Regional land use change is an important part of global change. The Wuding River Basin, located in the middle reach of the Yellow River, is characteristic with high sediment load in less water. Since the 1950s, various conservation measures have been adopted throughout the basin, including vegetation (trees, bushes and grasses) plantting, sand shifting control, terracing, reservoirs and dams construction, and so on. These measures have changed the underlying surface greatly. Based on Landsat TM images data in the 1990s, we analyze the spatial-temporal changes of land use of Wuding River Basin using GIS and statistic methods. The results show that the land use changed greatly in the Wuding River Basin in the 1990s. In the first five years, cultivated land, forestland and un-used land decreased obviously while grassland increased. In the second five years, the situation was reversed, grassland increased and cultivated land, forestland and un-used land decreased. During the ten years, cultivated land and un-used land reduced, at the same time, forestland and grassland increased. The rate of land use change in the first five years is higher than that of the second five years.The major change types were cultivated land turned to forestland and grassland, and un-used land converted into cultivated land and grassland. In the first five years, the rate of the land use change in the study was up to 0.85%. The changing rates of un-used land and grassland were higher, being 3.2% and 1.94% respectively. While, in the second five years, the rate of the regional land use change was 0.3%. The changing rates of forestland and un-used land were 2.75% and 1.71% respectively. Finally, we also come to the conclusion that there are obvious spatial differences in land use changes. For forestland change, the Nalin, Lu and Dali sub-basins were greater. Glassland and un-used land changes mainly occurred in Yuxi and Hailiutu sub-basins. Conservation measures and socio-economic development were the direct causes for land use change in the Wuding River Basin.

The intensity of sand-drift activities is the important theoretic base for both studying the formation and evolution of aeolian geomorphology and carrying out the sand-damage control measures. Based on statistics and calculations of wind data, this paper studied the intensities of the sand-drift of Taklimakan Desert and drawn some preliminary conclusio ns as follows: ① Except Ruoqiang district, the whole Taklimakan Desert belongs to low-energy environment and the drift potential in most areas is less than 20 0VU. ② With the increase of wind velocity, its frequency decreases gradually, so the most effective sand-moving winds range from 6.1m/s to 10.0m/s, but the most contributors to sand flux concentrate between 9.0 m/s and 11.0 m/s. ③ The intensity of sand-drift activities has great temporal and spatial variation s. As seasons concerned, the sand-drift activity is the strongest during spring and summer and is the weakest in winter, and the autumnlies between them. Ho wever, in the interior of the desert there is a phenomenon called as "wind-temp erature synchronization", that is, the monthly mean temperature and wind velocity get their maximum values during June and July. On the fringe of the desert, the maximum temperature occurs in June and July, while the maximum wind velocity in April and May. According to the calculated results of drift potential and sandflux, the intensity of sand-drift activities is stronger in the central and eastern parts than that of western, southern and southwestern parts. Although this study has got some results, there is still some important work to carry out in future. At first, to give a rational explanation of the temporal and spatial variations of the intensity of sand-drift activities, in combination with the circulation patterns at different elevations. Secondly, to give a det ailed explanation of the "wind-temperature synchronization" phenomenon through scientific experiments. And finally, to integrate the intensity of sand-drift activities with the degree of sand dune activities, so as to provide more effect ive base for sand-damage control measures.

Markov model was used to represent the land-use change data for several reasons.Firstly,land use change is not unidirectional in nature.A given parcel of land theoretically may change from one category of land-use to any other at any time.Markovian analysis uses matrices that represent all the multi-directional land-use changes between all the mutually exclusive land-use categories.Land use changes and scenarios in Lhasa district were analyzed in this paper using Markov model.The main conclusions are as follows: (1) Land use changes in Lhasa district during the last ten years were related to this period's integrated agricultural development project.In 10 years from 1990 to 2000,186.53 ha of cultivated land were converted into forest land,accounting for 54.857% of the total cultivated land area converting into the other land use categories;and 130.05 ha were converted into residential area,being 38.247%.The remaining limited area was converted into the other land use categories such as rangeland and water body. (2) The most extensive changes of land use from 1990 to 2000 in Lhasa district was rangeland conversion.Rangeland was converted into cultivated land,horticultural land,forestland,residential area and water body.Among them,2333.33 ha of forestland were converted from rangeland,or 94.093 %,the largest of all in area.These land use changes were related directly to the integrated development and construction project carried out in the central Tibetan Plateau in the mid 1990s.Because of the implementation of biological and engineering measures consisting of large scale of forestation and construction of field safeguarding forest,since the 1990s,remarkable effects in soil erosion control have been obtained through improving surface vegetation and land cover conditions. (3) Markov chain model prediction indicated that the general trends of land use changes,in Lhasa district in future were that cultivated land,rangeland,water body and unused land will decrease and forest,horticultural land and residential area will increase. (4) It should be pointed out that since there are many factors impacting land use changes,in particular in a short period of time,policies,regulations,important regional projects and human activities and other uncertain factors will affect regional land use changes,hence causing certain errors in prediction accuracy of land use changes in Lhasa district. (5) The simulated areas of land use changes in the future in Lhasa district by Markov mode are very close to the planning areas of land use changes of Tibet,therefore,land use change scenario based on the Markov model has an important value for making land use plan.

The origin and development of cities of Northeast China have a long history along with the formation of their peculiar civilization. But, before the 20th century, the level of urbanization in Northeast China lagged behind that in Central China for a long period of time due to some historical reasons. Modern cities of Northeast China originated in the early 20th century. Since the 20th century, Northeast China had gone through the immigrating and opening-up policies of the Qing government, later been invaded and occupied by the imperialist nations such as Russia and Japan for several decades. After the founding of the People's Republic of China, Northeast China has ever been the key region of China's industrialization. Today, due to economic growth and dramatic reform of economic structure, Northeast China's urban development has stepped into the rapid developing period, and been one of the regions with the highest standard of urbanization in China except for several municipalities directly under the central government, and made the great contribution to Chinese economy. Compared with other cities of China, cities of Northeast China have a special political and economic background, and clearly reflect the feature of synchronous developing and mutual promoting in the course of both urbanization and industrialization. In the paper, the authors identify the development mechanism of cities of Northeast China in the 20th century by revealing the relationships between the development of cities of Northeast China and their economic and social development. Simultaneously, the authors also analyze the historic role of the development of cities of Northeast China and some current major problems restricting their development in the course of renewing the old industrial base of Northeast China.

Adopting the simplified water balance model, the average infiltration coefficient of precipitation and specific yield in the Hebei Plain between 1985-1995 are simulated, and the annual average groundwater level dropping down by water use sectors and crops is calculated on the basis of the above simulations. The results show that the water use in agriculture is the main factor resulting in the decline of groundwater level in the Hebei Plain, and the industrial and domestic factors are the secondary. In the piedmont plain, agriculture has led to a decrease of 0. 63 m per year, industry of 0. 08 m and domestic of 0. 03 m, with the individual ratios being 85. 1% , 10. 8% and 4. 1% respectively. While in the low plain, the order of the decrease is 0. 23 m, 0. 005 m and 0. 015 m per year with the ratios being 92. 1%, 2. 0%, and 5. 9% accordingly. In both areas, as to the major role causing the decline of groundwater level among the crops, wheat is the first, being 0. 33 m and 0. 127 m per year, while millet is the least, being 0.01m and 0. 004 m annually. As for water consumed in producing unit output value, wheat also occupies the first place, being 1. 35m3/yuan and 0. 91m3/yuan, or resulting in the largest decline of 0. 02 m and 0. 008 m in producing 100 million yuan of wheat each. While vegetable is the least, being 0. 25 m3/ yuan and 0. 19 m3/yuan, or 0. 004 m and 0. 002 m decline per 100 million yuan. With the decline of groundwater level, a series ecological and environmental disasters have been caused which have become the key factors restricting the socio-economic sustainable development of the Hebei Plain. Therefore, it is high time to adjust planting structure in order to achieve sustainable use of the groundwater in the Hebei Plain.

In the paper, the dynamic features of mineral nitrogen （SMN, NH⁺₄-N+NO^-₃-N） of the 0-30cm Dark Chestnut soil were studied, its seasonal variations during growing season and the SMN content differences among different research points were analyzed. All the samples were taken randomly from three different managed Leymus chinensis grasslands of Xilin River Basin in Inner Mongolia of China. The results showed that in Dark Chestnut soil the prevailing form of SMN was NH⁺₄-N,the plant available nitrogen only takes a very small part of the soil total nitrogen, always below 1%（0.20%～0.92%）.With the increase of grassland grazing intensity, the SMN content changed oppositely. The sequence of SMN content from high to low was: fenced grassland﹥rotational grazing grassland﹥random grazed grassland. During the growing season, the contents of NH⁺₄-N and NO^-₃-N in different soil layers of three different managed grasslands changed evidently with the changes of soil temperature, moisture and plant absorbance, the trends of seasonal change were similar in different soil layers. The mineral nitrogen content of 0-10cm surface soils fluctuated most significantly, the content of NO^-₃-N was the highest in April and that of NH⁺₄-N was higher in July and August. The content of NH⁺₄-N was higher than that of NO^-₃-N in three different soil layers, and their contents decreased with the increase of sampling depth. The SMN content changed just the same order as the soil total nitrogen, organic carbon and soil water content with the increase of the depth, but there were no significant correlations between SMN content and anyone of them.

Based on spatial database of 1∶50000 soil map at county level in northwestern Shandong, according to farmer’s current devotion, current agricultural productivity of land resources was estimated using an "investigation method" and the results were compared with actual production records in statistical yearbook and simulation result using relevant computing models of mechanism methodology in this paper. Results indicate that: 1) Per unit area yields of winter wheat and summer corn of each soil type are divided into 5 classes under current management level, and per unit area yield of winter wheat changes from 1920 kg/ha to 7160 kg/ha. That of summer corn is slightly higher than winter wheat and changes from²730 kg/ha to 7725 kg/ha. 2)The management for winter wheat production is at a moderate level, with a small regional difference. However, there is a regular spatial change in the management of summer corn, and it shows a decrease in input from south to north, which is consistent with perceptual knowledge in spot check. 3) The current annual agricultural productivity of land resources changes from 10284 kg/ha to 12789 kg/ha, and the average amounts to 11358 kg/ha each year. Among all counties, Ningjin county has the highest annual productivity, which is 12789 kg/ha each year, and Qingyun county has the lowest, which is 10284 kg/ha each year. Compared with simulation result of mechanism methodology, the differences of potential land productivity between counties are more obvious than those of practical land productivity. As a result, soil quality contributes considerably to the practical agricultural productivity of land resources. The "investigation method" is proved to be effective for investigating land productivity. Moreover, it showed that the devotion in agricultural production has regional heterogeneousness among all counties. The results have important and realistic meanings for programming and layout of grain production.

In this study, we examined the pedoe co logical effects of three shrub species that occur generally in shifting, semi-s hifting and semi-fixed sand lands in the Horqin Sandy Land. Several important conclusions were drawn from this study. （1） There were significant differences in the interception and retention of sand and aeolian dust among three shrub spe cies. Of the three shrubs, the mean amount of the interception and retention of sand and aeolian dust perplant was the greatest （0.49 m³） in Caragana microphylla, followed by Artemisia halodendrom （0.16 m³） and Salix gordejvii （0.03 m³）. Regression analyses showed that the sediment a mount of sand and aeolian dust perplant was positively and significantly correl ated with its average canopy （accounting for 18-58% of the variance）, branching number （accounting for 16-31% of the variance） and shoot diameter （accounting for 14-17% of the variance）. （2） All three shrubs exhibited significant effects of "island of fertility", i.e. the soils under shrub canopies were significa ntly higher in nutrient availability than those beyond shrub canopies. Such effects may create a nutrient-rich substrate, thus providing a better environment for further invasion and establishment of other plant species on bare sandy land . The effects of "inland of fertility" varied markedly with the type of shrubs pecies. Of the three shrubs examined, Caragana microphylla had the greatest "fertile island" effect, followed by Artemisia halodendrom and Salix gord ejvii, largely because of significantly higher levels of organic matter, total N and available P in soils （0-20 cm） under the Caragana microphylla canopies than those under Artemisia halodendrom and Salix gordejvii canopies. Shrubs differed appreciably in accumulation efficiency of different nutrients. For example, the accumulation efficiencies of organic matter, total P, available P and total N in soils under shrub canopies averaged 1.20-1.44, 1.08-1.2 3, 1.11-1.36 and 1.17-1.40. （3） Wind direction appeared not to influence the spatial distribution of soil physical properties, but showed an effect on the spatial distribution of organic matter content. Organic matter contents in soils at the SE and NE directions of the shrubs were somewhat higher than the other directions.

Being a kind of agricultural and productive action,cultivation and reclamation have closely correlated with certain governmental policies.In the Qing Dynasty,the agricultural technology was in a poor condition,and the importance of certain policies of cultivation and reclamation was even more distinctive.As a result,a thorough analysis and implementation of the cultivation policies at that time is a very important way to know the cultivation and reclamation in the Qing Dynasty.The cultivation and reclamation policies during Kangxi,Yongzheng and Qianlong periods in the Qing Dynasty were analyzed in this paper,and the spatial and temporal distributions of cultivation and reclamation during the early Qing Dynasty were also set forth.The characteristics of cultivation and reclamation during these periods were as follows.The Kangxi period was characterized by the resume of the past cultivation that was stopped during the war.The most important aspect of cultivation during the Yongzheng period was the transitional character that was transformed from the resume of past cultivation to the settlement of requiring more cultivated land due to the quick increase of population.And the most important task of cultivation for the government duing the Qianlong period was to solve the problems of increasing poor population.Various cultivated policies were reflected in the field of reclamation and cultivation at that time.During the Kangxi period,the cultivation was resumed,and the cultivation during Yongzheng period was marked by the transformation from the reclamation of wasted cultivated land to the cultivation of virgin soils in some areas.And the characteristics of cultivation during the Qianlong period were the clear representations of cultivation of virgin soils.In the meantime,the cultivation in the early Qing Dynasty was distributed spatially.

Study of a historic sediment in the south margin of the Tarim Basin, where is influenced by the Westerlie force evidently, shows that the mass susceptibility correlates positively with carbonate δ¹³C and strongly with the components of 56.37-224.4μm(especially with components of 70.96-200μm), but correlates negatively with the components of 0.56-35.57μm (especially with components of 17.83-31.70μm.). The correlation among three proxies bears profound significance of climate and environmental changes. When temperature declined in the extreme arid area, the relative humidity increased greatly, resulting in restrains of evaporation and prosperity of vegetation, protecting the land surface from erosion, and only relative finer debris can be carried to deposit in lake, carbonate δ¹³C declined. Less oxidation strength during a relatively cold period led to lower mass susceptibility. Conversely, when temperature increased, relative humidity declined sharply and resulted in increase in evaporation, the vegetation cover reduced so that the erosion intensity on the land surface increased, leading to coarser component being loaded and deposited in lake and rise in carbonate δ¹³C. Strengthened oxidation during a relatively warm period resulted in an increase in mass susceptibility. Based on the interpretation of the proxies and widely regional comparison, this paper identifies 8 characteristic climatic periods during the last 4.0ka. Most significantly, the similarity which can be observed between the fluctuation of climate proxies in this paper (especially the proxies of grain size ) and the Greenland GISP2 ice core δ¹⁸O record shows that climate change of the studied area may have global background, and on the other hand, it also incarnates evident regional characteristics.

Differences in land use and land cover comprise a complicated process, which involves conversion of the natural soil ecosystem to an artificial ecosystem. This process may affect the accumulation of heavy metals in soils. The knowledge of the heavy metal concentrations for different land use types, which has been infrequently investigated, is of critical importance to assess human impact on heavy metal concentration in soils. Arsenic is a toxic heavy metal with an ADI (acceptable daily intake) of 2. 14 jug/kg body b. w. / day, according to the WHO. In this study, 500 samples were collected from 6 land-use types, including vegetable plot, paddy field, orchard, greenbelt, wheatfield, and natural soil, to compare differences between As concentrations of these soil-use types in Beijing. In comparison with background, the concentrations of As in the different land-use types increased to different extents. The accumulation of As in soils was widespread. Through ANOVA analysis, it was found that land-use type obviously influenced soil As concentrations. The natural soil type had the lowest concentration of As. The vegetable and paddy fields had the greatest concentrations of As. The intensity of anthropogenic activities, such as the use of pesticides, chemical fertilizers, and fuel combustion, was identified as an important factor affecting the concentration of As in soils. Using a baseline concentration as a reference, the ratio of all soil samples above this limit was 1. 8%, among which the ratios of soil samples from vegetable plot, orchard, and wheatfield were 2. 6%, 2. 7%, and 0. 7%, respectively. According to the mean concentrations of As, the order of the 6 land-use types, from the highest to the lowest As concentration, was paddy field > greenbelt > vegetable plot > orchard > wheatfield > natural soil. The environmental quality of paddy field and vegetable plot soils needs to be closely considered because of the high accumulation of As in these soil-use types.

It is an essential work to survey the relationships between pollen and vegetation for recovering past vegetation and climate from pollen data preserved in sediments. The pollen analysis of 39 sites covering various types of steppe in northern China shows that Artemisia and Chenopodiaceae are the most important pollen types. Artemisia is the dominant taxa of most pollen assemblages, however, the percentages of Gramineae are less than 10% in most steppes. The low Gramineae pollen value may relate with its tillering reproduction. There is no obvious correlation between pollen total concentrations and vegetation covers. The differences between typical steppe and desert steppe are obvious. Chenopodiaceae pollen percentages are usually less than 25% in typical steppes and more than 25% in desert steppes. Detrended Corresponding Analysis (DCA) shows that pollen types of needle trees, Cyperaceae and Caryophyllaceae represent a wetter environmental condition, pollen types of Artemisia, Chenopodiaceae, Caragana, Tamarix and Nitraria represent a drier environmental condition, and pollen types of Gramineae, Compositae, Ranunculaceae, Leguminosae, Labiatae, Ostryopsis+Corylus and Rosaceae represent a transitional environmental condition between the two. DCA is a good method to distinguish different steppe communities in the study of steppe surface pollens.

Information on the environmental effects of different land uses is lacking, especially in Beijing, a city with a rapidly increasing rate of development. Such information is important for the understanding of the sustainable development and regional agricultural plans. In this study, through the investigation of 6 types of land use in Beijing, including vegetable field, paddy field, orchard, greenbelt, cornfield, and natural soil, Cd concentrations of 595 soil samples were obtained. Compared with background concentration, the accumulation of Cd in the vegetable field, paddy field, and orchard was significant. ANOVA analysis indicated that land use greatly affected the accumulation of Cd in the soils, especially in the cornfield, vegetable field, and orchard land-use types. The mean Cd concentration in the vegetable field was the highest, while samples from greenbelt and cornfield had the lowest mean concentrations. In addition, Cd concentrations of cornfield samples, which comprised the majority of samples under investigation, were low. Factors such as atmospheric deposition, which controls the large-scale distribution of Cd, might not have an obvious effect. Using a baseline concentration as background, the ratio of soil samples above this limit in orchard, greenbelt, and vegetable field were 9.5%, 7.7%, and 4.6%, respectively, while the overall ratio for the study was 3.2%. According to this investigation, some anthropogenic factors such as industrial activities, traffic, and landfill waste, played quite important roles in the accumulation of soil sample Cd. The soil environment around the landfill, therefore, should be considered seriously. In the Shijingshan, Mentougou and Fengtai districts, the ratios of soil samples above baseline were much higher than those in other districts, and therefore reasonable planning of land use in these areas should be considered. According to the mean concentrations of Cd in the soil, the order of the 6 land-use types, from the highest to the lowest Cd concentration, was vegetable field > paddy field > orchard > natural soil > cornfield > greenbelt.

Stream structure in urbanized river network area has unique characteristics under the effect of physical factors and human modification. Hence the issues of what and how such changes worked on river network storage and flood control capacity become the focus of this study. Taking Shanghai as a sample area, which is one of the largest cities in China located in the eastern Yangtze Delta, by using Horton-Strahler classification and Horton laws as reference based on the stream classification system that is commonly adopted in Shanghai and other cities around it, this paper analyzed the stream structure characteristics in each catchment under various urbanization levels;approached the effect of urbanization on stream structure development; and demo nstrated the possible relations between stream structure and river network storage and flood control capacity. The flood storage and control functions of streams in each order were further discussed in this paper. The main results are: (1 ) The stream number and length within the river network were highly developed in the study area. Stream number developed better than stream length. (2) The stream structure could only be modified when urbanization was up to a certain high level. Physical laws still played important roles in those catchments with lower urbanization level. (3) The stream structure expressed the possible trends from comprehension to simplicity, from multiform to singleness during the process of urbanization. (4) There was an obvious converse change between river network storage and flood control capacity and urbanization level. River network stor age and flood control capacity was influenced both by the quantity of water area and stream structure and much more closely related to the number and length of streams in the lower order. (5) For those streams in the higher order, the stor age capacity was stronger than the control capacity and the converse situatione xisted in those streams in the lower order. (6) proper quantity of water area and better stream structure were the infrastructures to assure ecological flood storage and control in urban area.

West Liaohe Basin is one of the key regions in the West development strategies implemented by the Chinese Government,and its eco-environment is vulnerable.Study on land reclamation and its influence on environment is the only way to explore the cause of land desertification and seek for the proper pattern of land use. (1)This paper examines changes of the land reclamation in West Liaohe Basin in about 100 years(1902-1990).At the end of the Qing Dynasty,it had no land to open up in the south of West Liaohe,but areas of plowland got increased in counties and Qis(banners) in the north of West Liaohe.In the period of Republic of China,much plowland was turned into wasteland in the south of West Liaohe,but in the north of West Liaohe,a great amount of grassland was developed into arable land.After liberation(1949),because of unreasonable land policies,all grassland was almost opened up completely. (2)Above all,natural environment in West Liaohe Basin has been greatly influenced.First,vegetation was destroyed,so the virgin forest of the Qing Dynasty now becomes the secondary forest dominately composed of mountain polar and white pirch,and the thick forest gets the thin one.Secondly,wild animals lost their natural living environment owing to vegetation destruction,so small animals such as rabbits,pheasants,crows,pied magpies and so on,now become rarer and rarer besides of macro-animals being extinct. (3)Soil erosion happened in the Qing Dynasty,lately reclamation took place at a large scale at the end of the Qing Dynasty,much plowland changed into wasteland in Republic of China,and extensive reclamation after liberation makes it on the rise.

The south coastal plain of Laizhou Bay is one of the typical salt-water intruded areas, whose occurrence and development have a close relation with the environmental evolution since late Pleistocene. This paper deals mainly with the systematic palynological, microfossil, granularity research and ¹⁴C dating on more than 29 samples from a column core with a depth of 29m of core A1 for the purpose of revealing the characteristics of paleoenvironmental evolution since late Pleistocene.According to the systematic study, 7 phases of the paleo-climate fluctuations and paleo-vegetation successions since late Pleistocene are identified. And 7 climate periods can be listed in the ascending order for the convenience of correlation: ①120-85kaBP, the analysis of spores,pollens and sediments shows that the then climate evolved from cold into warm and a little dry gradually;②85～76kaBP,obvious manifold pteridophyte and exiguous granularity of sediments showed a local humid environment with swamps and lakes developed in the lower reaches of the Weihe River; ③76～50kaBP,equal to the secondary Ice Age of Dali, characterized by grassland vegetation type with conifer in domination, and coarse sediments showed a barren terrestrial environment;④50～24kaBP,cold,wet-resistant hydrophyte such as bulrush lived on the coastal wetlands where the sea interacted with rivers, being a littoral environment; ⑤24～10kaBP,the worst period of Quaternary natural environment, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; ⑥10～4kaBP,owing to the warm and wet weather, sea level was high and transgression occurred; the local marine-deposited stratum embodied exuberant hydrophyte and aquatic plants. The maximal transgression of Holocene ended at 4kaBP;⑦4～0kaBP,the modern sedimentary environment which inclines to dry. Three warm and wet periods and two cold periods can be found. Of which, the warm period of 85-76 kaBP is corresponded with the late Yangkou seawater transgression and there is no evidence of early Yangkou seawater transgression, the warm period of 50-24kaBP is corresponded with the Guangrao seawater transgression and the warm period of 10-4kaBP is corresponded with Kenli seawater transgression, the duration of the latter one is longer than Bohai and east of Laizhou Bay. The three periods formed the foundation for the salt-water intrusion in this area.

Dissolved inorganic nitrogen of soil is liable to be transferred into surface or subsurface waters with surface or subsurface runoff. So it is important to measure ammo-niac(NH₄⁺) and nitrate(NO₃^-) in soils for estimating non-point pollution nitrogen load in a drainage area. Commonly, saturated CaSO₄ solution and 2M KCl solution are respectively used as soil extractant for NO₃^-and NH₄⁺ Their efficiencies are high and experimental results are stable. But it is uncertain whether the two methods are fit for non-point pollution research because the output characteristic of soil-soluble inorganic nitrogen is not only related with soil content but also is influenced by soil solution environment. Characteristic of natural rainfall and irrigation water is respectively similar to deioned water and 0. 01M CaCl₂ solution. So deioned water and 0. 01M CaCl₂ solution can be used as soil extractants to simulate actual soil solution environment when rainfall and irrigation take place. In this paper, measured results extracted by deioned water and 0. 01M CaCl₂ solution are compared with results extracted by saturated CaSO₄ and 2M KC1 solutions in order to clarify the relations among them. Four soil samples, which were gathered in the suburb of Beijing, were blended and shaken for 30 minutes with four extractants (6 extracting forms) (According to traditional methods of soil extraction, the ratio of water to soil is 5 : 1 when saturated CaSO4 solution and 2M KC1 solution were used. The ratios are 20 : 1 and 100 : 1 when deioned water and 0. 01M CaCl₂ solution are used. ). Then the extracted solutions were filtrated by 0. 45μm filter paper. The concentrations of NH₄⁺ and NO₃^- in the filtrate are analyzed with Salicin-hypochlorite Method and Griess-Ilosvay Method by Autoanalyzer Ⅲ Colorimeter (BRAN LUEBBE). According to the measured results, such conclusions are drawn: (1) the measured values of NO₃^- by different extracting methods are coincident with each other; (2) the measured values of NH₄⁺ are obviously different. The values of NH₄⁺ extracted by deioned water (ratio of water to soil is 100 : 1) surpass the others by far; and (3) the measured values of NH₄⁺ extracted by deioned water and 0. 01M CaCl₂ solution are not as stable as the ones by saturated CaSO₄ and 2M KC1 solutions. On the basis of these, four kinds of extractants are fit when a research is centred only on NO₃^-. Or else, fit extractant and ratio of water to soil must be selected according to the goal of the research and characteristics of the researched system.

According to more than 1844 different kinds of chorographies of the Ming and Qing dynasties and other related historical books, 1401 notes which recorded the sand-dust weathers occurring on North China Plan from 1443 to 1913 were collected and sorted out. Based on these historical notes, the temporal distribution curve of the sand-dust weathers during this period was carefully reconstructed and analyzed. Analysis on the temporal distribution shows that the sand-dust weathers happened on North China Plain in historical time mainly concentrated in spring. About 71% of sand-dust weathers occurred in spring, 18 % in winter, 9 % in summer, and 2 % in fall. April had the highest amount of sand-dust weathers in a year, accounting for about 30% of the total. The frequency of the annual sand-dust weather curve fluctuated without obvious upward or downward tendency, but it did show periodicity to some degrees. From the period 1500 to 1700, there existed about 30 year's cycles, and from 1700 to 1913, there existed about 50 year's cycles. This temporal distribution of the sand-dust weathers had little relationship with human action, but controlled by natural factors. Comparson of the temporal distribution curve of sand-dust weathers with the curves of mean 10 years spring-winter temperature and mean annual precipitation in the North China Plain in the same period indicated that the occurrence of the sand-dust weathers had significant negative correlations with the mean annual precipitation curve and the mean spring-winter temperature curves. The time periods which had more precipitation usually respond to descending of the sand-dust weathers, whereas the periods of less precipitation respond to increasing of the sand-dust weathers. The lower temperature periods in spring-winter season, which generally had close relationship with the higher wind occurrence, usually had higher occurrence frequencies of the sand-dust weathers.

Watershed water quality management is a process with many steps. Mathematical model plays an important role in watershed management as it can resolve the problem quantificationally and be operated dynamically. HSPF (Hydrological Simulation Program Fortran) developed by USEPA was chosen for the application in this paper. Hydrology and water quality simulation processes in the non-point source pollution model were introduced in the study, in which Dianchi Lake Basin was chosen for the case study. The whole basin was divided into nine sub-basins firstly. Then the non-point source database for the Dianchi Lake Basin was built. Sensitivity analysis revealed that only a few parameters were sensitive to the simulation of runoff and water quality processes. In the paper, the simulation processes for river outflow, SS, BOD, TN and TP were introduced in detail. The simulation processes for Panlongjiang Sub-watershed was given as an example. Parameter values were estimated from watershed properties, previous experimental and modeling studies, regional field studies and literature. Optimization of the parameter values, calibration of the model and validation of the simulation was achieved using stream flow and concentration of pollutants in the river outflow of watershed. The simulation results showed that relative error for runoff simulation in some sub-watersheds was very small. On the whole, the runoff simulation results were good. After that, the total and non-point source pollution loads of SS, BOD, TN and TP in each sub-watershed were calculated using the calibrated model. The results revealed that the main contributors of the non-point source pollution in the Dianchi Lake Basin were SS, TN and TP. From the spatial distribution to the non-point sources, nitrogen pollution mostly came from Panlongjiang, Baoxianghe and Chaidahe sub-watersheds. It could be attributed to the large amount usage of fertilizers in agricultural lands. SS and TP pollution status was serious in Chaidahe sub-watershed and western diffused area. The main reason could be explained as many phosphorite mines were distributed in such areas. High water and soil runoff and phosphorous adsorption had caused high non-point source pollution in total phosphorous.

Eco-water demand is a focus of attention in ecological and water science research at present. Under the macroscopical background of implementing the west development strategy, pursuing the ecologi cal project of converting farmland into forest and grassland and realizing regional sustainable development of China, water and land resources distribution, esp ecially the deficiency of water resources has restrained the development and utilization of western region's resources and become an urgent problem awaiting sol ution. Just because of this, the assessment of the scale and intensity of basin ecosystem eco-water demand is of positive and realistic significance. This paper, with western arid climate and hungriness environment as the research object , through analyzing the structure characteristics of different ecosystem's eco-water demand, synthetically estimates the scale of eco-water demand and analyzes the question of equilibrium of supply and demand of eco-water requirement in terms of maintaining the basic amount of ecological base flow of the fundamental eco-environmental function of the drainage channels, keeping basin channels' moisture balance for sediment and salt discharge and maintaining the basin's ecol ogical balance by minimizing water consumed for vegetation evapotranspiration.The research result indicates that the total eco-water demand in the whole basin is about 6.93×10⁹m³/a, accounting for 50.5% of the total amount of the basin's recent available surface water resources, groundwater mining and many years spring average foot-path flow.The development and utilization degree of this basin surface water has already exceeded rational threshold value. The average minimum eco-water demand per ha of vegetation is 413.9 m³/a.Of the eco-water consumed for different types of vegetation, marshland, meadow and forest land separately account for 47.6%, 43.4% and 9.0% of the total water requirement. Marshland and meadow are the principal eco-water consumers. Resear chresults have important reference value to make development and utilization plan of water and land resources, for local government, guarantee the benign cycle of the water resources, realize the sustainable utilization of the water resources, restore and rehabilitate the eco-environment.

Integrated Physical Geography(IPG) is an important subdiscipline of physical geography,i.e.narrow-sensed Physical Geography.The IPG studies physiographical environment the whole terrene which is the habitation of human beings comprehensively and systmetically.It emphasizes the matter-energy relationship among factors of physiographical environment,interprets the historical formation,modern process,type structure,terrain differentiation and evolution of physiographical environment.Integrated study includes correlative and complementary aspects: modern process and historical process.The modern process integrated study of the physiographical environment involves the distribution,transformation of heat and water on land surface,as well as its function in physiographical environment.It also involves chemical elements migration in the physiographical environment,the matter-energy exchange between the biological community and the environment.Landscape science and land science study natural complex from type structure point view comprehensively,while physical geographical regionalization makes the integrated study at regional angle differently.The physiographical environment is the product of the history.Paleogeographical environment,especially the historical study about the paleogeographical environment-forming process since the Neogene,is a subdiscipline of the IPG,just the content of paleogeography.In China,the IPG with Chinese characteristics has been formed and developed since the 1950s.Chinese IPG integrated study has made so much remarkable progress in paleogeography:integrated physical geographical regionalization,landscape science,land science,modern physical geography processes,regional physical geography,integrated research of physical geography,etc.This paper will make a generalization and retrospection about the achievement from the aspects above.

This study has chosen the shrubs of Caragana opulens Kom., a natural zonal vegetation in the semiarid area on northwest Loess Plateau, and compared its soil moisture from 0⁹.9m to those of re-vegetated shrubs of C.korshinskii Kom., re-vegetated almond forest, natural grassland （protected） dominated by Stipa breviflora, intensively grazed grassland and continuous cropland. Soil moistures were measured at the depth over 3m with an interval of 0.2m beneath and with an interval of 0.3m. The purpose was to testify the hypothesis that the zonal natural shrub vegetation consumes less soil water than re-vegetated shrub and forest vegetations. The results show that the soil moisture of natural shrub of C.opulens Kom. was largely higher than those of re-vegetated shrub of C.Korshinskii Kom. and almond forest beneath 1m in soil profile, close to those of intensively grazed grassland and cropland,but slightly lower than cropland. The average soil moisture in 0⁹.9m soil profiles of natural shrub of C.opulens, re-vegetated shrub of C.korshinskii, re-vegetated almond forest, natural grassland, intensively grazed grassland and cropland were 9.5%, 7.4%, 7.7%, 8.5%, 9.3% and 9.8%, respectively.and the average soil water moisture from 1⁹.9m are 10.2%, 7.6%, 8.1%, 9.0%, 10.6% and 10.0% respectively. The soil moisture of natural shrub land of C.opulens was higher than the soil moisture of natural grassland between the soil layer of 0⁴m, but beneath 4m, their soil moistures were essentially the same. All vegetation types have resulted in a continuous dry soil layer within which the soil moistures were hard or unavailable to vegetation. The thickness of hard or unavailable water moisture layers of natural shrub of C.opulens , re-vegetated shrub of C.korshinskii,re-vegetated almond forest, natural grassland, intensively grazed grassland and cropland were 2, 5.6, 4.2, 3.6, 3.3 and 1.0m, respectively. According to previous studies, the layer of unavailable soil moisture above 2m in soil profile is rechargeable by annual precipitation in the study area, but it hardly can be recharged by precipitation for unavailable soil water layers beneath 2m. From this initial study, we concluded that the natural shrubs of C.opulens consumes less soil water than re-vegetated shrubs of C.korshinskii, re-vegetated almond forest, underlining the importance of the role of zonal vegetation in the vegetation reconstruction in the study area.

Nowadays, in an open economic system, due to the increasing integration process in capital, financial and product markets, economic interaction across regions is becoming more and more important. The economic growth of one region is not just decided by its endogenous factors as before, but increasingly affected by its surrounding regions. Economists call this influence as "spillover". It is the mutual spillover of regions that brings the economic development of whole China. So, to know the spillover will obviously do great help to understand the economic developing question of China and to make effective regional economic policy. In fact, many scholars have conducted researches on this topic. For example, Mckibbin established Mundell-Fleming model between two countries; Douver set up GDP-spillovers models on multi-countries; and Conley advanced a complete framework to analyse spillovers based on all these ideas. In this paper, according to the new growth theory and the spatial interactions, we calculate the cross-province spillovers in China with the ameliorated statistical analysis model of the regional spillovers presented by Conley and Ligon(2003). The results indicate that: Most of the cross-province spillovers in China are positive, and those in the western part of China are negative except Yunnan and Xinjiang. Shanghai has the highest level of spillovers, so we call Shanghai as the economic center of China. Hubei province is key in regional spillover, hence developing Hubei economy can promote economic development in central and western China. As a result, we suggest that it is an important stratagem to promote the integrated development of Western and Eastern economy. Further we also think that an effective measure to revitalize Northeast China's economy is to offer some preferential policies which were given to Xinjiang now to Northeast China.

From an interdisciplinary point of view of urban geomorphology,this paper discusses the land deformation process（LDP） of the urban area of central Shanghai,the controlling role to the sedimentation of river system,and relations to the flood prevention wall as well as the problems faced and countermeasures at present time.Conclusions can been drawn as follows: （1） The LDP has been characterized by obvious stages in relation to human activities during industrialization and urbanization since 1843.Five stages divided:（a） embryonic deformation stage from 1843¹920 AD;（b） relatively strong deformation stage from 1921¹956 AD;（c） strong deformation stage from 1957¹965AD;（d） slow deformation stage from 1966¹989 AD;and（e） accelerate deformation stage from 1990 to the present.Each stage has different extents of land subsidence and ranges of depression. （2） The LDP here is considered as a catastrophic process.It has given rise to many negative environmental effects and even calamities.The most serious one of them is the threatening of flood to the city safety.The LDP has become a controller of the sedimentation of rivers and creeks within the area of depression.Here the authors put forward a conceptual model of land deformation controlling sedimentation.If land deformation develops continuously,it can be foreseen that the drown valley system at the estuary of the Yangtze River will advance toward land area of Shanghai,and the depression will enlarge toward the lowland（or marshland） in the west of Shanghai.Land deformation has caused a loss of 260 billion Yuan（RMB）.In fact,the ultimate economic loss is difficult to calculate as known as an irreversible process. （3） The flood prevention wall standing along banks of Huangpu River and Suzhou Creek,the fourth flood-defending line in Shanghai,has close relation to the land deformation.So it is considered as a passive countermeasure to the catastrophic urban geomorphic environment.Further study shows that this countermeasure at present time is effective,but not in the future as a result of the ongoing land deformation.The flood prevention wall 5.72m（Wusong Elevation System） tidal table of "one time over one thousand year" recorded by Huangpu Park Station will be probably broken through soon.So a new flood-defending countermeasure for Shanghai is to be urgently needed. （4） The flood prevention wall,as a product of urban geomorphologic evolution,still has safety problems,e.g.uneven land subsidence,water erosion,artificial impacts,piles of heavy materials,and even purposely removal of it.An urgent response to the flood prevention wall system is still not established.So it should be strengthened both in design and management.Furthermore,its importance of eco-environmental effect must be recognized in the future development along Huangpu and Suzhou river banks. （5） Finally,the authors recognize that the urban geomorphic environmental problems should be solved completely only on a level of city planning.The pressure of human activities to the physical geographical system in central urban area must be reduced during re-urbanization,aiming to realize the sustainable development and avoid more economic loss.

Frequency distributions of contaminants in special medium can reflect from one profile its macroscopic statistic characteristics, and can also supply necessary basic information for the classical, multivariate and spacial statistic analysis, so as to ensure basic needs to all kinds of methods for statistic analytical data.So for special studies on statistic distribution characteristics of PAH content with large numbers of specimen in a vast region have been rarely seen. Characteristics of frequency distributions of anthracene and pyrene in the topsoil of Tianjin, China, which was polluted seriously by PAHs, were studied based on frequency analysis, K-Means clustering and least-square fitting. It was demonstrated that both anthracene and pyrene, especially the former, are bimodally distributed. Double gaussian function can be used to fit the empirical distribution well after log-transformation, suggesting the presence of two independent lognormally distributed populations for either anthracene or pyrene. The geometric means of the two populations were 2.73±2.17 ng/g and 26.52±1.55ng/g for anthracene and 11.05±2.11ng/g and 82.52±3.24ng/g for pyrene. Hereby, the research which adopts two-division-methods and three-division-methods indicates: that the spatial separation of the two pyrene populations is explicitely illustrated by symbol mapping, showing that the indiviudals of the high value population clustered in urban, near-suburb, and newly developed industrial areas.For anthracene, there is a tendency of local clustering. Besides, the similarity between the spatial distribution patterns of pyrene and pyrene/benzo\pyrene ratio suggests that the dual-modal distribution of pyrene was emission-source related. Fitting and separating methods of multi-modal distributions mentioned above provided methodological grounds for deep probing into their differences and origins of the distributive characteristics of different PAHs.

This article aims to explore the formation of the new industrial space in the Suzhou area in China driven by recent trans-border investment of Taiwanese IT companies in the last eight years and investigate the governance mechanisms of the local supply chains as well as its implication to regional development. We observed that the foreign brand-name companies had played important roles in propelling this wave of Taiwanese IT companies' trans-border investment in the Suzhou area. Although the strategic cooperation between Taiwanese OEM/ODM companies and foreign brand-name companies was consolidated, but the pressure from the foreign brand-name companies has changed the governance mechanisms of Taiwanese companies' supply chains and forged the dynamics of spatial agglomeration. We argue that the production networks' trans-border extension interweave with the exercise of power between enterprise organizations; and as to the new industrial space in the developing countries that were formed by the global production networks' transplantation, besides the essence of interdependence that characterized the industrial district's inter-firm relationship, economic geographers shouldn't ignore the asymmetric power relations that were embodied in the global commodity chains.

On the basis of analyzing ecogeographical models and studying those methods being realized at the present time, a new research method integrated by ARC/INFO and VC++ is put forward, which can overcome those limitations existed in the previous methods and techniques. In the operational process of our methods , before the Holdridge life zone model and ecological diversity model are simulated, the original data are interpolated and become grid data. Based on the daily surface air temperature and precipitation data observed at 735 stations in China from 1960 to 2002, and through runing these models with our available methods and techniques, we obtained the serial maps of temporal and spatial distribution of Holdridge life zones and the value of Holdridge life zone diversity in China. After finishing all simulations, we carried out a series of analyses with these results. First, according to the serial maps of temporal and spatial distribution of Holdridge life zones, we found changes in spatial distribution of Holdridge life zones correspond well with the changes of the climatic factors and land cover. Second, through comparing and analyzing Holdridge life zone diversity, annual mean biotemperature and annual mean precipitation in our research period of time, some rules and phenomena are archived in China: 1) The fluctuated changing pattern occurs in the Holudridge life diversity, biotemperature and precipitation. 2) While the fluctuated directions of precipitation and biotemperature are the same, the fluctuated direction of the Holdridge life diversity accords with them. However, 3) while the fluctuated directions of precipitation and biotemperature are reversed,more intensive fluctuated changing pattern would occur in the Holdridge life zone diversity and the fluctuated intensity and scope would increase with the enlargement of the reversed ratio. Furthermore, through analysing the Holdridge life zone diversity, shape index of patches and patch connectivity of the Holdridge life zone in China during the 1960s, 1970s, 1980s and 1990s, we attained the analytical results that the Holdridge life zone diversity, the number of patches and the number of patch types present a decreasing trend at ratios of 0.0692%, 1.7293% and 1.3515% in every ten years, respectively. Whereas the shape index of patches and the patch connectivity present an increasing trend at ratio of 0.2526% and 3.7928% in every ten years. Finally, we discuss the relationship between life zone diversity and eco-environmental stability according to the above results.

The ancient marine eroded landform located at Huangpuzhen town extends more than 200m along the eastern foot of Jianfengshan,a small relic mountain in Zhujiang river delta plain,with well formed marine notches,cliffs and platforms.It is one of the largest ancient marine eroded landforms in Guangdong.However,there is not any marine biological deposits remained in the cliffs or notches for radiocarbon dating to find out the age of the landform.The features of the marine eroded landform,stratum date and ¹⁴C dating from boreholes in the nearby areas,changes of transgression boundaries in Zhujiang estuary during the Holocene era and recording of historical documents have to be used together to identify ancient geographical environment of Huangpuzhen and the time when the landform was formed.The result of this study shows that the area of Huangpuzhen had been a projecting block of red Cretaceous conglomerate by the time of the first transgression which happened in the later Pleistocene.Jianfengshan,the relic mountain of the block,was therefore located as an island in the ancient Zhujing estuarine bay in the most of time of Holocene transgression.When the transgression ended,the shoreline of Zhujiang delta moved out seaward,and the bay was gradually filled into a deltaic plain and the low hill became a relic mountain on the plain.The period for the marine eroded landform at Huangpuzhen to be formed was 6100-1600 aBP,when the low hill was as an island in the Holocene transgression.

The Ejin natural oasis landscape lies in the lower reaches of the Heihe river basin in the arid inland regions of northwestern China. With decreasing water resources from the upper reaches of the Heihe river basin, many serious ecological and environmental issues in the Ejin natural oasis have become more and more pressing in recent years. Using remote sensing techniques, GIS, and landscape pattern analysis software APACK, the landscape patterns changing characteristics, and the eco-environmental effects for Ejin natural oasis landscape are studied based on Landsat Thematic Mapper data in 1987 and Landsat Enhanced Thematic Mapper Plus data in 2001. The main results show that: 1) During the past 15 years, both the water area and main oasis area sharply decreased. The degree of oasis desertification process, at present, is more serious than before. 2) The most intense conversion among different landscape types was occurring in the transitional zone between oasis landscapes and desert landscapes. 3) As a result of the change of Ejin natural oasis landscape, the landscape patches shape complexity and its heterogeneity were obviously reduced. Moreover, the landscape texture became more and more coarser, the landscape diversity was decreasing and the landscape stability turned into unsteady. 4) Sharply decreasing surface water from the upper reaches of Heihe river basin is the vital factor for Ejin natural oasis landscape degradation in the past 15 years. The eco-environmental effects for Ejin natural oasis landscape induced by landscape change include the acceleration of groundwater mineralization degree, the degeneration of groundwater quality, the degradation of natural oasis vegetation, the decrease of species diversity, the increasing threats of sandstorms, the increasing quantity of ecological refugee and so on. In conclusion, the landscape condition of Ejin natural oasis landscape, today, is much worse than in the past years, with bad unsustainable developing trend.

In recent years, the interaction between commercial development and population growth is a new active research area in human geography. This paper basically reviews the theories in the study on the spatial structure of urban commercial activities and discusses the several quantitative methods in commercial spatial analysis. However, the GIS and many other important spatial models have not been used very well in such a research. Based on the retrospection of domestic research concerned, the paper gives a detailed discussion on the analytical framework of the application of spatial interactive models in geographic distribution patterns between population and commerce in Haidian District of Beijing. As a matter of fact, the spatial interactive models including potential model and Lashmanan-Hansen model are successful analytical tools in transportation planning as well as urban and regional research, but these traditional models are seldom used in commercial spatial allocation and planning. In this paper, the calculation of population potential and the retailing probability (Lashmanan-Hansen model) in different areas in Haidian District generates two different spectrums. This kind of spatial spectrums are a significantly important way for better observing the spatial consistency between population distribution and commercial distribution. Therefore, the commercial spatial planning decision can be made according to the consistency and population growth forecast. This paper indicates that, since the 1980s, both population and commercial growth in Haidian District has been dramatically rapid than before. However, the quantitative analysis shows that there is little consistency between the development of population distribution and commercial distribution in Haidian District, which is the biggest administrative area in Beijing. The fact is that the commercial growth always lags behind population growth. In 2001, we can divide the commercial centers into four grades. Based on the results of population growth forecast and the spatial consistency, the commercial allocation for different areas in Haidian District has been calculated for spatial planning in the future.