基于景观格局的广州市边缘区生态压力研究——以番禺区为例

基于RS、GIS技术和统计分析方法,选取破碎化指数、斑块结合度指数、分形维数3个景观指数和土地利用脆弱性指数构建生态压力指数,以番禺为例从景观尺度研究城市边缘区在城市化梯度上的生态压力空间分异。结果表明:不同用地类型的景观指数在3个梯度区内依人为干扰的强烈程度出现明显的空间分异,生态压力呈现自北向南依次降低的空间分布格局。景观生态压力强弱的分布与区域内土地利用方式和强度具有较高的相关关系,人为干扰是影响景观生态压力扩散的重要原因。     

Identifying the Hydrochemical Characteristics, Genetic Mechanisms and Potential Human Health Risks of Fluoride and Nitrate Enriched Groundwater in the Tongzhou District, Beijing, North China

Fluoride and nitrate enriched groundwater are potential threats to the safety of the groundwater supply that may cause significant effects on human health and public safety, especially in aggregated population areas and economic hubs. This study focuses on the high F? and NO3? concentration groundwater in Tongzhou District, Beijing, North China. A total of 36 groundwater samples were collected to analyze the hydrochemical characteristics, elucidate genetic mechanisms and evaluate the potential human health risks. The results of the analysis indicate: Firstly, most of the groundwater samples are characterized by Mg-HCO3 and Na-HCO3 with the pH ranging from 7.19 to 8.28 and TDS with a large variation across the range 471–2337 mg/L. The NO3? concentration in 38.89% groundwater samples and the F? concentration in 66.67% groundwater samples exceed the permissible limited value. Secondly, F? in groundwater originates predominantly from water-rock interactions and the fluorite dissolution, which is also regulated by cation exchange, competitive adsorption of HCO3? and an alkaline environment. Thirdly, the effect of sewage disposal and agricultural activities have a significant effect on high NO3– concentration, while the high F? concentration is less influenced by anthropogenic activity. The alkaline environment favors nitrification, thus being conducive to the production of NO3?. Finally, the health risk assessment is evaluated for different population groups. The results indicate that high NO3? and F? concentration in groundwater would have the largest threat to children’s health. The findings of this study could contribute to the provision of a scientific basis for groundwater supply policy formulation relating to public health in Tongzhou District.     

ASSESSING THE SEISMIC RISK OF CITIES AT FINE-SCALE: A CASE STUDY OF HAIDIAN DISTRICT IN BEIJING,CHINA

In order to provide practical and useful information for the disaster prevention and relief actions, it is necessary to take into account spatial differences and temporal changes of seismic risk in evaluating seismic risk at a proper temporal and spatial scale. From the perspectives of identifying spatial difference of seismic risk within the city and performing disaster relief operations, the evaluation of urban seismic risk is done in this paper at the spatial scale of 500m*500m grids for day time and night time separately. For this purpose, this paper proposes the methods for the assessment of seismic risk, establishing the correspondence relations between the population and land use, and between the floor area of buildings destroyed and casualties at more reasonable spatial and temporal scales. Taking a case study of Haidian District in Beijing using these methods, we estimate the floor area and the value of buildings destroyed and the casualties at daytime and nighttime separately at the 500m grid scale. Results show that:a total of 185, 000m² of areas is expected to be destroyed annually in Haidian District, and the total loss of the houses is 325 million Yuan(excluding properties within the houses). During the day(night)time, 3, 159(2, 037)victims are expected to be killed and 12, 071(7, 790) injured. Destruction of buildings and loss of houses is spatially concentrated in the downtowns in the south and the industrial parks in the east. The casualties inflicted during the day and night descend from southeast to northwest, i.e. from urban core areas, urban fringes, urban outskirts, to village. Several regions suffer heavy casualties during the day, but nighttime casualties are scattered across different regions. The conclusions in this paper efficiently identify the spatial distribution of areas at the level of high and the very high seismic risk, which provides reliable decision support for identifying priority areas for pre-disaster prevention and mitigation, emergency rescue and the distribution of various relief supplies.     

利用扣除系数法估算灌区沟渠和农路面积

研究扣除系数法估算灌区沟渠和农路面积,进而计算耕地面积。以宁夏灌区中宁县第二次土地调查成果为基础进行。主要结论是:沟渠路面积误差可控在15%以内,耕地面积误差可控在2%以内;平均综合工效提高6.5倍。     

Timing of the late glacial and Younger Dryas cold reversal in southern Chile varved sediments

The timing of the last deglaciation in southern Chile is re-evaluated from a calendar varve chronology (Lago Puyehue, 40° S). The climate shifts are analysed by continuous annual varve-thickness measurements through the ∼17,100 cal. year to 10,800 cal. year BP time window (∼3.5 m sediment core). The varve years are determined by the alternation of light (phytoplankton-rich) and dark (terrigenous and organic-rich) layers forming graded annual couplets (∼0.2 to 0.8 mm/year). The varve chronology is constructed by conventional varve-counting methods on thin sections after correction for instantaneous volcanic and/or seismic events detected in the thin sections. The calibrated varve-age model derived from the manual varve counting is constrained by high-resolution grey-scale (GS) semi-automatic counts of the annual light phytoplankton-rich layers (∼120 μm to 300 μm thick). Due to physical sediment properties the GS constitutes a proxy record for the phytoplankton/terrigenous varve-thickness variations through the sediment record. The varve couplets are thicker/thinner during humid/dry phases and darker/lighter (negative/positive annual grey-scale index) during cold/warm phases. Our results show that at 40° S the last deglaciation took place in two phases between ∼17,100 cal. year and ∼15,500 cal. year BP. We note a climate instability between ∼15,500 cal. year and 13,300 cal. year BP and a significant dry phase between ∼15,000 and 14,500 cal. year BP. We evidence a cold event in two phases between ∼13,300 and 12,200 cal. year BP interrupted by a dry event between ∼12,800 and 12,600 cal. year BP. The onset of a significant warmer period is observed after ∼11,500 cal. year BP. Our results provide new evidence of a Younger Dryas cool reversal in southern Chile, i.e., the Huelmo/Mascardi event Hajdas et al. (2003) associated with an abrupt dry pulse at ∼12,800–12,600 cal. year BP. The high-resolution grey-scale measurements performed on the biogenic varves from Lago Puyehue provide a reliable calibrated chronology of the regional environmental and climate shifts during the last deglaciation. This is eighth in a series of eight papers published in this special issue dedicated to the 17,900 year multi-proxy lacustrine record of Lago Puyehue, Chilean Lake District. The papers in this issue were collected by M. De Batist, N. Fagel, M.-F. Loutre and E. Chapron.     

青岛市崂山区海岛资源的持续利用

青岛市崂山区海岛及其周围海域资源丰富,有较大的开发潜力。首先对崂山区海岛的资源特点进行了分析,并指出了制约崂山区海岛经济发展的因素,在此基础上,提出了合理保护与利用崂山区的海岛资源的对策和建议,为崂山区充分利用海岛的自然资源和加速海岛经济与社会的可持续发展提供了科学依据。     

基于TM数据的广州市番禺区土地覆被格局分析

以覆盖番禺区1990年、1995年、2000年、2005年4个时相Landsat-TM影像为主要数据源,借助GIS手段和景观生态学方法生成土地覆被图。在数量化研究LUCC的基础上,借助景观格局指数反映番禺区4个时相土地覆被的变化机制,对土地覆被景观格局生态效应研究提供依据。研究表明:番禺区的土地利用结构在1990~1995年间处于开发调整时期,2000年后土地利用结构调整趋于成熟,土地覆被变化伴随着城市化的进程趋于平缓。研究时期内,番禺区的景观破碎度增加,土地利用结构的复杂程度也在增加,人为因素导致的土地覆被类型变化的影响逐渐替代自然作用下土地覆被类型情况。     

居住—就业平衡与城市通勤——以上海普陀区为例

居住—就业平衡一直是城市规划界关注的热点之一。国内外规划学界对于能否解决居住—就业平衡问题以及是否有必要解决有着争论。通过对上海市普陀区居民进行随机抽样调查,得出上海市普陀区居民的通勤物理距离、时间距离和费用距离都在加大以及居住—就业匹配失衡情况较严重等结论。这种失衡加剧的可能原因是级差地租、市场经济下的政策和高房价,同时在市场机制下人们的选择较为复杂,通过规划实现居住和就业的就地平衡较为困难。因此,现阶段的重点仍应放在大力发展公共交通、提高公共交通的吸引力上,同时减少高峰时段私家车和非必要公务用车的使用,中远期应探索更好的解决方案。     

RAGA和PPCE在崩塌、滑坡、泥石流灾害评价中的应用——以重庆市北碚区为例

基于RAGA的PPCE方法解决了多维空间数据到一维投影的过程.本论文以重庆市北碚区地质灾害数据为基础,用该方法对区域地质灾害评价和区划做初探,得出如下结论:危岩体主要分布在溪家河组和上沙溪庙组砂岩区.滑坡和泥石流主要分布在泥岩层分布区;嘉陵江回水区和侵蚀岸分布灾害体较堆积岸多.高危险等级地质灾害主要分布在嘉陵江沿岸有支流汇入地区;高等级地质灾害主要分布在嘉陵江侵蚀沿岸及峡口附近;向斜的轴部距河较远地区灾害等级较低.RAGE和PPCE方法运用到河谷地质灾害评价中,能准确反映地质灾害危险等级,为河谷地质灾害研究提供了新的思路和方法;用GIS方法从点数据到面的研究有一定创新.