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141.
142.
内蒙古典型草原区植被NPP对气候变化的响应 总被引:4,自引:0,他引:4
研究植被生产力对气候变化的响应是理解陆地生态系统与气候变化相互作用的重要基础,论文利用近45a内蒙古典型草原区55个气象台站的气象数据,采用Holdridge生命地带的气候指标和NPP区域估算模型,研究了内蒙古典型草原区植被净第一性生产力(NPP)对气候变化的响应。结果表明,1960-2004年间,内蒙古典型草原区域内,发生了以生物温度升高和湿润度降低为代表的生物气候明显变化;典型草原区年NPP和春、夏、秋3个季节的NPP均呈现增加趋势,其中夏季是NPP增加速率最快,增加量最大的季节;在区域上,年NPP呈现由东北至西南的递减态势,不同区域年NPP均有增加趋势,其中以中部区最为明显。 相似文献
143.
桉木粉对塔玛亚历山大藻(Alexandrium tamarense)的抑制作用及其化学基础研究 总被引:2,自引:0,他引:2
摘要:探讨了托里桉(Eucalyptus torelliana)、尾叶桉(Eucalyptus urophylla)、窿缘桉(Eucalyptus exserta)等3种桉木粉对塔玛亚历山大藻(Alexandrium tamarense)生长的影响,并对其抑制赤潮藻类生长的化学基础进行了初步研究,以期为新除藻剂的筛选提供参考和依据。结果表明,不同桉木粉对塔玛亚历山大藻生长的抑制作用不同,托里桉木粉的抑藻作用明显强于尾叶桉和窿缘桉。灭菌与非灭菌托里桉木粉对塔玛亚历山大藻生长的抑制作用差别不大,提示细菌等微生物并非木粉抑藻的主要原因。不同溶剂粗提物对塔玛亚历山大藻生长的抑制作用不同,丙酮-水粗提物的抑藻活性明显强于乙酸乙酯、甲醇和水粗提物。进一步将丙酮-水粗提物分成A、B、C和D等4个组分,比较不同组分的抑藻活性。结果发现,丙酮-水粗提物中D组分的抑藻作用最强。该组分浓度为3 mg/L时,3 d时对塔玛亚历山大藻的去除率可达81.06 %。GC-MS分析表明,D组分中含有4-羟基-3,5,6-三甲基,1-4[(1z)-3-氧代-1-丁烯基]-2-环已烯酮和4,4,7a–三甲基,5,6,7,7a-四氢-2(4H)-苯并呋喃酮等酮类物质。这些结果表明,托里桉木粉可显著抑制赤潮藻的生长,其中存在的酮类化感物质可能是其抑制藻类生长的主要原因。 相似文献
144.
以汶川地震灾后恢复重建利用世行优惠紧急贷款四川省城镇市政基础设施项目环境监理开展情况为例,阐述了城镇基础设施建设项目环境监理开展过程中的重点,并分析了环境监理方案和环境监理的形式,通过对环境监理工作的经验总结分析,提供了一些建议以供参考,以期对其他城镇基础设施建设项目施工期环境监理工作的开展提供借鉴意义。 相似文献
145.
146.
Effects of spatial resolution of remotely sensed data on estimating urban
impervious surfaces 总被引:1,自引:0,他引:1
Impervious surfaces are the result of urbanization that can be explicitly quantified, managed and controlled at each stage of land
development. It is a very useful environmental indicator that can be used to measure the impacts of urbanization on surface runoff,
water quality, air quality, biodiversity and microclimate. Therefore, accurate estimation of impervious surfaces is critical for urban
environmental monitoring, land management, decision-making and urban planning. Many approaches have been developed to estimate
surface imperviousness, using remotely sensed data with various spatial resolutions. However, few studies, have investigated the
effects of spatial resolution on estimating surface imperviousness. We compare medium-resolution Landsat data with high-resolution
SPOT images to quantify the imperviousness in Beijing, China. The results indicated that the overall 91% accuracy of estimates of
imperviousness based on TM data was considerably higher than the 81% accuracy of the SPOT data. The higher resolution SPOT data
did not always predict the imperviousness of the land better than the TM data. At the whole city level, the TM data better predicts
the percentage cover of impervious surfaces. At the sub-city level, however, the ring belts from the central core to the urban-rural
peripheral, the SPOT data may better predict the imperviousness. These results highlighted the need to combine multiple resolution
data to quantify the percentage of imperviousness, as higher resolution data do not necessarily lead to more accurate estimates. The
methodology and results in this study can be utilized to identify the most suitable remote sensing data to quickly and efficiently extract
the pattern of the impervious land, which could provide the base for further study on many related urban environmental problems. 相似文献
147.
148.
The solid acid catalyst, N–F codoped TiO2/SiO2 composite oxide was prepared by a sol–gel method using NH4F as nitrogen and fluorine source. The prepared materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–Visible diffuse reflectance spectroscopy (UV–Vis), ammonia adsorption and temperature-programmed desorption (NH3-TPD), in situ Fourier transform infrared spectroscopy (FT-IR) and N2 physical adsorption isotherm. The photocatalytic activity of the catalyst for acrylonitrile degradation was investigated under simulant solar irradiation. The results showed that strong Lewis and Brønsted acid sites appear on the surface of the sample after N–F doping. Systematic investigation showed that the highest photocatalytic activity for acrylonitrile degradation was obtained for samples calcined at 450°C with molar ratio (NH4F to Ti) of 0.8. The degradation ratio of 71.5% was achieved with the prepared catalyst after 6-min irradiation, demonstrating the effectiveness of photocatalytic degradation of acrylonitrile with N–F codoped TiO2/SiO2 composite oxide. The photocatalyst is promising for application under solar light irradiation. Moreover, the intermediates generated after irradiation were verified by gas chromatography–mass spectrometry (GC–MS) analysis and UV–Vis spectroscopy to be simple organic acids with lower toxicity, and the degradation pathway was also proposed for acrylonitrile degradation with the prepared catalyst. 相似文献
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150.