Based on the meteorological and hydrologic data in the Lijang （丽江） basin from 1979 to 2006, variational trend and characteristics of climate change and its effect on runoff in Yanggong （漾弓） River were examined...Based on the meteorological and hydrologic data in the Lijang （丽江） basin from 1979 to 2006, variational trend and characteristics of climate change and its effect on runoff in Yanggong （漾弓） River were examined in the study. The results show that the temperature have significantly increased in the drainage basin during the past 28 years. The average temperature increased markedly from 1979 to 2006, and the increase of temperature in winter was higher than those in other seasons. The annual precipitation varied with a slightly upward trend in the same period, suggesting that the increase mainly occurred in spring and summer while the decrease occurred in autumn and winter. The streamflow at Yanggong River showed a significant increasing trend. During the four seasons, spring experienced the most significant increase, and autumn experienced the smallest. On the basis of the above study, we found that the increasing trend in runoff was more significant than the increase in precipitation in the study area. That was the synactic results of variation of groundwater, ice-snow meltwater and precipitation caused by global climate change.展开更多
Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and...Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and compare the cumulative effects on carbon dynamics of forest management and climate change on boreal and northern temperate forest sector in eastern Canada for the 2020–2100 period.Methods:We used the spatially explicit forest landscape model LANDIS-II and its extension Forest Carbon Suc-cession,in conjunction with the Carbon Budget Model for Harvested Wood Products framework.We simulated the dynamics of forest composition and carbon flows from forest ecosystems to wood products and their substitution effect on markets under increasing climate forcing,according to a tonne-year approach.Simulations were con-ducted for a series of forest management scenarios based on realistic practices principally by clearcut in the boreal territory and continuous-cover forestry in the northern temperate one.These scenarios included:i)a business-as-usual scenario(BaU),representing the current management strategy,ii)increased harvesting by 6.3%to 13.9%,iii)increased conservation(i.e.reduced harvesting by 11.1%to 49.8%),iiii)and a scenario representing the natural evolution of the forest landscape(i.e.without any management activity).Results:Our study revealed that increasing harvesting levels had contrasting effects on the mitigation potential in northern temperate(enhance net sequestration)and boreal forest sector(enhance net emissions)in comparison to the BaU from 2040 onwards,regardless of the future climate.Carbon storage in wood products and the substi-tution effect were not sufficient to offset carbon emissions from ecosystems.Moreover,climate change had a strong impact on the capacity of both landscapes to act as carbon sinks.Northern temperate landscapes became a net source of carbon over time due to their greater vulnerability to climate change than boreal landscapes.Conclusions:Our study highlights the need to consider the initial landscape characteristics in simulations to maximize the mitigation potential of alternative forest management strategies.The optimal management solution can be very different according to the characteristics of forest ecosystems.This opens the possibility of optimizing management for specific forest stands,with the objective of maximizing the mitigation potential of a given landscape.展开更多
Global mitigative and adaptive efforts have not been able to effectively address the adverse impacts caused by climate change.Therefore,a direct solution is needed to address the significant resulting loss and damage(...Global mitigative and adaptive efforts have not been able to effectively address the adverse impacts caused by climate change.Therefore,a direct solution is needed to address the significant resulting loss and damage(L&D).During the United Nations Framework Convention on Climate Change held in Doha in 2012,the issue of responding to L&D arising from climate change gained sudden traction and became one of the key issues that affected the outcome of the convention.In this paper,a study on the definition and connotations of L&D arising from climate change was conducted,together with an analysis of its relationship with related concepts,namely impacts,vulnerability,and risks.This led to the proposal of an L&D conceptual model that is more comprehensive,with the recognition of the need to address the issue through effective supplementation of existing mitigative and adaptive efforts.A systematic elaboration of an L&D response mechanism was made based on politics,law,and the market,leading to a preliminary presentation of a possible format for an L&D mechanism.Potential academic research directions for L&D were also proposed that could serve as references for the establishment of international and national L&D response mechanisms and related research.展开更多
Loss and damage(L&D) from climate change has threatened the sustainable development of humankind,while the progress of mitigative and adaptive measures carried out under the international multilateral framework ha...Loss and damage(L&D) from climate change has threatened the sustainable development of humankind,while the progress of mitigative and adaptive measures carried out under the international multilateral framework has been slow.The scientific community and policymakers have placed increasing emphasis on the international L&D response mechanism as a potential direct solution.This paper reviewed the origins of such a mechanism,with an in-depth analysis of the related connotations.A review of the existing situation in China on work related to L&D arising from climate change was conducted,followed by a summary of the findings.Finally,measures and recommendations to improve China's efforts were proposed in this issue.展开更多
Egypt suffers from the impacts of climate change. Adaption plans should solve the shortage in water resources and increase the use of renewable energy. Detailed data on rainfall as non conventional water and detailed ...Egypt suffers from the impacts of climate change. Adaption plans should solve the shortage in water resources and increase the use of renewable energy. Detailed data on rainfall as non conventional water and detailed data on potential renewable energy are important. The added value of this research is to investigate the suitability of satellite data locally in North Sinai in Egypt. The Tropical Rainfall Measuring Mission (TRMM) satellites and available data from ground rain gauges are studied at North Sinai of Egypt. Local multiplication factors and correlation equations on a monthly basis were developed based on short term historical data. General equation based on short term data was developed to enhance TRMM data for the rainy season to minimize spatial and temporal errors. This equation would be very useful, especially in the ungauged areas in North Sinai to adjust TRMM rainfall data. TRMM data are spatially distributed, so it enhances the hydrology models for runoff estimation. This runoff could be used as non conventional water resource. The runoff was estimated in the RasSudr area in the 2010 storm to be 3.6 (m3/s). The hydropower of this runoff was estimated and ranged from 15,135 to 57,352 (kWh). The solar energy is studied from (NASA) satellite data. The monthly averaged solar energy was estimated to get possible generated power from the solar panel at locations of rainfall ground stations. The generated solar energy would supply self-sufficient energy for ground stations measuring instruments rather than batteries. The results show that a small solar panel project of 200 (m2) could safe electric network power by generating about 20,385 (kWh/year). The results of this study could help in enhancing adapting plans for climate change and runoff estimation model that needs grid data, especially in the area lacking ground data.展开更多
Tectonic and environmental patterns and evolution of the present North Tibetan Plateau （NTP） prior to the India collision with Asia is significant to understand the formation of the Tibetan Plateau and its influence...Tectonic and environmental patterns and evolution of the present North Tibetan Plateau （NTP） prior to the India collision with Asia is significant to understand the formation of the Tibetan Plateau and its influence on the environment.In this study,we integrated and analyzed the tectonostratigraphy and the special sedimentary layers whose climatic implications are clear in the NTP.Additionally,we stressed the tectonic and environmental events and their evolutions from the Mesozoic to the Early Cenozoic.Our results show that four tectonic phases,which sequentially took place during the Triassic,Jurassic,Cretaceous and Paleogene,played an important role on the formation of the North Tibet.The climate was basically dry and hot from the Triassic to the Eocene and became dry and cool since the Oligocene in this region.The climatic evolution was characterized by a transition from a wet and hot phase during the Triassic-Middle Jurassic,to a dry and hot phase during the Late Jurassic-Eocene.Both phases encompassed 5 wet and hot periods followed by 5 dry and hot climate events,respectively.In addition,we found that the tectonic deformation and the climatic conditions were spatially and temporally different.In detail,in the regions north of the PaleoTian Shan and Paleo-Qilian Mts.the tectonic deformation and climatic condition were stronger and wetter than in regions south of the Paleo-Tian Shan and Paleo-Qilian Mts.during the Late Triassic-Jurassic.Whereas in the Cretaceous,the tectonic movement was intensive in the west but steady in the east,and climate was dry in the south but wet in the north of NTP.The formation of the tectonic and climatic patterns in NTP were the consequence of either global climate change or regional tectonics,including the Paleo-Asian Ocean closure and the Qiangtang block,Lhasa block and India plate collision subsequently to Asia.Furthermore,the regional tectonic events occurred before any global climate change and drove the climatic change in the NTP.展开更多
The seasonal and inter-annual variations of pH and EC （electrical conductivity） at Yulong （玉龙） Snow Mountain, Lijiang （丽江） City, are sensitive to precipitation variations and are important indicators of the ...The seasonal and inter-annual variations of pH and EC （electrical conductivity） at Yulong （玉龙） Snow Mountain, Lijiang （丽江） City, are sensitive to precipitation variations and are important indicators of the atmospheric environment. The pH of summer rainfall at Lijiang City ranges from 6.7 to 7.4, and alkaline mineral salts dominate the variations of rainfall acidity, pH values in the shallow firn profile at Baishui （白水） Glacier No. 1 range from 5.6 to 6.3, and EC values from 2.4 to 7.3 μs/cm. The ranges are lower than those in other firn cores from China because of stronger elution and the influence of marine aerosols. This indicates that environmental records from a monsoonal temperate glacier differ from those at continental glaciers.展开更多
It has been reported that trivalent cerium salts are effective inhibitors for corrosion of AA2024-T3 in neutral to alkaline co rrosive enviro nments,but poor in acidic environments.In this study,work was done for exte...It has been reported that trivalent cerium salts are effective inhibitors for corrosion of AA2024-T3 in neutral to alkaline co rrosive enviro nments,but poor in acidic environments.In this study,work was done for extending corrosion resistance provided by Ce(NO_(3))_(3)to acidic pHs as low as 2.5 through the addition of iodide ions.To this end,potentiodynamic polarization was used to ascertain the optimum Ce(Ⅲ)concentration for the inhibition of AA2024-T3 corrosion in 3.5%NaCl solution.This optimum concentration is found to be in a range between 0.1 and 0.3 mmol/L Ce(Ⅲ).This optimum concentration also gives a maximum width of the passive region under the pitting potential(Epit).Based on this optimization,further work was performed as a function of pH without and in the presence of 0.01 mol/L KI at five pH values(2.5,4,5,7,and 8).Without iodide the best inhibition provided by the Ce(Ⅲ)cation is at pH=7 but active corrosion is observed at pH=2.5 with an estimated inhibitor efficiency(-37.6%).The addition of iodide ions(I^(-))reverses the poor corrosion resistance whereby the inhibitor efficiency becomes 47.7%.Moreover,at pH=4 the efficiency is also increased from 54.0%to 81.0%with iodide addition providing a significant improvement over Ce(Ⅲ)cations alone under acidic conditions.There is a synergistic effect between I-anion and Ce(Ⅲ)cation,which is determined to be 2.4 and 2.1 at pH=2.5and 4.0,respectively.At pH=5 and 7 there is virtually no change in inhibition but at pH=8 the inhibition falls away due to a considerable amount of cerium precipitating out of solution as cerium carbonate.The protective film formed on sites in the aluminium alloy surface at different pH values was examined by both scanning electron microscopy with energy dispersive X-ray analysis and X-ray photoelectron spectroscopy to determine the role of these ions as a function of pH in surface inhibition.It is proposed that at pH=2.5 protection is provided by a bilayer adsorption of iodide with"capping"cerium ions,but at pH=4 protection occurs through precipitate formation on active cathodes thereby shutting down the oxygen reduction reaction.展开更多
Climate change caused by past,current,and future greenhouse gas emissions has become a major concern for scientists in the field in many countries and regions of the world.This study modelled future precipitation chan...Climate change caused by past,current,and future greenhouse gas emissions has become a major concern for scientists in the field in many countries and regions of the world.This study modelled future precipitation change by downscaling a set of large-scale climate predictor variables(predictors)from the second generation Canadian Earth System Model(CanESM2)under two Representative Concentration Pathway(RCP)emission scenarios(RCP4.5 and RCP8.5)in the semi-arid Borana lowland,southern Ethiopia.The Statistical DownScaling Model(SDSM)4.2.9 was employed to downscale and project future precipitation change in the middle(2036-2065;2050s)and far(2066-2095;2080s)future at the local scale.Historical precipitation observations from eight meteorological stations stretching from 1981 to 1995 and 1996 to 2005 were used for the model calibration and validation,respectively,and the time period of 1981-2018 was considered and used as the baseline period to analyze future precipitation change.The results revealed that the surface-specific humidity and the geopotential height at 500 hPa were the preferred large-scale predictors.Compared to the middle future(2050s),precipitation showed a much greater increase in the far future(2080s)under both RCP4.5 and RCP8.5 scenarios at all meteorological stations(except Teletele and Dillo stations).At Teltele station,the projected annual precipitation will decrease by 26.53%(2050s)and 39.45%(2080s)under RCP4.5 scenario,and 34.99%(2050s)and 60.62%(2080s)under RCP8.5 scenario.Seasonally,the main rainy period would shift from spring(March to May)to autumn(September to November)at Dehas,Dire,Moyale,and Teltele stations,but for Arero and Yabelo stations,spring would consistently receive more precipitation than autumn.It can be concluded that future precipitation in the semi-arid Borana lowland is predicted to differ under the two climate scenarios(RCP4.5 and RCP8.5),showing an increasing trend at most meteorological stations.This information could be helpful for policymakers to design adaptation plans in water resources management,and we suggest that the government should give more attention to improve early warning systems in drought-prone areas by providing dependable climate forecast information as early as possible.展开更多
The effects of the cropping system change for paddy field with double harvest rice on crops growth and soil nutrient in red soil were studied. The results indicated that the economic benefit and the ratio of the outpu...The effects of the cropping system change for paddy field with double harvest rice on crops growth and soil nutrient in red soil were studied. The results indicated that the economic benefit and the ratio of the output to input were all increased in terms of the market price for the crops under various treatments. The greatest economic benefit was obtained in the treatment of paddy-upland rotation, and the corresponding economic benefit was increased by 34.7, 21.4, and 2.2% in comparison with that of control （rice-rice-astragali）, pasture, and upland cropping treatments. The economic benefits in pasture and upland cultivation treatments were increased by I 1.0 and 31.8%, respectively, when compared with that of the control treatment （CK）. The ratio of output to input in pasture, paddy-upland rotation, and upland cropping treatments was enhanced by 0.9, 0.6, and 0.3, respectively, in comparison with that of control. To grow pasture is beneficial for improving soil fertility since the contents of soil organic matter, total nitrogen, total phosphorus, and available phosphorus are all enhanced significantly. However, the concentrations of the soil available nitrogen, the total potassium, the available potassium were somewhat reduced in all the treatments, suggesting that increasing the input of nitrogen, particularly potassium, was necessary under the present fertilization level. Based on the conditions of fertility, climate, cultivation, and management of paddy field with double harvest rice in red soil regions, it is feasible to alter the cultivation system of paddy field with bad irrigation condition. In particular, cultivation systems such as pasture and paddy-upland rotation can be selected to extend because better economic benefit and improvement of soil fertility in the purpose region were obtained.展开更多
Herein, we report on the use of chitosan-based engineered materials for the sequestration of naphthenic acid fraction compounds (NAFCs) and other species (matrix) in oil sands process-affected water (OSPW) in order to...Herein, we report on the use of chitosan-based engineered materials for the sequestration of naphthenic acid fraction compounds (NAFCs) and other species (matrix) in oil sands process-affected water (OSPW) in order to improve monitoring of NAFCs after phytoremediation. Chitosan pellets (CPs) were cross linked with glutaraldehyde (GLU) at variable feed ratios and characterized using thermogravimetric analysis (TGA). Sorption studies at equilibrium and kinetic conditions were carried on OSPW extract, raw and treated wetland samples. The materials were shown to have similar sorption capacity for NAFCs but with variable selectivity of the species in the complex mixture. As well, the matrix uptake varied according to the type of OSPW. Overall, CP in its native form outperformed the cross linked CP pellets, as evidenced by a reduction in matrix effects.展开更多
Loss of multiyear ice(MYI)is of great importance for Arctic climate and marine systems and can be monitored using active and passive microwave satellite data.In this paper,we describe an upgraded classification algori...Loss of multiyear ice(MYI)is of great importance for Arctic climate and marine systems and can be monitored using active and passive microwave satellite data.In this paper,we describe an upgraded classification algorithm using the data from the scatterometer and radiometer sensors onboard the Chinese Haiyang-2B(HY-2B)satellite to identify MYI and first-year ice(FYI).The proposed method was established based on K-means and fuzzy clustering(K-means+FC)and was used to focus on the transition zone where the ice condition is complex due to the highly commixing of MYI and FYI,leading to the high challenge for accurate classification of sea ice.The K-means algorithm was applied to preliminarily classify MYI using the combination of scatterometer and radiometer data,followed by applying fuzzy clustering to reclassify MYI in the transition zone.The HY-2B K-means+FC results were compared with the ice type products[including the Ocean and Sea Ice Satellite Application Facility(OSI SAF)sea ice type product and the Equal-Area Scalable Earth-Grid sea ice age dataset],and showed agreement in the time series of MYI extent.Intercomparisons in the transition zone indicated that the HY-2B K-means+FC results can identify more old ice than the OSI SAF product,but with an underestimation in identifying second-year ice.Comparisons between K-means and Kmeans+FC results were performed using regional ice charts and Sentinel-1 synthetic aperture radar(SAR)data.By adding fuzzy clustering,the MYI is more consistent with the ice charts,with the overall accuracy(OA)increasing by 0.9%–6.5%.Comparing against SAR images,it is suggested that more scattered MYI floes can be identified by fuzzy clustering,and the OA is increased by about 3%in middle freezing season and 7%–20%in early and late freezing season.展开更多
This study explores the integration of Synthetic Aperture Radar(SAR)imagery with deep learning and metaheuristic feature optimization techniques for enhanced oil spill detection.This study proposes a novel hybrid appr...This study explores the integration of Synthetic Aperture Radar(SAR)imagery with deep learning and metaheuristic feature optimization techniques for enhanced oil spill detection.This study proposes a novel hybrid approach for oil spill detection.The introduced approach integrates deep transfer learning with the metaheuristic Binary Harris Hawk optimization(BHHO)and Principal Component Analysis(PCA)for improved feature extraction and selection from input SAR imagery.Feature transfer learning of the MobileNet convolutional neural network was employed to extract deep features from the SAR images.The BHHO and PCA algorithms were implemented to identify subsets of optimal features from the entire feature dataset extracted by MobileNet.A supplemented hybrid feature set was constructed from the PCA and BHHO-generated features.It was used as input for oil spill detection using the logistic regression supervised machine learning classification algorithm.Several feature set combinations were implemented to test the classification performance of the logistic regression classifier in comparison to that of the proposed hybrid feature set.Results indicate that the highest oil spill detection accuracy of 99.2%has been achieved using the logistic regression classification algorithm,with integrated feature input from subsets identified using the PCA and the BHHO feature selection techniques.The proposed method yielded a statistically significant improvement in the classification performance of the used machine learning model.The significance of our study lies in its unique integration of deep learning with optimized feature selection,unlike other published studies,to enhance oil spill detection accuracy.展开更多
Based on the meteorological data of 20 stations in the Hengduan Mountains region during 1961–2009, the annual and seasonal variation of potential evapotranspiration was analyzed in combination with the Penman-Monteit...Based on the meteorological data of 20 stations in the Hengduan Mountains region during 1961–2009, the annual and seasonal variation of potential evapotranspiration was analyzed in combination with the Penman-Monteith model. With the method of Spline interpolation under ArcGIS, the spatial distribution of potential evapotranspiration was presented to research the regional difference, and the correlation analysis was used to discuss the dominant factor affecting the potential evapotranspiration. The results indicated that the an-nual potential evapotranspiration showed a decreasing tendency since the 1960s, especially from the 1980s to 1990s, while it showed an increasing tendency since 2000. Regional potential evapotranspiration showed a rate of –0.17 mm a？1. Potential evapotranspiration in north, middle and south of the Hengduan Mountains exhibited decreasing trends over the studied period, and its regional trend was on the decline from southwest to northeast.展开更多
Tamarix spp. （Saltcedar） is a facultative phreatophyte that can tolerate drought when groundwater is not accessed. In addition to deep water uptake, hydraulic redistribution （HR） is another factor contributing to ...Tamarix spp. （Saltcedar） is a facultative phreatophyte that can tolerate drought when groundwater is not accessed. In addition to deep water uptake, hydraulic redistribution （HR） is another factor contributing to the drought tolerance of Tarnarix spp. In this study, data on soil volumetric moisture content （0）, lateral root sap flow, and relevant climate variables were used to investigate the patterns, magnitude, and controlling factors of HR of soil water by roots of Tamarix ramosissima Ledeb. in an extremely arid land in Northwest China. Results showed evident diurnal fluctuations in 0 at the depths of 30 and 50 cm, indicating ＂hydraulic lift＂ （HL）. 0 increased remarkably at 10 and 140 cm but decreased at 30 and 50 cm and slightly changed at 80 cm after rainfall, suggesting a possible ＂hydraulic descent＂ （HD）. However, no direct evidence was observed in the negative flow of lateral roots, supporting HR （including HL and HD） of T. ramosissima. The HR pathway unlikely occurred via lateral roots; instead, HR possibly occurred through adventitious roots with a diameter of 2-5 mm and a length of 60-100 cm. HR at depths of 20-60 cm ranged from 0.01-1.77 mm/d with an average of 0.43 mm/d, which accounted for an average of 22% of the estimated seasonal total water depletion at 0-160 cm during the growing season. The climate factors, particularly vapor pressure deficit and soil water potential gradient, accounted for at least 33% and 45% of HR variations with depths and years, respectively. In summary, T. ramosissima can be added to the wide list of existing species involved in HR. High levels of HR may represent a considerable fraction of daily soil water depletion and substantially improve plant water status. HR could vary tremendously in terms of years and depths, and this variation could be attributed to climate factors and soil water potential gradient.展开更多
Aerosol and snow samples were collected at ablation zone of Baishui （白水） Glacier No. 1, Mt. Yulong （玉龙）, from May to June, 2006. The concentrations of Cl^-, NO3^-, SO4^2-, Na^＋, K^＋, Mg^2＋, and Ca^2＋ were ...Aerosol and snow samples were collected at ablation zone of Baishui （白水） Glacier No. 1, Mt. Yulong （玉龙）, from May to June, 2006. The concentrations of Cl^-, NO3^-, SO4^2-, Na^＋, K^＋, Mg^2＋, and Ca^2＋ were determined by ion chromatograph both in aerosol and snow samples. The average total aerosol loading is 25.45 neq.scm^-1, NO3^- and Na^＋ are the dominant soluble ions in the aerosol, accounting for 39% and 21% of average total aerosol loading, respectively. Monsoon circulation reduces the concentration of most ions, indicating that wet scavenging is effective for aerosol particles. In snow samples, SO4^2- and Ca^2＋ are the dominant anion and cation, respectively. A lower Na^＋/Cl^- ratio was found in fresh snow samples compared to the higher ratio that was found in aerosol samples. Analyzing the difference in SO4^2- and NO3^- in air and fresh snow indicated that the aerosol was influenced by local circulation, but the components in fresh snow samples were from long-distance transport. Enrichment of NO3^- in aerosol samples is attributed to motor exhaust emissions from tourism by calculating the SO4^2-/NO3^- ratio in aerosol and fresh snow samples. The temporal variation and correlation coefficients between soluble species in aerosol samples suggest that Cl^-, Na^＋ and K^＋ come from sea-salt aerosol, and SO4^2-, Mg^2＋ and Ca^2＋ are from continental crust sources.展开更多
To better characterize the optical properties of atmospheric aerosols, the multi-wavelength cavity ring-down aerosol extinction spectrometer(MCRD-AES) is developed and applied in this study. By using tunable light sou...To better characterize the optical properties of atmospheric aerosols, the multi-wavelength cavity ring-down aerosol extinction spectrometer(MCRD-AES) is developed and applied in this study. By using tunable light source and four parallel cavities, the MCRD-AES covers a wide and atmospherically relevant wavelength range from 360 to 663 nm. Four wavelengths(375 nm, 440 nm, 532 nm, and 620 nm) are particularly tested with ammonium sulfate and nigrosine. The refractive index values obtained from this study agree well with literature data. The stability and accuracy of the MCRD-AES are tested, and the minimum detectable extinction coefficient is 0.5 1/Mm. The high sensitivity, high precision, and wavelength changeable of MCRD-AES indicate its great application prospect in comprehensively quantifying the optical properties of atmospheric aerosols.展开更多
Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects...Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects of different concentrations of living/dead algae species,including Aphanizomenon flosaquae (AF) and Microcystis aeruginosa (MA),on the photoreduction rate of Hg2+ under various light conditions.The experimental results showed that percentage reduction of Hg2+ was significantly influenced by radiation wavelengths,and dramatically decreased with the presence of algae.The highest percentage reduction of Hg2+ was induced by UV-A,followed by UV-B,visible light and dark for both living and dead AF,and the order was dark > UV-A > UV-B > visible light for both living and dead MA.There were two aspects,i.e.,energy and attenuation rate of light radiation and excrementitious generated from algae metabolisms,were involved in the processes of Hg2+ photoreduction with the presence of algae under different light conditions.The percentage reduction of Hg2+ decreased from 15% to 11% when living and dead AF concentrations increased by 10 times (from 106 to 105 cells/mL),and decreased from11% to ~9% in the case of living and dead MA increased.Algae can adsorb Hg2+ and decrease the concentration of free Hg2+,thus inhibiting Hg2+ photoreduction,especially under the conditions with high concentrations of algae.No significant differences were found in percentage reduction of Hg2+ between living and dead treatments of algae species.The results are of great importance for understanding the role of algae in Hg2+ photoreduction.展开更多
As indispensable strategic materials for high-tech industries,rare earth elements and yttrium(REY)have become particularly important in recent years,raising the demand of developing new approaches for reclamation of R...As indispensable strategic materials for high-tech industries,rare earth elements and yttrium(REY)have become particularly important in recent years,raising the demand of developing new approaches for reclamation of REY from REY-rich materials such as coal combustion products(CCPs).In this study,five coal-fired power plants(CFPPs)in Guizhou of southwest China were selected for investigating REY concentrations of solid samples,atmospheric emissions,and recovery potentials.REY concentrations of feed fuels are higher in this study(147.2-468.6 mg/kg)than what have been reported previously for coals in China and the world.REY atmospheric emissions are extremely low(38.70-180.11 mg REY/t coal).REY are enriched in bottom ash and fly ash,with average of 658±296 mg/kg and maximum of 1257 mg/kg from the five CFPPs.Relative enrichment factors(REF)of REY in bottom ash and fly ash compared with the feed fuel are 0.86-1.02 and 0.91-1.04,respectively.REY concentrations in desulfurized gypsum are very low(6-17 mg/kg),and that is mostly inherited from limestone.Critical REY(Nd,Eu,Tb,Dy,Y,and Er)in bottom/fly ash account for 34%-39%of the total REY and the outlook coefficients(Cout1)are in the range of 0.89-1.11.This study indicates a promising prospect to reclaim REY from REYrich CCPs(bottom and fly ash)in CFPPs in Guizhou,especially in the central-north Guizhou,although such practices require further technology advancement.展开更多
Antarctic polynyas play an important role in regional atmosphere?ice?ocean interactions and are considered to help generate the global deep ocean conveyer belt.Polynyas therefore have a potential impact on the Earth’...Antarctic polynyas play an important role in regional atmosphere?ice?ocean interactions and are considered to help generate the global deep ocean conveyer belt.Polynyas therefore have a potential impact on the Earth’s climate in terms of the production of sea ice and high-salinity shelf water.In this study,we investigated the relationship between the area of the Terra Nova Bay polynya and the air temperature as well as the eastward and northward wind based on the ERA5 and ERAInterim reanalysis datasets and observations from automatic weather stations during the polar night.We examined the correlation between each factor and the polynya area under different temperature conditions.Previous studies have focused more on the effect of winds on the polynya,but the relationship between air temperature and the polynya area has not been fully investigated.Our study shows,eliminating the influence of winds,lower air temperature has a stronger positive correlation with the polynya area.The results show that the relationship between the polynya area and air temperature is more likely to be interactively influenced.As temperature drops,the relationship of the polynya area with air temperature becomes closer with increasing correlation coefficients.In the low temperature conditions,the correlation coefficients of the polynya area with air temperature are above 0.5,larger than that with the wind speed.展开更多
基金supported by the National Natural Science Foundation of China (No.40971019)the West Light Foundation of Chinese Academy of Sciences (No.O828A11001)+4 种基金the National Basic Research Program of China (No.2007CB411501)the Special Grant for Postgraduate Research,Innovation and Practicethe Major Directionality Program of the Chinese Academy of Sciences (No.KZCX-YW-317)the Fund from the State Key Laboratory of Cryospheric Sciencesthe Fund from Lijiang City Government
文摘Based on the meteorological and hydrologic data in the Lijang （丽江） basin from 1979 to 2006, variational trend and characteristics of climate change and its effect on runoff in Yanggong （漾弓） River were examined in the study. The results show that the temperature have significantly increased in the drainage basin during the past 28 years. The average temperature increased markedly from 1979 to 2006, and the increase of temperature in winter was higher than those in other seasons. The annual precipitation varied with a slightly upward trend in the same period, suggesting that the increase mainly occurred in spring and summer while the decrease occurred in autumn and winter. The streamflow at Yanggong River showed a significant increasing trend. During the four seasons, spring experienced the most significant increase, and autumn experienced the smallest. On the basis of the above study, we found that the increasing trend in runoff was more significant than the increase in precipitation in the study area. That was the synactic results of variation of groundwater, ice-snow meltwater and precipitation caused by global climate change.
基金This study was funded by the Quebec Ministry of Forests,Wildlife,and Parks(contrats de service de recherche forestier 142332156-2018-A and 142332174-E:PI:E.Thiffault)by the Natural Science and Engineering Research Council through a Discovery Grant to E.Thiffault(grant number RGPIN-2018-05755).
文摘Background:Forest based climate mitigation emerged as a key component of the Paris Agreement,and thus re-quires robust science to reduce uncertainties related to such strategies.The aim of this study was to assess and compare the cumulative effects on carbon dynamics of forest management and climate change on boreal and northern temperate forest sector in eastern Canada for the 2020–2100 period.Methods:We used the spatially explicit forest landscape model LANDIS-II and its extension Forest Carbon Suc-cession,in conjunction with the Carbon Budget Model for Harvested Wood Products framework.We simulated the dynamics of forest composition and carbon flows from forest ecosystems to wood products and their substitution effect on markets under increasing climate forcing,according to a tonne-year approach.Simulations were con-ducted for a series of forest management scenarios based on realistic practices principally by clearcut in the boreal territory and continuous-cover forestry in the northern temperate one.These scenarios included:i)a business-as-usual scenario(BaU),representing the current management strategy,ii)increased harvesting by 6.3%to 13.9%,iii)increased conservation(i.e.reduced harvesting by 11.1%to 49.8%),iiii)and a scenario representing the natural evolution of the forest landscape(i.e.without any management activity).Results:Our study revealed that increasing harvesting levels had contrasting effects on the mitigation potential in northern temperate(enhance net sequestration)and boreal forest sector(enhance net emissions)in comparison to the BaU from 2040 onwards,regardless of the future climate.Carbon storage in wood products and the substi-tution effect were not sufficient to offset carbon emissions from ecosystems.Moreover,climate change had a strong impact on the capacity of both landscapes to act as carbon sinks.Northern temperate landscapes became a net source of carbon over time due to their greater vulnerability to climate change than boreal landscapes.Conclusions:Our study highlights the need to consider the initial landscape characteristics in simulations to maximize the mitigation potential of alternative forest management strategies.The optimal management solution can be very different according to the characteristics of forest ecosystems.This opens the possibility of optimizing management for specific forest stands,with the objective of maximizing the mitigation potential of a given landscape.
基金supported by National Key Technologies R&D Program[2012BAC19B01]National Key Technologies R&D Program[2012BAC20B04]+1 种基金National Key Technologies R&D Program[2012BAC09B04]China Clean Development Mechanism Fund[1113113]
文摘Global mitigative and adaptive efforts have not been able to effectively address the adverse impacts caused by climate change.Therefore,a direct solution is needed to address the significant resulting loss and damage(L&D).During the United Nations Framework Convention on Climate Change held in Doha in 2012,the issue of responding to L&D arising from climate change gained sudden traction and became one of the key issues that affected the outcome of the convention.In this paper,a study on the definition and connotations of L&D arising from climate change was conducted,together with an analysis of its relationship with related concepts,namely impacts,vulnerability,and risks.This led to the proposal of an L&D conceptual model that is more comprehensive,with the recognition of the need to address the issue through effective supplementation of existing mitigative and adaptive efforts.A systematic elaboration of an L&D response mechanism was made based on politics,law,and the market,leading to a preliminary presentation of a possible format for an L&D mechanism.Potential academic research directions for L&D were also proposed that could serve as references for the establishment of international and national L&D response mechanisms and related research.
基金supported by National Key Technologies R&D Program[grant number 2012BAC19B01]National Key Technologies R&D Program[grant number 2012BAC20B04]+1 种基金National Key Technologies R&D Program[grant number2012BAC09B04]China Clean Development Mechanism Fund[grant number 1113113]
文摘Loss and damage(L&D) from climate change has threatened the sustainable development of humankind,while the progress of mitigative and adaptive measures carried out under the international multilateral framework has been slow.The scientific community and policymakers have placed increasing emphasis on the international L&D response mechanism as a potential direct solution.This paper reviewed the origins of such a mechanism,with an in-depth analysis of the related connotations.A review of the existing situation in China on work related to L&D arising from climate change was conducted,followed by a summary of the findings.Finally,measures and recommendations to improve China's efforts were proposed in this issue.
文摘Egypt suffers from the impacts of climate change. Adaption plans should solve the shortage in water resources and increase the use of renewable energy. Detailed data on rainfall as non conventional water and detailed data on potential renewable energy are important. The added value of this research is to investigate the suitability of satellite data locally in North Sinai in Egypt. The Tropical Rainfall Measuring Mission (TRMM) satellites and available data from ground rain gauges are studied at North Sinai of Egypt. Local multiplication factors and correlation equations on a monthly basis were developed based on short term historical data. General equation based on short term data was developed to enhance TRMM data for the rainy season to minimize spatial and temporal errors. This equation would be very useful, especially in the ungauged areas in North Sinai to adjust TRMM rainfall data. TRMM data are spatially distributed, so it enhances the hydrology models for runoff estimation. This runoff could be used as non conventional water resource. The runoff was estimated in the RasSudr area in the 2010 storm to be 3.6 (m3/s). The hydropower of this runoff was estimated and ranged from 15,135 to 57,352 (kWh). The solar energy is studied from (NASA) satellite data. The monthly averaged solar energy was estimated to get possible generated power from the solar panel at locations of rainfall ground stations. The generated solar energy would supply self-sufficient energy for ground stations measuring instruments rather than batteries. The results show that a small solar panel project of 200 (m2) could safe electric network power by generating about 20,385 (kWh/year). The results of this study could help in enhancing adapting plans for climate change and runoff estimation model that needs grid data, especially in the area lacking ground data.
基金supported by the Chinese NSFC funds (Nos. 41272127, 41330745, 41021091)
文摘Tectonic and environmental patterns and evolution of the present North Tibetan Plateau （NTP） prior to the India collision with Asia is significant to understand the formation of the Tibetan Plateau and its influence on the environment.In this study,we integrated and analyzed the tectonostratigraphy and the special sedimentary layers whose climatic implications are clear in the NTP.Additionally,we stressed the tectonic and environmental events and their evolutions from the Mesozoic to the Early Cenozoic.Our results show that four tectonic phases,which sequentially took place during the Triassic,Jurassic,Cretaceous and Paleogene,played an important role on the formation of the North Tibet.The climate was basically dry and hot from the Triassic to the Eocene and became dry and cool since the Oligocene in this region.The climatic evolution was characterized by a transition from a wet and hot phase during the Triassic-Middle Jurassic,to a dry and hot phase during the Late Jurassic-Eocene.Both phases encompassed 5 wet and hot periods followed by 5 dry and hot climate events,respectively.In addition,we found that the tectonic deformation and the climatic conditions were spatially and temporally different.In detail,in the regions north of the PaleoTian Shan and Paleo-Qilian Mts.the tectonic deformation and climatic condition were stronger and wetter than in regions south of the Paleo-Tian Shan and Paleo-Qilian Mts.during the Late Triassic-Jurassic.Whereas in the Cretaceous,the tectonic movement was intensive in the west but steady in the east,and climate was dry in the south but wet in the north of NTP.The formation of the tectonic and climatic patterns in NTP were the consequence of either global climate change or regional tectonics,including the Paleo-Asian Ocean closure and the Qiangtang block,Lhasa block and India plate collision subsequently to Asia.Furthermore,the regional tectonic events occurred before any global climate change and drove the climatic change in the NTP.
基金supported by the National Basic Research Program of China (No.2007CB411501)the National Natural Science Foundation of China (Nos.40971019,J0630966,90511007)+2 种基金the Special Grant for Postgraduate Research,Innovation and Practicethe West Light Foundation of Chinese Academy of Sciences (No.O828A11001)the Fund from State Key Laboratory of Cryospheric Sciences
文摘The seasonal and inter-annual variations of pH and EC （electrical conductivity） at Yulong （玉龙） Snow Mountain, Lijiang （丽江） City, are sensitive to precipitation variations and are important indicators of the atmospheric environment. The pH of summer rainfall at Lijiang City ranges from 6.7 to 7.4, and alkaline mineral salts dominate the variations of rainfall acidity, pH values in the shallow firn profile at Baishui （白水） Glacier No. 1 range from 5.6 to 6.3, and EC values from 2.4 to 7.3 μs/cm. The ranges are lower than those in other firn cores from China because of stronger elution and the influence of marine aerosols. This indicates that environmental records from a monsoonal temperate glacier differ from those at continental glaciers.
文摘It has been reported that trivalent cerium salts are effective inhibitors for corrosion of AA2024-T3 in neutral to alkaline co rrosive enviro nments,but poor in acidic environments.In this study,work was done for extending corrosion resistance provided by Ce(NO_(3))_(3)to acidic pHs as low as 2.5 through the addition of iodide ions.To this end,potentiodynamic polarization was used to ascertain the optimum Ce(Ⅲ)concentration for the inhibition of AA2024-T3 corrosion in 3.5%NaCl solution.This optimum concentration is found to be in a range between 0.1 and 0.3 mmol/L Ce(Ⅲ).This optimum concentration also gives a maximum width of the passive region under the pitting potential(Epit).Based on this optimization,further work was performed as a function of pH without and in the presence of 0.01 mol/L KI at five pH values(2.5,4,5,7,and 8).Without iodide the best inhibition provided by the Ce(Ⅲ)cation is at pH=7 but active corrosion is observed at pH=2.5 with an estimated inhibitor efficiency(-37.6%).The addition of iodide ions(I^(-))reverses the poor corrosion resistance whereby the inhibitor efficiency becomes 47.7%.Moreover,at pH=4 the efficiency is also increased from 54.0%to 81.0%with iodide addition providing a significant improvement over Ce(Ⅲ)cations alone under acidic conditions.There is a synergistic effect between I-anion and Ce(Ⅲ)cation,which is determined to be 2.4 and 2.1 at pH=2.5and 4.0,respectively.At pH=5 and 7 there is virtually no change in inhibition but at pH=8 the inhibition falls away due to a considerable amount of cerium precipitating out of solution as cerium carbonate.The protective film formed on sites in the aluminium alloy surface at different pH values was examined by both scanning electron microscopy with energy dispersive X-ray analysis and X-ray photoelectron spectroscopy to determine the role of these ions as a function of pH in surface inhibition.It is proposed that at pH=2.5 protection is provided by a bilayer adsorption of iodide with"capping"cerium ions,but at pH=4 protection occurs through precipitate formation on active cathodes thereby shutting down the oxygen reduction reaction.
文摘Climate change caused by past,current,and future greenhouse gas emissions has become a major concern for scientists in the field in many countries and regions of the world.This study modelled future precipitation change by downscaling a set of large-scale climate predictor variables(predictors)from the second generation Canadian Earth System Model(CanESM2)under two Representative Concentration Pathway(RCP)emission scenarios(RCP4.5 and RCP8.5)in the semi-arid Borana lowland,southern Ethiopia.The Statistical DownScaling Model(SDSM)4.2.9 was employed to downscale and project future precipitation change in the middle(2036-2065;2050s)and far(2066-2095;2080s)future at the local scale.Historical precipitation observations from eight meteorological stations stretching from 1981 to 1995 and 1996 to 2005 were used for the model calibration and validation,respectively,and the time period of 1981-2018 was considered and used as the baseline period to analyze future precipitation change.The results revealed that the surface-specific humidity and the geopotential height at 500 hPa were the preferred large-scale predictors.Compared to the middle future(2050s),precipitation showed a much greater increase in the far future(2080s)under both RCP4.5 and RCP8.5 scenarios at all meteorological stations(except Teletele and Dillo stations).At Teltele station,the projected annual precipitation will decrease by 26.53%(2050s)and 39.45%(2080s)under RCP4.5 scenario,and 34.99%(2050s)and 60.62%(2080s)under RCP8.5 scenario.Seasonally,the main rainy period would shift from spring(March to May)to autumn(September to November)at Dehas,Dire,Moyale,and Teltele stations,but for Arero and Yabelo stations,spring would consistently receive more precipitation than autumn.It can be concluded that future precipitation in the semi-arid Borana lowland is predicted to differ under the two climate scenarios(RCP4.5 and RCP8.5),showing an increasing trend at most meteorological stations.This information could be helpful for policymakers to design adaptation plans in water resources management,and we suggest that the government should give more attention to improve early warning systems in drought-prone areas by providing dependable climate forecast information as early as possible.
文摘The effects of the cropping system change for paddy field with double harvest rice on crops growth and soil nutrient in red soil were studied. The results indicated that the economic benefit and the ratio of the output to input were all increased in terms of the market price for the crops under various treatments. The greatest economic benefit was obtained in the treatment of paddy-upland rotation, and the corresponding economic benefit was increased by 34.7, 21.4, and 2.2% in comparison with that of control （rice-rice-astragali）, pasture, and upland cropping treatments. The economic benefits in pasture and upland cultivation treatments were increased by I 1.0 and 31.8%, respectively, when compared with that of the control treatment （CK）. The ratio of output to input in pasture, paddy-upland rotation, and upland cropping treatments was enhanced by 0.9, 0.6, and 0.3, respectively, in comparison with that of control. To grow pasture is beneficial for improving soil fertility since the contents of soil organic matter, total nitrogen, total phosphorus, and available phosphorus are all enhanced significantly. However, the concentrations of the soil available nitrogen, the total potassium, the available potassium were somewhat reduced in all the treatments, suggesting that increasing the input of nitrogen, particularly potassium, was necessary under the present fertilization level. Based on the conditions of fertility, climate, cultivation, and management of paddy field with double harvest rice in red soil regions, it is feasible to alter the cultivation system of paddy field with bad irrigation condition. In particular, cultivation systems such as pasture and paddy-upland rotation can be selected to extend because better economic benefit and improvement of soil fertility in the purpose region were obtained.
文摘Herein, we report on the use of chitosan-based engineered materials for the sequestration of naphthenic acid fraction compounds (NAFCs) and other species (matrix) in oil sands process-affected water (OSPW) in order to improve monitoring of NAFCs after phytoremediation. Chitosan pellets (CPs) were cross linked with glutaraldehyde (GLU) at variable feed ratios and characterized using thermogravimetric analysis (TGA). Sorption studies at equilibrium and kinetic conditions were carried on OSPW extract, raw and treated wetland samples. The materials were shown to have similar sorption capacity for NAFCs but with variable selectivity of the species in the complex mixture. As well, the matrix uptake varied according to the type of OSPW. Overall, CP in its native form outperformed the cross linked CP pellets, as evidenced by a reduction in matrix effects.
基金the National Key Research and Development Program of China under contract No.2021YFC2803301the Fundamental Research Funds for the Central Universities,China under contract Nos 2042024kf0037 and 2042022dx0001the Natural Science Foundation of Wuhan under cocntract No.2024040701010030.
文摘Loss of multiyear ice(MYI)is of great importance for Arctic climate and marine systems and can be monitored using active and passive microwave satellite data.In this paper,we describe an upgraded classification algorithm using the data from the scatterometer and radiometer sensors onboard the Chinese Haiyang-2B(HY-2B)satellite to identify MYI and first-year ice(FYI).The proposed method was established based on K-means and fuzzy clustering(K-means+FC)and was used to focus on the transition zone where the ice condition is complex due to the highly commixing of MYI and FYI,leading to the high challenge for accurate classification of sea ice.The K-means algorithm was applied to preliminarily classify MYI using the combination of scatterometer and radiometer data,followed by applying fuzzy clustering to reclassify MYI in the transition zone.The HY-2B K-means+FC results were compared with the ice type products[including the Ocean and Sea Ice Satellite Application Facility(OSI SAF)sea ice type product and the Equal-Area Scalable Earth-Grid sea ice age dataset],and showed agreement in the time series of MYI extent.Intercomparisons in the transition zone indicated that the HY-2B K-means+FC results can identify more old ice than the OSI SAF product,but with an underestimation in identifying second-year ice.Comparisons between K-means and Kmeans+FC results were performed using regional ice charts and Sentinel-1 synthetic aperture radar(SAR)data.By adding fuzzy clustering,the MYI is more consistent with the ice charts,with the overall accuracy(OA)increasing by 0.9%–6.5%.Comparing against SAR images,it is suggested that more scattered MYI floes can be identified by fuzzy clustering,and the OA is increased by about 3%in middle freezing season and 7%–20%in early and late freezing season.
基金The authors extend their appreciation to the Deputyship for Research&Innovation,Ministry of Education in Saudi Arabia for funding this research work through the project number RI-44-0456.
文摘This study explores the integration of Synthetic Aperture Radar(SAR)imagery with deep learning and metaheuristic feature optimization techniques for enhanced oil spill detection.This study proposes a novel hybrid approach for oil spill detection.The introduced approach integrates deep transfer learning with the metaheuristic Binary Harris Hawk optimization(BHHO)and Principal Component Analysis(PCA)for improved feature extraction and selection from input SAR imagery.Feature transfer learning of the MobileNet convolutional neural network was employed to extract deep features from the SAR images.The BHHO and PCA algorithms were implemented to identify subsets of optimal features from the entire feature dataset extracted by MobileNet.A supplemented hybrid feature set was constructed from the PCA and BHHO-generated features.It was used as input for oil spill detection using the logistic regression supervised machine learning classification algorithm.Several feature set combinations were implemented to test the classification performance of the logistic regression classifier in comparison to that of the proposed hybrid feature set.Results indicate that the highest oil spill detection accuracy of 99.2%has been achieved using the logistic regression classification algorithm,with integrated feature input from subsets identified using the PCA and the BHHO feature selection techniques.The proposed method yielded a statistically significant improvement in the classification performance of the used machine learning model.The significance of our study lies in its unique integration of deep learning with optimized feature selection,unlike other published studies,to enhance oil spill detection accuracy.
基金National Basic Research Program of China,No.2010CB951404National Basic Research Program of China,No.2007CB411501+5 种基金 National Natural Science Foundation of China （NSFC）,No.40971019 No.90511007 No.40801028 NSFC,No.J0630966 Major Directionality Program of the Chinese Academy of Sciences,No.KZCXZ-YW-317 West Light Foundation of the Chinese Academy of Sciences,No.O828A11001
文摘Based on the meteorological data of 20 stations in the Hengduan Mountains region during 1961–2009, the annual and seasonal variation of potential evapotranspiration was analyzed in combination with the Penman-Monteith model. With the method of Spline interpolation under ArcGIS, the spatial distribution of potential evapotranspiration was presented to research the regional difference, and the correlation analysis was used to discuss the dominant factor affecting the potential evapotranspiration. The results indicated that the an-nual potential evapotranspiration showed a decreasing tendency since the 1960s, especially from the 1980s to 1990s, while it showed an increasing tendency since 2000. Regional potential evapotranspiration showed a rate of –0.17 mm a？1. Potential evapotranspiration in north, middle and south of the Hengduan Mountains exhibited decreasing trends over the studied period, and its regional trend was on the decline from southwest to northeast.
基金supported by the Key Project of the Chinese Academy of Sciences (KZZD-EW-04-05)the National Natural Science Foundation of China (91025024)the Western Light Project of the Chinese Academy of Sciences
文摘Tamarix spp. （Saltcedar） is a facultative phreatophyte that can tolerate drought when groundwater is not accessed. In addition to deep water uptake, hydraulic redistribution （HR） is another factor contributing to the drought tolerance of Tarnarix spp. In this study, data on soil volumetric moisture content （0）, lateral root sap flow, and relevant climate variables were used to investigate the patterns, magnitude, and controlling factors of HR of soil water by roots of Tamarix ramosissima Ledeb. in an extremely arid land in Northwest China. Results showed evident diurnal fluctuations in 0 at the depths of 30 and 50 cm, indicating ＂hydraulic lift＂ （HL）. 0 increased remarkably at 10 and 140 cm but decreased at 30 and 50 cm and slightly changed at 80 cm after rainfall, suggesting a possible ＂hydraulic descent＂ （HD）. However, no direct evidence was observed in the negative flow of lateral roots, supporting HR （including HL and HD） of T. ramosissima. The HR pathway unlikely occurred via lateral roots; instead, HR possibly occurred through adventitious roots with a diameter of 2-5 mm and a length of 60-100 cm. HR at depths of 20-60 cm ranged from 0.01-1.77 mm/d with an average of 0.43 mm/d, which accounted for an average of 22% of the estimated seasonal total water depletion at 0-160 cm during the growing season. The climate factors, particularly vapor pressure deficit and soil water potential gradient, accounted for at least 33% and 45% of HR variations with depths and years, respectively. In summary, T. ramosissima can be added to the wide list of existing species involved in HR. High levels of HR may represent a considerable fraction of daily soil water depletion and substantially improve plant water status. HR could vary tremendously in terms of years and depths, and this variation could be attributed to climate factors and soil water potential gradient.
基金supported by the National Natural Science Foundation of China (Nos.40801028,40971019)the National Basic Research Program of China (No.2007CB411501)+1 种基金the West Light Foundation of Chinese Academy of Sciences (No.O828A11001)the Funds from the State Key Laboratory of Cryospheric Sciences and the Lijiang City Government
文摘Aerosol and snow samples were collected at ablation zone of Baishui （白水） Glacier No. 1, Mt. Yulong （玉龙）, from May to June, 2006. The concentrations of Cl^-, NO3^-, SO4^2-, Na^＋, K^＋, Mg^2＋, and Ca^2＋ were determined by ion chromatograph both in aerosol and snow samples. The average total aerosol loading is 25.45 neq.scm^-1, NO3^- and Na^＋ are the dominant soluble ions in the aerosol, accounting for 39% and 21% of average total aerosol loading, respectively. Monsoon circulation reduces the concentration of most ions, indicating that wet scavenging is effective for aerosol particles. In snow samples, SO4^2- and Ca^2＋ are the dominant anion and cation, respectively. A lower Na^＋/Cl^- ratio was found in fresh snow samples compared to the higher ratio that was found in aerosol samples. Analyzing the difference in SO4^2- and NO3^- in air and fresh snow indicated that the aerosol was influenced by local circulation, but the components in fresh snow samples were from long-distance transport. Enrichment of NO3^- in aerosol samples is attributed to motor exhaust emissions from tourism by calculating the SO4^2-/NO3^- ratio in aerosol and fresh snow samples. The temporal variation and correlation coefficients between soluble species in aerosol samples suggest that Cl^-, Na^＋ and K^＋ come from sea-salt aerosol, and SO4^2-, Mg^2＋ and Ca^2＋ are from continental crust sources.
基金supported by the National Natural Science Foundation of China (No.41227805)the National Key Research and Development Program of China (No.2016YFC0202704)
文摘To better characterize the optical properties of atmospheric aerosols, the multi-wavelength cavity ring-down aerosol extinction spectrometer(MCRD-AES) is developed and applied in this study. By using tunable light source and four parallel cavities, the MCRD-AES covers a wide and atmospherically relevant wavelength range from 360 to 663 nm. Four wavelengths(375 nm, 440 nm, 532 nm, and 620 nm) are particularly tested with ammonium sulfate and nigrosine. The refractive index values obtained from this study agree well with literature data. The stability and accuracy of the MCRD-AES are tested, and the minimum detectable extinction coefficient is 0.5 1/Mm. The high sensitivity, high precision, and wavelength changeable of MCRD-AES indicate its great application prospect in comprehensively quantifying the optical properties of atmospheric aerosols.
基金supported by the Science and Technology Department of Guizhou Province(No.Qiankehe LH zi [2017]7334hao)the China Postdoctoral Science Foundation(No.2017M613005)+2 种基金Foundation of Guizhou Educational Committee(No.Qian jiao he KY[2016]135)the National Natural Science Foundation of China(No.41563012)the Doctoral Scientific Research Foundation of Guizhou Normal University for 2014
文摘Photoreduction characteristics of divalent inorganic mercury (Hg2+) in the presence of specific algae species are still not well known.Laboratory experiments were conducted in the present study to identify the effects of different concentrations of living/dead algae species,including Aphanizomenon flosaquae (AF) and Microcystis aeruginosa (MA),on the photoreduction rate of Hg2+ under various light conditions.The experimental results showed that percentage reduction of Hg2+ was significantly influenced by radiation wavelengths,and dramatically decreased with the presence of algae.The highest percentage reduction of Hg2+ was induced by UV-A,followed by UV-B,visible light and dark for both living and dead AF,and the order was dark > UV-A > UV-B > visible light for both living and dead MA.There were two aspects,i.e.,energy and attenuation rate of light radiation and excrementitious generated from algae metabolisms,were involved in the processes of Hg2+ photoreduction with the presence of algae under different light conditions.The percentage reduction of Hg2+ decreased from 15% to 11% when living and dead AF concentrations increased by 10 times (from 106 to 105 cells/mL),and decreased from11% to ~9% in the case of living and dead MA increased.Algae can adsorb Hg2+ and decrease the concentration of free Hg2+,thus inhibiting Hg2+ photoreduction,especially under the conditions with high concentrations of algae.No significant differences were found in percentage reduction of Hg2+ between living and dead treatments of algae species.The results are of great importance for understanding the role of algae in Hg2+ photoreduction.
基金Project supported by the K.C.Wong Education FoundationNational Natural Science Foundation of China(U1612442)+3 种基金Key Grant for Creative Research Groups of Guizhou Provincial Education Department(Qian-Jiao-He KY Zi2016047)Young Scientific Talents Growth Project of Guizhou Provincial Education Department(Qian-Jiao-He KY Zi 2016252)Doctoralof Zunyi Normal University(Zun-Shi BS 201815)Science and Technology Project of Guizhou Provincial Science and Technology Department(Qian-Ke-He-Ping-Tai-RenCai 20175727-07)。
文摘As indispensable strategic materials for high-tech industries,rare earth elements and yttrium(REY)have become particularly important in recent years,raising the demand of developing new approaches for reclamation of REY from REY-rich materials such as coal combustion products(CCPs).In this study,five coal-fired power plants(CFPPs)in Guizhou of southwest China were selected for investigating REY concentrations of solid samples,atmospheric emissions,and recovery potentials.REY concentrations of feed fuels are higher in this study(147.2-468.6 mg/kg)than what have been reported previously for coals in China and the world.REY atmospheric emissions are extremely low(38.70-180.11 mg REY/t coal).REY are enriched in bottom ash and fly ash,with average of 658±296 mg/kg and maximum of 1257 mg/kg from the five CFPPs.Relative enrichment factors(REF)of REY in bottom ash and fly ash compared with the feed fuel are 0.86-1.02 and 0.91-1.04,respectively.REY concentrations in desulfurized gypsum are very low(6-17 mg/kg),and that is mostly inherited from limestone.Critical REY(Nd,Eu,Tb,Dy,Y,and Er)in bottom/fly ash account for 34%-39%of the total REY and the outlook coefficients(Cout1)are in the range of 0.89-1.11.This study indicates a promising prospect to reclaim REY from REYrich CCPs(bottom and fly ash)in CFPPs in Guizhou,especially in the central-north Guizhou,although such practices require further technology advancement.
基金the National Natural Science Foundation of China(Grant No.41830536,Grant No.41676190,and Grant No.41941009)the Fundamental Research Funds for the Central Universities(Grant No.12500-312231103)The authors thank the University of Bremen for providing the AMSR-E,AMSR-2 and SSMIS SIC data,as well as the University of Wisconsin-Madison Automatic Weather Station Program(NSF Grant No.ANT-1543305)。
文摘Antarctic polynyas play an important role in regional atmosphere?ice?ocean interactions and are considered to help generate the global deep ocean conveyer belt.Polynyas therefore have a potential impact on the Earth’s climate in terms of the production of sea ice and high-salinity shelf water.In this study,we investigated the relationship between the area of the Terra Nova Bay polynya and the air temperature as well as the eastward and northward wind based on the ERA5 and ERAInterim reanalysis datasets and observations from automatic weather stations during the polar night.We examined the correlation between each factor and the polynya area under different temperature conditions.Previous studies have focused more on the effect of winds on the polynya,but the relationship between air temperature and the polynya area has not been fully investigated.Our study shows,eliminating the influence of winds,lower air temperature has a stronger positive correlation with the polynya area.The results show that the relationship between the polynya area and air temperature is more likely to be interactively influenced.As temperature drops,the relationship of the polynya area with air temperature becomes closer with increasing correlation coefficients.In the low temperature conditions,the correlation coefficients of the polynya area with air temperature are above 0.5,larger than that with the wind speed.
