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731.
中国台风灾害及其影响的研究 总被引:37,自引:7,他引:37
中国是世界上受热带气旋影响最严重的国家之一。本文对影响和登陆中国的热带气旋活动的特征、台风灾害特点及其形成规律作了分析,并讨论了台风灾害对中国社会和经济发展的影响。分析结果指出,影响中国的台风灾害具有发生频率高、突发性强、群发性显著、影响范围广、成灾强度大等特点,这类灾害主要由台风带来的狂风、暴雨、风暴潮及其引发的灾害链所造成。台风灾害不仅造成大批人员伤亡,而且对中国各个经济部门都有严重影响,它所 相似文献
732.
Changes of Land Use and of Ecosystem Service Values in Sanjiang Plain, Northeast China 总被引:6,自引:0,他引:6
Wang Z Zhang B Zhang S Li X Liu D Song K Li J Li F Duan H 《Environmental monitoring and assessment》2006,112(1-3):69-91
Agricultural activities, especially reclamation, are considered major threats to the wetland ecosystems in Sanjiang Plain,
the largest concentrated area of the freshwater wetlands in China. In the past decades, the area of the cultivated land and
its grain production have been increased at the cost of wetlands shrinkage. The large-scale land reclamation severely affected
the ecosystems in this region. However, such effects at the regional scale are seldom evaluated quantitatively. We used three
datasets of LANDSAT MSS and/or TM imagery to estimate the area changes and the transition of land use types from 1980 to 2000.
We also valued changes in ecosystem services delivered by each land category using value coefficients published by Costanza
et al. [Nature 387, 1997, 253–260]. Sensitivity analysis suggested that these estimates were relatively robust. Finally, the contribution
of various ecosystem functions was ranked to the overall value of the ecosystem services in this study. According to our estimates,
the total annual ecosystem service values in Sanjiang Plain have declined by about 40% between 1980 and 2000 ($156284–182572.18
million in total over 20 years). This substantial decline is largely attributed to the 53.4% loss of wetlands. For individual
ecosystem functions, waste treatment, water supply and disturbance regulation account for more than 60% to the total ecological
values. During those two decades, the contribution of disturbance regulation, cultural and recreation decreased, while the
contribution of water regulation, nutrient cycling, food production, raw materials and climate regulation increased during
the same period. We also put forward a few proposals concerning the future land use policy formulation and sustainable ecosystems.
They are adjusting the ‘food first’ agricultural policy, establishing more nature reserves for wetlands, creating systems
for the rational use of water, harnessing the degraded cultivated land and encouraging eco-tourism. 相似文献
733.
Urbanization can exert a profound influence on land covers and landscape characteristics. In this study, we characterize the impact of urbanization on land cover and lacustrine landscape and their consequences in a large urban lake watershed, Donghu Lake watershed (the largest urban lake in China), Central China, by using Landsat TM satellite images of three periods of 1987, 1993 and 1999 and ground-based information. We grouped the land covers into six categories: water body, vegetable land, forested land, shrub-grass land, open area and urban land, and calculated patch-related landscape indices to analyze the effects of urbanization on landscape features. We overlaid the land cover maps of the three periods to track the land cover change processes. The results indicated that urban land continuously expanded from 9.1% of the total watershed area in 1987, to 19.4% in 1993, and to 29.6% in 1999. The vegetable land increased from 7.0% in 1987, 11.9% in 1993, to 13.9% in 1999 to sustain the demands of vegetable for increased urban population. Concurrently, continuous reduction of other land cover types occurred between 1987 and 1999: water body decreased from 30.4% to 23.8%, and forested land from 33.6% to 24.3%. We found that the expansion of urban land has at least in part caused a decrease in relatively wild habitats, such as urban forest and lake water area. These alterations had resulted in significant negative environmental consequences, including decline of lakes, deterioration of water and air quality, and loss of biodiversity. 相似文献
734.
735.
以马尾松为指示植物,对韶关的土壤进行了长期淋溶模拟并记录其化学状态。结果发现,土壤溶液的pH值下降到4.0,Bs值下降到几乎为零,有较大量的A1离子溶出。最后选取土壤溶液pn〉4.0、KS〉10%和[Al^3+]〈0.1mmol/L为临界化学指标,参考国内外应用广泛的MAGIC模型和SMART模型,确定韶关酸沉降临界负荷(S的临界负荷)为14.1keq/hm^2.a。 相似文献
736.
Jiang-Ping Wu Xiao-Jun Luo Ying Zhang Mei Yu She-Jun Chen Zhong-Yi Yang 《Environmental pollution (Barking, Essex : 1987)》2009,157(3):904-909
To evaluate the biomagnification extent of polybrominated diphenyls ethers (PBDEs) and polychlorinated biphenyls (PCBs) in a highly contaminated freshwater food web from South China, trophic magnification factors (TMFs) for 18 PBDE congeners and 53 PCB congeners were calculated. The TMF values ranged 0.26-4.47 for PBDEs and 0.75-5.10 for PCBs. Forty-five of 53 PCBs and BDEs 47, 100 and 154 had TMFs greater than one, suggesting their biomagnification in the present food web. The TMFs for PBDEs were generally smaller than those for PCBs with the same degree of halogenation, indicating a lower biomagnification potential for PBDEs compared to PCBs. For PCBs, it followed a parabolic relationship between TMFs and log KOW (octanol-water partition coefficient). However, this relationship was not significant for PBDEs, possibly due to the more complex behaviors of PBDEs in the food web (e.g., metabolism), compared to that of PCBs. 相似文献
737.
东北玉米热量指数预测方法研究(Ⅰ)——热量指数与玉米产量 总被引:7,自引:1,他引:6
利用东北地区典型站点1961-2005年气象资料和东北3省1961-2005年玉米产量资料,计算分析了东北不同地区玉米热量指数的变化趋势以及与产量的关系。结果表明:受气候变暖的影响,辽宁省热量指数出现下降的趋势,而吉林省和黑龙江省的热量指数出现显著升高的趋势,气候变暖对吉林省和黑龙江省玉米生产有有利的影响。热量指数较好地反映了玉米产量与环境温度的相关关系。因此,可通过对玉米热量指数的预测进行农作物低温冷害预测,为农业生产防灾减灾提供决策依据。 相似文献
738.
冬小麦旱灾风险评价的指标体系构建及应用——基于2009年北方春旱野外实地考察的认识 总被引:3,自引:1,他引:2
2009年2月初,我国北方冬麦区遭受了数十年未遇的严重干旱。基于野外实地考察,判断本次干旱对冬小麦造成的实际影响比气象统计与遥感监测结果要轻,同时因纬度、地貌类型、微地貌和田间管理水平的不同而呈现出明显的区域差异。在此基础上,提出应在已有的旱灾致灾指标(气象干旱)基础上,综合考虑地带性、地貌、水库等孕灾环境指标和田间管理水平等灾害适应指标来构建冬小麦旱灾风险的综合评价指标体系。并以北方冬麦区为例,选取SPI、地貌类型、DEM和水库缓冲区等指标得到的旱灾综合风险等级与实际旱情存在较高的吻合性。研究可为高风险区的冬小麦旱灾风险防范提供理论依据和案例支撑。 相似文献
739.
Distribution of polybrominated diphenyl ethers in breast milk from North China: Implication of exposure pathways 总被引:1,自引:0,他引:1
The breast milk concentrations of polybrominated diphenyl ethers (PBDEs; sum of eight congeners: BDE-28, 47, 99, 100, 153, 154, 183 and 209) were determined (by high resolution gas chromatographic high resolution mass spectrometry) in samples from primiparous women collected in 2006 in Tianjin, China. Dietary and lifestyle habits of the participants were obtained by questionnaires. The median total PBDE concentration (including BDE-28, 47, 99, 100, 153, 154, 183) was 2500 pg g−1 lipid weight, ranging from 1700 to 4500 pg g−1 lipid weight. These levels were in the same range as those from Europe and Japan but much lower than those from North America. The congener profile in China was also different from other countries. The contribution of BDE-28 was around 15%, much higher than any other country, implying that a different Penta-BDE formulation might be used in the Chinese market. The lower ratio of the sum of BDE-47, 99, and 100 to the sum of BDE-153 and 154 suggested that Octa-products were in more demand in China. A significant correlation was found between a woman’s PBDE concentration and the time she used electronic appliances (h/d). This implies that electronics are a potential source of PBDEs to people. Inhalation or ingestion of particulate matter (such as dust) may also be an important exposure pathway. There was no significant correlation between the PBDE concentration and the consumption of meat, fish, and milk. Further research is needed to determine the specific contribution of each exposure route and their health effects. 相似文献
740.
Small-scale mining in China: Assessing recent advances in the policy and regulatory framework 总被引:1,自引:0,他引:1
This paper explores the background of a proposed revision to the Mineral Resources Law of China, why and how the law was amended in the past, its salient features and objectives. Of equal importance is an analysis of how this national law, with its attendant regulations and policies, formed the basis for the growth and continued development of China's small-scale mining industry. The Xiaoqingling Gold Mountain case study is shown to justify the necessity and feasibility for formalizing and consolidating small-scale mines in China, and to some extent, the success of the nation-wide ASM resource consolidation policy at a local level. 相似文献