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Depth Estimation of Geothermal Heat Structures by Euler Deconvolution of Gravity Data at Eburru Area, Kenya 认领
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作者 Erick Rayora Nyakundi John Githiri Maurice K’Orowe 《地球科学和环境保护期刊(英文)》 2020年第3期148-158,共11页
Gravity survey was done at the Eburru area to estimate the source depth locations and delineate the fault boundaries using 3D Euler deconvolution. Gravity data was collected using CG-5 gravimeter. Gravity data reducti... Gravity survey was done at the Eburru area to estimate the source depth locations and delineate the fault boundaries using 3D Euler deconvolution. Gravity data was collected using CG-5 gravimeter. Gravity data reductions were done by applying drift correction, latitude correction, free air correction, Bouguer correction and terrain correction to the observed raw data to obtain complete bouguer anomaly (CBA). The CBA data was transferred to Oasis montaj software for Euler deconvolution processing. The 3D Euler deconvolution was carried out to determine and estimate the depth of the density bodies. Euler deconvolution locates the gravity anomaly source and estimates its depth from the gravity observation level. Euler deconvolution was preferred to other filtering methods in this study as solutions are only determined over identified analytic signal peaks, the window size varies according to anomaly size and the final solution involves only a few more precise depth estimates. The Euler deconvolution was performed using structural indices of 0.5, 1.0 and 2.0. Results from this analysis indicated that the CBA values in this study area range from gravity values of -272 mGal to -286 mGal and residual Bouguer anomaly amplitude range between -3 mGal and 3.4 mGal. The 0.5, 1.0 and 2.0 structural indices generated five solutions at depth range of 433 m - 2269 m, 801 m - 1433 m and 1170 m - 2246 m respectively occurring almost at the same locations on gravity highs. The deep structures were observed to occur in the northern part of the study area, and interpreted to be dense intruding masses likely to be trapped by the overlying cap rock at these depths. These could be geothermal heat sources that can be exploited to generate geothermal energy. 展开更多
关键词 EULER DECONVOLUTION SOURCE Depth Structural Index Gravity Data Bouguer ANOMALY GEOTHERMAL Heat SOURCE
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An integrated chemical mass balance and source emission inventory model for the source apportionment of PM2.5 in typical coastal areas 认领
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作者 Nana Cheng Cheng Zhang +4 位作者 Deji Jing Wei Li Tianjiao Guo Qiaoli Wang Sujing Li 《环境科学学报:英文版》 SCIE EI CAS CSCD 2020年第6期118-128,共11页
The source apportionment of PM2.5 is essential for pollution prevention.In view of the weaknesses of individual models,we proposed an integrated chemical mass balancesource emission inventory(CMB-SEI)model to acquire ... The source apportionment of PM2.5 is essential for pollution prevention.In view of the weaknesses of individual models,we proposed an integrated chemical mass balancesource emission inventory(CMB-SEI)model to acquire more accurate results.First,the SEI of secondary component precursors(SO2,NOx,NH3,and VOCs)was compiled to acquire the emission ratios of these sources for the precursors.Then,a regular CMB simulation was executed to obtain the contributions of primary particle sources and secondary components(SO4^2-,NO3^-3,NH4^+,and SOC).Afterwards,the contributions of secondary components were apportioned into primary sources according to the source emission ratios.The final source apportionment results combined the contributions of primary sources by CMB and SEI.This integrated approach was carried out via a case study of three coastal cities(Zhoushan,Taizhou,and Wenzhou;abbreviated WZ,TZ,and ZS)in Zhejiang Province,China.The regular CMB simulation results showed that PM2.5 pollution was mainly affected by secondary components and mobile sources.The SEI results indicated that electricity,industrial production and mobile sources were the largest contributors to the emission of PM2.5 gaseous precursors.The simulation results of the CMB-SEI model showed that PM2.5 pollution in the coastal areas of Zhejiang Province presented complex pollution characteristics dominated by mobile sources,electricity production sources and industrial production sources.Compared to the results of the CMB and SEI models alone,the CMB-SEI model completely apportioned PM2.5 to primary sources and simultaneously made the results more accurate and reliable in accordance with local industrial characteristics. 展开更多
关键词 Integrated model Chemical mass balance Source emission inventory Source apportionment PM2.5
Calibration of a neutron dose rate meter in various neutron standard fields 认领
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作者 Tuan Khai Nguyen Hoai-Nam Tran +4 位作者 Quynh Ngoc Nguyen Thi My Linh Dang Van Loat Bui Thiansin Liamsuwan Ngoc-Thiem Le 《核技术:英文版》 SCIE CAS CSCD 2020年第6期75-82,共8页
This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and ... This paper presents the calibration of a neutron dose rate meter and the evaluation of its calibration factors(CFs)in several neutron standard fields(i.e.,two standard fields with bare sources of252Cf and241Am-Be,and five simulated workplace fields with241Am-Be moderated sources).The calibration in standard fields with bare sources was conducted by following the recommendations of the ISO 8529 standard.The measured total neutron ambient dose equivalent rates,denoted as H*(10)tot,were analyzed to obtain direct components,denoted as H*(10)dir,using a reduced fitting method.The CF was then calculated as the ratio between the conventional true value of the neutron ambient dose equivalent rate in a free field,denoted as H*(10)FF,and the value of H*(10)dir.In contrast,in the simulated workplace neutron fields,the calibration of the neutron dose rate meter was conducted by following the ISO 12789 standard.The CF was calculated as the ratio between the values of H*(10)totmeasured by a standard instrument(i.e.,Bonner sphere spectrometer)and the neutron dose rate meter.The CF values were obtained in the range of 0.88–1.0.The standard uncertainties(k=1)of the CFs were determined to be in the range of approximately 6.6–13.1%. 展开更多
关键词 Neutron standard fields Neutron dose rate meter Calibration factor 252Cf source 241AmBe source
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Anatomy of Eastern Niger Rift Basin with Specific References of Its Petroleum Systems 认领
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作者 Kabir Shola Ahmed Keyu Liu +4 位作者 Mioumnde Arthur Paterne Kouassi Louis Kra Abigail Adu-Asante Kuttin Kue Petou Rokis Malquaire Kusi Micheline Michelle-Alexia Ngum 《地球科学国际期刊(英文)》 2020年第5期305-324,共20页
An attempt is made in this paper to present the dynamics of the Eastern Niger Rift Basin (ENRB) with references to the key features and processes of petroleum systems based on published information. The Eastern Niger ... An attempt is made in this paper to present the dynamics of the Eastern Niger Rift Basin (ENRB) with references to the key features and processes of petroleum systems based on published information. The Eastern Niger Basin is a superimposed rift basin with sedimentary structures emplaced during two rifts episodes. The Cretaceous episode is characterized by large, tilted normally faulted blocks trending NW-SE, that were reactivated in the Paleogene, while the Paleogene episode is characterized by normal faulted blocks that trend NNW-SSE. The rifting resulted in different basin structures with the north section dominated by asymmetric half-grabens while the south section is dominated by full-grabens. Three source rocks each belonging to three different play fairways exist: 1) The Paleogene Sokor-1 Member source belongs to second cycle syn-rift play associated with fluvial/deltaic facies;2) Cretaceous Yogou and Donga sources from first cycle post-rift play associated with alluvial/fluvial/deltaic and marine clastic and carbonate facies;and 3) Cretaceous Yogou source from first cycle transitional play associated with mudstone and shale of transitional facies. The ENRB comprises two source-reservoir-seal assemblages: a lower assemblage of Upper Cretaceous and an Upper assemblage of the Paleogene. Except for the Yogou source which possesses a self-contained petroleum system, the rest of the source rocks release their oils into the Paleogene Sokor-1 Member reservoir sealed regionally by the Oligocene Sokor-2 Member. The Paleogene assemblage is charged from the Upper Cretaceous Yogou Formation through fractures emplaced during the rifting episodes. 展开更多
关键词 RIFT Petroleum Source Rock Oil MIGRATION BASIN Evolution EASTERN NIGER RIFT BASIN
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Characterization of Novel Torrefied Biomass and Biochar Amendments 认领
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作者 Heather D. Baldi Tyler L. Foster +4 位作者 Xiaoqing Shen Sam E. Feagley Fred E. Smeins Dirk B. Hays Russell W. Jessup 《农业科学(英文)》 2020年第2期157-177,共21页
Nutrient management is vital for food, feed, fiber, and fuel production. However, excessive application and loss (volatilization, leaching, run-off, etc.) of inorganic and organic sources of nutrients have detrimental... Nutrient management is vital for food, feed, fiber, and fuel production. However, excessive application and loss (volatilization, leaching, run-off, etc.) of inorganic and organic sources of nutrients have detrimental environmental impacts, while increasing prices for petroleum-based and mined fertilizers further limit opportunities for their utilization in developing nations. This study evaluated a novel, alternative type of nutrient source through pretreatment processes of torrefaction and pyrolysis by converting high-biomass feedstocks into renewable soil amendments. Napiergrass (Pennisetum purpureum Schumach., [cv. Merkeron]) and pearl millet—napiergrass (Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.) (PMN) were converted under atmospheric pressure with minimal oxygen at 250&deg;C and 400&deg;C, ground to 1 millimeter (mm) and 2 mm particle sizes, and compared to urea in a full-season field trial and short-season nursery trial growing maize (Zea mays L.) and PMN for fertility response. When compared to urea in the field trial, the torrefied biomass amendment (TBA) and biochar had similar responses despite lower nitrogen (N) application rates. The nursery trial also produced equivalent responses from urea and TBA regardless of lower N application with the exception being phosphorus (P). Finally, maize and PMN had higher P uptake with the TBA in both trials. 展开更多
关键词 TORREFACTION BIOCHAR PYROLYSIS Soil Amendment ORGANIC NUTRIENT Source
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Assessing Groundwater Contamination Risk and Detection of Unknown Sources Using a Multi-Component Reactive Transport Model 认领
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作者 Haniel Torres 《地球科学和环境保护期刊(英文)》 2020年第5期132-158,共27页
One of the most serious and important environmental issues related to the mining sector in Central Queensland is the contamination of abandoned mine sites. Representative of this issue is the abandoned Mount Morgan go... One of the most serious and important environmental issues related to the mining sector in Central Queensland is the contamination of abandoned mine sites. Representative of this issue is the abandoned Mount Morgan gold mine. The potential dispersal of acid mine drainage (AMD), a product of more than 100 million tons of sulphide-rich waste rock, into the surrounding environment, is the most challenging environmental problem currently facing this abandoned mine site. The abandoned Mount Morgan gold mine has multiple pollutant species that involve complex geochemical processes. The present study simulated the flow and transport processes founded on hydrological and geochemical conditions of the real-life field at the mine site. To assess the groundwater contamination risk and detect unknown pollution sources, few chemical species such as Iron and Sulphur were considered as the contaminants. The flow model was simulated using the computer code MODFLOW, and PHT3D was used for the simulation of advection, dispersion and chemical reactions of constituents dissolved in this groundwater system, and to mimic the reactive chemical transport processes in the polluted groundwater. To improve on results from other studies (Datta et al., 2017;Scotney, 2016;Doyle, 2016), a calibrated model was a main focus for this study. Field concentration measurements were matched with the flow simulation outcomes to calibrate the model. The results obtained showed a great potential to model transport of contaminants in the groundwater system using a real-world situation. 展开更多
关键词 GROUNDWATER CONTAMINATION Source Characterization PHT3D Chemically REACTIVE Transport Simulation Mine Site CONTAMINATION
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Optimal reduction of anthropogenic emissions for air pollution control and the retrieval of emission source from observed pollutants II: Iterative optimization using a positive-negative discriminant 认领
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作者 Qingcun ZENG Lin WU Kece FEI 《中国科学:地球科学英文版》 SCIE EI CAS CSCD 2020年第5期726-730,共5页
In part Ⅰ of this paper series, the application of an incomplete adjoint operator to calculate the optimal reduction of the total emissions S was suggested. This paper, part Ⅱ of the series, focuses on calculating t... In part Ⅰ of this paper series, the application of an incomplete adjoint operator to calculate the optimal reduction of the total emissions S was suggested. This paper, part Ⅱ of the series, focuses on calculating the reduction of the anthropogenic emission source S. As aSc(the source term due to the chemical reaction in the atmosphere) is a complex function of the pollutant concentration, we propose an iterative optimization method using a positive-negative discriminant to obtain Sfrom he aS. Tconvergence of the iterations is also proven in this paper. 展开更多
关键词 Air pollution ANTHROPOGENIC emission SOURCE SOURCE DUE to chemical reaction Optimal control Iterative optimization Positive-negative DISCRIMINANT
Analysis of a Tropical Warm Spring Microbiota Using 16S rRNA Metabarcoding 认领
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作者 Deborah Fasesan Karim Dawkins +4 位作者 Roberto Ramirez Hadiza Rasheed-Jada Abiodun Onilude Oyekanmi Nash Nwadiuto Esiobu 《微生物学(英文)》 2020年第4期145-165,共21页
The Ikogosi Warm Spring is a unique ecological niche in Western Nigeria with an average temperature and pH of 38°C and 5.8 respectively. It mixes with an adjacent cold spring (28°C & pH 7.6), about 100 m... The Ikogosi Warm Spring is a unique ecological niche in Western Nigeria with an average temperature and pH of 38°C and 5.8 respectively. It mixes with an adjacent cold spring (28°C & pH 7.6), about 100 meters from source, yielding a confluence body of water of 32°C and pH 7.7. To explore the bacterial community structure of this uncommon environment and to scan for potentially useful bacteria, metagenomes extracted directly from five samples (source and mid-point of warm spring;source and midpoint of cold spring, and the confluence) were analyzed. Using the MiSeq Illumina next generation sequencing protocols, the V3-V4 region of the 16S rRNA gene pool was sequenced and analyzed by QIIME (Quantitative Insights into Microbial Ecology) and R software. At least 11% (47,446) of all the sequences were unknown to any of the databases employed. Bacterial diversity and abundance at the source of both springs were extremely low, accounting for less than 0.07% of the total sequence reads at the confluence, 100 m downstream. In contrast to the highly diversified mesophilic confluence community where 21 different phyla were identified, only 4 and 5 phyla were recovered from the source-point of the warm spring and cold spring respectively. The most prevalent phyla in all samples were members of the versatile Proteobacteria (35% - 50% relative abundance), and the hardy Firmicutes (33% - 40%). Operational taxonomic units (OTUs) obtained from all the samples averaged at 1414. Temperature and pH were equally significant predictors of genomic diversity and richness, with the warm and cold spring sources having less than 5 bacteria phyla. Exiguobacterium sp. (a potential plastic degrader) and other deep rooted bacteria were found in the warm spring while the cold spring outflow contained among others such as Rubrobacter sp. and Chloroflexi sp. (which is close to the phylogenetic root of the domain Bacteria). Many taxonomically unresolved sequences could indicate the presence of potentially novel bacteria in this unique body of wa 展开更多
关键词 Ikogosi WARM SPRINGS AMPLICON METAGENOMICS Next-Gen Sequencing QIIME Bacterial Diversity Source
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Uniqueness to Some Inverse Source Problems for the Wave Equation in Unbounded Domains 认领
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作者 Guang-hui HU Yavar KIAN Yue ZHAO 《应用数学学报:英文版》 SCIE CSCD 2020年第1期134-150,共17页
This paper is concerned with inverse acoustic source problems in an unbounded domain with dynamical boundary surface data of Dirichlet kind.The measurement data are taken at a surface far away from the source support.... This paper is concerned with inverse acoustic source problems in an unbounded domain with dynamical boundary surface data of Dirichlet kind.The measurement data are taken at a surface far away from the source support.We prove uniqueness in recovering source terms of the form f(x)g(t)and f(x1,x2,t)h(x3),where g(t)and h(x3)are given and x=(x1,x2,x3)is the spatial variable in three dimensions.Without these a priori information,we prove that the boundary data of a family of solutions can be used to recover general source terms depending on both time and spatial variables.For moving point sources radiating periodic signals,the data recorded at four receivers are prove sufficient to uniquely recover the orbit function.Simultaneous determination of embedded obstacles and source terms was verified in an inhomogeneous background medium using the observation data of infinite time period.Our approach depends heavily on the Laplace transform. 展开更多
关键词 INVERSE SOURCE problems LAPLACE transform moving point SOURCE UNIQUENESS
Organic Geochemical Evaluation of Shale Units of Bokh Formation, Ogaden Basin, Ethiopia 认领
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作者 Temesgen Oljira Matthew E. Nton Oluwadayo O. Sonibare 《地质学期刊(英文)》 2020年第5期565-578,共14页
Shale sample from Bokh Formation, Ogaden basin, Ethiopia was assessed for their petroleum potential by Rock-Eval pyrolysis. The Total Organic Carbon (TOC) values range from 0.76 to 0.86 wt%. These values exceed the mi... Shale sample from Bokh Formation, Ogaden basin, Ethiopia was assessed for their petroleum potential by Rock-Eval pyrolysis. The Total Organic Carbon (TOC) values range from 0.76 to 0.86 wt%. These values exceed the minimum value of 0.5 wt% required for potential petroleum source rocks. The genetic potential (GP) and hydrogen index (HI) values range from 0.09 to 0.5 mg/g and 8 - 32 mgHC/gTOC, respectively. These values are generally lower than the minimal 2 mg/g GP and 200 mgHC/g HI required for a potential source rock. Several plots from the Rock-Eval pyrolysis data classify the samples as type IV kerogen with no potential to generate hydrocarbons. The Tmax and Production Index (PI) values range from 388&deg;C to 453&deg;C and 0.28 to 0.46, respectively. These values indicate that the shales are thermally matured. These results show that the shales from the Bokh Formation in Ogaden basin have no potential to generate hydrocarbons mainly crude oil, but are thermally matured and may generate natural gas. 展开更多
关键词 Ogaden BASIN Bokh FORMATION SHALE HYDROCARBON Source ROCK
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A Possible Way to Realize Controlled Nuclear Fusion at Low Temperatures 认领
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作者 Shihao Chen Ziwei Chen 《核科学与技术国际期刊(英文)》 2020年第1期23-31,共9页
This paper presents a new way to realize controlled nuclear fusion. The way is that a single energy neutron beam fuses with given nuclei, such as lithium nuclei or boron nuclei, so that the nuclear energy is released.... This paper presents a new way to realize controlled nuclear fusion. The way is that a single energy neutron beam fuses with given nuclei, such as lithium nuclei or boron nuclei, so that the nuclear energy is released. The sort of fusion can be achieved at low temperatures, because a neutron has no charge and has a large reaction cross section with a nucleus. The fusion is easy to control and does not produce radioactive spent nuclear fuel. One of the five sorts of neutron sources is the electron neutron source in which a single energy electron beam collides with a single energy bare nucleus beam, such as the deuteron, to produce a single energy neutron. These neutrons irradiate target nuclei and are absorbed by the target nuclei, so that nuclear energy is released. Compared with conventional fusion, it has the disadvantage of releasing less energy and energy density. In addition, it takes a certain amount of energy to produce a beam of single-energy neutrons. However, if some of the input energy can be effectively recycled, the fusion process must produce more energy than the input energy. 展开更多
关键词 NUCLEAR Fusion at Low Temperature NEUTRON Source LITHIUM NEUTRON-RICH NUCLEUS
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Assessment of Toxicity Potential of Sedimentary PAHS from Refome Lake, South-East Nigeria over the Last Century 认领
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作者 Inyang O Oyo-Ita Emmanuella E Oyo-Ita +2 位作者 Ekpo O Ikip Bassey B Asuquo Orok E Oyo-Ita 《地球科学和环境保护期刊(英文)》 2020年第1期1-15,共15页
In this study, toxic equivalent factors and sediment quality guidelines were employed for the assessment of toxicity potential of PAHs in 2 sediment cores collected from the center (RC) and shoreline (RS) of Reforme l... In this study, toxic equivalent factors and sediment quality guidelines were employed for the assessment of toxicity potential of PAHs in 2 sediment cores collected from the center (RC) and shoreline (RS) of Reforme lake, SE Nigeria over the last ~1 century. Boundary cross plots of isomeric ratios such as Ant/Ant + Phe (>0.1) vs. Fl/Fl + Pyr (>0.4) and BaA/BaA + Chry (>0.35) vs. Icdp/Icdp + Bper (>0.2) indicated biomass combustion/domestic coal utilization as the main sources of PAHs input. The result revealed toxicity unit indices (TU1, 1.22 - 1.57) for the two cores were above the thresholds of no effect. The highest TU1 value found in the near-bottom layer (RS5, 20 - 25 cm) of the RS corresponding to geological time-frame ~1930-1947 coincided with the period of inhabitation by the European settlers along the lake’s catchments when coal or coal products utilization for domestic and recreational purposes was at its peak. On the other hand, TU2 values were <1 at all depth intervals, revealing unlikely PAH effects to resident organisms. Total toxicity equivalency factors (TEqFs) for the surface sediment of RS and RC were 9.29 ng/g TEqFs and 9.16 ng/g TEqFs, respectively, and indicated that more attention should be paid to BaPyr accumulation in the lake’s sediment. 展开更多
关键词 TOXICITY PAHS Refome LAKE Sediment CORES ASSESSMENT Source
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文章速递Variations of Vegetation Phenology Extracted from Remote Sensing Data over the Tibetan Plateau Hinterland during 2000–2014 认领
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作者 Ya LIU Junbang WANG +2 位作者 Jinwei DONG Shaoqiang WANG Hui YE 《气象学报:英文版》 SCIE CSCD 2020年第4期786-797,共12页
How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day mode... How vegetation phenology responds to climate change is a key to the understanding of the mechanisms driving historic and future changes in regional terrestrial ecosystem productivity. Based on the 250-m and 8-day moderate resolution imaging spectroradiometer(MODIS) normalized difference vegetation index(NDVI) data for 2000-2014 in the Three-River Source Region(TRSR) of Qinghai Province, China, i.e., the hinterland of the Tibetan Plateau, we extracted relevant vegetation phenological information(e.g., start, end, and length of growing season) and analyzed the changes in the TRSR vegetation in response to climate change. The results reveal that, under the increasingly warm and humid climate, the start of vegetation growing season(SOS) advanced 1.03 day yr-1 while the end of vegetation growing season(EOS) exhibited no significant changes, which led to extended growing season length. It is found that the SOS was greatly affected by the preceding winter precipitation, with progressively enhanced precipitation facilitating an earlier SOS. Moreover, as the variations of SOS and its trend depended strongly on topography, we estimated the elevation break-points for SOS. The lower the elevations were, the earlier the SOS started. In the areas below 3095-m elevation, the SOS delay changed rapidly with increasing elevation;whereas above that, the SOS changes were relatively minor. The SOS trend had three elevation break-points at 2660, 3880, and 5240 m. 展开更多
关键词 Three-River Source Region(TRSR) start of vegetation growing season(SOS) spatiotemporal change elevation climate change China
文章速递Parameter Sensitivities of the Community Land Model at Two Alpine Sites in the Three-River Source Region 认领
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作者 Qi LUO Jun WEN +2 位作者 Zeyong HU Yaqiong LU Xianyu YANG 《气象学报:英文版》 SCIE CSCD 2020年第4期851-864,共14页
The three-river source region plays an important role on China’s ecological security and Asia’s water supply. Historically, the region has experienced severe ecological degradation due to climate change and human ac... The three-river source region plays an important role on China’s ecological security and Asia’s water supply. Historically, the region has experienced severe ecological degradation due to climate change and human activities. Reasonable simulations of the energy and water cycles are essential to predict the responses of land surface processes to future climate change. Current land surface models involve empirical functions that are associated with many parameters. These parameter uncertainties will largely affect the simulation when applied to a new domain. The Community Land Model(CLM) is a widely used land surface model, and version 5.0 is the newest version. Compared to the prior version CLM4.5, CLM5.0 has largely updated plant hydraulic and stomatal conductance schemes. How these changes affect parameter sensitivities is unknown. In our work, we tested 17 key parameters in CLM4.5 and 19 parameters in CLM5.0 at two eddy flux sites in the three-river source region: the Maqu and Maduo sites. We adopted the simplest one-at-a-time changes on each parameter and quantified their sensitivities by the parameter effect(PE).We found that the Maqu site was more sensitive to vegetation parameters, while the Maduo site was more sensitive to the initial soil water content in both CLM4.5 and CLM5.0. This is because Maduo grid cell has wetland that does not respond to vegetation parameters in CLM, which may not reflect the reality. Further model development on wetland vegetation parameterization is important. Our validation on the default simulation showed CLM5.0 did not always improve the simulations. The largest difference between CLM5.0 and CLM4.5 was that soil moisture(SM) showed a much stronger decrease in response to a higher leaf area index(LAI) in CLM5.0 than in CLM4.5, suggesting that SM is more sensitive to vegetation changes in CLM5.0. 展开更多
关键词 parameter sensitivities Community Land Model(CLM) three-river source region
文章速递Environmental impact and health risk assessment of volatile organic compound emissions during different seasons in Beijing 认领
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作者 Chuanqi Li Qianqian Li +5 位作者 Dongge Tong Qingliang Wang Mingge Wu Bohua Sun Guijin Su Li Tan 《环境科学学报:英文版》 SCIE EI CAS CSCD 2020年第7期1-12,共12页
Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer fr... Volatile organic compounds(VOCs)are major contributors to air pollution.Based on the emission characteristics of 99 VOCs that daily measured at 10 am in winter from 15 December 2015 to 17 January 2016 and in summer from 21 July to 25 August 2016 in Beijing,the environmental impact and health risk of VOC were assessed.In the winter polluted days,the secondary organic aerosol formation potential(SOAP)of VOC(199.70±15.05 mg/m^3)was significantly higher than that on other days.And aromatics were the primary contributor(98.03%)to the SOAP during the observation period.Additionally,the result of the ozone formation potential(OFP)showed that ethylene contributed the most to OFP in winter(26.00%and 27.64%on the normal and polluted days).In summer,however,acetaldehyde was the primary contributor to OFP(22.00%and 21.61%on the normal and polluted days).Simultaneously,study showed that hazard ratios and lifetime cancer risk values of acrolein,chloroform,benzene,1,2-dichloroethane,acetaldehyde and 1,3-butadiene exceeded the thresholds established by USEPA,thereby presenting a health risk to the residents.Besides,the ratio of toluene-to-benzene indicated that vehicle exhausts were the main source of VOC pollution in Beijing.The ratio of m-/p-xylene-toethylbenzene demonstrated that there were more prominent atmospheric photochemical reactions in summer than that in winter.Finally,according to the potential source contribution function(PSCF)results,compared with local pollution sources,the spread of pollution from long-distance VOCs had a greater impact on Beijing. 展开更多
关键词 Volatile organic compounds(VOCs) Secondary organic aerosol formation potential(SOAP) Ozone formation potential(OFP) Risk assessment Potential source contribution function(PSCF)
文章速递Spatiotemporal variations of nitrate sources and dynamics in a typical agricultural riverine system under monsoon climate 认领
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作者 Hao Jiang Wenjing Liu +6 位作者 Jiangyi Zhang Li Zhou Xiaode Zhou Ke Pan Tong Zhao Yuchen Wang Zhifang Xu 《环境科学学报:英文版》 SCIE EI CAS CSCD 2020年第7期98-108,共11页
Nitrogen pollution is a serious environmental issue in the Danjiangkou Reservoir region(DRR),the water source of the South-to-North Water Diversion Project of China.In this research,seasonal surveys and a bi-weekly ti... Nitrogen pollution is a serious environmental issue in the Danjiangkou Reservoir region(DRR),the water source of the South-to-North Water Diversion Project of China.In this research,seasonal surveys and a bi-weekly time series survey were conducted in the Qihe River Basin,one of the most densely populated agricultural basins in the DRR.Hydrochemical compositions(NO3^-Cl^-),dual isotopes(δD-H2O,δ^18O-H2O,δ^15N-NO3^-,andδ^18O-NO3^-),and a Markov Chain Monte Carlo isotope mixing model were jointly applied to unravel the sources,migrations,and transformations of the nitrate(NO3^-)in the basin.It was revealed that the mixing between different sources was the main process controlling the isotopic compositions of the riverine NO3the upper-middle reaches.In contrast,denitrification occurred in the lower reaches.For the first time,the sources of NO3^-quantified at a basin scale in the DRR.Overall,the river transported 484.2 tons/year of NO3^-N to the reservoir,of which 32.6%,36.4%,28.0%,and 3.0%was from soil organic nitrogen,chemical fertilizer,residential sewage and atmospheric precipitation,respectively.The NO3^-N fluxes of the different sources were regulated by the monsoon climate and anthropogenic activities.For example,high precipitation and intense fertilization resulted in severe nonpoint source pollution.Denitrification thrived in soils and reservoirs in wet seasons.Temperature could regulate the migration,nitrification and denitrification processes.Based on the results,we suggest that the management strategies dealing with nitrogen pollution issue in the DRR should follow the specific spatiotemporal characteristics of NO3migration and transformation mechanisms. 展开更多
关键词 Nitrate Source Dynamics Isotope MCMC mixing model
文章速递Characteristics of subsurface mesoscale eddies in the northwestern tropical Pacifi c Ocean from an eddy-resolving model 认领
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作者 XU Anqi YU Fei +1 位作者 NAN Feng REN Qiang 《海洋湖沼学报(英文)》 SCIE CAS CSCD 2020年第5期1421-1434,共14页
Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of... Subsurface eddies(SSEs)are common features of the ocean interior.They are particularly abundant in oceanic basins and the vicinity of major intermediate water outfl ows.They are responsible for subsurface transport of mass,heat,and salt.Analysis of high-resolution general circulation model data has revealed the existence of subsurface anticyclonic eddies(SSAEs)and subsurface cyclonic eddies(SSCEs)in the northwestern tropical Pacifi c Ocean.SSEs are abundant east of the Philippines(0°–22°N,120°E–140°E)and in latitude bands between 9°N–17°N east of 140°E.The composite structure of SSEs was investigated.SSEs had a core at about 400-m water depth and their maximum meridional velocity exceeded 10 cm/s.They exhibited two cores with diff erent salinity polarities in the surface and subsurface.Additionally,spatial distributions of heat transport induced by SSEs in the northwestern tropical Pacifi c were presented for the fi rst time.A net equatorward heat fl ux toward a temperature up-gradient was observed.The analysis of eddy-mean fl ow interactions revealed that the circulation is baroclinically and barotropically unstable at diff erent depths and to diff ering degrees.The energy conversions suggest that both barotropic and baroclinic instabilities are responsible for SSE generation east of the Philippines,whereas baroclinic instability caused by a horizontal density gradient and vertical eddy heat fl ux are important between 9°N and 17°N east of 140°E.Meridional movement of the north equatorial current and the north equatorial undercurrent can contribute to SSE generation in our study region. 展开更多
关键词 the northwestern tropical Pacifi c Ocean subsurface eddies composite structures heat transport energy source
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文章速递《聊斋志异》之“异”与王铎傅山书风之“异”的根源探析 认领
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作者 何薇 《蒲松龄研究》 2020年第3期145-152,共8页
蒲松龄之《聊斋志异》于写作手法上一改唐宋以来志怪小说渐趋白话的历史发展潮流,而重启魏晋志怪小说的古文写作风尚,所谓“志异”之“异”即在于此。这种标新立异的创作理念与实践,与明末清初书坛王铎、傅山之张扬个性、追求新异的书... 蒲松龄之《聊斋志异》于写作手法上一改唐宋以来志怪小说渐趋白话的历史发展潮流,而重启魏晋志怪小说的古文写作风尚,所谓“志异”之“异”即在于此。这种标新立异的创作理念与实践,与明末清初书坛王铎、傅山之张扬个性、追求新异的书风可谓异源而同流。分析这两种艺术形式出现的内在原因,对认识《聊斋志异》在艺术上独树一帜的特殊性和王、傅书风的特异性,都具有一定的启示意义。 展开更多
关键词 蒲松龄 聊斋志异 王铎 傅山 书法风格 根源
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文章速递浅谈土壤镉污染的来源及存在形态 认领
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作者 黄凤 宋磊 +1 位作者 周浩 吴勇 《价值工程》 2020年第29期225-226,共2页
随着我国生产水平的提高,土壤镉污染也越发严重。镉是一种有毒元素,其作为植物和人体非必需元素,通过食物链最终危害人体健康。本综述从自然来源和人为来源两方面分析了我国土壤镉污染的来源途径,介绍了镉元素在土壤中的存在形态,总结... 随着我国生产水平的提高,土壤镉污染也越发严重。镉是一种有毒元素,其作为植物和人体非必需元素,通过食物链最终危害人体健康。本综述从自然来源和人为来源两方面分析了我国土壤镉污染的来源途径,介绍了镉元素在土壤中的存在形态,总结了判断土壤镉来源的思路和修复镉污染土壤的研究方向,以期为土壤镉污染的治理提供依据。 展开更多
关键词 土壤 镉污染 来源
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文章速递纤维素酶的研究进展 认领
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作者 何芳芳 王海军 王雪莹 《造纸科学与技术》 北大核心 2020年第4期1-8,共8页
纤维素酶是一种用于降解纤维素生成单糖或低聚糖的一类酶,具有高效、环保、专一等特征,广泛应用于纺织、洗涤剂、食品、制药、生物燃料等领域。微生物来源的纤维素酶数量庞大,价格低廉,制备容易而且用途广泛,与动植物来源的纤维素酶相... 纤维素酶是一种用于降解纤维素生成单糖或低聚糖的一类酶,具有高效、环保、专一等特征,广泛应用于纺织、洗涤剂、食品、制药、生物燃料等领域。微生物来源的纤维素酶数量庞大,价格低廉,制备容易而且用途广泛,与动植物来源的纤维素酶相比更容易获得高纯度的酶制剂。主要综述了纤维素酶的来源、分类、结构与功能以及降解机制,并总结展望了纤维素酶在工业中的应用及其发展趋势,为微生物工业化生产提供理论依据。 展开更多
关键词 纤维素 纤维素酶
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