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81.
Tao M Fengkui Duan Kebin He Yu Qin Dan Tong Guannan Geng Xuyan Liu Hui Li Shuo Yang Siqi Ye Beiyao Xu Qiang Zhang Yongliang Ma 《环境科学学报(英文版)》2019,31(9):8-20
With rapid economic growth and urbanization, the Yangtze River Delta(YRD) region in China has experienced serious air pollution challenges. In this study, we analyzed the air pollution characteristics and their relationship with emissions and meteorology in the YRD region during 2014–2016. In recent years, the concentrations of all air pollutants, except O_3,decreased. Spatially, the PM_(2.5), PM_(10), SO_2, and CO concentrations were higher in the northern YRD region, and NO_2 and O_3 were higher in the central YRD region. Based on the number of non-attainment days(i.e., days with air quality index greater than 100), PM_(2.5) was the largest contributor to air pollution in the YRD region, followed by O_3, PM_(10), and NO_2.However, particulate matter pollution has declined gradually, while O_3 pollution worsened.Meteorological conditions mainly influenced day-to-day variations in pollutant concentrations. PM_(2.5) concentration was inversely related to wind speed, while O_3 concentration was positively correlated with temperature and negatively correlated with relative humidity.The air quality improvement in recent years was mainly attributed to emission reductions.During 2014–2016, PM_(2.5), PM_(10), SO_2, NO_x, CO, NH_3, and volatile organic compound(VOC)emissions in the YRD region were reduced by 26.3%, 29.2%, 32.4%, 8.1%, 15.9%, 4.5%, and0.3%, respectively. Regional transport also contributed to the air pollution. During regional haze periods, pollutants from North China and East China aggravated the pollution in the YRD region. Our findings suggest that emission reduction and regional joint prevention and control helped to improve the air quality in the YRD region. 相似文献
82.
The exchange processes of CH4 were investigated in a paddy field in the Hari area of Kang Hwa Island over an 8 day period in late April 2002. The quantification of CH4 fluxes was made under dry field condition of early spring by concurrently measuring its concentrations (at the two heights of 1 and 5 m) and the relevant micrometeorological parameters. To help elucidate the factors determining the mobilization characteristics of CH4, the results of our measurement data were examined using a number of approaches. The results of the trajectory analysis indicated that its concentration changed very sensitively with the influence of different source types, as seen from the air mass movement patterns. The concentrations and fluxes of methane, when examined over this short-term scale, showed moderately strong patterns across 24 h period in which higher values tend to occur during morning or evening. The overall results of our field measurements suggest that CH4 exchange processes in the paddy area proceeded in a fairly complicated manner. The study area behaved as a net source of CH4 to the atmosphere with a net daily emission rate of 3.6 mg m−2 despite the fact that downward deposition was observed more frequently than upward emission. 相似文献
83.
Isoprene emission from tropical trees in Okinawa Island, Japan 总被引:1,自引:0,他引:1
Tambunan P Baba S Kuniyoshi A Iwasaki H Nakamura T Yamasaki H Oku H 《Chemosphere》2006,65(11):2138-2144
This study surveyed isoprene emission from 42 indigenous and exotic tropical trees in subtropic Okinawa, Japan. Of the 42 trees studied, 4 emitted isoprene at a rate in excess of 20 μg g−1 h−1, and 28 showed the rates of 1–10 μg g−1 h−1. The remainder emitted less than 1 μg g−1 h−1. The majority of trees in this study may therefore fall within the lower emitting species. However, species in Moraceae that is indigenous in Okinawa emitted isoprene at relatively higher rates with an average of 14.2 μg g−1 h−1. The highest emission rate of 107.1 μg g−1 h−1 for Ficus virgata yielded the area basis rate of 47.4 nmol m−2 s−1, which is almost equivalent to the rate of high emitting species. Furthermore, a linear relationship between light intensity and isoprene emission was noted with Ficus virgata up to 1700 μmol m−2 s−1. These findings may show the potential importance of subtropical areas as sources of isoprene to the atmosphere. 相似文献
84.
北京地区一次大气环境持续严重污染过程中SO2的垂直分布分析 总被引:28,自引:8,他引:20
在2004-09-27~2004-10-12期间,以325m气象与环境观测塔为平台,使用43CTL型高精度脉冲荧光SO2分析仪,分别布置在观测塔8m、47m、120m和280m 4层观测平台,对大气中的SO2气体浓度、PM10和PM2.5粒子质量浓度及同步气象因素进行了垂直梯度、连续观测.结合气象数据分析了观测期间大气中SO2气体浓度的垂直梯度分布及变化形势,进行了SO2浓度与混合层高度变化、海平面气压变化,风速、风向变化等要素的相关分析,观测到在实验期间大气边界层中SO2浓度由上向下递减分布的现象.由于地形与污染源分布的影响,北风最有利于污染扩散等状况.观测期间捕捉到一次主要由气象因素造成的大气环境严重持续污染及污染清除的全过程. 相似文献
85.
Dian Ding Jia Xing Shuxiao Wang Xing Chang Jiming Hao 《Frontiers of Environmental Science & Engineering》2019,13(5):76
86.
Mei Lei Ziping Dong Ying Jiang Philip Longhurst Xiaoming Wan Guangdong Zhou 《Frontiers of Environmental Science & Engineering》2019,13(2):24
87.
Jiajun Liu Long Wang Yun Zhu Che-Jen Lin Carey Jang Shuxiao Wang Jia Xing Bin Yu Hui Xu Yuzhou Pan 《Frontiers of Environmental Science & Engineering》2019,13(1):2
88.
A grazing experiment was started in 1984 and 1989 respectively, in two parts of a dune grassland in the nature reserve ‘Zwanenwater’,
North Holland; a third part with similar geology and topography was used as a control area and not grazed. An evaluation of
the effects of grazing on vegetation patterns, species composition, vegetation structure and humus form was made with the
help of vegetation maps from 1986 and 1992 as well as field surveys.
Dense tall-grass communities dominated byAmmophila arenaria increased over the period 1986–1992 in the grazed areas, and especially in the non-grazed area (increase in area to 20%,
22% and 50%, respectively). Open communities decreased in the grazed areas, but are still prevalent, while in the ungrazed
area they virtually disappeared, with the result that the present percentage areas are 53%, 38% and 17%.
Field survey data were classified by TWINSPAN producing four vegetation types. These occur more or less equally in grazed
and ungrazed areas, albeit with different percentage areas: (1) open vegetation dominated byCorynephorus canescens; (2) open vegetation characteized, byKoeleria macrantha; (3) heathland dominated byEmpetrum nigrum; and (4) tall-grass communities dominated byAmmophila arenaria. Within a vegetation type, species composition was only marginally affected by grazing regime.
Within the open communities the number of species, vegetation height, vegetation cover and soil organic horizons were not
affected by grazing. In the tall-grass communities the number of species was significantly larger and the height of the vegetation
significantly lower in the area grazed since 1984. In the heathland community the number of species and cover of the moss
layer were significantly higher in the 1984 area and ectorganic and endorganic horizons significantly thicker in the ungrazed
area.
It is suggested that these effects are the result of an increased availability of light, but possibly also of a decreased
stock of organic matter and nutrients, due to a decreased input of litter and accelerated rates of decomposition. 相似文献
89.
“W型低NOx环保燃烧器”采用先进的复合多级混合式雾化技术,强化喷射、混合和扩散,燃烧充分从而控制NOx生成。 相似文献
90.
通过应用箱工模型,模拟研究了实施排放标准对大气环境质量的影响,分析讨论了实施2排放标准的技术经济可行性。得出如下结论:(1)重庆市实施大气二氧化硫污染物排放标准能基本满足在气环境质量减级标准的要求。(2)实施标准所需二氧化硫治理静态投资费用总额计26.369亿元。(3)实施标准减少环境污染损失6.440亿元。 相似文献