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1.
Wetland Is an important landscape existing almost DEFINITIONS OF WETLANDall over the world．In China，wetlands are distributedeverywhe。加mfrlgld－tern。。。ie zone to tropical zone，XU QI et al．dehned wetland as the soil which isfrom lmoral！o Inland from paln to pforeau and moisten by under－ground water or Is permanently ormountains．＞ome ot the wetlands share the sam。char－temno。rllv soak。d by ground。ater（XU，1995）．Thisacterlstlcs of other countries，and some are un…  相似文献   

2.
The research on the present situation of soil and water development and utilization in Shiyang River Basin shows that water resources and eco-environment situation in this area are near the edge of collapse. Since the water crises occurred in the 1970s, problems caused by continuous decrease of water resources have been becoming serious year by year and eco-environment crisis occurred as a consequence. Up to now, 10 380ha of irrigated lands have been abandoned due to sand coverage and water shortage in the basin. Ground water was over exploded in Wuwei and Minqin because of water shortage. Ground water table in many places dropped under 5m (which is the ecology water table level), thus about 3000ha of Elaeagnus angustifolia forest come to dead and another 5800ha become feeble, and wind-drift sand near the oasis become alive. According to the current situation, if water utilization scope was not enlarged, a water transfer volume of 600×106m3/a from other areas will be suitable to keep water resources and eco-environment safety in the basin, and also 70×106m3/a will be left as spare water. Under this condition the water resources and eco-environment of the basin can reach the critical safety line of 2.032×109m3/a; or if 180×106m3 of water can be transferred from other areas, the water resources can reach the safety warning line of 1.732×109m3/a. Foundation item: Under the auspices of the National Natural Science Foundation of China (No. 40235053) and Lanzhou Jiaotong University "Qinglan" Foundation Biography: ZHANG Ji-shi (1963-), male, a native of Tongwei of Gansu Province, senior engineer, specialized in water resources and climate change in Northwest China. E-mail: zjs1963@yahoo.com.cn; hangjs@mail.lzjtu.cn  相似文献   

3.
Based on the simulation with the Ocean-Atmosphere Coupled Model CCSM and Ocean Model POP under the greenhouse gas emission scenario of the IPCC SRES A2 (IPCC, 2001), and on the earth crust subsidence and glacier melting data, the relative sea level change is obtained along the coast of China in the 21st century. Using the SRTM elevation data the submergence of coastal low land is calculated under the extreme water level with a 100-year return period. The total flooding areas are 98.3×103 and 104.9×103 km2 for 2050 and 2080, respectively. For the three regions most vulnerable to extreme sea level rise, i.e., the coast of Bohai Bay, the Yangtze River Delta together with neighboring Jiangsu Province and northern Zhejiang Province, and the Pearl River Delta, the flooded areas are 5.0×103, 64.1×103 and 15.3×103 km2 in 2050 and 5.2×103, 67.8×103 and 17.2×103 km2 in 2080, respectively.  相似文献   

4.
After the winter and summer current structures on two or three latitudinal sections in Taiwan Strait were obtained from the measured current data, the seawater fluxs through the sections were calculated. In summer, the currents in the central and northern part of Taiwan Strait normally flow northward at a net flux of 3.32×106m3/s. In winter, the high temperature and salinity Kuroshio and South China Sea water enter Taiwan Strait from the southem section at 1.69×106m3/s and 0.59×106 m3/s respectively, while the East China Sea water enters Taiwan Strait from the northern section at 1.02×106m3/s. About 0.40×106 m3/s of the seawater enters the South China Sea along the coast of Fujian and Guangdong; the other 0.62×106 m3/s of the seawater is mixed with the Kuroshio water and the South China Sea water in the northern sea areas. The net northward flux is 1.74×106m3/s in winter.  相似文献   

5.
Energy crops are a basic material in the bioenergy industry, and they can also mitigate carbon emissions and have environmental benefits when planted on marginal lands. The aim of this study was to evaluate the potential productivity of energy crops on marginal lands in China. A mechanistic model, combined with energy crop and land use characteristics, and meteorological and soil parameters, was used to simulate the potential productivity of energy crops. There were three main results. 1) The total marginal land in China was determined to be 104.78 × 10~6 ha. The 400-mm precipitation boundary line, which is the dividing line between the semi-humid and semi-arid zones in China, also divided the marginal land into shrub land and sparse forest land in the southeast and bare land, bare rock land, and saline alkali land in the northeast. 2) The total area of the marginal land suitable for planting energy crops was determined to be 55.82 × 10~6 ha, with Xanthoceras sorbifolia and Cerasus humilis mainly grown in the northern China, Jatropha curcas and Cornus wilsoniana mainly grown in the southwest and southeast, and Pistacia chinensis mainly grown in the central area, while also having a northeast-southwest zonal distribution. 3) Taking the highest yield in overlapping areas, the potential productivity of target energy crops was determined to be 32.63 × 10~6 t/yr. Without considering the overlapping areas, the potential productivity was 6.81 × 10~6 t/yr from X. sorbifolia, 8.86 × 10~6 t/yr from C. humilis, 7.18 × 10~6 t/yr from J. curcas, 9.55 × 10~6 t/yr from P. chinensis, and 7.78 × 10~6 t/yr from C. wilsoniana.  相似文献   

6.
The objective of this study is to quantify the values of greenhouse gases (GHGs) exchange in carbon equivalents of marshes and paddy fields in the Sanjiang Plain, Heilongjiang Province, China. We obtained the GHGs exchange values based on comparable price by calculating the carbon sequestration values and the GHGs emission values of marshes and paddy fields respectively in four periods of 1982, 1995, 2000 and 2005. It is noted that the GHGs emission values are always negative. In this study, the marshes areas decreased from 1438977.0 to 775,132.2ha and the paddy fields areas increased from 417195.8 to 934205.0ha. The values of GHGs exchange of marshes varied from 135877.156×106 to 136882.534×106 yuan (RMB) and those of paddy fields varied from 1006.256×106 to 2767.645×106 yuan. The GHGs exchange values of marshes decreased from 1982 to 2005 on the whole, reversely, those of paddy fields increased, but those in 2005 were lower than those in 2000. In different periods, the GHGs exchange values were always higher in marshes than in paddy fields. The contribution rate of GHGs exchange values per unit area of marshes was also very high in different periods, and the maximum was up to 98.35% in 2005. As far as the whole wetland ecosystem (including marshes and paddy fields), assuming a linear change in GHGs exchange values, it represented a cumulative increase of 20926.757×106 yuan from 1982 to 2005. By adding GHGs exchange values increased during those four periods, we obtained a cumulative net increase values of GHGs exchange of wetland ecosystem of 18200.860×106 yuan. The results will be useful for understanding the indirect services provided by marshes and paddy fields.  相似文献   

7.
The South China Sea water can be divided according to depth into three boxes by the pycnoclineand a sill.Using a box model with matter balance,the net seawater fluxes were calculated to be317.9×10~4 m~3/s in box Ⅰ for the upper homogeneous layer outflowing to the adjoining oceans;67×10~4 m~3/s in box Ⅲ for the water entering the basin;240×10~4 m~3/s in box Ⅱ for water entering theSouth China Sea.The upward speed of basin water was calculated to be 8.4×10~(-5) cm/s and that ofseawater flowing up along the pycnocline was calculated to be 8.9×10~(-5) cm/s.  相似文献   

8.
Soil organic carbon is of great importance to terrestrial ecosystems.Studies on the amount and spatial distribution of soil organic carbon stock in various types of soil can help to better understand the role of soil in the global carbon cycle and provide a scientific basis for the assessment of the magnitude of carbon stored in a given area.Here we present estimates of soil organic carbon stock in soils in the upper reaches of the Yangtze River based on soil types as defined by Chinese Soil Taxonomy and recently compiled into a digital soil database.The results showed that the total soil organic carbon stock of the upper Yangtze River to a depth of 100 cm was 1.452×1013kg.The highest soil organic carbon stock was found in felty soils(2.419×1012kg),followed by dark brown soils(1.269×1012kg),and dark felty soils(1.139×1012kg).Chernozems and irrigation silting soils showed the lowest soil organic carbon stock,mainly due to the small total area of such soils.The soil organic carbon density of these major soil types ranged from 5.6 to 26.1 kg m-2.The average soil organic carbon density of the upper reaches of the Yangtze River was 16.4 kg m-2,which was higher than that of the national average.Soil organic carbon density indicated a distinct decreasing trend from west to east,which corresponds to the pattern of increasing temperature from cold to subtropical.  相似文献   

9.
1 THE NATURAL ENVIRONMENTAL CHARACTERISTICS The Sanjiang Plain is located in the northeast of Heilongjiang Province, China. Russia borders this region in the north and east. Its total area is 1.088×107ha. The area of plain occupies 61.21％of the total land area and that of hill and mountain amounts to 38.79％of the total land area. It is not only one of the most important regions with large area of fresh water wetlands and with varieties of rare migratory waterfowls, but a…  相似文献   

10.
Based on the data from the Cost-benefit Data of Farm Produce and the China Agricultural Yearbook, this paper aims to examine the spatial and temporal change characteristics of total grain production and its affecting factors. The results show that: 1) During 1980 to 2007, total grain production increased from 3.20 × 108 t to 5.02 × 108 t in China, with annual increasing rate of 1.68%. From the regional disparities, most of the regions present increasing trend of total grain production except for several regions with higher level of economic development; 2) Grain sown area decreased from 1.17 × 108 ha in 1980 to 1.06 × 108 ha in 2007, which has negative effect on total grain production; 3) The increase of grain yield per unit area caused by land use intensity changes contributed to the increase of total grain yield greatly. However, as the land use intensity showed that farmers pay more attention to labor-saving input but not yield-increasing input, the less enthusiasm of farmers in grain production may become an important constraint on future grain production increase in China; 4) Based on the results, this paper proposed different land management policies in different regions, for example, the government should protect cultivated land, promote large scale production. As to the less developed regions, the government should pay more attention to agricultural subsidies to promote farmers’ enthusiasm in grain production.  相似文献   

11.
We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary. The average numbers of Synechococcus spp.(Syn) and picoeukaryotes(Euk) were(2.7 ±5.1) ×103 and(1.1±1.4) ×103 cells m L-1, respectively. Prochlorococcus spp.(Pro) was only found in the high-salinity brackish water with the concentration of 3.0×103 cells m L-1. Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk. The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean. The response of different picophytoplankton groups to environmental variables was different. Water temperature was more important in its control over Euk than over Syn, while nutrients were more important in their influence over Syn than over Euk. Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient(i.e., freshwater zone with 0-5 range, fresh and saline water mixing zone with 5-20 range, and high-salinity brackish water zone with 20-32 range), where three different phytoplankton communities were discovered, suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.  相似文献   

12.
Transfort of oxygen,nutrients and carbonates by the Kuroshio Current   总被引：1，自引：0，他引：1  
Measured concentrations of dissolved oxygen, phosphate, silicate, total alkalinity and calculated total CO2 in a section between 121° E and 125° E across the Kuroshio near 22° N off Taiwan and the geostrophic velocity were used to estimate the gross transport of oxygen, nutrients and carbonates. The flux of dissolved oxygen is 6.7×106 mol/s northward and 0.9×106 mol/s southward. The net flux equals 5.8×106 mol/s down-stream. The northward flux of phosphate is 22.6×103 mol/s; the southward flux is 1.4×103 mol/s. The net phosphate flux is 21.2×103 mol/s northward. The flux of silicate is 967×103 northward and 59×103 mol/s southward; the net transport is 908×103 mol/s down-stream. The flux of alkalinity is 75.5×106 mol/s northward, and 10.8×106 mol/s southward, the net flux is 64.7×106 mol/s northward. For total CO2 the transport is 73.4×106 mol/s northward and 10.8×106 mol/s southward, or a net transport of 62.6×106 mol/s horthward.  相似文献   

13.
1　Introduction　Manhasmodifiedmanyoftheworld’scoastlines ,eitherdirectlybyconstructionordredging ,orindi rectlyasaresultofenvironmentalchangesthatinflu encesedimentsupply ,runoff,orclimate (Johns ,1995 ) .HumanactivityhasalsoproducedthemostprofoundeffectsonthecoastalenvironmentinChina .Forex ample,damconstructions ,whichrestrictpeakflowsintheupstreamoftheYellowRiver ,couldgreatlyre ducethenaturalsupplyofsedimentintotherivermouthandresultintheerosionofbeaches .　Inrecentyears,manystudiescon…  相似文献   

14.
A catastrophic landslide occurred at Xinmo village in Maoxian County, Sichuan Province,China, on June 24, 2017. A 2.87×106 m3 rock mass collapsed and entrained the surface soil layer along the landslide path. Eighty-three people were killed or went missing and more than 103 houses were destroyed. In this paper, the geological conditions of the landslide are analyzed via field investigation and high-resolution imagery. The dynamic process and runout characteristics of the landslide are numerically analyzed using a depth-integrated continuum method and Mac Cormack-TVD finite difference algorithm.Computational results show that the evaluated area of the danger zone matchs well with the results of field investigation. It is worth noting that soil sprayed by the high-speed blast needs to be taken into account for such kind of large high-locality landslide. The maximum velocity is about 55 m/s, which is consistent with most cases. In addition, the potential danger zone of an unstable block is evaluated. The potential risk area evaluated by the efficient depthintegrated continuum method could play a significant role in disaster prevention and secondary hazard avoidance during rescue operations.  相似文献   

15.
In recent years,wetland ecological water requirements (EWRs) have been estimated by using hydrological and functional approaches,but those approaches have not yet been integrated for a whole ecosystem.This paper presents a new method for calculating wetland EWRs,which is based on the response of habitats to water level,and determines water level threshold through the functional integrity of habitats.Results show that in the Huanghe (Yellow) River Delta water levels between 5.0 m and 5.5 m are required to maintain the functional integrity of the wetland at a value higher than 0.7.One of the dominant plants in the delta,Phragmites australis,tolerates water level fluctuation of about ± 0.25 m without the change in wetland functional integrity.The minimum,optimum and maximum EWRs for the Huanghe River Delta are 9.42×106 m3,15.56×106 m3 and 24.12×106 m3 with water levels of 5.0 m,5.2 m and 5.5 m,corresponding to functional integrity indices of 0.70,0.84 and 0.72,respectively.A wetland restoration program has been performed,which aims to meet these EWRs in attempt to recover from losses of up to 98% in the delta's former wetland area.  相似文献   

16.
ＩＮＴＲＯＤＵＣＴＩＯＮＰｈｙｔｏｐｌａｋｔｏｎｈａｓａｋｅｙｒｏｌｅｉｎｔｈｅｍａｒｉｎｅｅｃｏｓｙｓｔｅｍａｓｔｈｅｂａｓｉｃｐａｒｔｉｎｔｈｅｆｏｏｄｃｈａｉｎ ,ｗｈｉｃｈｉｓｉｍｐｏｒｔａｎｔｉｎｆｏｒｍａｔｉｏｎｆｏｒａｓｓｅｓｓｉｎｇｐｒｏｄｕｃｔｉｖｉｔｙｐｏｔｅｎｔｉａｌａｎｄｆｉｓｈｅｒｙｒｅｓｏｕｒｃｅｓ.Ｐｈｙｔｏｐｌａｎｋｔｏｎａｌｓｏｈａｓａｎｉｍｐｏｒｔａｎｔｒｏｌｅｉｎｔｈｅｃａｒｂｏｎｂｉｏｇｅｏｃｈｅｍｉｃａｌｃｙｃｌｅ,ｂｅｃａｕｓｅｉｔｃａｎａｂｓｏｒｂａｌａ…  相似文献   

17.
Fifty-one tree leaves were sampled in the industrial area,residential area,and Fenhe River ecological zone,for the purpose of a magnetic study on atmospheric pollution in Linfen City,Shanxi Province,China.Measurements of mass-specific magnetic susceptibility(χ) show a significant variation range(from 11.6 × 10-8 m3/kg to 129.7 × 10-8 m3/kg).Overall values of magnetic susceptibility decline in the following sequence:industrial area > residential area > Fenhe River ecological zone.The relatively elevated concentration-related magnetic parameters(saturation isothermal remanent magnetization,anhysteretic remanent magnetization and magnetic susceptibility) appear in the industrial area,with their highest values in the vicinity of Linfen Steel Mill.Magnetic particles are dominated by multidomain,magnetite-like minerals.Magnetic particle concentration and grain size both decrease with the increasing distance from industrial area,indicating the industrial area,especially Linfen Steel Mill,is the main source of atmospheric particle pollution.Residential area and Fenhe River ecological zone are also affected by industrial emission to a certain extent.The results of this study indicate that magnetic measurements of tree leaves are practicable for monitoring and determination of atmospheric pollution in Linfen City.  相似文献   

18.
During the 15th Conference of the Parties(COP 15),Parties agreed that reducing emissions from deforestation and forest degradation and enhancing ’removals of greenhouse gas emission by forests’(REDD+) in developing countries through positive incentives under the United Nations Framework Convention on Climate Change(UNFCCC) was capable of dealing with global emissions.As REDD+ seeks to lower emissions by stopping deforestation and forest degradation with an international payment tier according to baseline scenarios,opportunities for ecosystem benefits such as slowing habitat fragmentation,conservation of forest biodiversity,soil conservation may be also part of this effort.The primary objective of this study is to evaluate ecosystem-based benefits of REDD+,and to identify the relationships with carbon stock changes.To achieve this goal,high resolution satellite images are combined with Normalized Difference Vegetation Index(NDVI) to identify historical deforestation in study area of Central Kalimantan,Indonesia.The carbon emissions for the period of 2000-2005 and 2005-2009 are 2.73 × 10 5 t CO 2 and 1.47 × 10 6 t CO 2 respectively,showing an increasing trend in recent years.Dring 2005-2009,number of patches(NP),patch density(PD),mean shape index distribution(SHAPE_MN) increased 30.8%,30.7% and 7.6%.Meanwhile,largest patch index(LPI),mean area(AREA_MN),area-weighted mean of shape index distribution(SHAPE_AM),neighbor distance(ENN_MN) and interspersion and juxtaposition index(IJI) decreased by 55.3%,29.7%,15.8%,53.4% and 21.5% respectively.The area regarding as positive correlation between carbon emissions and soil erosion was approximately 8.9 × 10 3 ha corresponding to 96.0% of the changing forest.These results support the view that there are strong synergies among carbon loss,forest fragmentation and soil erosion in tropical forests.Such mechanism of REDD+ is likely to present opportunities for multiple benefits that fall outside the scope of carbon stocks.  相似文献   

19.
Three-North Shelterbelt Forest(TSF) program, is one of six key forestry programs and has a 73-year construction period, from 1978 to 2050. Quantitative analysis of the carbon sequestration of shrubs in this region is important for understanding the overall function of carbon sequestration of the forest and other terrestrial ecosystems in China. This study investigated the distribution area of shrubland in the TSF region based on remote sensing images in 1978 and 2008, and calculated the carbon density of shrubland in combination with the field investigation and previous data from published papers. The carbon sequestration quantity and rate from 1978 to 2008 was analyzed for four sub-regions and different types of shrubs in the TSF region. The results revealed that: 1) The area of shrubland in the study area and its four sub-regions increased during the past thirty years. The area of shrubland for the whole region in 2008 was 1.2 × 10~7 ha, 72.8% larger than that in 1978. The Inner Mongolia-Xinjiang Sub-region was the largest shrubland distribution area, while the highest coverage rate was found in the North China Sub-region. 2) In decreasing order of their carbon sequestration, the four types of shrubs considered in this study were Hippophae rhamnoides, Caragana spp., Haloxylon ammodendron and Vitex negundo var. heterophylla. The carbon sequestration of H. rhamnoides, with a maximum mean carbon density of 16.5 Mg C/ha, was significantly higher than that of the other three species. 3) The total carbon sequestration of shrubland in the study region was 4.5×10~7 Mg C with a mean annual carbon sequestration of 1.5 ×10~6 Mg C. The carbon density in the four sub-regions decreased in the following order: the Loess Plateau Sub-region, the North China Sub-region, the Northeast China Sub-region and the Inner Mongolia-Xinjiang Sub-region. The paucity of studies and data availability on the large-scale carbon sequestration of shrub species suggests this study provides a baseline reference for future research in this area.  相似文献   

20.
采用Landsat TM遥感影像,辅以MODIS数据产品,应用像元的分类方法,选用水体指数AWEI（Automated Water Extraction Index）提取水体,估算了2011年南美洲陆表水域总面积。同时,在南美洲各大气候带内监测其典型水域的年内季节性面积及其变化。研究表明,南美洲陆表水域总面积为30.5×104 km2,水域率为1.69%,主要集中分布在亚马逊河流域、巴拉那河流域,以及南部巴塔哥尼亚高原。南美洲共计有湖泊9579个,总面积为14.2×104 km2,占水域总面积的46.42%;河渠总面积达15.7×104 km2,占水域总面积的51.56%;水库坑塘总面积达6144.8 km2,占南美洲地表水域总面积的2.01%。从各大气候区看,热带地区的水域面积明显受到旱雨季的影响,其中,热带沙漠气候带内水域的干湿季变化最为明显;温带地区的水域面积变化相对较小,但有明显的四季之分;高原山地气候区由于其独特的气候特征,水域面积变化较小;亚热带季风性湿润气候和地中海气候区内的水域面积季节性波动很小,但是冬夏2个季节变化明显。从南美洲各国家看,水域面积最大的国家为巴西（14.7×104 km2）,占南美洲水域总面积的48.17%,水域率为1.72%;其次为阿根廷（3.4×104 km2）,占南美洲水域总面积的11.24%,水域率为1.23%;委内瑞拉的水域率最大（3.08%）。  相似文献   

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