Warming and drying trends on the Tibetan Plateau (1971–2005)   总被引：1，自引：0，他引：1  

Hong Xie  Jiansheng Ye  Xiuming Liu  Chongyi E 《Theoretical and Applied Climatology》2010,101(3-4):241-253

Annual and seasonal trends in maximum and minimum temperatures, precipitation and vapour pressure deficit (VPD) were examined with the goal of understanding trends in temperature and moisture across the Tibetan Plateau, using meteorological data (1971–2005) collected at 63 stations. Trends in pan evaporation (PE; 1971–2001, 68 stations) and runoff (1971–2002) in the headwater of the Yellow River were also analysed. Positive trends in maximum and minimum temperatures were observed across the Tibetan Plateau. The highest increases were observed during winter, with results from the majority of stations statistically significant at the 95% level. A decrease trend in diurnal temperature range (DTR) was also observed. Trends in annual and seasonal precipitation and VPD were positive, while the trend in PE was negative. However, the increase in precipitation was not as pronounced as the increase in temperature. Although PE decreased during the time series, actual evaporation probably increased because of the warming across the Tibetan Plateau, where the annual potential water loss measured as PE is three to four times the annual water supply by precipitation. Warming was expected to increase evapotranspiration, causing more water vapour to escape into the atmosphere, thus counteracting or even exceeding the slight increase in precipitation. The increases in annual and seasonal VPD trends indicated a drying tendency and were further substantiated by the observed decrease in runoff in the headwater catchment of the Yellow River. The results provided insight into recent climatic changes across the Tibetan Plateau.  相似文献   

Chemical character of precipitation and related particles and trace gases in the North and South of China     

Mingqun Huo  Qian Sun  Yuhua Bai  Peng Xie  Zhaorong Liu  Jinlong Li  Xuesong Wang  Sihua Lu 《Journal of Atmospheric Chemistry》2010,67(1):29-43

Rainwater samples were collected at four sites, including Beijing and Mazhuang Town in the north of China, Shenzhen and Mangdang Mountain in the south of China. Character of atmospheric particles and gases were also measured at Mazhuang Town and Mangdang Mountain. Both of Beijing and Shenzhen are urban sites; Mazhuang Town and Mangdang Mountain are rural and remote sites respectively. The atmospheric pollution at rural plain site in the north of China was more serious than that at remote mountain site in the south of China. At Beijing, Mazhuang Town, Shenzhen and Mangdang Mountain the average pH values in rainwater were 6.02, 5.97, 4.72 and 4.81, respectively and the concentrations of total ions in rainwater were 1454, 1125, 187 and 191 μeq/l, respectively. While the acidity of the rain was higher in the south than that in the north, the rainwater in the north of China was more severely polluted than that in the south. The major acidic ion in the rainwater is SO₄^2-, and NH₄⁺ is the most important neutralizing ion in rainwater at the four sites, followed by Ca²⁺. The amounts of organic acid in precipitation were compared with other sites in the world. The ratios of organic acid to total free acid in rainwater at Mangdang Mountain was 13.8% and the influence of organic acid on acidity of rainwater at mountain site in the south of China is more important. The variation of atmospheric particles, gases and components in rainwater and cloud-fog water during special rain and cloud-fog events was discussed. The importance of washout process varied with atmospheric species. The impacts of rainfall, rain duration time and wind speed on wash-out process were estimated by regression analysis.  相似文献   

酸碱软硬度在成矿理论研究中的应用     

兰斌明  贾建业  谢娟  王建成 《地球科学与环境学报》1999,21(2):71

以Ｌｅｗｉｓ酸碱理论为基础发展起来的酸碱软硬度的理论广泛地应用于解释各类化学现象，包括类质同象置换，共生，应用于评价和预测化学反应极为简便和实用。然而，软硬酸碱度原理的理论基础尚在不断地充实之中。本文简要讨论了硫化物矿物的酸碱势标度，用酸碱软硬度理论解释了矿物的类质同象现象，是应用酸碱软硬度理论揭示和完善矿物成矿理论的一种偿试。  相似文献   

SPECIES COMPOSITION AND SEASONAL DENSITY DYNAMICS OF CILIATED PROTOZOA IN BAOAN LAKE WITH PARTICULAR REFERENCE TO THE SUBMERGED MACROPHYTES     

宋碧玉  谢平 《中国海洋湖沼学报》1999,17(1):86-96

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Effects of algal concentration and initial density on the population growth of Diaphanosoma celebensis Stingelin （Crustacea, Cladocera）   总被引：1，自引：0，他引：1  

王岩  谢宁峡  王伟良 《中国海洋湖沼学报》2009,27(3):480-486

The effects of algal concentration and initial density on the population growth of the estuarine cladocera,Diaphanosoma celebensis Stingelin,were evaluated in an indoor experiment.A 2 × 4 layout that included two algal concentrations(Chlorella pyrenoidosa,1 × 106 and 3 × 106 cell/mL) and four inoculation densities(100,200,300 and 400 ind./L) were established.Diaphanosoma celebensis were reared in 150 mL flasks containing 50 mL of algal medium at 22°C,under salinity of 10 and a photoperiod of 12 h L:12 h D.T...  相似文献   

Morphodynamic modelling of open-sea tidal channels eroded into a sandy seabed, with reference to the channel systems on the China coast   总被引：3，自引：0，他引：3  

Dongfeng Xie  Shu Gao  Ya Ping Wang 《Geo-Marine Letters》2008,28(4):255-263

In this contribution, the morphodynamics of open-sea tidal channels eroded into sandy seabed in regions of flow constriction is simulated by a one-dimensional model using the Bagnold formula for bedload transport rate, and accounting for the effect of bed slope. The results show that equilibrium conditions for such channels can be reached over a period of 10²–10³ years. Sediment eroded from the channel floor is transported in the direction of the dominant current, and deposited beyond the regions of flow constriction where the current looses competence due to spreading. In this way, the material remobilized from older strata in the channels is deposited in younger sand banks near the channel heads. Where several successive channels are incised along the current axis, they interact in their morphological evolution. The morphodynamic equilibrium of a tidal channel is reached once the combined interacting sedimentological and hydrodynamic factors, such as sediment particle diameter, tidal current velocity and flood/ebb dominance, are balanced. The model output shows that the equilibrium shape of the tidal channels appears to be related mainly to flow field characteristics and, to a lesser extent, to particle size. A positive correlation exists between the depth of the channels and their response times. The equilibrium water depths of the channels are more sensitive to current speed than to either particle size or the time–velocity asymmetry of the flow field. The response times for overall morphological equilibrium are sensitive to all of the above-mentioned parameters. In particular, sediment characteristics associated with critical current velocities have far-reaching effects on the morphodynamic behaviour of tidal channels.  相似文献   

A study on one‐dimensional consolidation of layered structured soils          下载免费PDF全文

Kang‐He Xie  Chang‐Qing Xia  Ran An  Hong‐Wei Ying  Hao Wu 《国际地质力学数值与分析法杂志》2016,40(7):1081-1098

The governing equations for one‐dimensional consolidation of layered structured soils under time‐dependent loading are established. Using simplified k‐σ′ and m_v‐σ′ models, n‐layered structured soils are transformed into (n + 1) or (n + 2)‐layered soils in which the thickness of upper and lower layers are gradually changing. The approximate solutions for the governing equations are then obtained under two types of boundary conditions, and the computer program is developed. Based on the solutions and computer program, the consolidation behavior of layered structured soils with soft interlayer is studied. It is shown that the permeability and compressibility of the soft interlayer have the greatest influences on the rate of settlement and rate of the dissipation of excess pore water pressure. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

A range-dependent echo-association algorithm and its application insplit-beam sonar tracking of migratory salmon in the Fraser Riverwatershed     

Xie  Y. 《Oceanic Engineering, IEEE Journal of》2000,25(3):387-398

Fish sonars have long been used to survey and monitor migratory salmon in rivers and at sea. However, research has been lacking in the development of algorithms to extract fish tracks from data collected in a riverine or oceanic environment. Current fish trackers, based on a pulse-to-pulse tracking method, only work well under ideal conditions when targets are well separated and the signal-to-noise ratio is high. Fisheries biologists often have to identify fish traces visually from raw echograms. This approach is both labor-intensive and time-consuming, limiting the usefulness of hydroacoustic techniques for fisheries management. This paper presents a fish-tracking algorithm which sorts randomly distributed echoes into coherent fish traces. Fish counts obtained with the algorithm compare well with visual counts at two quite different sites in the Fraser River watershed. The key features of the algorithm are: (1) the linking mechanisms among sequential fish echoes are range-dependent; (2) the growth echo for a developing track depends not only on its space-time relation with the previous track echo (the pulse-to-pulse statistics) but also on its relation to the entire track being constructed; (3) there are a total of only five echo-association criteria in the algorithm; (4) the simplicity of the algorithm structure provides a convenient platform for implementing specific and sophisticated tracking criteria to meet specific needs; and (5) the user can fully control the performance of the algorithm by choosing values for the 11 well-defined tracking parameters  相似文献   

Geochemistry of the Martian Meteorite GRV 99027     

王鹤年  谢志东  梁英 《极地研究(英文版)》2009,20(2):110-134

GRV 90027 is a Martian lherzolitic shergottites (L-S) containing poikilitic, non-poikilitic, and melted pocket components. GRV 99027 is mainly composed of olive (55 vol%) and pyroxene (37.5 vol%), with minor maskelynite (6 vol%) and chromite (1.5 vol%), and trace whitelockite and troilite, ect. In this paper, the mineralogy and petrology of GRV 99027 are reported; in addition, the geochemical characteristics of the REEs and H isotopes in the GRV 99027 are also further investigated. The ΣREE in GRV 99027 is relatively low; HREEs are enriched in olivine and pyroxene grains; LREEs are enriched in plagioclase with a high positive Eu anomaly. High ΣREE value is found in rare mineral whitlockite (less than 0.2 vol%), LREE≈HREE, and whitlockite has a negative Eu anomaly. The REE distribution patterns of the whole -rock of GRV 99027 is similar to but different from that of other L-S Martian meteorites, indicating that they came from different location of Mars. GRV 99027 has a high δD value. Different water-bearing minerals give different contribution for δD value. The δD of phosphates generally does not correlate with water content, and δD has a weak negative correlation with water content. GRV 99027 can be classified as an L-S Martian meteorite based on mineralogical assemblage patterns, REE distribution patterns, and hydrogen isotope. The isotope data of Sr, Nd, Pb, Os and REE from other L-S Martian meteorites were collected to discuss the formation history of the GRV 99027. Similar to other L-S Martian meteorites, GRV 99027 originated from part of Mar's mantle; during one strong impact event about 4M years ago, the meteorites were ejected from deep mantle into space, and traveled for a different duration in space (indicated by different cosmic exposure time), and captured by the Earth later in different time, ultimately falling on the Antarctica as L-S Martian meteorites.  相似文献   

Preparation by enzymolysis and bioactivity of iron complex of fish protein hydrolysate （Fe-FPH）from low value fish   总被引：6，自引：0，他引：6  

邓尚贵  霍健聪  谢超 《中国海洋湖沼学报》2008,26(3):300-306

Preparation of Fe^2＋ chelate of fish protein hydrolysate （Fe-FPH） obtained from low value fish proteins was introduced and its bioactivity was studied by compound enzymolysis. The optimum conditions for hydrolysate chelating Fe^2＋ are DH （degree of hydrolysis） at 5%, pH 7.0, 20℃ and 15 min chelating time for FM （material not being defatted）. Four types of Fe-FPH including CA （deposit after chelating）, CB （deposit in 50% of absolute ethanol solution）, CC （suspended deposit in 80% of absolute ethanol solution）, and CD （bottom deposit in 80% of absolute ethanol solution） were fractionated with absolute ethanol from FM. Structural analysis through infra-red spectrum revealed that Fe^2＋ was combined strongly with amino-group and carboxyl-group in each chelate and each Fe^2＋ could form two five-member ring structures. All of the four chelates were shown more significant antioxidative activity and can be used as natural hydrophobic and hydrophilic antioxidant. Among all the chelates, the CB possesses the most effective antioxidative activity at 92% as high as that of a-tocopherol. Among all Fe-FPHs, only CD showed the most effective antibacterial activity against Escherichia coli, Staphylococcus aureus, Salmonella typhi, and Bacillus subtilis and can be used as natural antibacterial. It provides a more effective way for utilization of low value fish proteins and key information of Fe-FPH as additive in food industry.  相似文献