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481.
482.
城市环境质量多级模糊综合评价 总被引:40,自引:0,他引:40
文章将模糊聚类与层次分析相结合,提出了城市环境质量多级模糊综合评价法,并将该方法应用于宣州市环境质量综合评价,结果表明,该方法克服了综合指数法受人为因素影响大的缺点,较好地反映了环境质量分级界限的模糊性,并且较好地解决了权值分配问题,使评价结论更合理,可靠,是一种有价值的城市环境质量综合评价方法。 相似文献
483.
China's national government and Beijing city authorities have adopted additional control measures to reduce the negative impact of vehicle emissions on Beijing's air quality. An evaluation of the effectiveness of these measures may provide guidance for future vehicle emission control strategy development. In-use emissions from light-duty gasoline vehicles (LDGVs) were investigated at five sites in Beijing with remote sensing instrumentation. Distance-based mass emission factors were derived with fuel consumption modeled on real world data. The results show that the recently implemented aggressive control strategies are significantly reducing the emissions of on-road vehicles. Older vehicles are contributing substantially to the total fleet emissions. An earlier program to retrofit pre-Euro cars with three-way catalysts produced little emission reduction. The impact of model year and driving conditions on the average mass emission factors indicates that the durability of vehicles emission controls may be inadequate in Beijing. 相似文献
484.
The Avoidance Responses of Daphnia magna to the Exposure of Organophosphorus Pesticides in an On-Line Biomonitoring System 总被引:1,自引:0,他引:1
Zong-Ming Ren Zhi-Liang Li Jin-Miao Zha Kai-feng Rao Mei Ma Zijian Wang Rong-Shu Fu 《Environmental Modeling and Assessment》2009,14(3):405-410
In this study, avoidance behavior of the freshwater cladoceran Daphnia magna Straus was used as indicator to assess the early stress of accidental organophosphorus pesticide (OP) contamination. The
movement behavior was detected by a multi-species biomonitoring system. There was obvious concentration–response relationship
between the OP stress and the behavioral response even at sublethal exposure. A rising OP stress resulted in a significant
decrease of response time to escape (RTE; p<0.05). In comparison of different OPs, it was found that there was a power regression between RTE and the toxic unit of OPs.
Therefore, the avoidance behavior of D. magna was a sensitive indicator of sublethal OP stress, and the power relationship could be used to predict the early warning thresholds
of more OPs in the on-line biomonitoring system. 相似文献
485.
Tao Chuanjiang Li Dahui Zhang Xinzhong Chen Shanshan Fu Lijuan Piao Xiuying Shi Jie Jiang Hui Li Chongjiu Li Jianzhong 《Environmental monitoring and assessment》2010,165(1-4):685-692
To analysze the dynamic degradation and final residues of acephate and its metabolite methamidophos, field-experiments with pakchoi (Brassica campestris L.) in open field and greenhouse were carried out in Beijing, China in 2004 and 2005. The degradation dynamics and final residues were determined by gas chromatography (GC) equipped with a pulsed flame photometric detector and GC coupled to mass spectrometry (MS)/MS after acephate was applied on open field and green house pakchoi (B. campestris L.). The dynamic degradation results showed that the half-lives of acephate and methamidophos in open field pakchoi were 1.36 days with dynamic degradation equation C t ?=?133.01e???0.5107t , and 2.86 days with C t ?=?6.5753e???0.2422t , respectively. While the half-lives of acephate and methamidophos in the greenhouse were 1.07 days with C t ?=?59.134e???0.4353t and 0.79 days with C t ?=?0.2703e???0.2595t , respectively. The final residue analysis demonstrated that >50% of total methamidophos were resulted from the degradation of acephate 7 and 18 days after it was applied on the greenhouse pakchoi, respectively. While in the open-field pakchoi, >90% of total methamidophos was found to be the metabolite of acephate. 相似文献
486.
Qin QZ Chen Y Fu TT Ding L Han LL Li JC 《Environmental monitoring and assessment》2012,184(3):1533-1540
To understand electromagnetic radiation field strength and its influencing factors of certain 110-kV high-voltage lines in
one urban area of Chongqing by measuring 110-kV high-voltage line’s electromagnetic radiation level. According to the methodology
as determined by the National Hygienic Standards, we selected certain adjacent residential buildings, high-voltage lines along
a specific street and selected different distances around its vertical projection point as monitoring points. The levels of
electromagnetic radiations were measured respectively. In this investigation within the frequency of 5–1,000 Hz both the electric
field strength and magnetic field strength of each monitoring sites were lower than the public exposure standards as determined
by the International Commission on Non-Ionizing Radiation Protection. However, the electrical field strength on the roof adjacent
to the high-voltage lines was significantly higher than that as measured on the other floors in the same buildings (p < 0.05). The electromagnetic radiation measurements of different monitoring points, under the same high-voltage lines, showed
the location which is nearer the high-voltage line maintain a consistently higher level of radiation than the more distant
locations (p < 0.05). Electromagnetic radiation generated by high-voltage lines decreases proportionally to the distance from the lines.
The buildings can to some extent shield (or absorb) the electric fields generated by high-voltage lines nearby. The electromagnetic
radiation intensity near high-voltage lines may be mitigated or intensified by the manner in which the high-voltage lines
are set up, and it merits attention for the potential impact on human health. 相似文献
487.
An innovative approach of mean emission by vehicle type was used in this paper to assess the impact of new vehicle emission
standards in Beijing, China during the period of 2000–2005. It was found that CO and NOx emissions decreased by 48% and 23%, respectively, from Type O (before 2000) to Type I (year 2000) vehicles. The reductions
from Type O to Type II (year 2002) vehicles were 85% and 73% for CO and NOx, respectively. When all three types of vehicles (Types O, I and II) are combined, the annual per vehicle CO emissions decreased
from 586 kg per vehicle per year in 2000 to 324 kg per vehicle per year in 2005, while that of NOx decreased from 66.9 to 43.4 kg per vehicle per year, which was mainly resulted from the impact of stringent new vehicle emission
standards implemented in years 2000 and 2002. However, the vehicle population increased by 70% during the same time period,
which offset the impact of cleaner vehicles. Thus, the total vehicle emission decreased little for CO (885,000 tons in 2000,
837,000 tons in 2005) and even increased slightly for NOx (101,000 and 112,000 tons in 2000 and 2005, respectively). The ambient concentrations of CO decreased significantly throughout
2000–2005, the same trend was not observed for NO2. Correlation analysis (grey correlation and Pearson correlation) between the annual vehicle emissions and annual concentrations
of CO, the annual NOx emission and annual NO2 concentration indicated that the implementation of new vehicle emission standards was associated with the abatement of ambient
CO and NO2 concentrations in Beijing. 相似文献
488.
489.
Kun Lei Xuejiao Han Guo Fu Jian Zhao Libiao Yang 《Environmental monitoring and assessment》2014,186(12):8857-8864
The wide use and occurrence of antibiotics in water environments have caused wide concerns. Ofloxacin (OFL) was selected as a target antibiotic, and the interaction between OFL and sequential extracted dissolved organic matter (DOM) from the sediment of Dianchi, a hypertrophic lake in Southwest China, was explored using fluorescence quenching technology. The method of fuorescence quenching was used to characterize the interaction between OFL and sequentially extracted DOM. The result indicated that static and dynamic quenching both existed in the interaction. The interaction in the background water (0.01 mol/L NaCl and 200 mg/L NaN3) became increasingly weak with the further extraction of DOM. A low non-linear factor N value (0.53~0.63) of Freundlich model was observed, indicating a non-linear interaction between OFL and DOM. Elemental characterization and infrared spectrum analysis showed an enhanced OFL-DOM binding with the decrease in humic acid (HA) polarity. The effect of ion strength was tested in the OFL-DOM interaction to show the impact of usually existing metal ions in water environment on the OFL behavior. The result showed that K+ had little influence, but Cu2+ had a significant promotion (p?0.05) in the OFL-DOM interaction in background water, indicating that divalent metal ions, which have the bridge bond or complexation capacity, are more active in the OFL-DOM interaction than monovalent ions, with no bridge bond or complexation capacity. This work would be useful in the fate and risk assessment of antibiotics in water environments. 相似文献
490.