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田至美 《中国ISO14000认证》2009,(2):11-15
主体功能区划主要在于解决区域问题,用科学发展观协调区域发展。本文从区域发展的整体性出发,用空间发展的相互作用理论分析了北京山区各主体功能区协调发展的区域背景。 相似文献
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Distribution of heavy metals in sediments of the Pearl River Estuary, Southern China: Implications for sources and historical changes 总被引:2,自引:0,他引:2
The distribution of heavy metals (Pb, Zn, Cd and As) in sediments of the Pearl River Estuary was investigated. The spatial distribution of heavy metals displayed a decreasing pattern from the turbidity maxima to both upstream and downstream of the estuary, which suggested that suspended sediments played an important role in the trace metal distribution in the Pearl River Estuary. In addition, metal concentrations were higher in the west part of the estuary which received most of the pollutants from the Pearl River. In the sediment cores, fluxes of heavy metals were consistent with a predominant anthropogenic input in the period 1970-1990. From the mid-1990s to the 2000s, there was a significant decline in heavy metal pollution. The observed decline has shown the result of pollution control in the Pearl River Delta. However, it is noteworthy that the metal concentrations in the most recent sediment still remained considerably high. Taken together, the enrichment of heavy metals in sediments was largely controlled by anthropogenic pollution. 相似文献
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Variation of cyanobacteria with different environmental conditions in Nansi Lake, China 总被引:1,自引:1,他引:0
Nansi Lake is located on the east line of the South-to-North Water Diversion Project in China. A comprehensive study was carried out to investigate the spatial and temporal distribution of cyanobacteria in the lake from June 2008 to May 2011 based on monthly sample monitoring from five stations. The effect of environmental factors on cyanobacterial abundance was also evaluated. The cyanobacterial community contained 15 genera and 23 species. The cyanobacterial abundance of each monitoring station ranged from 0 to 1.53× 107 cells/L with an average of 1.45×106 cells/L, which accounted for 11.66% of the total phytoplankton abundance. The dominant species of cyanobacteria were Pseudanabaena (32.94%) and Merismopedia (19.85%), not the bloom-forming algae such as Microcystis and Anabaena. In addition, the cyanobacterial community structure and water quality variables changed substantially over the survey period. Redundancy analysis (RDA) suggested that temperature and phosphorus were important environmental factors that affected cyanobacteria. Temperature was the most important factor affecting cyanobacterial abundance. The effect of phosphorus on cyanobacterial abundance was more notable in warm periods than in periods with low temperature. 相似文献
126.
适冷微生物(包括嗜冷微生物、耐冷微生物)是在低温下仍具有生存和繁殖的能力的一类微生物,低温会对微生物产生如酶活性降低、膜流动性变差、蛋白质冷变性、不适当的蛋白质空间折叠和低温下细胞内部构造破坏等不利影响。适冷微生物能克服低温带来的消极影响,并能在极端环境下生长及代谢。随着宏基因组测序、蛋白质组学以及其它分析手段在环境微生物中的应用,作者对低温微生物的一些适应性改变有了新的认识。酶活性中心结构的改变、膜中脂质成分含量的增加,冷适应蛋白的快速表达等都被证明在对低温适应中起着重要作用。文章综述了适冷微生物的适冷机理及其在污染控制领域的应用,为适冷微生物的实际工程应用提供参考,为适冷微生物在环境工程中的进一步广泛应用奠定基础。 相似文献
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Manganese and ammonium pollution in surface water sources has become a serious issue.In this study, a pilot-scale filtration system was used to investigate the effect of ammonium on manganese removal during the simultaneous removal of ammonium and manganese from surface water using a manganese co-oxide filter film(MeO_x ). The results showed that the manganese removal efficiency of MeO_x in the absence of ammonium was high and stable, and the removal efficiency could reach 70% even at 5.5 °C. When the influent ammonium concentration was lower than 0.7 mg/L, ammonium and manganese could be removed simultaneously. However, at an ammonium concentration of 1.5 mg/L, the manganese removal efficiency of the filter gradually decreased with time(from 96% to 46.20%). Nevertheless, there was no impact of manganese on ammonium removal. The mechanism by which ammonium negatively affected manganese removal was investigated, demonstrating that ammonium affected manganese removal mainly through two possible mechanisms. On one hand, the decreased p H caused by ammonium oxidation was unfavorable for the oxidation of manganese by MeO_x ; on the other hand, the presence of ammonium slowed the growth of new MeO_x and retarded the increase in the specific surface area of the Me Ox-coated sand, and induced changes in the morphology and crystal structure of Me Ox. Consequently, the manganese removal efficiency of the filter decreased when ammonium was present in the inlet water. 相似文献
128.
雄安新区是千年大计、国家大事,水资源短缺与水体污染成为制约其发展的主要问题。从水资源利用效率及节水潜力视角出发,以深圳发展历程为标杆,结合情景分析与方向性距离函数等模型,展示到2035年不同情景的雄安水资源利用效率及节水潜力发展图景和路径。研究表明:从利用效率看,在基准、起步、建成情景下雄安呈现出由低效率区到较高效率区再到高效率区的变化态势。从节水潜力看,效率改善空间减小、技术落差比增加等表明雄安节水潜力得到充分挖掘。杜绝污水直排、积极发展污水处理技术、优化新区产业结构等是促使水资源利用效率提高的有效手段,是雄安实现绿色生态发展的重要保障。 相似文献
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Noninvasive prenatal diagnosis for Duchenne muscular dystrophy based on the direct haplotype phasing