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  • 2012 Volume 67 Issue 9
    Published: 20 September 2012
      
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  • Spatiotemporal Variation of PM10 Concentration and Its Relationship with Autumn Daily Temperature over Central and Eastern China
    GUO Yuanxi, GONG Daoyi, WANG Wenshan, ZHANG Ziyin, MAO Rui
    2012, 67(9): 1155-1164. https://doi.org/10.11821/xb201209001
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    Based on the autumn data of daily PM10 concentrations in 83 key cities and daily temperature, precipitation and total cloud cover in 63 key cities over Central and Eastern China from 2000 to 2010, the spatiotemporal distribution and variation of PM10 concentration were studied. The results were as follows. (1) During the past 11 years, the averaged PM10 concentration in autumn has showed a relatively steady downward trend on both all days and clear days, with a linear trend of -2.87 μg·m-3/yr and -4.92 μg·m-3/yr respectively. As to spatial variation, PM10 concentrations in most cities of Central and Eastern China have decreased significantly. (2) There were significant correlations between PM10 concentrations and daily temperatures in autumn. The quantitative statistics showed that as PM10 concentration increased by each 10 μg·m-3, the daily maximum temperature, daily minimum temperature, daily mean temperature and diurnal temperature range would decrease by 0.15 ℃, 0.14℃, 0.16℃ and 0.01℃ respectively. (3) The changes of daily temperature in autumn may be caused mainly by direct effect of PM10. When PM10 concentration increased, the surface solar radiation and surface net radiation would decrease significantly, and hence, the daily maximum temperature and daily mean temperature would decrease significantly.
  • Methane Dynamics of a Brackish-water Tidal Phragmites australis Marsh in the Minjiang River Estuary
    TONG Chuan, HUANG Jiafang, WANG Weiqi, LIAO Ji, LIU Zexiong, ZENG Congsheng
    2012, 67(9): 1165-1180. https://doi.org/10.11821/xb201209002
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    In 2008 and 2009, methane emission to the atmosphere was measured seasonally using an enclosed static chamber technique in the Minjiang River estuary, southeast China, a brackish-water tidal marsh dominated by P. australis. Measurements were taken at three tidal stages. Potential rates of methane production and oxidation from the marsh sediments were also estimated in situ in summer and winter using acetylene as a methane oxidation inhibitor. We devised a ‘hanging' enclosed static chamber to measure methane transport and emission directly from single stems of P. australis on days of neap tide. Methane emission from the P. australis tidal marsh showed a seasonal variation in all the three tidal stages, and reached a maximum during the summer when soil temperature was relatively high. The ranges of methane flux were 0.69-40.95, 0.26-9.57 and 0.74-22.10 mg m-2 h-1 before the flood, during the flood/ebb and after the ebb respectively and the average methane fluxes were 7.53, 2.19 and 4.93 mg m-2 h-1, respectively. Methane production and oxidation potentials in summer were all higher than those in winter. Methane concentrations within the lacunal of the P. australis stems were the greatest at the base and decreased faster compared with stem height, which start at the stem base, and showed lower lacunal methane concentrations at daytime and higher lacunal methane concentrations at night-time. On an annual basis, the average methane transport and emission of a single P. australis culm was 33.67 μg·culm-1·h-1. These methane transport rates differed between growth stages, with the highest transport and emission detected within the stage of fastest plant growth. Nearly half (43.4%) of the whole plant transport and emission occurred from P. australis culms nearest the ground (0-20 cm above the ground). We estimated that plant-mediated methane transport contributed 2.3%-28.5% of the total methane emission within this P. australis-dominated marsh.
  • Emergy Analysis of Tourism Ecological System of Tai'an City
    WEI Min, FENG Yongjun, LI Fen, ZHENG Yuqing
    2012, 67(9): 1181-1189. https://doi.org/10.11821/xb201209003
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    Based on emergy theory and analysis methods, this paper discusses the theory of tourism ecological emergy and the concept, measurement basis and calculation methods of tourism income emergy, emergy from tourist exports, tourism emergy exchange ratio, and tourism emergy sustainable index. It quantitatively analyzes the sustainability of the tourism eco-economic system in Tai'an City. The results are shown as follows. (1) The total emergy used was 15867.32×1019 sej (solar emjoules), tourism emergy from income (Eti) of eco-economic system was 1766.59×1019 sej, and the tourism emergy from tourist consumption (Ete) was about 679.40×1019 sej, while tourism emergy exchange ratio (TEER) was 2.60. The tourism emergy sustainable index (TSEI) was 1.76. (2) It is feasible to use the emergy analysis method to evaluate the sustainable development of tourism level.
  • Comparisons of Reconstructed Cropland Area from Multiple Datasets for the Traditional Cultivated Region of China in the Last 300 Years
    HE Fanneng, LI Shicheng, ZHANG Xuezhen, GE Quansheng, DAI Junhu
    2012, 67(9): 1190-1200. https://doi.org/10.11821/xb201209004
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    Land cover change is an important boundary condition in climate and ecological simulations. Although they have been widely used in researches, SAGE and HYDE, the two global scale historical land use datasets, have been rarely discussed about their rationality and accuracy in regional scale. On the basis of CHCD, the historical cropland dataset of traditional cultivated region of China (TCRC, hereafter) which was established by Chinese scholars, we analyzed the rationality and accuracy of TCRC part of SAGE (2010) and HYDE3.1 by comparing them with CHCD in the whole study area scale, provincial scale and 60 km × 60 km grid cell scale. The results indicated that (1) TCRC part of SAGE (2010) dataset was established by linear interpolation and the average annual growth rate was 0.51% from 1700 to 1950 and -0.34% after 1950. The normalized trend could not reflect TCRC's history of cultivation, and the estimation of cropland area was obviously high compared with CHCD dataset. (2) In comparison of more regional research results, HYDE3.1 dataset was very close to CHCD dataset in the whole study area scale. However, there were significant differences between HYDE3.1 and CHCD in provincial and 60 km×60 km grid cell scales. The percentages of grid cells whose relative differences are greater than 70% (<-70% or > 70%) and 90% (<-90% or >90%) were 56%~63% and 40%~45% respectively while those whose relative difference ranges from -10% to 10% and from -30% to 30% were only 5%~ 6% and about 17%, respectively. (3) Making full use of abundant historical archives in China and establishing historical land use dataset of China with high accuracy are significant ways of improving the quality of climate and ecological simulation results.
  • Fractal-based Effective Utilization Coefficient of Irrigation Water Space Scale Variability
    WANG Xiaojun, ZHANG Qiang, GU Xuanqing
    2012, 67(9): 1201-1212. https://doi.org/10.11821/xb201209005
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    Based on the measured data and remote sensing images of 75 sample irrigation areas of Guangdong province in 2010, grid box dimension method was used to analyze the box dimension of sample irrigation area. The results show that irrigation area of the province is subjected to fractal characteristics with the box dimension ranging from 1.0004 to 1.675, the mean of fractal dimension of 1.308 and mean shape index of 0.335, and shows a decreasing trend with the irrigation area scale. The box dimension of irrigation area at different scales is listed in the order of large-scale irrigation area (1.442) > medium-sized irrigation area (1.287) > small-scale irrigation area (1.195). The most significant factor is logarithm of non-empty grid with the correlation coefficient of 0.941. In this case, a variation function of spatial scale between irrigation district area, the effective utilization coefficient of irrigation water and the box dimension under different grid scales is achieved. Meanwhile, five indicators related to many influencing factors, the value of the project evaluation, box dimension, irrigation area shape index, the reference crop evapotranspiration ET0 and precipitation are analyzed in this study. And the factors influencing the spatial pattern are also thoroughly investigated. The above-mentioned analysis and also those by the gray relational calculation show that the highest correlation of spatial influence factors is the engineering evaluation of 0.8478, followed by topographical features and meteorological factors.
  • Identifying Contributions of Climate Change to Crop Yields Based on Statistical Models: A Review
    SHI Wenjiao, TAO Fulu, ZHANG Zhao
    2012, 67(9): 1213-1222. https://doi.org/10.11821/xb201209006
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    Statistical models and crop models are two major tools for research of contributions of climate change to agricultural production. The researchers have paid much attention to the studies of effects of climate change on crop growth based on crop models. However, the topic based on statistical models has not been fully realized. This paper starts with the difference and relation between statistical models and crop models, and introduces three main statistical methods for identifying contributions of climate change to crop yields including time-series model, cross-section model and panel model. It reviews the topic on different scales, e.g. global scale, national scale, provincial scale, regional scale, county scale and site scale. There are four problems in identifying response sensitivity of crop yields to climate change, namely spatial and temporal scale, non-climatic trend removal, co-linearity existing in climate variables and the non-consideration of adaptation.
  • Effect of Chilling Injury on Rice Yield in Heilongjiang Province
    LIU Xiaofei, ZHANG Zhao, SHUAI Jiabing, WANG Pin, SHI Wenjiao, CHEN Yi, TAO Fulu
    2012, 67(9): 1223-1232. https://doi.org/10.11821/xb201209007
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    This study is focused on indexes for the rice chilling injury in Heilongjiang Province during 1960-2009. Firstly, we compared a new derived climate data weighted by rice planting density with the traditional method, and found that the new one is more reasonable to assess the impact of climate change on crop yields. Considering the frequency and intensity of rice chilling in the province, secondly, chilling indexes defined by meteorological, national and international levels were assessed. The result showed that the meteorological standards were suitable for the delayed injury, while the international one, so-called sum of Growing Degree Day below threshold (GDDn-), characterized best the chilling sterile injury for rice. The explanation ability of the rice yield time series model including both injury types as two independent variables reached approximately 92% (p < 0.05). Finally, we concluded that the contribution rates of human and weather factors to rice yields are about 87.2% and 12.8% respectively, and a slight increasing trend for sterile chilling injury was found during heading to flowing period in recent years, indicating a high chilling risk for rice planting in Heilongjiang Province in the future global warming.
  • The Present Situation and Hot Issues in the Salt-affected Soil Research
    LI Jianguo, PU Lijie, ZHU Ming, ZHANG Runsen
    2012, 67(9): 1233-1245. https://doi.org/10.11821/xb201209008
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    With the global warming, soil salinization has become a global concern in the world, and about 7% of the global land is threatened by salinity. In addition, this figure is rising. Soil salinization in China is critical, and the area of salt-affected soil is vast, which poses a great threat to agricultural development. This study summarizes the framework of the soil salinization research in China over tha past 70 years, and make comments on the inadequencies in previous studies at home and abroad. This study summarizes the present situation and future tendency of soil salinization research across the world in the last 30 years by using the literature database and data-sharing network, and identifies five research priorities and orientations for providing new ideas to carry out the saline soil research in the future.
  • Seasonal Variations of Soil Temperature and Moisture at the Upper Limit of Alpine Meadow in North-facing Slope of the Nianqingtanggula Mountains
    YU Jiehui, LIU Xinsheng, LUO Tianxiang, ZHANG Lin
    2012, 67(9): 1246-1254. https://doi.org/10.11821/xb201209009
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    Based on the three-year observations in a plot at the upper limit of the alpine Kobresia meadow (5125 m a.s.l.) on the Nianqingtanggula Mountains in the southern part of Namco Basin in Tibet, we analyzed the seasonal variations of soil temperature and moisture at soil depths of 10 and 30 cm. The results were obtained as follows. 1) The soil thawed in late April and froze in late October. The daily amplitude of soil temperature from June to August, which was 3.8℃ at 10 cm and 1.4℃ at 30 cm on average, reflected the highest values throughout the year. 2) The unfrozen soil water content increased (declined) when the soil began to thaw (freeze). And the soil moisture was relatively high from May to October, which was 2%-6% at 10 cm and 15%-20% at 30 cm. 3) Based on the soil temperature measurements at 10 cm depth, the growing season length for vegetation at the upper limit of the alpine Kobresia meadow was calculated to last 80-87 days, which began in early June and ended in late August or early September. And the average soil temperature and moisture were 6.78±0.73℃ and 4.14±0.91%, respectively. The lowest daily temperature during the growing season was mainly observed between 3℃ and 7℃. 4) Compared with the soil temperature and moisture at the lower altitude of 4980 m a.s.l., those at 5125 m were significantly lower. Also, the number of days of daily minimum temperature < 5℃ in August at the higher altitude was far more than that at the lower.
  • Spatial Differences of Variations of Vegetation Coverage in Inner Mongolia during 2001-2010
    MU Shaojie, LI Jianlong, CHEN Yizhao, GANG Chengcheng, ZHOU Wei, JU Weimin
    2012, 67(9): 1255-1268. https://doi.org/10.11821/xb201209010
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    Global climate change has led to significant vegetation changes in the past half century. Inner Mongolia, most of which was located in arid and semi-arid areas, is undergoing a process of prominent warming and drying. It is necessary to investigate the response of vegetation to the climatic variations (temperature and precipitation) for a better understanding of the accumulated consequence of climate change. Vegetation coverage, which is an important indicator for evaluating terrestrial environment, is used to monitor vegetation change. MODIS-NDVI data and climate data were used to analyze the vegetation dynamics and its relationship with climate change on different spatial (forest, grassland and desert biome) and temporal (yearly and monthly) scales in Inner Mongolia during 2001-2010. It was found that vegetation coverage increased from west to east across Inner Mongolia with a change rate of 0.2/10°N. During 2001-2010, the mean vegetation coverage was 0.57, 0.4 and 0.16 in forest, grassland and desert biome, respectively, exhibiting evident spatial heterogeneities. There is a slight increase of vegetation coverage over the study period. Across Inner Mongolia, the vegetation coverages with extremely significant and significant increase accounted for 11.25% and 29.13% of the total study area, respectively, while those with extremely significant and significant decrease were 7.65% and 26.61%, respectively. The correlation analysis between vegetation coverage and climate shows that annual vegetation coverage was better correlated with precipitation, while the change of monthly vegetation coverage is consistent with both the changes of temperature and precipitation, indicating that the vegetation growth within a year is more sensitive to the joint function of hydrothermal combination rather than either climate factor. The vegetation coverage of forest biome was mainly affected by temperature on both yearly and monthly scales, while that of desert biome was mainly influenced by precipitation on the two temporal scales.
  • Processes of Suspended Sediment Mixture in the Yangtze River Estuary
    LIU Hong, HE Qing, WANG Ya, CHEN Jiyu
    2012, 67(9): 1269-1281. https://doi.org/10.11821/xb201209011
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    Based on the sub-simultaneous data of grain size distributions (GSDs) of suspended and surface sediment, current velocity, suspended sediment concentration (SSC), the mixing processes between suspended and surface sediment were conducted in the Yangtze River Estuary and adjacent area. The characteristics of suspended sediment D50 (SSD) were showed a fine-coarse-fine pattern from the Yangtze River Estuary to continental shelf. The SSD were 8.9 μm, 10.5 μm and 4.5 μm in the upper Yangtze River Estuary, mouth bar area and continental shelf respectively, and were 9.9 μm and 5.6 μm in the North Branch and Hangzhou Bay respectively. Clayey silt was the dominant sediment type in the study area. The vertical mixing processes between suspended and surface sediments were weak in the upper estuary and the continental shelf, while it was strong in the mouth bar area. Only surface layer of suspended sediment retained the characteristics of GSDs from the Yangtze River basin. Good positive correlations were observed between the SSD and SSC, and the sediment resuspension by the shear flow was the main causes of SSC and SSD increase near the bottom. The SSD of the Yangtze Estuary in the year 2007 decreased by 11% compared with 2003, while the SSC decreased by 22% in the same period.
  • Tidal Dynamics of Yangshan Harbor Sea Area and Its Response to the Project
    YANG Zhongyong, CHENG Heqin, ZHU Jianrong, LI Shenduo
    2012, 67(9): 1282-1290. https://doi.org/10.11821/xb201209012
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    As the first offshore-port in China, the Yangshan Deep Water Port was set up along the Xiaoyangshan island chain, locating about 32 km away from the mainland of Shanghai. The port is shaped by three main fork channel closures and throw-filling land-making projects. The topography of this area was changed strongly by the large-scale man-made landform projects, which led to the response of tidal dynamics of Yangshan Harbor sea area. According to the observation data of tidal level and tidal flow before and after the project, we found the main tidal dynamics in Yangshan Harbor sea area are as follows. The amplitude of over-tide and compound tide are strengthened due to the project, showing a distinct non-linear effect. Backwater phenomena occurs in the central part of this sea area. The tidal wave shows that standing waves near the landline area cause a weak tidal circulation in the slack tidal period.