SOME NEW UNDERSTANDINGS OF LAND-SURFACE PROCESSES IN ARID AREA FROM THE HEIFE*

The survey for the HEIFE(Atmosphere-Land Surface Processes Experiment at Heihe River Basin,Western China) is given in the paper.The following basic subjects for land-surface processes in arid areas are studied:(1) the general characteristics of the energy budget on ground surface in arid areas;(2) the parameterization of the land surface processes;(3) the interaction between oasis and its desert circumstances,a special phenomenon in arid areas.The analysis shows that the sensible heat flux in the surface energy budget is in the majority,and the latent heat flux may be neglected.The influence of atmospheric stratification stability on the turbulent transfer of energy and substance must be considered in parameterization of land surface processes in arid areas.The "cold island effect" phenomenon in oasis and the "humidity inversion" phenomenon in desert near oasis are the result of the interaction between them.The results would improve the understanding of land surface processes in arid areas.     

试论我国城市发展方针

在执行重重工业的发展战略和城乡分割体制的计划经济背景下,我国制定了“控制大城市规模,合理发展中等城市,积极发展小城市”的城市建设方针。但是分析表明,这一方针不能适应市场经济和对外开放形势的需要,也不符合我国人多地少、农村剩余劳动力多的国情,必须调整现有的城市发展方针,选择适宜的城市化发展道路。因此,本文就适度发展大中城市,提高城市现代化水平;加速乡村城市化,积极合理发展小城镇;以及根据不同地区的具体情况,因地制宜地指定城市化途径等方面作了探讨。     

《中国21世纪议程》与西北持续发展

本文概要介绍了我国２１世纪发展白皮－《中国２１世纪议程》;全面列举了国际社会对西北地区第一批优先项目支持的承诺,勾勒了西北地区“可持续发展之路”的轮廓。     

地震综合效应场函数及其在地震预报中的应用──（一）地震综合效应场函数及其计算方法

在系统地分析了目前各种测震学地震预报方法科学思路的基础上,认为测震学地震预报方法基本上可以分为两大类。一类是以已经发生的一些地震作为未来可能发生的地震的“因”,即由于已经发生的地震对区域应力场的影响,导致未来发生较强地震。这一类包括的预报方法较多,如空区、条带、ｂ值、地震迁移、相关地震等等及其由此衍生出来的各种方法。另一类是把已经发生的一些地震作为区域应力场增强的“果”,即已经发生的地震是区域应力场增强过程中的一种反映,而未来地震不一定是已经发生的地震所导致的结果。这一类包括“地震窗口”、小震群活动等方法。针对第一类方法,各种预报方法都是力图从地震三要素中提取未来地震的信息,而具体作法又都是利用地震三要素这个多维空间的某个剖面。为了从地震活动诸要素的多维空间提取综合信息,我们对每个地震加入了破裂面方位,构成了地震第四要素,并依据地震４要素建立了地震综合效应场函数。地震综合效应场函数概括了多种测震学地震预报方法的科学思路和预报经验,从而可以形成测震学的综合预报方法。     

Environmental geochemistry of the River Gomti: A tributary of the Ganges River

Water and sediment samples collected from the Gomti River, a tributary of the Ganges River system, during the postmonsoon season have been analyzed to estimate major elemental chemistry. Water chemistry of the River Gomti shows almost monotonous spatial distribution of various chemical species, especially because of uniform presence of alluvium Dun gravels throughout the basin. The river annually transports 0.34×10⁶ tonnes of total suspended material (TSM) and 3.0×10⁶ tonnes of total dissolved solids (TDS), 69 percent of which is accounted for by bicarbonate ions only. Samples collected downstream of the city of Lucknow show the influence of anthropogenic loadings for a considerable distance in the river water. Na⁺, Cl^–, and SO₄ ^2– concentrations build up downstream. The bed sediment chemistry is dominated by Si (36 percent), reflecting a high percentage of detrital quartz, which makes up about 74 percent of the mineralogy of the bed sediments in the River Gomti. The average Kjeldahl nitrogen concentration (234 g/g) indicates indirectly the amount of organic matter in the sediments. The Hg concentration in sediments has been found to be higher (average 904 ppb) than the background value. The suspended sediments are well sorted, very finely skewed, and extremely leptokurtic, indicating a low energy condition of flow in the Gomti River. The influence of chemical loads in the Gomti has been found to be small or nonexistent on the Ganges River, perhaps because the water discharge of the Gomti (1.57 percent) to the Ganges is quite low.     

Information structure analysis for quantitative assessment of mineral resources and the discovery of a silver deposit

We propose an information-structure-analysis (ISA) method to quantify the correlations between quantitative and qualitative variables as well as within each type of variable. This method is applied to the evaluation of mineral resources in the western Zheijiang Province of China. The district contains a number of silver-bearing Fe–Cu–Pb–Zn mineral deposits near igneous complexes and FeCuPbZn zones away from the complexes. Silver anomalies occur not only in the known Fe–Cu–Zn–Pb deposits, but also in the country rock, suggesting the possible existence of silver deposits far from the igneous complexes.The tonnage distribution of silver is modeled by Monte Carlo simulation. This simulation is conducted on the basis of the correlations between silver (Ag) and lead (Pb), since no known data on silver is available. The known tonnage distribution of lead in 11 control cells was used to approximate the tonnage distribution of silver in the Monte Carlo simulation. With ISA and Monte Carlo methods, the total amount of potential polymetallic resources in 49 cells in the western Zhejiang Provice is predicted. Significantly, a deposit with about 24 tonnes of silver has been found within our exploration target area.     

抓“热点”、解“难点”，依法行政搞矿管

原达县地区是全省矿业活动最频繁的地区之一,也一度成了全省有名的“采煤混战”大区。近几年来,以《矿产资源法》为指针,抓住“重点”,调处“热点”,解决“难点”,以点带面,加强矿管行政执法工作,促进了全区矿业秩序的全面好转,矿业生产也相应得到健康发展。矿业产值占全区工业总产值的１５％左右,是全区的一大支柱产业,有力地促进了地方经济的发展。     

Palaeolimnological studies of the eutrophication of volcanic Lake Albano (Central Italy)

We use palaeolimnological techniques to reconstruct the eutrophication history of a volcanic lake (Lake Albano, central Italy) over the past three centuries. The presence of annual varves down to the bottom of the core (c. 1700 A.D.) indicated the lack of bioturbation and likely long-term meromixis. Sedimentation rates were estimated by varve counts (calcite/diatom couplets), indicating a mean rate of 0.15 cm yr^–1. The reconstruction of eutrophication was traced using past populations of algal and photosynthetic bacteria (through their fossil pigment), and geochemistry, as well as fossil remains of chironomids. Phaeophorbidea and the red carotenoid astaxanthin were used to detect past zooplankton development.The first sign of trophic change related to human activities is datedc. 1870 A.D. From that period onward a sharp increase of authigenic CaCO₃, nitrogen, N:P ratio, and dinoxanthin, a characteristic carotenoid of Chrysophyceae and Dinophyceae, is observed.Chironomid analyses showed the near absence of a deep water fauna throughout the core length. The populations of chironomid larvae are restricted to oxygenated littoral zones. In fact, the few fossil remains found are primarily of littoral origin, representing shallow water midges that were transported to profundal waters. The reduction of total chironomid in the uppermost layers of the core is to be related to human land uses.     

Densities of Huanghe River estuary and Bohai Bay waters

The densities of 36 water samples from the Huanghe River estuary and Bohai Bay were determinedby a magnetic float densimcter under three temperatures from 15℃ to 25℃.All the measured densities ofsamples were greater than that of the values calculated from the International Equation of State of Seawater.The differences between the measured and calculated densities increased with the decrease of salinities.The dif-ferences appeared exponentially correlated with[Ca~(2+)]/s,[Mg~(2+)]/s and[SO_4~(2-)]/s,and had"s"type curverelationship with the alkalinity in all salinity range.But in the salinity ranging from 25.72 to 31.57,therelationships were all linear.The density difference can be estimated from the equation △ρ（10~3kg·m~(-3)）=（-2.79+236.5([Ca~(2+)]/s)/(-9.7464×10~（-3）+[Ca~(2+)]/s).It was the high alkalinity and[Ca~(2+)]/s that resulted in the measured densi-ties of seawaters being higher than the calculated densities in the Huanghe estuary and Bohai Bay.     

Periodic orbits and their bifurcations in a 3-D system

We study some simple periodic orbits and their bifurcations in the Hamiltonian . We give the forms of the orbits, the characteristics of the main families, and some existence diagrams and stability diagrams. The existence diagram of the family 1a contains regions that are stable (S), simply unstable (U), doubly unstable (DU) and complex unstable (). In the regionsS andU there are lines of equal rotation numberm/n. Along these lines we have bifurcations of families of periodic orbits of multiplicityn. When these lines reach the boundary of the complex unstable region, they are tangent to it. Inside the region there are linesm/n, along which the orbits 1a, describedn-times, are doubly unstable; however, along these lines there are no bifurcations ofn-ple periodic orbits. The families bifurcating from 1a exist only in certain regions of the parameter space (, ). The limiting lines of these regions join at particular points representing collisions of bifurcations. These collisions of bifurcations produce a nonuniqueness of the various families of periodic orbits. The complicated structure of the various bifurcations can be understood by constructing appropriate stability diagrams.