Traffic congestion and ozone precursor emissions in Bilbao (Spain)

GOAL. SCOPE. BACKGROUND: In urban environments, the measured levels of ozone are the result of the interaction between emissions of precursors (mainly VOCs and NOx) and meteorological effects. In this work, time series of daily values of ozone, measured at three locations in Bilbao (Spain), have been built. Then, after removing meteorological effects from them, ozone and traffic data have been analyzed jointly. The goal was to identify traffic situations and link them to ozone levels in the area of Bilbao. METHODS: To remove meteorological effects from the selected ozone time series, the technique developed by Rao and Zurbenko was used. This is a widely used technique and, after its application, the fraction obtained from a given ozone time series represents an ozone forming capability attributable to emissions of precursors. This fraction is devoid of any meteorological influence and includes only the apportion of periodicities above 1.7 years. In the case of Bilbao, the ozone fractions obtained at three locations have been compared on that time scale with traffic data from the area. RESULTS AND DISCUSSION: For the 1993-1996 period, a regression analysis of the ozone and traffic fractions due to periodicities above 1.7 years (long-term fractions), shows that traffic is the main explanatory factor for ozone with R2 ranging from 0.916 to 0.996 at the three locations studied. Analysis of these longterm fractions has made it possible to identify two traffic regimes for the whole area, associated to different profiles of ozone forming capability. The first one favors low ozone forming capability, and is associated with a situation of fluent traffic. The second one shows high ozone forming capability and represents congestion. Joint analysis of raw data of ozone and traffic do not show any clear pattern due to the strong masking effects that seasonal-meteorological effects (mainly radiation) have on the measured ozone signal. If only immission data of ozone are available, as in this case, a comparison between ozone and traffic can only be made on the long-term time scale, since that is the only fraction embedded in the ozone time series that can exclusively be attributed to emissions of precursors. This fact stresses the need to study the different fractions embedded in the time series of ozone measured levels separately. CONCLUSION: Though the coefficients obtained in the regression are only valid for the 1993-1996 period, these traffic regimes represent long-term targets (congestion or fluent traffic) that can inspire policies for a joint management of the traffic and pollution by ozone in the area of Bilbao beyond that period. RECOMMENDATIONS AND OUTLOOK: The results of this work show the need of a joint management of ozone and traffic in Bilbao. Since an accurate knowledge of traffic was not available, the use of emission factors to relate traffic and actual ozone levels has not been possible. For this reason, this study has focused on the long-term fractions of traffic and ozone. In the future, if a more accurate knowledge of traffic is available, it will be possible to find relationships between traffic and ozone on all time scales.     

Simultaneous removal of ammonia and N-nitrosamine precursors from high ammonia water by zeolite and powdered activated carbon

When adding sufficient chlorine to achieve breakpoint chlorination to source water containing high concentration of ammonia during drinking water treatment, high concentrations of disinfection by-products(DBPs) may form. If N-nitrosamine precursors are present, highly toxic N-nitrosamines, primarily N-nitrosodimethylamine(NDMA), may also form. Removing their precursors before disinfection should be a more effective way to minimize these DBPs formation. In this study, zeolites and activated carbon were examined for ammonia and N-nitrosamine precursor removal when incorporated into drinking water treatment processes.The test results indicate that Mordenite zeolite can remove ammonia and five of seven N-nitrosamine precursors efficiently by single step adsorption test. The practical applicability was evaluated by simulation of typical drinking water treatment processes using six-gang stirring system. The Mordenite zeolite was applied at the steps of lime softening, alum coagulation, and alum coagulation with powdered activated carbon(PAC) sorption. While the lime softening process resulted in poor zeolite performance, alum coagulation did not impact ammonia and N-nitrosamine precursor removal. During alum coagulation, more than67% ammonia and 70%–100% N-nitrosamine precursors were removed by Mordenite zeolite(except 3-(dimethylaminomethyl)indole(DMAI) and 4-dimethylaminoantipyrine(DMAP)). PAC effectively removed DMAI and DMAP when added during alum coagulation. A combination of the zeolite and PAC selected efficiently removed ammonia and all tested seven N-nitrosamine precursors(dimethylamine(DMA), ethylmethylamine(EMA), diethylamine(DEA), dipropylamine(DPA), trimethylamine(TMA), DMAP, and DMAI) during the alum coagulation process.     

汶川地震的异常及地震预测问题

汶川MS8.0级地震造成了巨大的灾害.我国对这个巨震未能作出预测,于是国内外各界对地震预测问题议论纷纷.笔者经过地震现场的调查与深入思考,认为汶川地震前是有异常的,之所以未能作出预测,根本上是因为地震预测的科学难关尚未突破,但还有与我国目前地震监测与预测工作上存在多方面的不足与问题有关;同时还认为,汶川地震的预测失败并不意味着地震不能预测,因为我国有规模宏大的地震监测台网,积累了大量的震例,取得了一定成功预测的经验,因此对未来的某些地震仍可作出成功预测并取得显著的减灾实效.     

汶川地震期间天津地震前兆台网运行与管理

汶川地震发生后,天津市地震局迅速进入应急体制,高效应对突发事件.监测中心、预报中心全体人员坚守岗位,履行职责,较好地完成了汶川地震期间天津地震前兆台网运行监控、数据管理、台站综合评比、数据服务、总结评估等项工作,以无私奉献的团队精神为地震监测预报工作做出了应有的贡献.     

震前小震调制比空间异常消失的映震能力研究

利用小震调制比方法的时空异常进行跟踪分析,通过对比发现,近几年震前小震调制比的空间异常变化与有感地震的发生具有一定的对应关系.进一步的分析研究认为,利用震前小震调制比的空间异常消失可进行有感地震甚至中强地震的地点预测.     

基于水量变化的塔里木河统一管理成效评价

为科学明确评价塔里木河统一管理成效,论文基于源流及干流的来水与耗水量数据,利用非参数检验、周期叠加模型等构建人类活动对源流区水量影响分离模型,进而结合距平百分比和变异系数等参数,对比分析统一管理措施对塔里木河利用管理水平的影响,结果表明：1）人类活动对源流区水资源的影响程度在1994—2001、2002—2010、2011—2013年呈减弱趋势,流域过度引水的现象得到一定的好转,源流区水资源利用水平和管理效能提高;2）实施统一管理后,干流来水保证度提高,干流来水距平百分比的变异系数由-4.67减小至0.33,源流与干流来水距平百分比差异的平均值由-19.6%变为-4.9%,且源流干流来水差异值累积距平曲线由上升转为下降,源流和干流来水的波动性减弱,尤其是干流来水波动性要弱于源流,同时源流及干流来水更具协调性,管理部门对塔里木河径流的调度和管控能力明显提升,统一管理成效显著。     

广东省主要土类的三卤甲烷生成潜能(THMFP)

通过振荡浸出实验,测定了广东省几种主要土类的三卤甲烷生成潜能(THMFP),比较了土壤浸提液中溶解态(可过滤态)有机物与悬浮态(不可过滤态)有机物在形成三卤甲烷(THMs)中的作用,并对影响土壤THMFP的各种因素进行讨论结果表明:①各主要土类表层土中,未过滤浸提液的整体THMFP(b-THMFP)含量范围为:0.7～36.8μg/g土,中值为10.6μg/g土;过滤浸提液的THMFP(指可溶性有机物的THMFP,即d-THMFP)含量范围为:0.5～21.2μg/g土,中值为3.9μg/g土;其中,19号石灰土的b-THMFP和d-THMFP最高,20号紫色土的b-THMFP最低,5号赤红壤的d-THMFP最低.②总体上,悬浮态有机物对THMs生成量有较大的正贡献.③影响土壤THMFP的因素主要是有机质含量、各种氧化物含量、土壤发生层次、植被等.     

三氯乙醛前驱物的筛选及其生成影响因素探讨

选取苹果酸、酒石酸、柠檬酸、色氨酸、组氨酸、酪氨酸代表自然界中低分子量的有机酸和氨基酸,实验室模拟氯化,GC/MS确证了氯化产物中的三氯乙醛,GC-ECD定量测定了氯化产物中三氯乙醛的浓度,筛选了生成三氯乙醛主要前驱物,并进一步探讨了各种因素对三氯乙醛形成的影响。     

乌鲁木齐9、10号泉F~-映震特征的研究

从监测泉点的水文地质概况入手，结合近18年来的观测资料，分析并总结了9、 10号泉水中F-的映震特征： F-的地震前兆异常基本上都是正异常，且具有较好的重复性，即基本上遵循： 背景值-脉冲式突升-最高值-突降-恢复至背景值的规律。 而地震常常发生在F-含量恢复背景值后数天或数十天，仅有个别地震发生在F-含量达最高值时。 最后，初步认定了泉点较好的地震构造环境是造成该9、 10号泉F-具有映震灵敏性的原因。     

洪水前兆的初步探讨

根据历史洪水和现有研究 ,比较系统地分析了各种洪水前兆 ,可以为洪水预报提供一定的理论依据 ,同时指出 ,为了提高预报精度 ,必须对洪水前兆进行综合分析 ,去伪存真 ,最终达到防洪减灾的目的