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141.
142.
This study analyzes the regional and temporal distributions of PM10 concentrations observed in major metropolitan cities in Korea before, during and after a recent Asian dust episode in 2002. There were spatial and temporal variations in PM10 concentrations among the mid-western, the southwestern, the southeastern, and the southern parts of Korea during this Asian dust period due to the different air mass movement time and the different wind directions and speeds of prevailing winds in each city or region. The origins of the three-day Asian dust episode were identified by an analysis of two-day backward isentropic air trajectories. The different origins for each day also significantly contributed to the spatial and temporal variations in PM10 concentrations. A significant relationship was found between PM10 concentrations on the day preceding the first peak day and the first peak day of the Asian dust period but only in the mid-western areas. The concentrations of PM10 just after the Asian dust episode were much higher than those just before. There was a significant increase in a coarse fraction, having soil origins, of particles during the Asian dust episode. Concentrations of Mn, Fe, Ni and Cr extracted from the total suspended particulate (TSP) samples collected in 7 cities during the Asian dust episode were much higher when compared with other days in 2001. However, the Asian dust did not consistently increase the concentrations of lead, cadmium and copper as they are influenced by local sources such as local traffic or industrial emissions. 相似文献
143.
Leaching of bisphenol A (BPA) to seawater from polycarbonate plastic and its degradation by reactive oxygen species 总被引:4,自引:0,他引:4
In this study, (1) change in the concentration of bisphenol A (BPA) leached from polycarbonate (PC) tube to control water (BPA free), seawater and river water at 20 and 37 degrees C as a function of time, (2) the fate of BPA caused by addition of H(2)O(2) and Fe(3+) to seawater containing BPA leached from PC tube were assessed. BPA leached from PC tube to all water samples increased with the ascendant of temperature and with the passage of time. The BPA leaching velocity in seawater was the fastest in three samples (11 ng/day for seawater, 4.8 ng/day for river water 0.8 ng/day for control water at 37 degrees C).BPA leaching velocity from PC tube was significantly high at pH 8 (50 mM Na(2)HPO(4)) and increased dose-dependently. There was no difference in the velocity of BPA among the 50 mM phosphate-buffers at pH 6.5, 7.0 and 7.5. BPA was leached three times higher by addition of Na(+) than K(+). However, the higher the K(+) concentration, the larger the BPA leached from PC tube. Na(+) mixed with PO(4)(-) was effective on BPA leaching from PC tube, but not with SO(4)(-) or Cl(-). The results suggested that BPA leaching from PC tube would be attributed to the concentration of bibasic phosphate such as Na(2)HPO(4) and K(2)HPO(4) in water samples. BPA was degraded in both control water and seawater in the presence of radical oxygen species, but the degradation rate was lower in seawater than in control water, suggesting that anti-oxidative system exists in seawater. Neo-synthesized substance in both control water and seawater in the presence of reactive oxygen species was identified as BPA-quinone by LC-MS. 相似文献
144.
Oh CJ Lee SO Yang HS Ha TJ Kim MJ 《Journal of the Air & Waste Management Association (1995)》2003,53(7):897-902
This study was carried out to recover valuable metals from the printed circuit boards (PCBs) of waste computers. PCB samples were crushed to smaller than 1 mm by a shredder and initially separated into 30% conducting and 70% nonconducting materials by an electrostatic separator. The conducting materials, which contained the valuable metals, were then used as the feed material for magnetic separation, where it was found that 42% of the conducting materials were magnetic and 58% were nonmagnetic. Leaching of the nonmagnetic component using 2 M H2SO4 and 0.2 M H2O2 at 85 degrees C for 12 hr resulted in greater than 95% extraction of Cu, Fe, Zn, Ni, and Al. Au and Ag were extracted at 40 degrees C with a leaching solution of 0.2 M (NH4)2S2O3, 0.02 M CuSO4, and 0.4 M NH4OH, which resulted in recovery of more than 95% of the Au within 48 hr and 100% of the Ag within 24 hr. The residues were next reacted with a 2 M NaCl solution to leach out Pb, which took place within 2 hr at room temperature. 相似文献
145.
146.
氯代烃污染地下水在外加有机质(电子供体)进行强化还原脱氯时,存在有机质消耗快、pH持续降低等影响脱氯效率的问题。利用乳化油(EVO)与胶体氢氧化镁复配的方法,制备了一种兼具电子供体缓释性和OH-缓释性的双功能缓释剂EVO-Mg(OH)2;成功制备了不同EVO∶Mg(OH)2配比的EVO-Mg(OH)2试剂,并对其稳定性、分散性及粒径分布进行了研究;向模拟砂柱中注入不同体积的EVO-Mg(OH)2,考察试剂的迁移性能以及试剂注入对三氯乙烯(TCE)迁移的影响;开展了EVO-Mg(OH)2强化TCE还原脱氯摇瓶实验,考察了该试剂对脱氯效果的影响。结果表明:不同EVO∶Mg(OH)2配比的试剂稳定性及分散性良好,粒径无明显差异;EVO-Mg(OH)2可以有效地在多孔介质中迁移并实现部分滞留;注入量对EVO-Mg(OH)2的迁移性有一定的影响;EVO-Mg(OH)2可以促进TCE溶解和迁移从而减小EVO-Mg(OH)2和TCE之间的传质阻力;EVO-Mg(OH)2能够实现电子供体及OH-的双重缓释,有效促进脱氯微生物的生长,提高TCE的降解速率(k=0.128 d-1),同时抑制pH的降低(pH=7.5)。 相似文献
147.
钢铁企业总排口废水回用新工艺应用 总被引:2,自引:0,他引:2
就当前国内几个典型的钢铁企业总排口废水水质特性作了分析,探索钢铁企业废水回收利用的工艺路线,提出在吸收国外新技术的基础上研究开发出符合国情的新工艺技术. 相似文献
148.
论我国非煤矿山安全生产标准体系构建思路 总被引:2,自引:3,他引:2
本文分析了我国目前非煤矿山安全生产标准体系建设的现状及存在的主要问题,阐述了建立一套科学、合理、完善的标准化体系对我国非煤矿山安全生产行业的重要意义;并根据非煤矿山安全生产标准体系建设的现状提出了我国非煤矿山安全生产标准体系建设的思路和基本框架,为今后非煤矿山安全生产标准体系建设提供一定基础。 相似文献
149.
探讨了在不同矿物投加量、不同振荡时间、不同Pb2 浓度、不同矿物颗粒细度和不同pH条件下,钠基膨润土、膨胀蛭石和沸石3种粘土矿物对Pb2 的吸附效果.结果表明:对于具有可膨胀层间的粘土矿物而言,其对溶液中Pb2 的吸附量不仅仅由单一的阳离子交换量所决定;Pb2 在矿物表面的吸附过程是个迅速的过程,矿物对Pb2 的吸附在10 min内即可完成;粘土矿物不同颗粒细度对Pb2 的去除率有所不同,但考虑到实际应用中的成本问题,并非颗粒越细越好;就试验所采用的3种粘土矿物而言,其对Pb2 的吸附效果是,钠基膨润土和沸石明显优于膨胀蛭石;较高的pH有助于粘土矿物对溶液中Pb2 的吸附,但考虑到实际操作的其他因素,不能把pH调得过高. 相似文献
150.
高COD焦化废水的吸附研究 总被引:1,自引:0,他引:1
研究了粉末活性炭对焦化废水COD的去除效率.结果表明,在pH值为6左右时,向50 mL焦化废水中投加1 g粉末活性炭,吸附1 h,COD去除率可达98.5%. 相似文献