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  • 2000 Volume 55 Issue 6
    Published: 15 November 2000
      
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  • Spatial Distribution and Accumulation of Heavy Metals in Tidal Flat Sediments of Shanghai Coastal Zone
    CHEN Zhenlou, XU Shiyuan, LIU Lin, YU Jia, YU Lizhong
    2000, 55(6): 641-651. https://doi.org/10.11821/xb200006001
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    Surface and core sediment samples were taken from 15 sites at high, middle and low tidal flats of Shanghai coastal zone on July, 1998. The sediment cores were sliced into 1 cm thick sections. All surface and sliced core sediment samples were dried, ground and sieved, then digested with HFHClO4HNO3and made up to a standard volume. Concentrations of Cu, Pb, Zn, Cr, Fe and Mn were determined by a flame atomic absorption spectroscopy （AAS）. For the determination of Cd, AAS with graphite furnace was used. The average concentrations of heavy metals in surface sediments of Shanghai coastal zone are arranged in the following order: Zn>Cu>Cr>PbCd. The concentrations of Cd is almost three orders of magnitude lower than that of other heavy metals and shows no obvious pollution. However, the concentrations of Cu, Pb, Zn and Cr are 2～5 time higher than their background values and show very serious pollution trend due to the direct discharge of industrial and municipal sewage along the Shanghai tidal flat. Along the south bank of Yangtze estuary, the concentrations of Cu, Zn and Cr decrease from the upper estuary to lower estuary, with the peak at both sites of Shidongkou and Bailonggang sewage outlet. However, there are no obvious changes in the concentrations of Cu, Zn and Cr along the north bank of Hangzhou bay. The average concentrations of heavy metals in the south bank of Yangtze estuary are 50%～180% higher than that in the north bank of Hangzhou bay, Chongmingdongwangsha bank and Jiuduanzhongsha bank. These results indicate that heavy metals prefer to accumulate in the sediments near sewage outlet. The concentrations of Cu, Zn and Cr in sediments of the study area are closely related with geomorphic units of tidal flat except Pb. They appear to be enriched in the sediments of high flat, with a concentration being 30%～70% higher than that of middle and low flat. This cross section pattern is mainly caused by tidal hydrodynamic action. However, the violent human activities, such as the building of large engineering projects in the bank, can totally destroy this regular pattern. The crosssection distribution of Pb reflects that it is mainly originated from wet and dry depositions of automobile tail gas and industrial dust. The vertical profiles of heavy metals in sediment cores show multipeak patterns, with the largest peak appearing at the depth of 10～30 cm. This subsurface enrichment of heavy metals in tidal flat sediments is mainly controlled by the redox cycle of Fe and Mn during early diagenesis near the sedimentwater interface. The multipeak pattern may be related with the windstorm tide which results in unlinear sedimentation.
  • Application of Environmental Decision Support System to Water Quality Management
    ZENG Fan tang, LIN Kui, SHEN Qian, CHEN Xian cheng, XIE Guo liang
    2000, 55(6): 652-660. https://doi.org/10.11821/xb200006002
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    EDSS is a comprehensive software system for water quality management in tidal river networks in general and for the Pearl River Delta in specific. Its purpose is to provide a practical tool which could assist government agencies in decision making for the efficient management of water resources in terms of both quantity and quality. By combining the capabilities of geographical information system(GIS), database management system(DBMS), model management system(MMS) and expert system, EDSS integrates relevant environmental databases, hydrodynamic and water quality models, optimization procedures, knowledge based expert systems, and environmental regulations so that data, models, human intuitions, expertise, and policies can be used in a seamless manner. This paper first outlines the basic concepts and philosophy adopted in developing EDSS, the system architecture, design features, implementation techniques and facilities provided. Thereafter, the core part of the system-the hydrodynamic and water quality models are described briefly. The final contribution in this paper describes the application of EDSS to the Pearl River Delta, which has the most complicated tidal river network patterns as well as the fastest economic development in the world. Examples are given of the real world problems that can be addressed using the system. These include trans boundary water pollution analysis, regional drinking water take up site selection, screening of important polluters, environmental impact assessment, and water quality zoning. It is illustrated that EDSS can provide efficient and scientific analytical tools for planning and decision making purposes in the age of information.
  • Relationship between Human Activities and Environmental Changes in The Yangtze Delta of China before Qin Dynasty
    ZHANG Li, WU Jianping, LIU Shu ren
    2000, 55(6): 661-670. https://doi.org/10.11821/xb200006003
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    The paper discusses the topic from two aspects: 1 The trace of human activities before Qin Dynasty in Jiangnan （south of the Yangtze River）. Jiangnan situated on the Yangtze Delta （30°00′～32°20′N, 117°～122°E）, topographically is lower in the eastern part and higher in the western. In western Jiangnan, human activities intervened as early as from Old Stone Age, and the affected region continued to extend gradually towards the southeastern during Neolithic. Up to the Qin Dynasty, the cultural sites had been distributed over Jiangnan, with obvious density center of those in various cultural times. 2 Man environment relationship in various cultural times before Qin Dynasty in Jiangnan. It showed certain regularities that the spatial position changes of density center of the cultural sites in Jiangnan in various times were compatible with natural conditions such as temperature, humidity and sea level changes. Based on studies of connotation and changing position of those sites and analysis of man environment relationship and the reasons accountable for cultural layers within sites interrupted in Jiangnan before Qin Dynasty, the changing route of cultural center in Jiangnan before Qin Dynasty was put forward. Finally this paper gives a conclusion that the changes of human activity center are directly related with environmental change. If changes of temperature, precipitation and sea level did not exceed certain limitations, then the Lake Taihu region became cultural center when sea level descended and the amount of precipitation was less than that at the present; whereas sea level rose and the amount of precipitation was higher than that at present, the cultural center moved northward to Ningbo Zhenjiang region. Such a cycling made Jiangnan culture continue to penetrate, blend and change.
  • On Extraction and Fractal of Urban and Rural Residential Spatial Pattern in Developed Area
    YANG Shan
    2000, 55(6): 671-678. https://doi.org/10.11821/xb200006004
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    Changjiang River Delta is a developed and rich area in China, which has become one of the most crowded urban and rural residential areas. From the late 1970s, urbanization process in Changjiang River Delta has been quickened greatly, which resulted in number increasing and spatial expansion of urban and rural settlements. In the 1990s urbanization level in Changjiang River Delta has been about 50%, and many cities such as Suzhou, Wuxi and Changzhou have become large cities with a population of more than one million, many small cities have also become medium sized cities with a population of 100 thousand to 200 thousand. At the same time, the most typical economic development character in Changjiang River Delta is prosperous rural industrial enterprises. So spatial pattern of urban and rural residential areas has changed greatly, which was reflected mainly in spatial diffusion. Along with the above mentioned spatial changes, the problem of how can we realize sustainable development of urban and rural residential areas in scale, form, pattern and function in a certain spatial and temporal range should be paid attention to. In light with above mentioned problem, we need to analyze urban and rural residential spatial pattern and find inner basic law of spatial pattern change. But the basics to study spatial pattern change lie in how to extract information of urban and rural residential areas rapidly and exactly. The paper explores how to exact residential information from topographic map and remote sensing images at first, then it studies the spatial pattern and change characters of urban and rural residential areas in Changjiang River Delta according to fractal theory.
  • Danxia Landform Genesis and Scenic Feature on Guanzai Mountain, Fujian Province
    ZHU Cheng, YU Jin biao, ZHAO Ning xi, LI Gang, WU Cheng zhao
    2000, 55(6): 679-688. https://doi.org/10.11821/xb200006005
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    At present, the genesis mechanism and evolution processes of Danxia landforms are the foci of study on the field of geomorphology and tourism. Guanzai Mountain of Fujian Province is a National A level scenic district. Its landform belongs to Danxia landforms in the maturity stage. Since late Jurassic period, this area experienced the stages of intermontane basin formation and the thick sandy gravels （J3c, K 2s and K 2ch）accumulation and diagenetic evolution. During the neotectonic movement, the area experienced stages of basin uplift and joint development. The four grade planation surfaces and the monoclinal mountain characteristics with strata dip of 110°SE and dip angle of 13°～25°in the area illustrate that the area has experienced four episodes of large scale tilting uplift processes since Tertiary period. According to the relative height differences of the four grade planation surfaces, we can infer that the difference of uplift amplitude is 34～78 8 m between the first and second uplift movement, 81～100 m between the second and third, and 38～46 m between the third and fourth. During the uplift processes, influenced by internal agent compression, gradual disappearance of wall rock pressure and stress release, the hard K 2ch rock body formed numerous deep fissures and vertical joints. Then, the surface water eroded and dissected the rock along the fissures and joints, so made the K 2ch rock body collapse and retreat incessantly. As a result, a lot of rock core and rock prisms were created from the rock body. Thus, the Danxia landscapes with peak cluster and gullies were formed. Since the landscapes consist of dike wall, castellated peak, steep cliff, columnar peak, rock ridge, crack valley, flat bottom valley with same width from top to bottom, peak forest, canyon, lane valley, natural bridge, roof like cave, penetrative cave, flat niche and so on, therefore, they are of very high value for tourism exploitation.
  • New Recognition on Boundary between Tropical and Subtropical Zone in the Middle Section of Ecogeographic System
    WU Shao hong, ZHENG Du
    2000, 55(6): 689-697. https://doi.org/10.11821/xb200006006
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    This paper discusses division on tropical and subtropical boundary in middle portion of South China. This discussion results in new understanding on eco geographic regions and their boundaries, especially on gradual changes of natural conditions between eco geographic regions. It also analyzes results of the same area by other researchers, clarifies differences and causes of the differences of the results. Boundaries of eco geographic region cannot be drawn as a line as changes from tropical to subtropical zone are gradual. Therefore, for an eco geographic region like tropical zone, definite boundaries must be drawn while considering gradual changes. Temperature, vegetation and soil are relevant indexes to divide tropical and subtropical zones. After indexes of the tropical zone are confirmed, data of annual average index reflect general state of the tropical zone. Line from such data is called “tropical boundary”. On the other hand, affected by the monsoon climate, some years are hotter and some are cooler. In hotter year, temperature of north area of tropical boundary reaches tropical state while in cooler year, such area moves southward. Boundary of the hottest year is called annual tropical line and that of the coolest year is called real tropical line. Temperatures in areas of south to annual tropical line can probably reach that of tropical zone in some years. Temperatures in areas of south to real tropical line can reach that of tropical every year. Area from true tropical to annual tropical is called tropical fluctuating zone. Therefore, new concepts of tropical, annual tropical, true tropical and tropical fluctuating zone are formed to understand tropical area in a new point of view in the paper. Based on the index of climate, vegetation and soil, boundaries of tropical, annual tropical, true tropical and tropical fluctuating zone of the study area are established. The tropical fluctuating zone explains different locating of different researchers. The paper also puts forward a new method to displaies boundary for eco geographic regions.
  • Land Use Change of China during the 20th Century
    GE Quansheng, ZHAO Mingcha, ZHENG Jing yun
    2000, 55(6): 698-706. https://doi.org/10.11821/xb200006007
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    The research of landuse and land cover change is a core project in the international global environmental change studies, and project aims at revealing how landcover has been changed in China in the last century will be an important and necessary action. Based on the standardized and unified data collected from numrable and valuable historical documents and various statistical reports which were published before 1950 but now are scattered in the nationwide libraries and archives, and the classification data obtained by investigations and remote sensing after 1950, the landcover change and characteristics of land use in China during the 20th century are traced and analyzed in this paper. The results are: ① The unused and non arable land keeps decreasing and landcover has been changed obviously. ② The cultivated land, forestland, horticultural land, settlement, and mining land, and transportation land are increasing, in which, the augmentations from 1914 to 1997 for cultivated land, forest land, horticultural land, settlement and mining land, and transportation land were 49×106hm2, 49×106hm2, 7 1×106hm2, 17 5×106hm2, 3 1×106hm2, respectively. ③ The grasslands, uncultivated arable land, water bodies and wetland are decreasing, in which, the decrements from 1950 to 1990 for the grasslands and uncultivated arable land were 65×106hm2 and 90×106hm2. ④ The proportional structure of land use consisted in the cultivated, forestland, grassland, horticultural land, settlement and mining land, transportation land, water bodies, and others by 10 19%, 13 02%, 40 83%, 0 11%, 0 49%, 0 21%, 2 35%, 32 8% in 1949, and by 14 14%, 23 65%, 26 91%, 0 85%, 2 33%, 0 53%, 4 30%, 27 29% in 1997, respectively.
  • Regional Economic Structural Adjustment and Water Environmental Protection: A Case of Guanzhong Region in Shaanxi Province
    WANG Xi qin, YANG Zhi feng, LIU Chang ming
    2000, 55(6): 707-718. https://doi.org/10.11821/xb200006008
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    Water environmental improvement depends not only on the combination of water pollution prevention and water resources exploitation, but also on the connection of water pollution control with economic development. Thus it is necessary to solve the water pollution problems radically. Guided by the sustainable development idea, focused on the improvement and protection of water environment and regarded the coordinated development of water environment and economy as a target, the paper puts forward the basic thought of model design, which means comprehensive study of economy, environment and resources must be carried out alongside the study of the coordination of water environment and economy, and the economic system should be taken as a fundamental starting point to study how to control pollution to the optimulevel so as to gain suitable economic structure and developing speed. According to above analysis and based upon the improved Input-Output model of environment-economy-resources-pollution control, the regional multiple-objective optimization model of water environment-economic system is established using quantitative method of systematic analysis, which includes production structure optimization model and industrial structure optimization model. The water environmental protection of Guanzhong region in Shaanxi Province was analyzed with water resources renewable capacity of Yellow River basin. The application of the multiple-objective optimization model is discussed with Guanzhong region in Shaanxi province as an example. The prediction results obtained by using the environment-economy input-output model indicated that if the economy develops at the planned speed, without involvement of the economic structural adjustment, the situation of water environmental pollution will not be improved, and the trends will be worsened, even if the treatment is strengthened. According to the predicted index of economic structure and development, water resources utilization, water environment (discharge of waste water and waste material), investment of water treatment, the economic structure optimization model of water environment-economy was applied to the following items: firstly, the production structure of Guanzhong region in 2010 was optimized at the grade one, and 4 sets of alternative schemes and 1 recommending scheme were given; secondly the industrial structure of Guanzhong region in 2010 was also optimized at the grade two, and 4 sets of alternaial schemes at different investment levels and 1 recommending scheme were given. The results showed that under conditions of the recommended production structure and industrial structure, the economic development rate can not only be kept normal to ensure the realization of the economic target, but the target of water environmental pollution control and the protection of water environment (can also be achieved, leading to the coordinated development between water environment and economy. The study indicates that the economic structure optimization model of water environment-economy can better coordinate the relationship between economy and environment, simultaneously providing an operable method for the sustainable development of water environment and economy.
  • Sustainability Evaluation of Land Use in Development Zone: the Case of Kunshan
    LONG Hualou, CAI Yunlong, WAN Jun
    2000, 55(6): 719-728. https://doi.org/10.11821/xb200006009
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    The land in Development Zone includes not only non agricultural land with certain infrastructure, but also agricultural land in the sphere of planning, which is to be requisitioned. Land use sustainability of Development Zone involves two aspects, one is sustainability of every land use unit itself, and the other is the sustainability on structural side. To realize sustainable land use of Kunshan Economic and Technological Development Zone (KETDZ), it is necessary to understand the status quo of land use. Land use classification and evaluation are the feasible tools to understand it. In this paper, Landscape eco classification is applied to classify land use types of KETDZ. First, according to the human influencing intensity and the existing situation, four types of land use can be classified: Land in planning sphere without being requisitioned (type A); land requisitioned or granted use right without being constructed (type B); land granted use right and conducted construction activities without being utilized (type C); and utilized land (type D). Then, 17 subtypes and 20 subdivisions are classified according to the differentiation of succession process and conditions, and differentiation of functions, respectively. Accordingly, forecast evaluation of type A is to determine its developing sequence in the future development, evaluation of type B is to determine suitable utilizing and disposing ways to attain sustainable land use, and evaluation of types C and D is to evaluate their sustainability ranks. At last, sustainability evaluation of land use of KETDZ is carried out based on the establishment of the corresponding index systems of evaluation. According to the results of land use classification and evaluation, it can be seen that many land use types are not sustainable in KETDZ, and on the structural side, this is also particularly problematic.
  • The Evolutionary Tendency Forecast of Channel Morphology and River State of the Wandering Braided Rivers in the Lower Yellow River
    LU Zhong chen, CHEN Shao feng, CHEN Hao
    2000, 55(6): 729-736. https://doi.org/10.11821/xb200006010
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    From the 1960s, the evolution of channel morphology and river state in the lower Yellow River has been studied to different degrees with mapping methods and aerial photos by academic circles of geomorphology. With increasing accumulation of research materials, this study has been gradually deepening. During “the Eighth Five Year Plan”, a further analysis of mainstream line in the lower Yellow River has been carried out by hydrological circles and the results indicated that this status must be further analyzed and discussed because of different conclusions. In our study, the following conclusions are drawn: Firstly, the asymmetrical channel morphology in the lower Yellow River is a geological evolutionary process and a kind of synthesized result influenced by such factors as tilting down from north to south caused by neotectonic movement inheriting from old structural movement, coriolis force, recent human activities and geomorphological factor. Recent human activities including construction of the Xiaolangdi reservoir will not change the asymmetrical pattern of the channel in the lower Yellow River, but facilitate further development of asymmetrical channel morphology. Secondly, a kind of deflective resultant force southward caused by impact of asymmetrical channel in the lower Yellow River on the water body leads to continually stronger erosion to the southern bank of the river than to the northern. Thus, the tendency of southward shifting and meandering of the mainstream line will not change. The same is true of the Xiaolangdi reservoir after the completion of the project. Thirdly, according to empirical analysis of the Sanmenxia reservoir, there is an indication that although the wandering intensification of the channel was influenced by reservoir to some extent, the channel pattern didn’t change completely. It is expected that construction of the Xiaolangdi reservoir will not change the channel pattern in the lower Yellow River. Lastly, although construction works for harnessing the lower Yellow River channel can control meandering range and weakening wandering intensification of the channel, they cannot change the evolutionary tendency of channel morphology above mentioned ultimately.
  • Effect of Geographical Characteristics of River Basins on Relation of Sediment Yield and Rainfall in the Middle Yellow River
    LU Jin fa
    2000, 55(6): 737-743. https://doi.org/10.11821/xb200006011
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    Nineteen river basins in different geographical environments have been chosen to study the relations of sediment yield and rainfall in the Middle Yellow River Basin. Four major types of river basins were categorized, i.e., loess river basin with low vegetation coverage, mixed loess and rocky basin, rocky basin partly covered by loess and rocky basin. A composite index K was used as rainfall index for analysis of relations of sediment yield and rainfall. It was showed by data plotting that obvious positive relation exists between specific sediment yield and rainfall index K . The slope of line much varied from one type of river basins to another, indicating different rates at which specific sediment yield increases with the increase of rainfall index K . Moreover, obvious variation of specific sediment yield was observed for the same K value. Specific sediment yield tends to become increasingly greater from the south to the north within the studied area as index K increases. The environment features of river basins contribute a great deal to the control of the relations of specific sediment yield and rainfall index. An index VSD, integrated vegetation cover, surface material and morphological features, was used to indicate the resistance of river basin environment to erosion and relate to he specific sediment yield of river basin. It was revealed that specific sediment yield has obviously positive relations to the index VSD . It is of great interest that the places where different river basins were located on the plotting diagram are perfectly coincided with those on the diagram of the relation of specific sediment yield and rainfall K . Since rainfall index K relates to both rainstorms and the total rainfall different frequencies and intensities of rainstorms could occur for the same K value. By comparing the temporal variations of specific rainfalls with specific sediment yield, it was shown that the peaks of specific sediment yield could be produced either by one rainstorm event or by several rainstorm events, even the total volume of precipitation.
  • The Little Ice Age and Its Environmental Effects in the Tropical Zone of China
    ZHANG Wei qiang, HUANG Zhen guo
    2000, 55(6): 744-750. https://doi.org/10.11821/xb200006012
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    According to the historical data, climate was probables warm during the Medieval Period, the Yuan Dynasty and former part of the Ming Dynasty in China’s tropical zone. Based on the historical records about cold winter with snowfall, frost or freeze occurring in the tropical zone from 1245 to 1915, it has been found out that the Little Ice Age began in 1485 and ended in 1897. The records about historical weather are divided into three groups according to the locations of cold winter occurring in the subtropical, northern tropical and central tropical. Except the first which is not located at tropical, the second and the third kinds are called cool year and cold year, respectivily. As a result, it has been found out that there were three cold periods, i.e. the first （Ⅰ, 1485 1527）, the second （Ⅱ, 1606 1767） and the third （Ⅲ, 1835 1897） while two cool periods intercalated in the cold ones. The dating of the cold periods was later than that of north China. The frequency of cold winter got higher and higher from period Ⅰto period Ⅲ, but the amplitude of drop in annual mean temperature was <0 6℃ than present all of the three periods. However the maximum of low temperature reached -1 0℃ resulting in the removal of the south limit of snowfall southward by 2～3℃ latitudes or 1 0～1 5℃ of drop in temperature. Some natural disasters including flood, drought, typhoon and earthquke were frequent in the Little Ice Age especially the drought disasters which shows a desiccation trend of climatic change. The impacts of climate in the Little Ice Age on the poor agricultural harvest, ecological degeneration, migration of population, famine and society turbulence are also discussed in this paper.