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101.
This study investigated concentrations of PM2.5, PM10, SO2, NO2, CO and O3, and air quality index(AQI) values across 368 cities in mainland China during 2015–2018. The study further examined relationships of air pollution status with local industrial capacities and vehicle possessions. Strong correlations were found between industrial capacities(coal, pig iron, crude steel and rolled steel) and air pollution levels. Although statistical and ... 相似文献
102.
基于VOCs加密监测的上海典型臭氧污染过程特征及成因分析 总被引:6,自引:0,他引:6
针对2017年8月4—7日在上海市及周边城市发生的臭氧污染过程,结合30个采样点连续4 d的大气挥发性有机物(VOCs)苏玛罐样品分析数据及O_3和NO_2在线监测数据,分析了此次污染过程的O_3和NO_2的时间变化特征、VOCs组分及臭氧生成潜势(OFP)的空间分布特征,并对VOCs来源进行了研究.结果表明,采样期间,上海市的O_3和NO_2平均浓度水平总体均高于周边的5个城市.VOCs均值浓度的空间分布总体为西北部高于东南部,上海市VOCs均值浓度为48×10~(-9),相较周边城市处于中间水平.上海市各类VOCs浓度为OVOCs烷烃卤代烃芳香烃烯炔烃,OFP贡献为芳香烃烯炔烃烷烃OVOCs和卤代烃.VOCs源解析结果显示机动车、溶剂使用、化工和石化工艺过程是上海市VOCs的3个主要来源.结合VOCs来源解析与OFP的贡献分析,控制上海市臭氧污染需重点削减溶剂使用和化工工艺过程中的甲苯、乙苯、间/对二甲苯、邻二甲苯和苯等芳香烃的排放,同时加强机动车和石化工艺过程中丙烯、乙烯和乙炔的排放控制. 相似文献
103.
Chi-Chuan Kan Mannie C Aganon Cybelle Morales Futalan Maria Lourdes P Dalida 《环境科学学报(英文版)》2013,25(7):1483-1491
The adsorption of Mn2+ onto immobilized Mn-oxide and Fe-oxide adsorbent such as manganese oxide-coated sand1 (MOCS1), manganese oxide-coated sand2 (MOCS2), iron oxide-coated sand2 (IOCS2), and manganese and iron oxide-coated sand (MIOCS) was investigated. The effects of pH (5.5 to 8.0) and temperature (25 to 45℃) on the equilibrium capacity were examined. Equilibrium studies showed that there is a good fit with both Freundlich and Langmuir isotherm, which indicates surface heterogeneity and monolayer adsorption of the adsorbents. Kinetic data showed high correlation with the pseudo second-order model, which signifies a chemisorption-controlled mechanism. The activation energies, activation parameters (ΔG*, ΔH*, ΔS*), and thermodynamic parameters (ΔG0, ΔH0, ΔS0) confirmed that adsorption with MIOCS was endothermic and more spontaneous at higher temperature while an opposite trend was observed for the other adsorbents. Thermodynamic studies showed that adsorption involved formation of activated complex, where MOCS1 and MIOCS follow a physical-chemical mechanism, while MOCS2 and IOCS2 follows purely chemical mechanism. 相似文献
104.
The release of trace metals (Mn, Ni, Co, Cu, Zn, Pb, and Cd) and inorganic compounds (As) from initially anoxic Trepangier Bayou sediments, Louisiana and the sources of the released metals were investigated. After 1 to 2 d aeration, significant amounts of trace metals (Mn, Zn, Cd, Ni, and Co) were released to the aqueous phase with increased acidity, primarily due to the oxidation of acid-volatile sulfide and ferrous iron and iron sulfide minerals. The addition of a bacterial inhibitor, NaN,, to the Trepangier sediment during resuspension inhibited metal release, suggesting that microbial catalysis can regulate metal mobilization during sediment resuspension. In a well buffered system, oxidation of iron sulfides alone did not appear to induce trace metal release. Moreover, when Trepangier sediment was resuspended in anoxic conditions at neutral pH, <1% of the trace metal content was released, whereas a significant release of metal was observed under acidic anoxic conditions. Although oxidation of iron sulfide minerals is an essential prerequisite for the release of Zn, Co, Cd, and Ni, carbonates and oxides also play a role. The trace metals and inorganic compounds investigated could be classified into three groups according to their release characteristics: (i) Mn, Zn, Cd, Ni, and Co; (ii) Fe, Pb, and As; and (iii) Cu. The groupings appeared to depend on the sources of compounds and their relative affinity, after oxidation, to iron oxyhydroxides or organic matter. 相似文献
105.
106.
Stability and deformation of surrounding rock in pillarless gob-side entry retaining 总被引:2,自引:0,他引:2
We analyzed the stability of the retained gob-side entry in four different Chinese coal mining sites and evaluated the influencing factors of roadway deformation such as mining depth, support strength and area of gob-side hanging roof. It was found that the length of cantilever roof block above roadway has a major impact on the deformation, whereas the impact of mining depth is minor if the depth is less than 500 m. Minimum support resistance of 0.3 MPa is essential to effectively confine the deformation of a retained roadway. We performed physical experiments to further study the features of roof fracturing and their impact on roadway deformation under three typical immediate roof conditions, i.e., thick-immediate roof, thin-immediate roof and non-immediate roof. In addition, equations to calculate desired support resistance of filled gob-side wall were derived based on superimposed continuous laminate model. The results provide valuable theoretical and practical guidance for implementing pillarless gob-side entry retaining in engineering practices. 相似文献
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110.
Laying hens were fed with feed from the Belgian dioxin incident diluted ten-fold with non-contaminated feed, resulting in concentrations of 61 ngTEQkg(-1) PCDD/Fs, 23 ngTEQkg(-1) non-ortho PCBs, 116 ngTEQkg(-1) mono-ortho PCBs and 3.2 mgkg(-1) of the seven indicator PCBs. Following exposure for seven days, feed was replaced by non-contaminated feed for a period up to six weeks. Concentrations of PCDD/Fs in eggs showed a maximum of 214 pgTEQg(-1) fat after nine days and decreased to 44 pgTEQg(-1) after seven weeks. Dioxin concentrations in abdominal fat of chickens killed just after the last treatment, or after 1, 3 or 6 weeks on clean feed were 69, 84, 54 and 41 pgTEQg(-1) fat, respectively. Concentrations in livers decreased more rapidly, being 35, 7, 4 and 3 pgTEQg(-1) tissue, respectively. In both eggs and tissues, total TEQ concentrations were 3-4 times higher. Concentrations of the seven indicator PCBs in egg fat showed a stronger decrease with concentrations of 16.5 microgg(-1) at the peak (day 9) and 2.2 microgg(-1) after seven weeks. Corresponding concentrations in abdominal fat were, respectively, 4.6 and 2.6 microgg(-1) fat, and in livers 0.77 and 0.14 microgg(-1) tissue. The ratio of indicator PCBs to PCDD/Fs in feed was 52200. In eggs this ratio was initially higher (85000), but decreased towards 50000 after six weeks on clean feed. In abdominal fat the ratio varied between 49000 and 67000. In livers, the ratio was initially low (22000) but increased to 45000 towards the end of the study. It is concluded that the behaviour of PCDD/Fs and PCBs in laying hens is comparable and that the use of indicator PCBs appears to be a good alternative for PCDD/Fs but only in the case of co-exposure to both PCBs and PCDD/Fs, such as in incidents with PCB oil. 相似文献