Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than t...Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. Br C is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, Br C could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of Br C(in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic,and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of Br C like Absorption?ngstr€om Exponent(AAE) and Mass Absorption Efficiency(MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning Br C is available. Considering biomass burning as a dominant source of Br C, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of Br C merits more investigation in the future.展开更多
A comparison between simulated land surface fluxes and observed eddy covariance （EC） measurements was conducted to validate Integrated Biosphere Simulator （IBIS） at Tongyu field observation station （44°25＇N...A comparison between simulated land surface fluxes and observed eddy covariance （EC） measurements was conducted to validate Integrated Biosphere Simulator （IBIS） at Tongyu field observation station （44°25＇N, 122°52＇E） in Jilin Province, China. Results showed that the IBIS model could reproduce net ecosystem CO2 exchange （NEE）, sensible and latent heat fluxes reasonably, as indicated by correlation coefficients exceeding the significant level of 0.05. It was also evident that the NEE and sensible heat fluxes were characterized by diurnal and seasonal variation both in the grassland and the cropland ecosystems, while the latent heat fluxes correlated with evapotranspiration, only took on the diurnal variation during the growing season. Moreover, both sensible heat fluxes and the latent heat fluxes were larger in the cropland ecosystem than that in the degraded grassland ecosystem. This different characteristic was possibly correlated with vegetation growing situation in the two kinds of ecosystems. A close agreement between observation and simulation on NEE, sensible heat fluxes and latent heat flux was obtained both in the degraded grassland and the cropland ecosystems. In addition, the annual NEE in the model was overestimated by 23.21% at the grassland and 27.43% at the cropland, sensible heat flux with corresponding 9.90% and 11.98%, respectively, and the annual latent heat flux was underestimated by 4.63% and 3.48%, respectively.展开更多
The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to effici...The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to efficiently reduce the influence of CO2 spring-out.Moreover, collar insertion depth substantially affected soil respiration measurement, i.e. when collar was shallowly inserted into soil,transversal gas diffusion and the CO2 re-spring-out caused by unstable collars in the measurement could lead to overestimating soil respiration rate; however, when collar was deeply inserted into soil, root respiration decline caused by root-cut and the most active respiratory of the surface soil separated by the inserted collars could lead to underestimating soil respiration rate. Furthermore, an error less than 5% could be guaranteed in typical sunny day if the target [CO2] was set to the mean value of ambient [CO2] in most time of the day, but it should be carefully set in early morning and late afternoon according to changing ambient [CO2]. This protocol of measurement is useful in real measurement.展开更多
Diamonds are renowned as the record of Earth's evolution history.Natural diamonds on the Earth can be distinguished in light of genetic types as kimberlitic diamonds(including peridotitic diamonds and eclogitic di...Diamonds are renowned as the record of Earth's evolution history.Natural diamonds on the Earth can be distinguished in light of genetic types as kimberlitic diamonds(including peridotitic diamonds and eclogitic diamonds),ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.According to the inclusion mineralogy,most diamonds originated from continental lithospheric mantle at depths of 140-250 km.Several localities,however,yield ultradeep diamonds with inclusion compositions that require a sublithospheric origin(>~250 km).Ultradeep diamonds exhibit distinctions in terms of carbon isotope composition,N-concentration,mineral inclusions and so on.The present study provides a systematic compilation concerning the features of ultradeep diamonds,based on which to expound their genesis affinity with mantle-carbonate melts.The diamond-parental carbonate melts are proposed to be stemmed from the Earth's crust through subduction of oceanic lithosphere.Ultradeep diamonds are classified into a subgroup attaching to kimberlitic diamonds grounded by formation mechanism,and present connections in respect of carbon origin to eclogitic diamonds,ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.展开更多
基金supported by National Science Foundation of China (41522103, 41501082 and 41225002)Strategic Priority Research Program-Climate Change:Carbon Budget and Relevant Issues (XDA05100105)
文摘Recently, the light-absorbing organic carbon, i.e., brown carbon(Br C), has received an increasing attention, because they could significantly absorb the solar radiation in the range of short wavelengths rather than the purely scattering effect. Br C is ubiquitous in the troposphere. It could undergo long range transport within the atmospheric circulation. After the deposition on the surface of snow or ice in the cryospheric region, as the major light absorbing impurities with black carbon and dust, Br C could reduce the snow albedo and accelerate the glacier melting. In this context, this paper summarized the current knowledge of Br C(in aerosols and snow) in the cryospheric regions including the Arctic, Antarctic,and Alpines. Although some works have been conducted in those region, the current dataset on the optical properties of Br C like Absorption?ngstr€om Exponent(AAE) and Mass Absorption Efficiency(MAE) is still limited, which hampers stimulating an accurate evaluation of its climate effects. Especially in the Himalayas and Tibetan Plateau, where very limited information concerning Br C is available. Considering biomass burning as a dominant source of Br C, a large amount of emissions from biomass burning in South Asia could reach the Himalayas and Tibetan Plateau, where the climate effect of Br C merits more investigation in the future.
基金This paper was supported by the National Basic Research Program of China (2006CB400506).
文摘A comparison between simulated land surface fluxes and observed eddy covariance （EC） measurements was conducted to validate Integrated Biosphere Simulator （IBIS） at Tongyu field observation station （44°25＇N, 122°52＇E） in Jilin Province, China. Results showed that the IBIS model could reproduce net ecosystem CO2 exchange （NEE）, sensible and latent heat fluxes reasonably, as indicated by correlation coefficients exceeding the significant level of 0.05. It was also evident that the NEE and sensible heat fluxes were characterized by diurnal and seasonal variation both in the grassland and the cropland ecosystems, while the latent heat fluxes correlated with evapotranspiration, only took on the diurnal variation during the growing season. Moreover, both sensible heat fluxes and the latent heat fluxes were larger in the cropland ecosystem than that in the degraded grassland ecosystem. This different characteristic was possibly correlated with vegetation growing situation in the two kinds of ecosystems. A close agreement between observation and simulation on NEE, sensible heat fluxes and latent heat flux was obtained both in the degraded grassland and the cropland ecosystems. In addition, the annual NEE in the model was overestimated by 23.21% at the grassland and 27.43% at the cropland, sensible heat flux with corresponding 9.90% and 11.98%, respectively, and the annual latent heat flux was underestimated by 4.63% and 3.48%, respectively.
基金National Natural Science Foundation of China (30300271),Program of Key Basic Research from Ministry of Science and Technology (2004CCA02700) and Sina-Japan cooperation project on larch forest study.
文摘The correct method used in forest soil respiration measurement by Li-6400 is a premise of data quality control. According to the study in a larch plantation, collars should be inserted at 12 hours in advance to efficiently reduce the influence of CO2 spring-out.Moreover, collar insertion depth substantially affected soil respiration measurement, i.e. when collar was shallowly inserted into soil,transversal gas diffusion and the CO2 re-spring-out caused by unstable collars in the measurement could lead to overestimating soil respiration rate; however, when collar was deeply inserted into soil, root respiration decline caused by root-cut and the most active respiratory of the surface soil separated by the inserted collars could lead to underestimating soil respiration rate. Furthermore, an error less than 5% could be guaranteed in typical sunny day if the target [CO2] was set to the mean value of ambient [CO2] in most time of the day, but it should be carefully set in early morning and late afternoon according to changing ambient [CO2]. This protocol of measurement is useful in real measurement.
基金supported by National Natural Science Foundation of China (Grant Nos.U1232204 & 41473056)
文摘Diamonds are renowned as the record of Earth's evolution history.Natural diamonds on the Earth can be distinguished in light of genetic types as kimberlitic diamonds(including peridotitic diamonds and eclogitic diamonds),ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.According to the inclusion mineralogy,most diamonds originated from continental lithospheric mantle at depths of 140-250 km.Several localities,however,yield ultradeep diamonds with inclusion compositions that require a sublithospheric origin(>~250 km).Ultradeep diamonds exhibit distinctions in terms of carbon isotope composition,N-concentration,mineral inclusions and so on.The present study provides a systematic compilation concerning the features of ultradeep diamonds,based on which to expound their genesis affinity with mantle-carbonate melts.The diamond-parental carbonate melts are proposed to be stemmed from the Earth's crust through subduction of oceanic lithosphere.Ultradeep diamonds are classified into a subgroup attaching to kimberlitic diamonds grounded by formation mechanism,and present connections in respect of carbon origin to eclogitic diamonds,ultrahigh-pressure metamorphic diamonds and ophiolitic diamonds.
