic analysis indicated that the AOA amoA sequences could be grouped into eight unique operational taxonomic units(OTUs)with a 97%sequence similarity and were affiliated with three group 1.1b Nitrososphaeraclusters.The results indicated that heterogeneous environmental factors(e.g.,the carbon and nitrogen contents of soil)along the High Arctic tundra transect strongly affected the nitrogen transformation rate and relevant functional gene abundances in soil.展开更多
北极夏季无冰区苔原CO_(2)的释放对全球碳循环起着重要的作用。在第4次北极科学考察(2008年7月26日—8月5日)期间,采用密闭箱法在北极新奥尔松(Ny-Ålesund)黄河站区附近的鸟类保护区苔原(Tundra in Seabird Sanctuary,TSB)、普通...北极夏季无冰区苔原CO_(2)的释放对全球碳循环起着重要的作用。在第4次北极科学考察(2008年7月26日—8月5日)期间,采用密闭箱法在北极新奥尔松(Ny-Ålesund)黄河站区附近的鸟类保护区苔原(Tundra in Seabird Sanctuary,TSB)、普通海滩苔原(Tundra in Non-seabird Colony,TNS)和两者间的过渡苔原(Tundra in Transition Zone,TTR)监测CO_(2)净通量(Net CO_(2)Fluxes,NEE)空间变异规律及其影响因素。结果表明:鸟类保护区苔原TSB的平均NEE为(–39.0±6.0)mg·m^(–2)·h^(–1),为CO_(2)吸收汇,且对CO_(2)的吸收随着植被覆盖度和海鸟活动强度的增强而显著增强;普通海滩苔原TNS和过渡苔原TTR的平均NEE分别为(12.0±6.3)mg·m^(–2)·h^(–1)和(40.5±29.3)mg·m^(–2)·h^(–1),均为CO_(2)净排放源。普通海滩苔原TNS的CO_(2)排放强度随土壤水分的减少和地势增高而增强;过渡苔原TTR中高地苔原区的平均NEE为(106.4±23.1)mg·m^(–2)·h^(–1),为CO_(2)强排放源;而泥炭苔原区的平均NEE为(–58.3±9.5)mg·m^(–2)·h^(–1),为CO_(2)强吸收汇。苔原土壤的理化性质对苔原NEE有重要影响,鸟类保护区苔原TSB和普通海滩苔原TNS的NEE与土壤含水率呈显著负相关关系(r=–0.44,P=0.003)。鸟类保护区苔原TSB的NEE与土壤温度弱正相关(r=0.32,P=0.06),与NH4+-N(P<0.05)和NO_(3)^(–)-N(P<0.05)含量均显著负相关。在全球变暖的驱使下,不同地形地貌和海鸟活动特征的北极苔原区域CO_(2)排放的复杂性将显著增强,对全球碳循环产生较大的影响,本研究也将为此提供科研资料。展开更多
Matrix-bound phosphine （MBP） is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. Antarctic seabird guanos and ornith...Matrix-bound phosphine （MBP） is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. Antarctic seabird guanos and ornithogenic soils were used as materials to compare the different digestion methods for transforming matrix-bound phosphine into phosphine gas. The results demonstrated that more phosphine gas in most of Antarctic environmental materials was formed of matrix-bound phosphine by caustic digestion than by acidic digestion. The comparative study on different digestion methods also revealed that the fraction of MBP converted to gaseous phosphine during the digestion depended on the temperature. The optimal digestion temperature was close to 70℃and the optimal digestion time was about 20 min. Acidic conditions were more favorable for the release of matrix-bound phosphine compared to the neutral conditions. A proper water dilution can increase the production and emission of phosphine from the Antarctic penguin guanos.展开更多
In coastal Antarctica, frequent freezing-thawing cycles （FTCs） and changes to the hydrological conditions may affect methane （CH4） and nitrous oxide （N2O） production and respiration rates in tundra soils, which ...In coastal Antarctica, frequent freezing-thawing cycles （FTCs） and changes to the hydrological conditions may affect methane （CH4） and nitrous oxide （N2O） production and respiration rates in tundra soils, which are difficult to observe in situ. Tundra soils including omithogenic tundra soil （OAS）, seal colony soil （SCS） and emperor penguin colony soil （EPS） were collected. In laboratory, we investigated the effects of FTCs and water addition on potential N2O and CH4 production and respiration rates in the soils. The CH4 fluxes from OAS and SCS were much less than that from EPS. Meanwhile, the N2O fluxes from OAS and EPS were much less than that from SCS. The N2O production rates from all soils were extremely low during freezing, but rapidly increased following thawing. In all cases, FTC also induced considerably enhanced soil respiration, indicating that soil respiration response was sensitive to the FTCs. The highest cumulative rates of CH4, N2O and CO2 were 59.5 mg CH4-C·kg-1 in EPS, 6268.8μg N2O-N·kg-1 in SCS and 3522.1mg CO2-C·kg-1 in OAS. Soil water addition had no significant effects on CH4 production and respiration rates, but it could reduce N2O production in OAS and EPS, and it stimulated N2O production in SCS. Overall, CH4 and N2O production rates showed a trade-off relationship during the three FTCs. Our results indicated that FTCs greatly stimulated soil N2O and CO2 production, and water increase has an important effect on soil N2O production in coastal Antarctic tundra.展开更多
To improve our understanding and ability to predict biological responses to global climate change, it is important to be able to distinguish the influences of natural forcing from anthropogenic impacts. In the ice-fre...To improve our understanding and ability to predict biological responses to global climate change, it is important to be able to distinguish the influences of natural forcing from anthropogenic impacts. In the ice-free areas of Antarctica, lake and terrestrial sediments that contain penguin guanos, seal excrement and other biological remains provide natural archives of ecological, geological and climatic information that range from hundreds to thousands of years old. Our review focuses on the paleoecology of typical Antarctic marine organisms （penguins, seals and Antarctic krill） and their responses to climate change and human activities over centennial and millennial timescales. Land-based seabirds and marine mammals play an important role in linking the marine and terrestrial ecosystems and act as bio-vectors, transporting large amounts of nutrients and contaminants from ocean to land.展开更多
The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tun...The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange （NEE）, ecosystem respiration （ER）, and photosynthesis were investigated at six tundra sites （DM1-DM6） on Ny-A.lesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source （-3.3 to 19.0 mg CO2·m-2.h-1）. ER and gross photosynthesis were 42.8 to 92.9 mg CO2·m-2·h-1 and 54.7 to 108.7 mg CO2·m-2·h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Qm value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.展开更多
Methane （CH4） is one of important greenhouse gases with chemical activity. The determination of isotopic compositions for CH4 emitted from the soils helps us to understand its production mechanisms. CH4 isotope meas...Methane （CH4） is one of important greenhouse gases with chemical activity. The determination of isotopic compositions for CH4 emitted from the soils helps us to understand its production mechanisms. CH4 isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of CH4 have been reported from Antarctic tundra soils. In this paper, ornithogenic soil profiles were collected from four penguin colonies, and potential CH4 production rates and its 13C ratio （δ13C） were investigated based upon laboratory incubation experiments. The mean CH4 production rates are highly variable in these soil profiles, ranging from 0.7 to 20.3μg CH4-C kg-1·h-1. These omithogenic soils had high potential production rates of CH4 under ambient air incubation or under N2 incubation, indicating the importance of potential CH4 emissions from penguin colonies. Most of the soil samples had higher δ13C-CH4 under N2 incubation （-39.28%-43.53%） than under the ambient air incubation （-42.81%-57.19%）. Highly anaerobic conditions were conducive to the production of CI-h enriched in 13C, and acetic acid reduction under N2 incubation might be a predominant source for soil CH4 production. Overall the δ13C-CH4 showed a significant negative correlation with CH4 production rates in ornithogenic tundra soils under N2 incubation （R2=0.41,p〈0.01） or under the ambient air incubation （RE=0.50,p〈0.01）. Potential CH4 production from ornithogenic soils showed a significant positive correlation with total phosphorus （TP） and NH4＋-N contents, pH and soil moisture （Mc）, but the δ13C-CH4 showed a significant negative correlation with TP and NH4＋ -N contents, pH and Me, indicating that the deposition amount of penguin guano increased potential CH4 production rates from tundra soils, but decreased the δ13C-CH4. The CH4 emissions from the ornithogenic soils affect carbon isotopic compositions of atmospheric CH4 in coastal Antarctica.展开更多
The relationships of nitrous oxide(N2O)and methane(CH4)emissions to other environmental parameters have been studied extensively in Antarctic terrestrial ecosystems.However,the effects of sunlight on soil N2O and CH4 ...The relationships of nitrous oxide(N2O)and methane(CH4)emissions to other environmental parameters have been studied extensively in Antarctic terrestrial ecosystems.However,the effects of sunlight on soil N2O and CH4 fluxes are neglected across the Antarctic tundra.Here,fluxes of N2O and CH4 from maritime Antarctic tundra soils were measured in the absence and presence of sunlight during three summers.The N2O fluxes averaged-4.6±1.2μg·m^-2·h^-1 in the absence of sunlight and 5.7±1.5μg·m^-2·h^-1 in its presence;CH4 fluxes averaged 119.8±24.5μg·m^-2·h^-1(absence)and-40.5±28.3μg·m^-2·h^-1(presence).The correlations between N2O and CH4 fluxes and other environmental variables(e.g.,soil moisture,temperature,organic and inorganic material)were not statistically significant(P>0.05)at all sites.On average,sunlight significantly increased N2O emissions and CH4 uptake by 10.3μg·m^-2·h^-1 and 160.3μg·m^-2·h^-1,respectively.This study indicates that sunlight is critical for accurately estimating N2O and CH4 budgets from maritime Antarctica and necessary for constraining the role of their emissions from tundra soil.展开更多
Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric....Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric.Scapes yellow,7.2-20 cm.Male inflorescences red,ovoid-ellipsoid,(5-10)cm×(2-6)cm.Male flowers:reddish,actinomorphic,each subtended by a single stout and truncate bract.Perianth lobes 4-6,elliptic-lanceolate,(3-7)mm×(1-2.5)mm.Synandria elliptic-ovate,2.5-5 mm,stalked;anthers 4 or 5,U-shaped,longitudinally dehiscent.Female inflorescences globose,3-5 cm in diam.Spadicles subclavate,to 2 mm,apical 1/2 to 2/3 ellipsoid-obovoid;cuticular ridges of apical cells short but distinct and congested all over.Female flowers:basally on spadicles and main axis of inflorescence.Flowering October to December.展开更多
Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric....Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric.Scapes yellow,7.2-20 cm.Male inflorescences red,ovoid-ellipsoid,(5-10)cm×(2-6)cm.Male flowers:reddish,actinomorphic,each subtended by a single stout and truncate bract.Perianth lobes 4-6,elliptic-lanceolate,(3-7)mm×(1-2.5)mm.Synandria elliptic-ovate,2.5-5 mm,stalked;anthers 4 or 5,U-shaped,longitudinally dehiscent.Female inflorescences globose,3-5 cm in diam.Spadicles subclavate,to 2 mm,apical 1/2 to 2/3 ellipsoid-obovoid;cuticular ridges of apical cells short but distinct and congested all over.Female flowers:basally on spadicles and main axis of inflorescence.Flowering October to December.展开更多
基金This study was funded by the National Key Research and Development Program of China(Grant no.2020YFA0608501)the National Natural Science Foundation of China(Grant no.41976220)the State Key Laboratory of NBC Protection of Civilians(Grant no.SKLNBC2020-10).
文摘Soil nitrogen(N)transformation processes in the High Arctic tundra are poorly understood even though nitrogen is one of the main limiting nutrients.We analyzed soil samples collected along a High Arctic tundra transect to investigate spatial variability in key nitrogen transformation processes,functional gene abundances,ammonia-oxidizing archaea(AOA)community structures,and key nitrogen transformation regulators.The potential denitrification rates were higher than the nitrification rates in the soil samples,although nitrification may still regulate N2O emissions from tundra soil.The nutrient(total carbon,total organic carbon,total nitrogen,and NH_(4)^(+)-N)contents were important determinants of spatial variability in the potential denitrification rates of soil along the tundra transect.The total sulfurcontent was the main variable controlling potential nitrification processes,probably in association with sulfate-reducing bacteria.The nitrate content was the main variable affecting potential dissimilatory nitrate reduction to ammonium.AOA and ammonia-oxidizing bacteria amoA,nirS,and anammox 16S rRNA genes were found in all of the soil samples.AOA play more important roles than ammonia-oxidizing bacteria in soilnitrification.Anammox bacteria may utilize NO_(2)^(-)produced through nitrification.Phylogenetic analysis indicated that the AOA amoA sequences could be grouped into eight unique operational taxonomic units(OTUs)with a 97%sequence similarity and were affiliated with three group 1.1b Nitrososphaeraclusters.The results indicated that heterogeneous environmental factors(e.g.,the carbon and nitrogen contents of soil)along the High Arctic tundra transect strongly affected the nitrogen transformation rate and relevant functional gene abundances in soil.
文摘北极夏季无冰区苔原CO_(2)的释放对全球碳循环起着重要的作用。在第4次北极科学考察(2008年7月26日—8月5日)期间,采用密闭箱法在北极新奥尔松(Ny-Ålesund)黄河站区附近的鸟类保护区苔原(Tundra in Seabird Sanctuary,TSB)、普通海滩苔原(Tundra in Non-seabird Colony,TNS)和两者间的过渡苔原(Tundra in Transition Zone,TTR)监测CO_(2)净通量(Net CO_(2)Fluxes,NEE)空间变异规律及其影响因素。结果表明:鸟类保护区苔原TSB的平均NEE为(–39.0±6.0)mg·m^(–2)·h^(–1),为CO_(2)吸收汇,且对CO_(2)的吸收随着植被覆盖度和海鸟活动强度的增强而显著增强;普通海滩苔原TNS和过渡苔原TTR的平均NEE分别为(12.0±6.3)mg·m^(–2)·h^(–1)和(40.5±29.3)mg·m^(–2)·h^(–1),均为CO_(2)净排放源。普通海滩苔原TNS的CO_(2)排放强度随土壤水分的减少和地势增高而增强;过渡苔原TTR中高地苔原区的平均NEE为(106.4±23.1)mg·m^(–2)·h^(–1),为CO_(2)强排放源;而泥炭苔原区的平均NEE为(–58.3±9.5)mg·m^(–2)·h^(–1),为CO_(2)强吸收汇。苔原土壤的理化性质对苔原NEE有重要影响,鸟类保护区苔原TSB和普通海滩苔原TNS的NEE与土壤含水率呈显著负相关关系(r=–0.44,P=0.003)。鸟类保护区苔原TSB的NEE与土壤温度弱正相关(r=0.32,P=0.06),与NH4+-N(P<0.05)和NO_(3)^(–)-N(P<0.05)含量均显著负相关。在全球变暖的驱使下,不同地形地貌和海鸟活动特征的北极苔原区域CO_(2)排放的复杂性将显著增强,对全球碳循环产生较大的影响,本研究也将为此提供科研资料。
基金supported by the National Natural Sci-ence Foundation of China (No. 40676005)
文摘Matrix-bound phosphine （MBP） is a general term used to indicate non-gaseous reduced phosphorus compounds that are transformed into phosphine gas upon reaction with bases or acids. Antarctic seabird guanos and ornithogenic soils were used as materials to compare the different digestion methods for transforming matrix-bound phosphine into phosphine gas. The results demonstrated that more phosphine gas in most of Antarctic environmental materials was formed of matrix-bound phosphine by caustic digestion than by acidic digestion. The comparative study on different digestion methods also revealed that the fraction of MBP converted to gaseous phosphine during the digestion depended on the temperature. The optimal digestion temperature was close to 70℃and the optimal digestion time was about 20 min. Acidic conditions were more favorable for the release of matrix-bound phosphine compared to the neutral conditions. A proper water dilution can increase the production and emission of phosphine from the Antarctic penguin guanos.
基金supported by the National Natural Science Foundation of China (Grant nos.41576181,41601304 and 41176171)
文摘In coastal Antarctica, frequent freezing-thawing cycles （FTCs） and changes to the hydrological conditions may affect methane （CH4） and nitrous oxide （N2O） production and respiration rates in tundra soils, which are difficult to observe in situ. Tundra soils including omithogenic tundra soil （OAS）, seal colony soil （SCS） and emperor penguin colony soil （EPS） were collected. In laboratory, we investigated the effects of FTCs and water addition on potential N2O and CH4 production and respiration rates in the soils. The CH4 fluxes from OAS and SCS were much less than that from EPS. Meanwhile, the N2O fluxes from OAS and EPS were much less than that from SCS. The N2O production rates from all soils were extremely low during freezing, but rapidly increased following thawing. In all cases, FTC also induced considerably enhanced soil respiration, indicating that soil respiration response was sensitive to the FTCs. The highest cumulative rates of CH4, N2O and CO2 were 59.5 mg CH4-C·kg-1 in EPS, 6268.8μg N2O-N·kg-1 in SCS and 3522.1mg CO2-C·kg-1 in OAS. Soil water addition had no significant effects on CH4 production and respiration rates, but it could reduce N2O production in OAS and EPS, and it stimulated N2O production in SCS. Overall, CH4 and N2O production rates showed a trade-off relationship during the three FTCs. Our results indicated that FTCs greatly stimulated soil N2O and CO2 production, and water increase has an important effect on soil N2O production in coastal Antarctic tundra.
基金funded by the Chinese Polar Environment Comprehensive Investigation and Assessment Program (Grant nos. CHINARE2017-02-01, 2017-04-04, 2017-04-01)
文摘To improve our understanding and ability to predict biological responses to global climate change, it is important to be able to distinguish the influences of natural forcing from anthropogenic impacts. In the ice-free areas of Antarctica, lake and terrestrial sediments that contain penguin guanos, seal excrement and other biological remains provide natural archives of ecological, geological and climatic information that range from hundreds to thousands of years old. Our review focuses on the paleoecology of typical Antarctic marine organisms （penguins, seals and Antarctic krill） and their responses to climate change and human activities over centennial and millennial timescales. Land-based seabirds and marine mammals play an important role in linking the marine and terrestrial ecosystems and act as bio-vectors, transporting large amounts of nutrients and contaminants from ocean to land.
基金supported by the National Natural Science Foundation of China (Grant nos.41576181 and 41176171)Specialized Research Fund for the Doctoral Program of Higher Education (Grant no.20123402110026)
文摘The Arctic ecosystem, especially High Arctic tundra, plays a unique role in the global carbon cycle because of amplified warming in the region. However, relatively little research has been conducted in High Arctic tundra compared with other global ecosystems. In the present work, summertime net ecosystem exchange （NEE）, ecosystem respiration （ER）, and photosynthesis were investigated at six tundra sites （DM1-DM6） on Ny-A.lesund in the High Arctic. NEE at the tundra sites varied between a weak sink and strong source （-3.3 to 19.0 mg CO2·m-2.h-1）. ER and gross photosynthesis were 42.8 to 92.9 mg CO2·m-2·h-1 and 54.7 to 108.7 mg CO2·m-2·h-1, respectively. The NEE variations showed a significant correlation with photosynthesis rates, whereas no significant correlation was found with ecosystem respiration, indicating that NEE variations across the region were controlled by differences in net uptake of CO2 owing to photosynthesis, rather than by variations in ER. A Qm value of 1.80 indicated weak temperature sensitivity of tundra ER and its response to future global warming. NEE and gross photosynthesis also showed relatively strong correlations with C/N ratio. The tundra ER, NEE, and gross photosynthesis showed variations over slightly waterlogged wetland tundra, mesic and dry tundra. Overall, soil temperature, nutrients and moisture can be key effects on CO2 fluxes, ecosystem respiration, and NEE in the High Arctic.
基金supported by the National Natural Science Foundation of China (Grant nos.41576181,41176171)Specialized Research Fund for the Doctoral Program of Higher Education (Grant no.20123402110026)
文摘Methane （CH4） is one of important greenhouse gases with chemical activity. The determination of isotopic compositions for CH4 emitted from the soils helps us to understand its production mechanisms. CH4 isotope measurements have been conducted for different types of global terrestrial ecosystems. However, no isotopic data of CH4 have been reported from Antarctic tundra soils. In this paper, ornithogenic soil profiles were collected from four penguin colonies, and potential CH4 production rates and its 13C ratio （δ13C） were investigated based upon laboratory incubation experiments. The mean CH4 production rates are highly variable in these soil profiles, ranging from 0.7 to 20.3μg CH4-C kg-1·h-1. These omithogenic soils had high potential production rates of CH4 under ambient air incubation or under N2 incubation, indicating the importance of potential CH4 emissions from penguin colonies. Most of the soil samples had higher δ13C-CH4 under N2 incubation （-39.28%-43.53%） than under the ambient air incubation （-42.81%-57.19%）. Highly anaerobic conditions were conducive to the production of CI-h enriched in 13C, and acetic acid reduction under N2 incubation might be a predominant source for soil CH4 production. Overall the δ13C-CH4 showed a significant negative correlation with CH4 production rates in ornithogenic tundra soils under N2 incubation （R2=0.41,p〈0.01） or under the ambient air incubation （RE=0.50,p〈0.01）. Potential CH4 production from ornithogenic soils showed a significant positive correlation with total phosphorus （TP） and NH4＋-N contents, pH and soil moisture （Mc）, but the δ13C-CH4 showed a significant negative correlation with TP and NH4＋ -N contents, pH and Me, indicating that the deposition amount of penguin guano increased potential CH4 production rates from tundra soils, but decreased the δ13C-CH4. The CH4 emissions from the ornithogenic soils affect carbon isotopic compositions of atmospheric CH4 in coastal Antarctica.
基金supported by the National Natural Science Foundation of China(Grant nos.41776190,41976220)。
文摘The relationships of nitrous oxide(N2O)and methane(CH4)emissions to other environmental parameters have been studied extensively in Antarctic terrestrial ecosystems.However,the effects of sunlight on soil N2O and CH4 fluxes are neglected across the Antarctic tundra.Here,fluxes of N2O and CH4 from maritime Antarctic tundra soils were measured in the absence and presence of sunlight during three summers.The N2O fluxes averaged-4.6±1.2μg·m^-2·h^-1 in the absence of sunlight and 5.7±1.5μg·m^-2·h^-1 in its presence;CH4 fluxes averaged 119.8±24.5μg·m^-2·h^-1(absence)and-40.5±28.3μg·m^-2·h^-1(presence).The correlations between N2O and CH4 fluxes and other environmental variables(e.g.,soil moisture,temperature,organic and inorganic material)were not statistically significant(P>0.05)at all sites.On average,sunlight significantly increased N2O emissions and CH4 uptake by 10.3μg·m^-2·h^-1 and 160.3μg·m^-2·h^-1,respectively.This study indicates that sunlight is critical for accurately estimating N2O and CH4 budgets from maritime Antarctica and necessary for constraining the role of their emissions from tundra soil.
文摘Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric.Scapes yellow,7.2-20 cm.Male inflorescences red,ovoid-ellipsoid,(5-10)cm×(2-6)cm.Male flowers:reddish,actinomorphic,each subtended by a single stout and truncate bract.Perianth lobes 4-6,elliptic-lanceolate,(3-7)mm×(1-2.5)mm.Synandria elliptic-ovate,2.5-5 mm,stalked;anthers 4 or 5,U-shaped,longitudinally dehiscent.Female inflorescences globose,3-5 cm in diam.Spadicles subclavate,to 2 mm,apical 1/2 to 2/3 ellipsoid-obovoid;cuticular ridges of apical cells short but distinct and congested all over.Female flowers:basally on spadicles and main axis of inflorescence.Flowering October to December.
文摘Balanophora indica(Arn.)Griff.belongs to Balanophoraceae.Plants dioecious.Rhizome yellowish orange to brown,surface coarsely tessellated and with stellate warts;branches subglobose,0.5-5.6 cm in diam,rarely cylindric.Scapes yellow,7.2-20 cm.Male inflorescences red,ovoid-ellipsoid,(5-10)cm×(2-6)cm.Male flowers:reddish,actinomorphic,each subtended by a single stout and truncate bract.Perianth lobes 4-6,elliptic-lanceolate,(3-7)mm×(1-2.5)mm.Synandria elliptic-ovate,2.5-5 mm,stalked;anthers 4 or 5,U-shaped,longitudinally dehiscent.Female inflorescences globose,3-5 cm in diam.Spadicles subclavate,to 2 mm,apical 1/2 to 2/3 ellipsoid-obovoid;cuticular ridges of apical cells short but distinct and congested all over.Female flowers:basally on spadicles and main axis of inflorescence.Flowering October to December.
