铜管模拟输配系统中氯胺衰减过程与模拟

研究了氯胺在铜管模拟输配系统中的衰减过程,并利用一级反应动力学模型对氯胺衰减规律进行了模拟;考察了pH、初始氯胺浓度等水质条件与流速等水力条件对氯胺衰减速率的影响.结果表明,pH值是影响氯胺衰减速率与金属铜溶出的重要因素,pH越低氯胺衰减越快;提高氯胺初始浓度可加快氯胺衰减速度,也可增加金属铜的溶出量;流速对氯胺衰减速率的影响不大.此外,衰减动力学过程模拟结果表明,采用一级反应动力学模型可以较好地拟合不同条件下的氯胺衰减规律.从而对于工程中不同条件下消毒剂浓度预测具有重要意义.     

O3氧化结合化学吸收同时脱硫脱硝的动力学及热力学研究

构建了O3氧化多种污染物的反应机制,并对O3氧化SOx、NOx过程进行动力学模拟,然后利用热力学原理计算出Ca(OH)2和CaCO3湿法烟气同时脱硫脱硝吸收反应达到平衡时SOx和NOx的分压力.结果表明,Ca(OH)2作吸收剂湿法烟气同时脱硫脱硝比CaCO3作吸收剂效果好,而且两者几乎100％地去除烟气中的SOx和NO...     

试论中国城市公共安全规划与应急管理体系建设

1国内外公共安全形势与城市公共安全的新挑战 　　进入21世纪,国际公共安全形势日趋严峻,城市面临的灾害形势从传统的自然灾害、火灾、瘟疫等为主扩大到传统灾害和生命线系统故障、信息安全、恐怖事件等非传统灾害共同影响的情况,呈现出以下特点:重大自然灾害的发生频率、量级加大,经济损失更严重;随着工业化、现代化和城市化的发展,事故灾难以及复合型事件的影响日益突出;生物和公共卫生危机严重威胁和影响公众健康;恐怖主义威胁呈现出新型化、大规模化和强灾难性的特点;经济危机连锁反应,各种社会危机交相激荡.……     

Risk assessment on disinfection by-products of drinking water of different water sources and disinfection processes

The occurrences of trihalomethanes (THMs) and haloacetics (HAAs) in the water supply in Beijing and Canada were investigated. The concentrations of THMs and HAAs in Beijing and Canada were below the maximum contaminant levels specified by the USEPA and WHO standards. The multi-pathway risk assessment (assessed through oral ingestion, dermal absorption and inhalation exposure to drinking water) was used to assess the cancer risk and the hazard index of THMs and HAAs from fifteen waterworks in Beijing, China and three treatment plants using different disinfection processes in Canada. Residents in Beijing and residents who were served by three treatment plants using different disinfection processes in Canada had a higher risk of cancer through oral ingestion than through the other two pathways. The cancer risk resulted from disinfection by-products (DBPs) was 8.50E-05(for males), 9.25E-05(for females) in Beijing, China, while it was 1.18E-04, 1.44E-04 in Canada. The risk was higher when water treatment plants used surface water source than when they used ground water source and mixture water source in Beijing. The risk showed different changes in three treatment plants using different disinfection processes in Canada. The lifetime cancer risk for THMs followed the order: Plant 2>Plant 1>Plant 3. And, the lifetime cancer risk for HAAs was: Plant 1>Plant 2>Plant 3.     

Blood mercury concentration among residents of a historic mercury mine and possible effects on renal function: a cross-sectional study in southwestern China

This cross-sectional study aimed to investigate blood mercury (B-Hg) concentration of residents living in the vicinity of Chatian mercury mine (CMM) in southwestern China and to assess the possible effects on renal function. It evaluates the effects of gender and age (children, <18 years; adults, 18–60 years; elderly, >60 years) on the B-Hg and serum creatinine (SCR) and serum urea nitrogen (SUN) levels. In the CMM, elevated levels were found for B-Hg, SCR, and SUN with mean values at 6.09 μg/L, 74.21 μmol/L, and 13.26 mmol/L, which were significantly higher than those in the control area, respectively. Moreover, the coefficients between paired results for B-Hg and SCR and SUN levels were positive at statistical significance (B-Hg vs. SCR, r?=?0.45, p?<?0.01; B-Hg vs. SUN, r?=?0.20, p?<?0.05). The aforementioned results revealed that mercury exposure can cause human renal function impairment. B-Hg, SCR, and SUN can also be useful biomarkers to assess the extent of mercury exposure among residents in areas with extensive mining activities. Furthermore, data analysis revealed that there was a tendency for higher B-Hg, SCR, and SUN levels in females than in males, and the levels of B-Hg, SCR, and SUN increased among the older residents. We conclude that females and the elderly in the mining area were more susceptible to mercury exposure, and therefore, they deserve further research.     

河北省典型污灌区农田镉污染特征及环境风险评价

以河北省石家庄市典型历史污灌区农田为研究对象,对污灌区内土壤和小麦、玉米植株内Cd的含量进行分析,评价污灌区农田Cd污染程度、潜在生态风险和潜在健康风险.结果表明,上游污灌区和中下游污灌区土壤表层Cd含量分别为ND～3.88、0.10～2.30 mg·kg~(-1),明显高于清灌区(0.13～0.23 mg·kg~(-1))及河北土壤背景值(0.094 mg·kg~(-1)),超农用地土壤污染风险筛选值(0.3 mg·kg~(-1))点位分别达42.9%和35.2%;小麦和玉米籽粒平均Cd含量均未超标,小麦籽粒富集浓度高于玉米,污灌区小麦和玉米籽粒已出现明显累积现象.潜在生态风险表明上游污灌区和中下游污灌区表层土壤基本处于轻度～中度风险,部分区域生态风险较高～极高.健康风险评价结果表明Cd通过皮肤、呼吸、经口摄入暴露途径对人体健康造成的风险在可接受范围内.研究结果为污灌区农田土壤的安全利用和管理决策依据,并为开展农田土壤修复工程提供科学参考.     

基于非线性能量阱的悬吊摆对输电塔-振动控制的研究

针对输电塔结构在地震作用下动力响应过大的问题,提出一种基于非线性能量阱的悬吊摆以降低输电塔的动力响应。首先利用拉格朗日方程推导了这种悬吊摆的运动方程,再以一单自由度结构为例,建立了摆式非线性能量阱—结构的动力方程,计算了摆式非线性能量阱在正弦激励下的减振效果,并对正弦激励周期、悬吊摆周期、立方刚度、质量比等参数对减振效果的影响进行了分析。最后选取一柔性输电塔为例,研究了不同地震作用下摆式非线性能量阱的减振效果,并与传统的悬吊质量摆和线性弹簧摆进行对比。结果表明,在地震作用下,摆式非线性能量阱对输电塔动力响应的峰值和均值都有较好的减振效果。     

The Relationship Between Exposure to Arsenic Concentrations in Drinking Water and the Development of Skin Lesions in Farmers from Inner Mongolia, China

Associations between the concentration of arsenic naturally occurring in drinking water and the development of skin lesions in people have been documented for some years at various locations around the world. Data on the exposure-response relationship between concentrations of arsenic in drinking water and prevalence of skin lesions in farmers from five locations in Inner Mongolia, China have been collected from the original publications and re-analysed together as a meta-study. The calculated data show a positive linear exposure-response relationship without a threshold. The reasons for this linear correlation are discussed and compared with the data from Xinjiang, another arsenism area located in a different geographical area of China. Here a different relationship was recorded that involved a threshold concentration before skin lesions developed. The significance of these two different exposure-response scenarios is discussed.