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961.
建立生命线工程的灾害保险制度 总被引:4,自引:2,他引:2
论述了实行生命线工程自然灾害保险制度的必要性,并在总结国内外工程项目灾害保险现状的基础上,提出了建立我国生命线工程自然灾害保险制度的几个关键问题。 相似文献
962.
Occupational and indoor air exposure to persistent organic pollutants: a review of passive sampling techniques and needs 总被引:1,自引:0,他引:1
Exposure to persistent organic pollutants (POPs) and related compounds such as PCBs, brominated flame retardants, organochlorine pesticides and PAHs is regarded as an important environmental risk factor for humans. Recently concerns about POPs resulted in the international protocol called the Stockholm Convention on POPs. Air quality standards (indoor, outdoor and occupational) for PAHs and other POPs will also be applied in the EU in the future. This will bring requirements for monitoring, to check for compliance and to reduce human exposures to POPs. This can occur from point sources and in various microenvironments, indoors, outdoors and in workplaces. Monitoring can be undertaken either by an active (pumped) method or using a passive (diffusive) air sampling (PAS) device. To date, PAS for POPs have mainly been used as integrating (long-term) samplers for ambient (outdoor) air. However, there are several reasons to develop PAS for monitoring of POPs in occupational and indoor environments. We discuss the potential advantages, limitations and developments needed, so that PAS can be used reliably and routinely indoors and in occupational settings for POPs. 相似文献
963.
Little is known about how the growth of trihalomethanes (THMs) in drinking water is affected in copper pipe. The formation of THMs and chlorine consumption in copper pipe under stagnant flow conditions were investigated. Experiments for the same water held in glass bottles were performed for comparison. Results showed that although THMs levels firstly increased in the presence of chlorine in copper pipe, faster decay of chlorine as compared to the glass bottle affected the rate of THMs formation. The analysis of water phase was supplemented by surface analysis of corrosion scales using X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDX). The results showed the scales on the pipe surface mainly consisted of Cu2O, CuO and Cu(OH)2 or CuCO3. Designed experiments confirmed that the fast depletion of chlorine in copper pipe was mainly due to effect of Cu2O, CuO in corrosion scales on copper pipe. Although copper(II) and copper oxides showed effect on THMs formation, the rapid consumption of chlorine due to copper oxide made THM levels lower than that in glass bottles after 4 h. The transformations of CF, DCBM and CDBM to BF were accelerated in the presence of copper(II), cupric oxide and cuprous oxide. The effect of pH on THMs formation was influenced by effect of pH on corrosion of copper pipe. When pH was below 7, THMs levels in copper pipe was higher as compared to glass bottle, but lower when pH was above 7. 相似文献
964.
Although linear binding isotherms of hydrophobic organic chemicals (HOCs) with dissolved organic matter (DOM) are widely reported, several studies showed nonlinear HOC-DOM interactions. This study pointed out that fluorescence static quenching modeling (FSQM), which often uses a Stern-Volmer type plot to process the data from fluorescence quenching experiments, is conceptually different from the classic Stern-Volmer equation. We also emphasized that although linear Stern-Volmer plots are generally observed in literature, it does not necessarily indicate a linear HOC-DOM interaction. According to both mathematical simulation and laboratory sorption experiments in this study, nonlinear interactions could be concealed by the use of Stern-Volmer plot. Moreover, this study tested the two assumptions for applying FSQM to process binding data. Our results showed that binding coefficient (K(DOC)) for phenanthrene is neither independent of free solute concentration, nor DOM concentration, which is a critical limitation for using FSQM in a form of Stern-Volmer equation to examine HOC-DOM interactions. Therefore, the true characteristics of HOC-DOM interactions need to be examined using different ways of experimental design and data processing. 相似文献
965.
966.
超声强化混凝去除蓝藻实验研究 总被引:13,自引:2,他引:11
研究了超声波对藻类的混凝去除强化,证明超声波可以快速、高效地提高藻类混凝去除效率,减少混凝剂用量.在混凝剂投加量为0.8 mg/L时,5 s超声处理,藻类去除效果比对照样好30%.同样,藻类去除率都为92%时,5 s超声预处理可以将混凝剂投加量降低至1/3.超声预处理时间对强化混凝效果有很大的影响,在实验条件下,1~5 s的超声处理均可产生满意的结果,1 s为最优、最经济时间,而预处理超过30 s反而降低混凝效果.低频下不同处理频率对超声强化混凝效果影响不大,在80 kHz的频率下,最佳功率为50 W.最佳pH值在8~9范围内. 相似文献
967.
968.
在不同的入水pH值条件下,考察了铜离子存在时的均相情况和铜氧化物存在时的非均相情况下,水中余氯的分解和消毒副产物的生成规律.结果表明,与不含铜的情况相比,铜的存在,无论是均相还是非均相,对余氯的分解均有促进作用.不同的pH值条件下,铜均相和非均相对挥发性氯化消毒副产物三卤甲烷(THMs)的生成和非挥发性氯化消毒副产物二氯乙酸(DCAA)和三氯乙酸(TCAA)生成的影响不同,这主要是由于pH值影响了水中可溶性铜离子的浓度造成的.随着pH值的升高,在铜均相和非均相催化下,水中可溶性铜离子的浓度均降低.可溶性铜离子的浓度会影响水中消毒副产物的生成.对于挥发性氯化消毒副产物THMs来说,当铜离子浓度小于2.5 mg·L-1时,随着铜离子浓度增加,对THMs生成的促进作用加强;当铜离子浓度大于2.5 mg·L-1后,对THMs生成的促进作用减弱;对于非挥发性氯化消毒副产物DCAA和TCAA,随着铜离子浓度增加,DCAA的生成量逐渐增加,TCAA的生成量逐渐减少. 相似文献
969.
Juan WU Jian ZHANG Wenlin JIA Huijun XIE Bo ZHANG 《Frontiers of Environmental Science & Engineering in China》2009,3(2):241-247
The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N2O) emissions, together with the relationships between N2O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems.
N2O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and
the total N2O emission in the system with middle COD influent concentration was the least. The relationships between N2O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear
regression analysis to predict N2O flux. The multiple linear regression model against principal components indicated that different water parameters affected
N2O flux with different COD concentrations in the influent, but nitrate nitrogen affected N2O flux in all systems. 相似文献
970.
循环经济是以科学发展观为统领,以先进的科学技术为基础,以低消耗、低排放、高效率为特征的集约化、内涵式经济增长模式。为了促使我国走上循环经济发展之路,就必须建立循环经济科技支撑体系,即以政府为主导、企业为主体、社会化服务机构健全的循环经济科技创新体系和完善的循环经济科技政策体系、法律法规体系以及绿色文化与教育体系。 相似文献