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春季黄海边界层内海盐细粒子氯亏损及混合状态研究 总被引:2,自引:2,他引:0
为了解海盐气溶胶和亚洲出流污染物的相互影响,对2001年春季黄海边界层内观测的气溶胶细粒子可溶离子浓度(AGE-Asia中NCAR C-130飞机航测)进行了研究.所分析的6个航段(航段1~航段6)都位于黄海中部(124.0°E~125.1°E,34.3°N~36.4°N)的大气边界层内.离子摩尔比和相关分析表明,在所... 相似文献
574.
Examining driver behavior using data gathered from red light photo enforcement cameras 总被引:1,自引:0,他引:1
INTRODUCTION: To develop an effective driver assistance system that can prevent red light violations, it is important to have a thorough understanding of contributing factors and circumstances surrounding such violations. METHODS: Red light violation behavior was examined using about 47,000 violation records that were captured by photo enforcement cameras from 11 signalized intersections in the city of Sacramento, California, over a four-year period. This examination identified factors with strong correlation to red light running behavior. RESULTS: Key findings based on Sacramento's red light violation records include: (a) younger drivers showed a higher tendency of running the red light and were more likely to commit such a violation at speeds above the posted speed limit; (b) off-peak time period between 8 p.m. to 5 a.m. had lower violation counts, but red light violators in this time frame had a higher propensity of racing through intersections at high speeds; (c) also during the time period between 8 p.m. to 5 a.m., violators showed a higher probability of entering intersections two or more seconds after the onset of red light; and (d) violators were less likely to cross high traffic-volume intersections with speeds greater than the posted speed limit. DISCUSSION: Sacramento's data suggest that some red light violators might have committed such an offense unintentionally. The top three violation speeds were all below 20 mph and more than 94% of red light runners crossed intersections within 2 seconds after the onset of the red light. IMPACT ON INDUSTRY: In the next several years, studies will be executed to assess whether a red light violation warning system can reduce "unintentional red light running" such as drivers who made incorrect judgment regarding the adequate time to clear the intersection and inattentive motorists who fail to observe the presence and status of the red light. 相似文献
575.
Seasonal and Regional Patterns in Performance for a Baltic Sea Drainage Basin Hydrologic Model 下载免费PDF全文
Steve W. Lyon Roya Meidani Ype van der Velde Helen E. Dahlke Dennis P. Swaney Carl‐Magnus Mörth Christoph Humborg 《Journal of the American Water Resources Association》2015,51(2):550-566
This study evaluates the ability of the Catchment SIMulation (CSIM) hydrologic model to describe seasonal and regional variations in river discharge over the entire Baltic Sea drainage basin (BSDB) based on 31 years of monthly simulation from 1970 through 2000. To date, the model has been successfully applied to simulate annual fluxes of water from the catchments draining into the Baltic Sea. Here, we consider spatiotemporal bias in the distribution of monthly modeling errors across the BSDB since it could potentially reduce the fidelity of predictions and negatively affect the design and implementation of land‐management strategies. Within the period considered, the CSIM model accurately reproduced the annual flows across the BSDB; however, it tended to underpredict the proportion of discharge during high‐flow periods (i.e., spring months) and overpredict during the summer low flow periods. While the general overpredictions during summer periods are spread across all the subbasins of the BSDB, the underprediction during spring periods is seen largely in the northern regions. By implementing a genetic algorithm calibration procedure and/or seasonal parameterization of subsurface water flows for a subset of the catchments modeled, we demonstrate that it is possible to improve the model performance albeit at the cost of increased parameterization and potential loss of parsimony. 相似文献
576.
南黄海南部海域表层沉积物重金属来源解析及风险评价 总被引:3,自引:1,他引:2
基于2012年夏季对南黄海南部海域的调查资料,分析了表层沉积物中7种重金属元素的含量分布特征;采用多元统计分析,揭示了研究区表层沉积物重金属污染的主要来源及各元素之间的相关性;应用地质累积指数法和Hakanson潜在生态风险指数法对重金属元素进行了污染及风险分析.结果表明:Cd、Pb的含量均符合国标规定的一类沉积物标准,Zn、Cu、Cr在绝大部分站位也都低于国标规定的一类沉积物的最高标准,仅在个别站位处达到二类或三类沉积物标准;除Cr、Cd、Mn外,其余各重金属与Al2O3、平均粒径之间有显著的相关性,表明它们均以自然来源为主,并受到沉积物粒度的控制,遵循"元素的粒度控制律";Cr、Cd、Mn与Al2O3的相关系数较小,表明其可能受到人为污染源的影响.通过主成分分析和聚类分析可将7种重金属元素辨识为2个主成分,PC1(Zn、Cu、Pb、Fe、Mn)为自然源因子,PC2(Cr、Cd)为工农业源因子;其中,Cr、Cd在PC1和PC2上均具有一定的正载荷,受自然地质背景和人类活动的共同控制.地质累积指数法评价结果表明,Zn、Cu、Cd、Pb整体均处于清洁级别,而Cr则处于轻微污染水平,污染程度排序依次为CrPbCdZnCu;潜在生态风险评价结果表明,各元素潜在生态危害等级排序依次为CdPbCuCrZn,Cr、Zn、Cu和Pb均为低生态危害等级,Cd以低中等生态危害等级为主,局部出现较重生态危害等级,综合潜在生态风险评价为低度. 相似文献
577.
Concerning the high volume of wastewater containing dye in Iran and its adverse effects, it is necessary to develop scientific solutions for treating these wastewaters. The aim of this study was to evaluate the efficiency of the alumina-coated multi-walled carbon nanotubes in removing the Reactive Red 198 (RR 198) and Blue 19 (RB 19) dyes. Synthetic samples including dye with different concentrations were prepared. These samples were put in contact with different contents of alumina/multi-walled carbon nanotubes, in different pH values, in different contact times, different temperatures and the presence of sodium sulfate or sodium carbonate. The optimum pH, dye concentration and temperature for removal of the two dyes was 3, 50 mg l−1 and 25 °C, respectively. The optimum adsorbent dose for removal the RR 198 dye was 0.5 g l−1 and for Blue 19 was 0.4 g l−1. The optimum contact time for RR 198 was 150 min and RB 19 was 180 min. In this condition, maximum removal efficiency for RR 198 and RB 19 was 91.54% and 93.51%, respectively. The adsorption study was analyzed kinetically, and the results revealed that the adsorption fitted a pseudo-second order kinetic model. According to these results alumina/multi-walled carbon nanotubes can effectively remove RR 198 and RB 19 from aqueous solutions. 相似文献
578.
Sources and characteristics of fine particles over the Yellow Sea and Bohai Sea using online single particle aerosol mass spectrometer 总被引:2,自引:0,他引:2
Huaiyu Fu Mei Zheng Caiqing Yan Xiaoying Li Huiwang Gao Xiaohong Yao Zhigang Guo Yuanhang Zhang 《环境科学学报(英文版)》2015
Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm weremeasured onboardby a single particle aerosol mass spectrometer (SPAMS). The average hourly particle number (PN) was around 4560 ± 3240 in the South Yellow Sea (SYS), 2900 ± 3970 in the North Yellow Sea (NYS), and 1700 ± 2220 in the Bohai Sea (BS). PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied slightly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were classified using an adaptive resonance theory based neural network algorithm (ART-2a). Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflowonmarine environment. Variation of source types dependedmainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of high-time-resolution source apportionment by ART-2a. 相似文献
579.
Kristina Veidemane Olgerts Nikodemus 《Journal of Environmental Planning and Management》2015,58(6):949-975
The aim of this paper is to contribute to coherence in marine, coastal and land use planning and management from the perspective of landscape values. At a time when new sea uses are emerging and marine spatial planning laws and regulations are being adopted, but have not yet been put into practice, research studies are required that provide spatial planners with informed insights concerning public stakeholder attitudes to controversial policies. The undertaken research explored the attitudes of two important social groups (local residents and tourists/recreational users) regarding locating wind parks in the marine and/or terrestrial environment along the Latvian coast of the Baltic Sea. The results of the study indicate that both groups support land-based wind park development versus offshore. Moreover, the visibility of wind turbines influences the willingness of tourists to visit recreation sites and impacts directly on their duration of stay. Research findings indicate that policy makers and spatial planners from both marine and land domains should adopt a broader and more integrated approach when setting priorities and allocating space for development activities where both domains are involved. 相似文献
580.