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971.
Marmolejo-Rodríguez AJ Sánchez-Martínez MA Romero-Guadarrama JA Sánchez-González A Magallanes-Ordóñez VR 《Journal of environmental monitoring : JEM》2011,13(8):2182-2189
Extensive waste deposits (tailings) and ash from the ignition oven of the abandoned gold mine of mining district El Triunfo (MD-ET) in Baja California Sur, Mexico have released trace elements into the sediments of the Hondo-Las Gallinas-El Carrizal arroyo, which connects to the Pacific Ocean through an evaporitic basin. Migration of these elements through the arroyo is mainly caused by winds or tropical hurricanes that occur sporadically during the summer and cause the otherwise dry arroyo to overflow. To evaluate the concentration and distribution of the elements As, Hg, Pb, and Zn along the 48 km arroyo, surface sediments were collected from 26 sites, ranging from close to the MD-ET to the mouth of the arroyo at the Pacific Ocean. Concentrations in tailings and ash were for As 8890 and 505?000 mg kg(-1); for Hg 0.336 and 54.9 mg kg(-1); for Pb 92,700 and 19,300 mg kg(-1); and for Zn 49,600 and 1380 mg kg(-1). The average of the Normalized Enrichment Factor (Av-NEF) in surface sediments, calculated using background levels, indicates that the sediments are severely contaminated with As and Zn (Av-NEF = 22), Pb (Av-NEF = 24) and with a moderate contamination of Hg (Av-NEF = 7.5). The anthropogenic influence of those elements is reflected in the arroyo sediments as far as 18 km away from the MD-ET, whereas the samples closest to the discharge into the Pacific Ocean show a natural to moderate enrichment for As and Zn and low or no enrichment for Hg and Pb. A principal components analysis identified four principal components that explained 90% of the total variance. Factor 1 was characterized by a high positive contribution of the anthropogenic source elements, especially As, Pb, and Zn (37%), whereas Factor 2 was strongly correlated with the oxy-hydroxides of Fe and Mn (27%). Factor 3 was correlated with Li (16%) and Factor 4 with Al (10%), which indicates more than one source of lithogenic composition, though they played a minor role in the distribution of the elements. 相似文献
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974.
Jian Gao Yuechong Zhang Meng Zhang Jingqiao Zhang Shulan Wang Jun Tao Han Wang Datong Luo Fahe Chai Chun Ren 《环境科学学报(英文版)》2014,26(1):44-53
Beijing sufered from serious air pollution in October, 2011 with the occurrence of three continuous episodes. Here we analyze the pollution status of particulate matter, the relationship between the gaseous pollutants, physical and chemical properties of single particles, and the profile of watersoluble ions in PM2.5during the three episodes. Regional and photochemically aged air masses, which were characterized as having high values of O3and SO2, were hypothesized to have played a dominant role in the first episode. After mixing local air masses with freshly-emitted primary pollutants, the concentration of NOx continued to increase and the size of SO4 2, NO3 and NH4 +in the particle population continued to become smaller. The amount of elemental carbon-rich and organic carbonrich particles in the scaled single particles(0.2–2 μm) and water-soluble K+in PM2.5also increased in the episodes. All the available information suggests that the biomass or fuel burning sources in or around Beijing may have had a huge impact on the last two episodes. 相似文献
975.
高压电晕放电对五氯酚的降解研究 总被引:1,自引:1,他引:0
研究了放电电压、溶液pH等因素对高压电晕放电降解PCP效果的影响,并对高压电晕放电处理PCP的动力学进行了初步探讨,同时对高压电晕放电降解PCP的COD和TOC的变化进行了分析。结果表明:放电电压和溶液pH值对PCP降解性能影响很大,放电电压和溶液pH值越高,PCP的降解速度越快。当溶液pH值为11.2、PCP初始质量浓度40 mg/L、电晕放电电压为25 kV时,经30 min电晕放电,PCP的降解率达90%以上,电晕放电降解PCP的反应符合一级反应动力学。在氧化过程中PCP可能转化为苯醌等中间产物,TOC几乎无变化,PCP分解成的小分子有机物使COD升高,可生化性提高。 相似文献
976.
沈阳市冬季一次严重污染天气过程成因分析 总被引:1,自引:1,他引:0
为探讨沈阳市冬季重污染天气的初步成因。以2013年1月11日~16日沈阳市发生的一次严重污染天气为例,利用中国气象局的MICAPS系统和美国的HYSPLT模式,从污染形成的天气背景、污染物扩散受地形的影响情况以及外来污染物输送的气流轨迹等几方面综合分析,从而探讨此次严重污染过程的成因:长白山小高压和西部倒槽双重系统的控制下,地面吹东北风,风速较小,湿度大,不利于污染物的水平扩散;有较强接地逆温存在时,不利于污染物的垂直扩散,导致近地面污染物累积;受来自于北部和东北部低层气流的影响,将内蒙古、辽宁东北部的污染物携带到沈阳地区汇聚。 相似文献
977.
978.
Minjie Hu Hongchang Ren Peng Ren Jiabing Li Benjamin J. Wilson Chuan Tong 《环境科学学报(英文版)》2017,29(2):210-222
Although estuarine tidal marshes are important contributors to the emission of greenhouse gases into the atmosphere, the relationship between carbon dioxide(CO_2), methane(CH_4)emission, and environmental factors, with respect to estuarine marshes, has not been clarified thoroughly. This study investigated the crucial factors controlling the emission of CO_2 and CH_4from a freshwater marsh and a brackish marsh located in a subtropical estuary in southeastern China, as well as their magnitude. The duration of the study period was November 2013 to October 2014. Relevant to both the field and incubation experiments, the CO_2 and CH_4emissions from the two marshes showed pronounced seasonal variations. The CO_2 and CH_4emissions from both marshes demonstrated significant positive correlations with the air/soil temperature(p 0.01), but negative correlations with the soil electrical conductivity and the pore water/tide water Cl-and SO_4~(2-)(p 0.01). The results indicate no significant difference in the CO_2 emissions between the freshwater and brackish marshes in the subtropical estuary, whereas there was a difference in the CH_4 emissions between the two sites(p 0.01). Although future sea-level rise and saltwater intrusion could reduce the CH_4 emissions from the estuarine freshwater marshes, these factors had little effect on the CO_2 emissions with respect to an increase in salinity of less than 5‰. The findings of this study could have important implications for estimating the global warming contributions of estuarine marshes along differing salinity gradients. 相似文献
979.
通过综合学习借鉴发达国家不同历史阶段污染防治的历程与积累的经验,有助于我国在比较的视野中正确认识我国重金属污染防治中存在的问题,以及学习借鉴他国的经验教训,探索属于自己的跨越式发展道路,包括污染防治政策制度设计、环境管理经验、各国的协调合作等。 相似文献
980.
通过计算地震活动能量距平场,研究了黑龙江及其附近区域3次中等地震前的研究区能量场在地震孕育过程中相关的物理时空变化特征。结果显示,地震活动能量场的时间曲线呈较大幅度上升可能预示了发生中强震的时间段,而地震活动能量场等值线高值变化区对应了可能发生M5以上地震的区域。结合热红外卫星长波辐射(OLR)值发现,地震前能量场等值线高值变化区升温明显,表明研究区能量场处于能量积累(释放)增强的状态。这些特征的提取,对该地区中强地震的中短期预测有一定的指导意义。 相似文献