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991.
992.
H2O2对载银TiO2光催化降解Aroclor1260的影响 总被引:7,自引:0,他引:7
光催化氧化法降解水中有机污染物是近来发展较为迅速的废水处理技术,以锐钛型载银TiO2为催化剂,在发射光谱波长为254nm,功率的15W紫外灯照射下,考察不同H2O2浓度对Aroclor1260的光催化降解的影响,结果表明:低浓度的H2O2对Aroclor1260的光催化降解有促进作用,而当H2O2的浓度高于30mol/l时,光催化降解受到抑制,而且这种影响对不同PCB单体化合物的效果基本一致。 相似文献
993.
994.
以对亚硝基-N,N-二甲基苯胺盐为指示剂,测定化合物对降解微生物的毒性,测定条件为:温度25℃,菌种投加量之1ml/L沉降0.5h活性污泥,指示剂浓度1mg/L曝气量400ml/min,作用时间4h,实验证明,当指示剂显著降解率〉70%时无为毒,〈30%为毒性较大,当降解率为50%其毒性浓度抑制值与文献数据基本一致。 相似文献
996.
The influence of tetracycline(TC) antibiotics on phosphine(PH_3) production in the anaerobic wastewater treatment was studied. A lab-scale anaerobic baffled reactor with three compartments was employed to simulate this process. The reactor was operated in a TC-absence wastewater and 250 μg/L TC-presence wastewater for three months after a start-up period,respectively. The responses of p H, oxidation–reduction potential(ORP), chemical oxygen demand(COD), total phosphorus(TP), enzymes activity(dehydrogenase and acid phosphatase),and microbial community were investigated to reveal the effect of TC on PH_3 production.Results suggested that the dehydrogenase(DH) activity, acid phosphatase(ACP) activity and COD have positive relationship with PH_3 production, while p H, ORP level and the TP in liquid phase have negative relationship with PH_3 production. With prolonged TC exposure, decrease in p H and increase in DH activity are beneficial to PH_3 production, while decrease in COD and ACP activity are not the limiting factors for PH_3 production. 相似文献
997.
Fast screening compositions of PM2.5 by ATR-FTIR: Comparison with results from IC andOC/EC analyzers
Xu Yu Wei Song Qingqing Yu Sheng Li Ming Zhu Yanli Zhang Wei Deng Weiqiang Yang Zhonghui Huang Xinhui Bi Xinming Wang 《环境科学学报(英文版)》2018,30(9):76-88
Chemical speciation of fine particles or PM_(2.5) collected on filters is still a costly and timeconsuming task. In this study, filter-based PM_(2.5) samples were collected during November–December 2013 at four sites in Guangzhou, and the major components were fast screened(~7 min per filter sample) by Attenuated Total Reflectance(ATR)-Fourier Transform Infrared Spectroscopic(FTIR) in comparison with that measured by Organic carbon/Element carbon(OC/EC) analyzer and Ion Chromatography(IC). The concentrations of nitrate, ammonium, sulfate,primary organic carbon(POC) and secondary organic carbon(SOC) measured by OC/EC and IC analyzers were better correlated with their infrared absorption peak heights at 1320 cm~(-1) for nitrate, 1435, 3045 and 3215 cm~(-1) for ammonium, 615 cm~(-1) for sulfate, 690, 760 and 890 cm~(-1) for POC and 1640 and 1660 cm~(-1) for SOC respectively, during polluted days(PM_(2.5) 75 μg/m~3) than during clean days(PM_(2.5)≤ 75 μg/m~3). With the evolution of a haze episode during our field campaign, the concentrations of the major PM_(2.5) components displayed consistent variations with their infrared absorption peak heights, suggesting ATR-FTIR could be a fast and useful technique to characterize filter-based PM_(2.5) compositions particularly during pollution events although cautions should be taken when PM_(2.5) levels are low. Notably, elevated PM_(2.5) mass concentrations occurred with enhanced ratios of [NO_(-3)]/[SO_4~(2-)] and [NH~(+4)]/[SO_4~(2-)], implying that nitrogenous components play vital roles in the PM_(2.5) pollution events in the study region. 相似文献
998.
Qingyu Zhang Juwang Fan Weidong Yang Fang Ying Zhen Bao Yi Sheng Cheng Lin Xuan Chen 《环境科学学报(英文版)》2018,30(9):197-206
In this study, the influences of accumulated mileage(deterioration) and technological changes(emission standards) on emission factors(EFs) of regulated pollutants(CO, HC, and NO_x) from gasoline passenger vehicles were investigated based on Inspection and Maintenance(I/M) data using the chassis dynamometer method. The accumulated mileage of passenger vehicles was significantly linearly correlated with vehicle age. For most cases,the average EFs of CO, HC and NO_x were significantly linearly correlated with accumulated mileage, indicating that emission deterioration had a significant impact on pollutant EFs.Implemented emission standards markedly influenced the EFs of regulated pollutants, and EFs markedly decreased with progressing emission standards. The present study also compared EFs of regulated pollutants between this study and the International vehicle emission(IVE) model, and marked differences in EFs were seen with variations in emission standards, vehicle types and accumulated mileage; NO_x EFs in this study were higher than in the IVE model. The results provide new insight into estimating regulated pollutant emissions using the IVE model. 相似文献
999.
1000.
ABSTRACT: Long term trends in Japan's annual and monthly precipitation are investigated in this study. The statistical significance of a trend at a study site is assessed by the Mann‐Kendall (MK) test, and field significance of trends in climatic Regions II, III, and IV is evaluated using the bootstrap test preserving cross correlation. The practical significance of a trend is judged by a percentage change of the sample mean over an observation period. The field significance assessment demonstrates that annual precipitation in Region II did not show any significant change, but regional precipitation shifts occurred in different months. Precipitation significantly increased by 12.2 percent in May, while it significantly decreased by 12.0, 10.5, 15.6, and 19.7 percent, respectively, in April, September, October, and December. In Region III, annual precipitation declined by 11.8 percent, and monthly precipitation significantly decreased from September through January and in April, with the greatest decrease (38.2 percent) in December. In Region IV, significant reductions occurred in both annual precipitation (by 15.6 percent) and monthly precipitation from September through February and in June and July, with the worst reduction (44.7 percent) in December. 相似文献