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311.
The ambient air in vicinity of different industrial sources for PCDD/PCDFs was sampled by TSP/PM10 active samplers and
passive PUF disk samplers in Tangshan City, a metropolis containing clusters of various industrial plants. The TEQ concentrations
of PCDD/PCDFs ranged from 44.2 to 394.1 fg I-TEQ/m3 with an average of 169.9 fg I-TEQ/m3. 2,3,4,7,8-PeCDF was the dominant
contributor to PTEQ, contributing 41% (12% to 55%), while 1,2,3,4,6,7,8-HpCDF, OCDD and OCDF were the major congeners for
the total concentrations. The ratios of PPCDF/PPCDD reached 2.54 on average, suggesting that de novo synthesis in thermal processes
played an important role to the airborne pollution of PCDD/PCDFs. The similarities congener profiles indicated that TSP and PM10
active sampling methods are comparable for the determination of the PCDD/PCDFs in ambient air, and the ratios of concentrations
determined by the two methods suggested that the PCDD/PCDFs tended to stay in fine particles. It was found that 2,3,7,8-TCDF and
OCDD were the dominating congeners in the passive PUF disks samples. Through principal components analysis, the coke industry
was suggested to be a relatively high potential emission source for PCDD/PCDFs in the ambient air of Tangshan, which was possibly
formed by de novo synthesis mechanism. In this study, the atmospheric impacts to the environment from di erent industrial sources
could be ranked as follows (from high to low): coking, iron sintering, steel making, power generation and chlorinate alkali chemical
production industries. 相似文献
312.
黄精多糖对老龄大鼠衰老生理生化指标的影响 总被引:28,自引:1,他引:28
以水提法从黄精(Polygonatumsp)中得到的粗多糖成分(PP)进行了老龄大鼠的衰老生理生化指标测定试验.两种剂量的PP灌喂老龄大鼠1mo后,测定其12项衰老生理生化指标:胸腺指数和脾脏指数,外周血淋巴细胞ANAE活性,红细胞、视网膜、晶体核、晶体皮质的SOD活性,心脏、血浆中过氧化脂质含量,肝脏、肾脏中脂褐质含量及脑中B型单胺氧化酶活性.结果表明:除胸腺指数、血浆中过氧化脂质含量无显著性变化外,其他10项指标均有明显的改善作用;试验结果经统计学处理有显著性差异. 相似文献
313.
Estimation and characterization of PCDD/Fs, dl-PCBs, PCNs, HxCBz and PeCBz emissions from magnesium metallurgy facilities in China 总被引:2,自引:0,他引:2
Magnesium production is considered to be one potential source of unintentional persistent organic pollutants (unintentional POPs). However, studies on the emissions of unintentional POPs from magnesium metallurgy are still lacking. Emissions of unintentional POPs, such as polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs), polychlorinated naphthalenes (PCNs), hexachlorobenzene (HxCBz) and pentachlorobenzene (PeCBz) are covered under the Stockholm Convention. In this study, these emissions were investigated through a magnesium smelting process. Stack gas and fly ash samples from a typical magnesium plant in China were collected and analyzed to estimate the emissions of unintentional POPs from magnesium metallurgy. Emissions factors of 412 ng TEQ t−1 for PCDD/Fs, 18.6 ng TEQ t−1 for dl-PCBs, 3329 μg t−1 for PCNs, 820 μg t−1 for HxCBz, and 1326 μg t−1 for PeCBz were obtained in 2009. Annual emissions from magnesium metallurgy in China were estimated to be 0.46 g WHO-TEQ for PCDD/Fs and dl-PCBs, 1651 g for PCNs, 403 g for HxCBz and 653 g for PeCBz, respectively. 相似文献
314.
Chen Pengfei Kang Shichang Tripathee Lekhendra Panday Arnico K. Rupakheti Maheswar Rupakheti Dipesh Zhang Qianggong Guo Junming Li Chaoliu Pu Tao 《Environmental science and pollution research international》2020,27(10):10617-10628
Environmental Science and Pollution Research - Total suspended particles (TSP) were collected in Lumbini from April 2013 to March 2016 to better understand the characteristics of carbonaceous... 相似文献
315.
江苏某地长江、太湖水源水及出厂水中有机物雌激素活性的比较 总被引:1,自引:0,他引:1
于2010年10月~2012年3月期间4次采集江苏WX和SZ地区长江、太湖水源水及相关自来水厂出厂水共43个水样,通过XAD-2树脂吸附、洗脱、浓缩其中的非挥发性有机物(nonvolatile organic compounds,NVOCs);应用重组酵母雌激素筛检试验(recombinant yeast estrogen screen,YES试验)检测和比较水中有机物雌激素活性水平.结果表明所有长江、太湖水源水样均具有雌激素活性,太湖水源水的雌二醇当量(EEQs)为0.04~2.07 ng.L-1,EC25-E2水样量为5.78~207.98 mL,长江水源水的雌二醇当量(EEQs)为0.69~1.15 ng.L-1,EC25-E2水样量为9.06~31.62 mL;SZ地区太湖水源水中具类雌激素内分泌干扰物的污染程度(0.69 ng.L-1)高于WX地区(0.44 ng.L-1);长江、太湖水源水经自来水厂常规净水工艺处理后,58.3%的出厂水样未检出雌激素活性,长江水源自来水厂可降低雌激素活性80.3%~100%,而太湖水源自来水厂可降低55.5%~100%. 相似文献
316.
Air quality model can be an adequate tool for future air quality prediction, also atmospheric observations supporting and emission control strategies responders. The influence of emission control policy (emission reduction targets in the national "China’s 12th Five-Year Plan (2011-2015)") on the air quality in the near future over an important industrial city of China, Xuanwei in Yunnan Province, was studied by applying the AERMOD modeling system. First, our analysis demonstrated that the AERMOD modeling system could be used in the air quality simulation in the near future for SO2 and NOx under average meteorology but not for PM10. Second, after evaluating the simulation results in 2008 and 2015, ambient concentration of SO2, NOx and PM10 (only 2008) were all centered in the middle of simulation area where the emission sources concentrated, and it is probably because the air pollutions were source oriented. Last but not least, a better air quality condition will happen under the hypothesis that the average meteorological data can be used in near future simulation. However, there are still heavy polluted areas where ambient concentrations will exceed the air quality standard in near future. In spatial allocation, reduction effect of SO2 is more significant than NOx in 2015 as the contribution of SO2 from industry is more than NOx. These results inspired the regulatory applications of AERMOD modeling system in evaluating environmental pollutant control policy 相似文献
317.
High speed machining (HSM) of tool steels in their hardened state is emerging as an attractive approach for the mold and die industry due to its potential for significant cost savings and productivity improvement. An experimental study was conducted to investigate the tool wear mechanism and surface integrity in high speed ball nose end milling of hardened AISI A2 tool steel using coated tungsten carbide and polycrystalline cubic boron nitride (PCBN) tools. It is found that coated carbide tools can only be used at low speed (120 m/min) while high content PCBN tools are suitable for HSM range (470 m/min). PCBN tools produce a damage free workpiece with better surface finish and less work hardening. Despite the higher tool cost, HSM with PCBN tools lead to reduction in both total cost and production time per part. 相似文献
318.
为解决现有加油机胶管的油品污染和油品挥发渗透问题,研发了新型的防污染低渗透加油机胶管,在胶管内壁增加了由氟聚合物THV构成的防渗阻隔层。阻隔层能够有效隔离内胶层和油品,防止相互污染和渗透。经油品污染测试和防渗透性能测试,证明胶管性能良好,对提升油品质量和防止资源浪费有重要意义。 相似文献
319.
320.
本文分析研究了峨山高精度地温观测值1998-2006年的正常、异常变化特征,玉溪及邻区破坏性地震前异常情况.结果表明:峨山高精度地温观测值的变化对观测点100 km范围内的M>5.0级地震异常十分显著,多数地震在异常过程中或结束后发震,对于短期预测具有重要的科学意义. 相似文献