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Simulating the transfer and fate of hexachlorocyclohexane in recent 50 years in beijing, china

Science china Earth Sciences 2005年第12期48卷 2203-2213页

作者： CAO Hongying1, LIANG Tao1 & TAO Shu2 1. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, beijing 100101, china 2. laboratory for Earth Surface Processes, Peking University, beijing 100871, china 1. Institute of Geographical Sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. laboratory for Earth Surface Processes Peking University 100871 Beijing China

Taking beijing as a study area, a dynamic fugacity model was used to simulate the transfer and fate of technical HCHs according to the physic-chemical properties of the studying environment and HCH isomers. Dynamic changes of the transfer fluxes and concentrations of HCH isomers during 1952―2003 were simulated and the model results suggest good agreement between the calculated and measured concentrations of HCH isomers. During 1952―1983, the average input and output amount of HCHs through agricultural application and degradation are 130 t and 150 t respectively. The dominant transfer processes of HCHs in the study area are air-soil deposition, soil erosion and soil-air diffusion, transfer fluxes of these processes are 80 t?a?1, 16 t?a?1 and 11 t?a?1, which account for 92% of total transfer fluxes of HCHs isomers. There were approximately 253t HCHs in all environmental compartments of the study area during this period and 97% of which existed in soil compartment. Air and water advection became the dominant input sources of HCHs after 1984 when the application of technical HCHs was prohib-ited, concentration of HCHs quickly descended to a quite low level in several years. Total amount of HCHs isomers remaining in the study area environment now is less than 5% that before 1983, and this percentage may descend to 0.5% after 20 years by prediction.

关键词： fugacity model, hexachlorocyclohexane, compartment, transfer flux, fate.

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SHRIMP ages of detrital zircons from the Changcheng System in the Ming Tombs area,beijing:Constraints on the protolith nature and maximum depositional age of the Mesoproterozoic cover of the North china Craton

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Chinese Science Bulletin 2003年第22期48卷 2500-2506页

作者： WAN Yusheng1,2, ZHANG Qiaoda1 & SONG Tianrui1 1. Institute of Geology, Chinese Academy of Geological Sciences, beijing 100037, china 2. beijing SHRIMP laboratory, beijing 100037, china Correspondence should be addressed to Wan Yusheng (e-mail: wanyusheng@***) Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China

The Mesoproterozoic Changcheng System is widely distributed in the North china Craton. Determining its time of deposition and sources is important to understand the Precambrian crustal evolution of the North china Craton. This paper suggests age distribution patterns for detrital zircons from clastic sediments of the Changcheng System in the Ming Tombs area, beijing. Samples of feldspar-bearing sandstone (CHc-2) and pure sandstone (CHc-9) were collected from the Changzhougou Formation, which constitutes the basal part of the Changcheng System. Detrital zircons show an age range from 2.35 to 2.60 Ga. However, sample CHc-9 in the upper Changzhougou Formation also contains some zircons with ages of 1.9-1.8 Ga and 2.3-2.1 Ga. The age patterns lead to the following conclusions: (1) Most of the detrital material came from a source area composed predominantly of ~2.5 Ga continental crust of the North china Craton; (2) 1.9-1.8 Ga reflects the age record of Palaeoproterozoic continent-continent collisional event in the North china Craton; and (3) the oldest age for deposition of the Changcheng System is 1.8 Ga.

关键词：锆石原岩中国北部地区地壳演变

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Recommendation Method for Contrastive Enhancement of Neighborhood Information

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Computers, Materials & Continua 2024年第1期78卷 453-472页

作者： Hairong Wang beijing Zhou Lisi Zhang He Ma School of Computer Science and Engineering North Minzu UniversityNingxia750021China

Knowledge graph can assist in improving recommendation performance and is widely applied in various person-alized recommendation ***,existing knowledge-aware recommendation methods face challenges such as weak user-item interaction supervisory signals and noise in the knowledge *** tackle these issues,this paper proposes a neighbor information contrast-enhanced recommendation method by adding subtle noise to construct contrast views and employing contrastive learning to strengthen supervisory signals and reduce knowledge ***,first,this paper adopts heterogeneous propagation and knowledge-aware attention networks to obtain multi-order neighbor embedding of users and items,mining the high-order neighbor informa-tion of users and ***,in the neighbor information,this paper introduces weak noise following a uniform distribution to construct neighbor contrast views,effectively reducing the time overhead of view *** paper then performs contrastive learning between neighbor views to promote the uniformity of view information,adjusting the neighbor structure,and achieving the goal of reducing the knowledge noise in the knowledge ***,this paper introduces multi-task learning to mitigate the problem of weak supervisory *** validate the effectiveness of our method,experiments are conducted on theMovieLens-1M,MovieLens-20M,Book-Crossing,and Last-FM *** results showthat compared to the best baselines,our method shows significant improvements in AUC and F1.

关键词： Contrastive learning knowledge graph recommendation method

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Progress and review of the studies on the end-Triassic mass extinction event

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Science china Earth Sciences 2005年第12期48卷 2049-2060页

作者： DENG Shenghui1,2, LU Yuanzheng1,2,3 & XU Daoyi4 1. Research Institute of Petroleum Exploration and Development, beijing 100083, china 2. Key laboratory of Oil and Gas Reservoir of Petrochina, beijing 100083, china 3. china University of Geosciences, beijing 100083, china 4. Institute of Geology, china Earthquake Administration, beijing 100029, china 1. Research Institute of Petroleum Exploration and Development 100083 Beijing China 2. Key laboratory of Oil and Gas Reservoir of Petrochina 100083 Beijing China 3. china University of Geosciences 100083 Beijing China 4. Institute of Geology China Earthquake Administration 100029 Beijing China

The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. china has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

关键词： progress, review, end-Triassic, mass extinction, mechanism, Tr-J boundary.

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Spatio-temporal carbon isotope variation during the Ediacaran period in South china and its impact on bio-evolution

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Science china Earth Sciences 2009年第10期52卷 1520-1528页

作者： WANG XinQiang1 & SHI XiaoYing1,2 1 School of Earth Science and Mineral Resources, china University of Geosciences, beijing 100083, china 2 State Key laboratory of Geological Processes and Mineral Resources, beijing 100083, china School of Earth Science and Mineral Resources China University of Geosciences Beijing 100083 China State Key laboratory of Geological Processes and Mineral Resources Beijing 100083 China

The Ediacaran period is characterized by the extremely negative carbon isotope anomalies and great biotic evolution in Earth history. At least four negative carbon isotope anomalies have been reported from this interval in South china so far. It is traditionally argued that the isotope variations can be used as a useful tool for global correlation of Ediacaran succession; however, more and more researches argued against this idea. We reviewed the previously published carbon isotope data in South china, and distributed the mean values of a certain time to the paleogeographic maps. The results show that the carbon isotope values (δ13C) vary greatly in different environments, but a clear tendency of becoming lighter from shallow platform to deep basin, with a maximum variation up to 1‰ Moreover, the important changes in Ediacaran biota, marked by the introducing of new taxa or ecologic groups, seemed to always postdate the negative anomalies but coincide with the positive shift. If the negative excursions represented the oxidation of a large dissolved organic carbon (DOC) reservoir in the ocean, the diverse Ediacaran organisms and the carbon isotope anomalies may suggest totally different environments: oxic and anoxic/euxinic. We also suggest that the elimination of euxinic state through precipitation of pyrites is one of the important environment factors in prompting the Ediacaran bio-evolution.

关键词： Ediacaran South china carbon isotope spatio-temporal variations bio-evolution

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Seasonal variations and bioavailability of inorganic phosphorus in soils of Yeyahu Wetland in beijing,china

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International Journal of Sediment Research 2011年第2期26卷 181-192页

作者： ZHANG Jing,LI Min,LIU Shuang,LIU Yujin,ZHANG Liqiang,CAO Qi,and SUN Dezhi 1 Ph.D.student,~ 2 Assoc,Prof,~(3,6) Master,~7 Prof,College of Environmental Science and Engineering,beijing Forestry University,beijing,P.R.china,100083 ~(4,5) Senior Engineer,beijing Yanqing Yeyahu Wetland Nature Reserve,beijing,P.R.china,102101 [a]Ph.D. student College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 [b]Assoc. Prof. College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 [c]Master College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 [f]Master College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 [g]Prof. College of Environmental Science and Engineering Beijing Forestry University Beijing P.R. China 100083 [d]Senior Engineer Beijing Yanqing Yeyahu Wetland Nature Reserve Beijing P.R. China 102101 [e]Senior Engineer Beijing Yanqing Yeyahu Wetland Nature Reserve Beijing P.R. China 102101

Phosphorus(P) in soils has an important influence on the development and productivity of wetland. The objective of this study was to investigate the distribution,bioavailability and seasonal variations of inorganic phosphorus(IP) in soils of Yeyahu *** results showed that the concentration of Ca-bound P(Ca-P) remained the main occurrence in all IP fractions despite the season,at the same time the Al-bound P(Al-P) was always the lowest IP fraction despite the ***-P and Fe-bound P (Fe-P) concentration were all reached the highest value in May and the lowest in November,which was opposite to the occluded P(Oc-P) *** notable higher Oc-P concentration in November observed in this study was probably due to the decomposition of plants and the subsequently releasing of oxides to ***-P didn’t change much with season *** P(Ex-P) and Oc-P were all positively correlated with soil moisture content and organic matter content,but Al-P was negatively correlated with these two soil *** a stable form,Ca-P was not associated with soil ***-P,Fe-P and Ca-P might contribute to the storage of P in studied wetland with the principle component analysis *** concentration rank order of the bio-available P in soils was generally as follows:Olsen-P > Algal available P(AAP) > Water soluble P(WSP) > Readily desorbed P(RDP).Olsen-P was positively correlated with Ex-P and Oc-P,and it was thought to be a more suitable indicator for bio-available P in soils.

关键词： Inorganic phosphorus fractions Distribution Bioavailability Seasonal variations

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Flotation Separating Rutile from Calcium and Silicon Gangue Minerals

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Rare Metals 2001年第4期20卷 205-208页

作者： Hao Ding1, HaiLin 2 1) beijing Academy of Building Materials, beijing 100041, china 2) University of Science and Technology beijing, beijing 100083, china beijing Acad Bldg Mat Beijing 100041 Peoples R China Univ Sci & Technol beijing Beijing 100083 Peoples R China

Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phos... 详细信息

关键词： rutile calcium and silicon gangue minerals flotation separate alkyl-imino-bismethylene phosphoric acid sodium hexametaphosphate

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Investigation of Al-based Alloys for Brazing SiC_p/Al Composites

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稀有金属材料与工程 2011年第S3期40卷 132-135页

作者： Wu Mao1,2, Chang Lingling2, Peng Zirong2, Feng Zelong2, Yong Weina2, Wang Wei2, He Xinbo1,2, Qu Xuanhui1,2 1State Key laboratory for Advanced Metals and Materials, University of Science and Technology beijing 100083, china 2 beijing Key laboratory for Powder Metallurgy and Particulate Materials, University of Science and Technology beijing, beijing 100083, china Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Univ Sci & Technol beijing Beijing Key Lab Powder Met & Particulate Mat Beijing 100083 Peoples R China

The brazing of SiCp/Al composites is limited owing to the unavailability of suitable commercial intermediate temperature brazes. Adding a third constituent of copper to aluminum-silicon brazing alloy can depress the melting point sharply. While, it generates a large volume fraction of the hard Al2Cu intermetallic compounds (IMCs), which makes the alloy brittle and reduces its corrosion resistance. A quaternary addition of nickel that partly substitute for copper can refine grain size significantly, improve the mechanical properties, and without altering the melting range of aluminum-silicon-copper alloy. Al-Cu-Ni-Si braze alloy has been prepared and a fluxless process has been employed to braze SiCp/Al composites that leads to a good bonding strength of brazing joint.

关键词： SiCp/Al composites Al-based brazes brazing intermetallic compounds (IMCs)

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Distribution and health risk assessment of organochlorine pesticides(OCPs) in industrial site soils:A case study of urban renewal in beijing,china

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Journal of Environmental Sciences 2009年第3期21卷 366-372页

作者： YANG Wenrui,WANG Rusong,ZHOU Chuanbin,LI FengState key laboratory of Urban and Regional Ecology,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,beijing 100085,china. [a]State key laboratory of Urban and Regional Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China

A field survey was conducted in a contaminated industrial site of southern beijing, china to investigate the contents and distribution of the organochlorine pesticides （α-, β-, y-, δ-HCH, p,p＇-DDT, p,p＇-DDE, p,p＇-DDD and o,p＇-DDT） in the profiles of soil, and a health risk assessment was carded out with CalTOX multimedia exposure model. Results showed that mean concentrations of total hexachlorocyclohexane isomers （HCHs） and total dichlorodiphenyltrichloroethane isomers （DDXs） in soils were in the range of 13.20- 148.71 mg/kg, and 3.02-67.43 mg/kg, respectively. Organochlorine pesticides （OCPs） content peaked in the surface and declined in soil profile with depth. The amounts of HCHs in three profiles of soil were larger than DDXs. Composition analysis indicated that there was a trend of degradation of OCPs in the site, but the mean of HCHs and DDXs concentration were over the state warning standard limit （HCHs, 0.50 mg/kg; DDXs, 0.50 mg/kg）. According to current land use development, health risk assessment with CalTOX and Monte Carlo analysis showed that health risks mainly came from two exposure pathways： dermal uptake and inhalation, and the total risk values all exceeded the general acceptable health risk value （10-6）. The sensitivity analysis indicated that five parameters significantly contributed to total risk.

关键词： pollution hexachlorocyclohexane isomers (HCHs) dichlorodiphenyltrichloroethane isomers (DDXs) soil profiles Monte Carlo sensitivity

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Science china Earth Sciences 2004年第10期47卷 896-911页

作者： ZHANG Changhou1,2, WU Ganguo1,2, WANG Genhou2, ZHANG Weijie2 & SONG Honglin2 1. Key laboratory of Lithospheric Tectonics and Lithoprobing Technology, china University of Geosciences, Ministry of Education of china, beijing 100083, china 2. School of Earth Sciences and Mineral Resources, china University of Geosciences, beijing 100083, china 1. Key laboratory of Lithospheric Tectonics and Lithoprobing Technology China University of Geosciences Ministry of Education of China 100083 Beijing China 2. School of Earth Sciences and Mineral Resources China University of Geosciences 100083 Beijing China

The northwest trending tectonic belt in the middle part of the Mesozoic intraplate Yanshan Orogenic Belt, northeast Hebei Province, is composed of thrusts, extensional faults, strike-slip faults and syntectonic sedimentations as well. The northeastward basement-involved major thrusting deformation occurred between 174Ma and 168MaBP and was followed by an intrusion of the granitic plutonic rocks. As a part of the post-thrusting extensional deformations a northwest extending volcano-sedimentation system of Late Jurassic and Early Cretaceous formed in the southwest side of the belt. These volcano-sedimentary sequences are divided into Tuchengzi Formation, Zhangjiakou Formation, Yixian Formation and Jiufotang Formation re- spectively. They are characterized by southeastward migration as a result of the increasing down-dip slip displacement along the major extensional fault toward the southeast of the belt. The provenance area of the Jiufotang Formation north to it experienced southwestward thrusting during and after its later sedimentation. The thrusting in this stage resulted in the formation of an asymmetric footwall syncline with vergence to SW in the Jiufotang Formation in the NE side of the basin. Finally a dextral strike-slip deformation occurred along the NW tectonic belt. The striking tectono-geomorphological features and present seismic activities along this belt indicate that it has been being active since Cenozoic era and is still in the active state at present. This northwest extending tectonic belt was following the same direction and location as the existing fault systems within the basement as revealed by former geological and geophysical studies. So it is reasonable to infer the Mesozoic deformation along this belt to be a result of reactivation of the basement structures in a favorable tectonic stress field. The reactivation of basement struc- tures might be taken as one of the mechanisms of intraplate deformation and orogeny.

关键词： Yanshan Orogenic Belt, northwest extending tectonic complex, thrust system, geochronology.

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