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761.
This paper focused on the pollution characteristics,sources and lung cancer risk of atmospheric polycyclic aromatic hydrocarbons(PAHs) in a new urban district of Nanjing,China.Gaseous and aerosol PM_(2.5)(particulate matter with aerodynamic diameter smaller than2.5 urn) samples were collected in spring of 2015.Sixteen PAHs were extracted and analyzed after sampling.Firstly,arithmetic mean concentrations of PAHs and BaP_(eq)(benzo[a]pyrene equivalent) were calculated.The mean concentrations of PAHs were 29.26±14.13,18.14±5.37 and 48.47±16.03 ng/m~3 in gas phase,particle phase and both phases,respectively.The mean concentrations of BaP_(eq) were 0.87±0.51,2.71±2.17 and 4.06±2.31 ng/m~3 in gas phase,particle phase and both phases,respectively.Secondly,diagnostic ratios and principal component analysis were adopted to identify the sources of PAHs and the outcomes were the same:traffic exhaust was the predominant source followed by fuel combustion and industrial process.Finally,incremental lung cancer risk(ILCR) induced by whole year inhalation exposure to PAHs for population groups of different age and gender were estimated based on a Monte Carlo simulation.ILCR values caused by particle phase PAHs were greater than those caused by gas phase PAHs.ILCR values for adults were greater than those for other age groups.ILCR values caused by total(gas + particle) PAHs for diverse groups were all greater than the significant level(10~6),indicating high potential lung cancer risk.Sensitivity analysis results showed that cancer slope factor for BaP inhalation exposure and BaP_(eq) concentration had greater impact than body weight and inhalation rate on the ILCR.  相似文献   
762.
Magnetic cationic hydrogel (MCH) was synthesized, and its removal efficiency and mechanisms in regard to natural organic matter (NOM, represented by humic acid and fulvic acid) from the aqueous environment were studied. The effects of time, adsorbent dosage, initial pH, ionic strength, background ions, and NOM types were also investigated. MCH was characterized and found to have a strong magnetic character, yielding an extra advantage for recycling and reuse. Batch studies showed that the removal of Aldrich humic acid (AHA) by MCH was effective. The main mechanism for the removal of NOM is believed to be due to electrostatic interaction. NOM with larger molecular weight tended to be preferentially removed. Solutions with low pH, high ionic strength, and background electrolytes containing calcium, sulfate and bicarbonate were unfavorable for AHA removal. The adsorption-desorption of MCH was evaluated in three cycles, and demonstrated high regeneration rates.  相似文献   
763.
运用灰色关联分析方法,分析了河北省产业结构升级及三次产业内部结构对劳动力就业的影响,揭示了河北省产业结构调整过程中存在的问题及扩大就业存在的障碍,并提出促进就业结构良性发展的建议。  相似文献   
764.
道路交通安全状况预测及管理规划方案研究   总被引:1,自引:0,他引:1  
为研究道路交通安全规划方案的设计,探讨国内外道路交通安全状况规划方案的研究现状。以台州市为例,在对台州市的交通安全特性统计分析的基础上,针对台州市道路交通安全现状,进行了安全趋势分析。从预测可以看出,随着台州市经济的持续增长、道路交通的快速发展,台州市的道路交通安全形势不容乐观,面临道路交通事故有可能继续上升的巨大压力。结合台州市区道路交通安全管理规划的目标,重点从完善道路基础设施及安全设施、建立交通安全管理的科技保障体系、构建台州市道路交通事故紧急救援系统3个方面提出近期道路交通安全管理规划方案,有效地提高台州市道路交通安全水平。  相似文献   
765.
以镇江市安监局提供的应急救援预案申报、应急预案演练和培训、预案修订和互助协议签订、应急救援设备物资台账等21项指标调研数据为基础,根据数理统计的相关方法,对调研数据进行统计和分析.通过分析发现,国有企业、三资企业和外资企业在企业预案衔接和企业互助协议签订方面仍有欠缺;私营企业在应急救援建设方面相对薄弱,集中体现在应急教育不专业、不具体;应急演练不规范、不全面;缺乏预案修订和应急物资检查制度等.根据调研中发现的问题提出企业园区化建设的方法,利用园区管理的集中性和统一性,将应急救援技术政府外包,以提高企业应急救援能力.  相似文献   
766.
Taking 29 Chinese lakes and 29 Italian lakes as two separate case studies, the paper presented the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. The exergies (Ex) and structural exergies (Exst) were calculated based on phytoplankton biomass (BA) and zooplankton biomass (BZ). A trophic state index (TSI) scaling from 0 to 100 was developed to classify trophic status for Chinese and Italian lakes based on three indicators, chlorophyll-a concentration (Chl-a, in mg/m3), total phosphorus (TP in mg/m3) and transparency in Secchi disk depth (SD in m). The relationships between TSI and Ex, Exst, total biomass, BZ/BA ratios were analyzed. The following results were obtained: (1) with the increase of TSI in Chinese and Italian lakes, there is an increasing trend for Ex, and a decreasing trend for Exst, generally. The obvious negative correlations exist between TSI and Exst, at the significant level of 0.01 for Italian lakes, and 0.05 for Chinese lakes. The obvious positive correlations exist between TSI and Ex, at the significant level of 0.01 for Chinese lakes, and for Italian lakes in Spring, Autumn and the all-year. (2) The structural exergy is more dependent on the ratio of phytoplankton biomass to zooplankton biomass (BZ/BA) than the exergy, and the exergy is more dependent on total biomass than the structural exergy. (3) The phytoplankton biomass (BA) and zooplankton biomass (BZ) are increased with the increasing TSI in Chinese and Italian lakes, and phytoplankton biomass (BA) increases more rapidly then zooplankton biomass (BZ) does. This results in the definite decrease of BZ/BA ratio with the increasing trophic status index. Such changes of BA, BZ and BZ/BA ratio could explain successfully the variations of exergies and structural exergies along eutrophication gradients in Chinese and Italian lakes. From the two separate case studies of Chinese lakes and Italian lakes, it could be concluded that exergy and structural exergy are feasible to serve as the system-level ecological indicators to give appropriate information on the trophic status of different lakes.  相似文献   
767.
基于微藻在资源化大规模培养过程中,其胞外产物对藻细胞生长影响的不确定性,对比研究了两株高含油脂藻种,栅藻LX1(Scenedesmus sp.LX1)和雨生红球藻(Haematococcus pluvislis)的生长特征、胞外产物的产生特性,以及胞外产物对藻细胞生长的影响。研究结果表明,在相同培养条件下,栅藻LX1与雨生红球藻的内禀生长速率基本相当,分别为0.16和0.17 d-1。两株藻在不同生长期的胞外产物(以DOC值表征)产生速率不同,其中栅藻LX1胞外产物的对数期产生速率(1.4 mg·L-1·d-1)﹥稳定期后期产生速率(0.56 mg·L-1·d-1)﹥稳定期产生速率(0.48 mg·L-1·d-1);雨生红球藻胞外产物的稳定期后期产生速率(2.3 mg·L-1·d-1)﹥稳定期产生速率(0.88 mg·L-1·d-1)﹥对数期产生速率(0.66 mg·L-1·d-1)。栅藻LX1胞外产物对其整个生长过程都有明显抑制;雨生红球藻胞外产物则在稳定期后期才对其生长产生明显抑制作用。  相似文献   
768.
多环芳烃(PAHs)具有高的疏水性,在水体中优先分布于沉积物.采用物种敏感性分布法(SSDs法),依据水生生物慢性毒性数据计算5%物种危害浓度(HC5);并结合欧盟委员会风险评价技术导则(TGD)进而得到沉积物预测无效应浓度(PNEC-sed),以报道的太湖的沉积物中浓度数据作为预测环境浓度(PECsed);用商值法P...  相似文献   
769.
This study explored the spatio-temporal dynamics and evolution of land use/cover changes and urban expansion in Shanghai metropolitan area, China, during the transitional economy period (1979?C2009) using multi-temporal satellite images and geographic information systems (GIS). A maximum likelihood supervised classification algorithm was employed to extract information from four landsat images, with the post-classification change detection technique and GIS-based spatial analysis methods used to detect land-use and land-cover (LULC) changes. The overall Kappa indices of land use/cover change maps ranged from 0.79 to 0.89. Results indicated that urbanization has accelerated at an unprecedented scale and rate during the study period, leading to a considerable reduction in the area of farmland and green land. Findings further revealed that water bodies and bare land increased, obviously due to large-scale coastal development after 2000. The direction of urban expansion was along a north-south axis from 1979 to 2000, but after 2000 this growth changed to spread from both the existing urban area and along transport routes in all directions. Urban expansion and subsequent LULC changes in Shanghai have largely been driven by policy reform, population growth, and economic development. Rapid urban expansion through clearing of vegetation has led to a wide range of eco-environmental degradation.  相似文献   
770.
The concentrations of organochlorine pesticides (OCPs) in atmospheric particulate matter in Jinan, China, over the period from July 2009 to June 2010, were determined to study their pollution levels, compositions, size distribution and seasonal variations. All target compounds except endosulfan sulfate were detected. The annual average concentration of ∑18 OCPs was 92 ± 82 pg m(-3). Total HCH, total endrin, aldrin, endosulfan compounds and total DDT compounds were the primary components, accounting for approximately 27%, 20%, 16%, 14% and 10% of total OCPs, respectively. The annual mean ng g(-1) concentrations of ∑18 OCPs in PM(2.5), PM(5), PM(10) and TSP were 481 ± 190, 433 ± 161, 414 ± 158 and 264 ± 193, respectively, indicating that most OCPs tend to be strongly absorbed by fine air particles which were strongly related to a potential health risk. Distinct seasonal trends were found in OCPs concentrations with high concentrations appearing in November and March whereas low concentrations appeared in the summer, which were significantly positively correlated with particulate mass concentrations and Air Pollution Index (API). The high OCPs levels could be attributed to the seasonal usage, long-range atmospheric transport as well as adverse meteorological conditions.  相似文献   
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