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991.
以往的环境功能区划将城市或某一区域作为整个目标范围的功能区划,这种方法划分环境功能区不是过细就是过笼统,使保护目标定的过高或过低。环境功能区划模糊,无法从整体上解决城市结构性污染和布局不合理的现象,达不到“分级管理、分类保护、分区防治”的环境管理目的。针对新疆特殊绿洲环境特征,本文提出新的区划方法,重新对全疆各地环境功能进行特殊环境功能区划,以期明确各类特殊环境功能区的主要特点、主要问题、主导功能和建设要求,在今后的可持续发展过程中,为国民经济和社会发展提供科学的决策依据,将对新疆社会经济的快速、稳定、持续发展具有十分现实和深远的意义。 相似文献
992.
上海高温和低温气候变化特征及其影响因素 总被引:1,自引:0,他引:1
基于上海11个气象站逐日最高、最低气温、降水资料和西太平洋副热带高压(简称副高,下同)环流指数,分析了上海夏季高温和冬季低温的气候变化特征及其影响因素。结果表明,1873~2007年,上海高温日数表现为少-多-少-多的年代际变化,低温日数则表现为多-少的年代际变化。2001~2007年,上海年均高温日数、各级高温过程数和高温过程日数都最多,低温日数、低温过程数和低温过程日数都最少。1960~2007年,上海每年高温日数与当年夏季副高面积和强度指数显著正相关,低温日数与当年冬季副高面积和强度指数显著负相关。降水对上海极端气温有一定的缓解作用,上海高温日数与夏季降水量弱显著负相关,低温日数与冬季降水量显著负相关。上海高温过程数受城市化影响较大,其时间变化具有明显的城郊差异,低温过程数则受城市化影响较小。 相似文献
993.
994.
Kristina L. Sundqvist Mats Tysklind Ingemar Cato Anders Bignert Karin Wiberg 《Environmental science and pollution research international》2009,16(4):396-409
Background, aim, and scope The primary aim of this study was to explore the variations in PCDD/F levels and homologue profiles of Baltic surface sediments
by comprehensively analyzing polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in samples from a large number of sites, encompassing not only previously
known hotspot areas, but also sites near other potential PCDD/F sources, in pristine reference areas (in which there was no
industrial activity) and offshore sites.
Materials and methods Surface sediment samples (146 in total) were collected at various points along the Swedish coast and offshore areas. In addition,
bulk deposition was sampled, monthly, at a single site in northern Sweden during 1 year. The concentrations of tetra- through octa-substituted CDD/Fs were determined in both matrices.
Results Highly elevated concentrations of PCDD/Fs were found at many sites in coastal areas and concentrations were also slightly
elevated in some offshore areas. Homologue profiles varied substantially amongst samples from coastal sites, while those from
offshore and other pristine sediments were relatively similar. The offshore sediments showed different profiles from those
observed in the deposition samples. Sediment levels of PCDD/Fs were not generally significantly correlated to organic carbon
levels, except in some pristine areas. Comparison of data obtained in this and previous studies suggest that both their levels
and profiles are similar today to those observed 20 years ago in coastal and offshore areas. The only detected trend is that
their levels appear to have decreased slightly in the offshore area of the Bothnian Sea.
Discussion The localization of hotspot areas along the coast, the lack of consensus between PCDD/F profiles of sediments and general
background, and their weak correlations with organic carbon suggest that PCDD/Fs in the study area largely originate from
local/regional emissions. However, due to complicating factors such as sediment dynamics and land upheaval, it is not possible
to conclude whether these pollutants derive from recent emissions or from a combination of recent emissions and re-distribution
of previous inputs.
Conclusions The results show that: elevated levels of PCDD/Fs are present in both coastal and offshore areas of the Baltic Sea, the major
hotspots are close to the shore, and there are large variations in profiles, indicating that local emissions are (or have
been) the major causes of pollution.
Recommendations and perspectives In order to identify other hotspot areas and trace sources, comprehensive analysis of PCDD/Fs in surface sediments is needed
in all areas of the Baltic Sea that have not been previously investigated. The high levels of PCDD/Fs observed in surface
sediments also indicate a need to elucidate whether they are due mainly to current emissions or a combination of recent pollution
and re-distribution of historically deposited pollutants. To do so, better understanding of sediment dynamics and present-day
inputs, such as riverine inputs, industrial effluents, and leakage from contaminated soil is required. There are indications
that contaminated sediments have a regional impact on fish contamination levels. However, as yet there is no statistically
robust evidence linking contaminated sediments with elevated levels in Baltic biota. It should also be noted that the Baltic
Sea is being massively invaded by the deep-burrowing polychaete Marenzielleria ssp., whose presence in sediments has been shown to increase water concentrations of hydrophobic pollutants. In awareness
of this, it is clear that high levels in sediments cannot be ignored in risk assessments. In order to investigate the emission
trends more thoroughly, analysis of PCDD/Fs in offshore sediment cores throughout the Baltic Sea is also recommended.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
995.
葫芦岛市近岸海域水生动物重金属污染状况的监测 总被引:4,自引:0,他引:4
参考国内外有关生物残毒研究理论 ,对葫芦岛市沿岸海区 ,包括东起笊笠码头 ,西至绥中芷锚湾海滨海水中现存动物体重金属污染状况进行监测和评价。 相似文献
996.
石墨炉原子吸收法测定海水中Pb——以0.1NHNO3抗坏血酸-NaI作基体改进剂 总被引:2,自引:0,他引:2
研究了以0.1N HNO3抗坏血酸-NaI作基体改进剂测定海水中Pb的方法,讨论并确定了测定的最佳条件.结果表明在仪器最佳条件下,以0.1N HNO3抗坏血酸-NaI作基体改进剂可有效消除海水基体干扰,检出限为1.2μg/L,实际样品相对标准偏差小于4%,加标回收率为95%~104%. 相似文献
997.
北京市近郊区乡村景观规划方法初探 总被引:12,自引:0,他引:12
以北京西北近郊白家疃村为例 ,分析了乡村景观的现状和动态演变的特征 ,重点探讨了乡村景观规划的原则和方法 ,并提出了白家疃村景观规划方案和设计要点 相似文献
998.
重气泄漏扩散事故后果评估系统研究 总被引:3,自引:1,他引:2
分析重气扩散过程和影响因素,对目前主要应用的唯象模型、箱及相似模型、三维流体力学模型、浅层模型等4类模型进行比较分析并介绍基于浅层模型发展而来的SLAB模型。根据重气浓度划分致死区、重伤区、轻伤区和吸入反应区等4个等级的事故后果评估区域。以Visual Basic和Fortran为开发工具,通过TECPLOT进行图形可视化输出,建立基于SLAB模型的重气泄漏扩散事故后果评估系统和重气理化参数信息库。该系统通过重气理化参数和重气泄漏的初始状态和气象条件,以可视化方式直观表现不同等级的事故后果评估区域。 相似文献
999.
对哈密市区锅炉烟尘验收监测结果作了分析阐述,论述了市区烟尘控制区烟尘排放规律及特点,并对监测统计结果进行了小结,为日后的实测工作积累经验。 相似文献
1000.
LLEWELLYN C. FOXCROFT VOJTĚCH JAROŠÍK PETR PYŠEK DAVID M. RICHARDSON MATHIEU ROUGET 《Conservation biology》2011,25(2):400-405
Abstract: Human land uses surrounding protected areas provide propagules for colonization of these areas by non‐native species, and corridors between protected‐area networks and drainage systems of rivers provide pathways for long‐distance dispersal of non‐native species. Nevertheless, the influence of protected‐area boundaries on colonization of protected areas by invasive non‐native species is unknown. We drew on a spatially explicit data set of more than 27,000 non‐native plant presence records for South Africa's Kruger National Park to examine the role of boundaries in preventing colonization of protected areas by non‐native species. The number of records of non‐native invasive plants declined rapidly beyond 1500 m inside the park; thus, we believe that the park boundary limited the spread of non‐native plants. The number of non‐native invasive plants inside the park was a function of the amount of water runoff, density of major roads, and the presence of natural vegetation outside the park. Of the types of human‐induced disturbance, only the density of major roads outside the protected area significantly increased the number of non‐native plant records. Our findings suggest that the probability of incursion of invasive plants into protected areas can be quantified reliably. 相似文献