Speciated mercury in size-fractionated particles in Shanghai ambient air

Size-fractionated particles were collected at two sites from July 2004 to April 2006 in Shanghai. The mercury in particles was extracted and divided operationally into four species: exchangeable particulate mercury (EXPM), HCl-soluble particulate mercury (HPM), elemental particulate mercury (EPM) and residual particulate mercury. The total particulate Hg concentration during the study period ranged from 0.07 ng m^?3 to 1.45 ng m^?3 with the average 0.56 ± 0.22 ng m^?3 at site 1, while 0.20 ng m^?3–0.47 ng m^?3 with the average 0.33 ± 0.09 ng m^?3 at site 2, which is far higher than some foreign cities and comparable to some cities with heavy air pollution in China. The Hg mass content also displayed evident size distribution, with higher value in PM_1.6–3.7, somewhat higher or lower than the source profile. EXAM was only found in the summer, HPM have higher percentage in summer and fall rather than in winter and spring. The different mercury species showed different correlation to temperature, relative humidity, wind speed. HPM positively depends on temperature at both sites which implies the importance of mercury transformation on particles. In foggy days TPM increased greatly, but HPM didn't vary greatly as anticipated. Instead, RPM gained a distinguished increase. It demonstrated that aqueous reaction and complex heterogenic reactions in droplet might happen in acidic environment. The correlation of mercury with other pollutants including SO₂, NO₂, CO and PM₁₀ varies with the different mercury forms. Hybrid single-particle lagrangian integrated trajectories (HYSPLIT) model was used to back trace air mass at different representative days and results indicated that transportation from Huabei Plain will increase mercury concentration in winter and fall to some extent. The possible existing compounds and their atmospheric behavior of HPM, EPM and RPM were calculated and the compared to analyze its implication on atmospheric mercury cycle.     

零价铁活化过硫酸钠深度处理电镀添加剂生产废水

采用零价铁(ZVI)活化过硫酸钠(PS)产生·SO_4~-,以·SO_4~-为氧化剂深度处理电镀添加剂生产废水。考察了废水p H、n(ZVI)∶n(PS)、c(S_2O_8~(2-))和反应温度对废水COD去除率的影响。实验得出废水处理的最佳工艺条件:废水p H为5.0,n(ZVI)∶n(PS)=1.00,c(S_2O_8~(2-))=15 mmol/L,反应温度为50℃。在此最佳工艺条件下反应60 min,COD去除率达到76.8%,出水COD约为42 mg/L,满足GB 18918—2002《城镇污水处理厂污染物排放标准》的一级标准要求。     

Selenium speciation in flue desulfurization residues

Flue gas from coal combustion contains significant amounts of volatile selenium (Se). The capture of Se in the flue gas desulfurization (FGD) scrubber unit has resulted in a generation of metal-laden residues. It is important to determine Se speciation to understand the environmental impact of its disposal. A simple method has been developed for selective inorganic Se(IV), Se(VI) and organic Se determination in the liquid-phase FGD residues by hydride generation atomic fluorescence spectrometry (AFS). It has been determined that Se(IV), Se(VI) and organic Se can be accurately determined with detection limits (DL) of 0.05, 0.06 and 0.06 g/L, respectively. The accuracy of the proposed method was evaluated by analyzing the certified reference material, NIST CRM 1632c, and also by analyzing spiked tap-water samples. Analysis indicates that the concentration of Se is high in FGD liquid residues and primarily exists in a reduced state as selenite (Se(IV)). The toxicity of Se(IV) is the strongest of all Se species. Flue gas desulfurization residues pose a serious environmental risk.     

十三陵抽水蓄能电站地下水污染与水质恢复的研究

十三陵抽水蓄能电站施工期间排放废水,造成了对周围地下水的污染。本工作沿地下水流动方向４．４ｋｍ＾２的范围内,进行了地下水的环境质量调查,分析和评价,查明了地下水污染因子和污染程度及范围,通过消除污染源,建设污水处理站等一系列水质恢复措施后,该地区地下水水质明显好转。     

关于温室气体限排目标的确定（巴西提案）

巴西提案是巴西代表团在联合团气候变化谈判中，提出的一套系统的全新的对中国家有利的理论体系，文章在对巴西提案中的有效排放量、简单气候模式、斐和限额分配方法、消沽发展基金等，进行深入睥评价的基础上，提出应将有效排放量与人均排放量与有机结合， 交圾效人均排放量曙室气体限排目标的指标。     

北京环境辐射水平现状与分布

在北京市按网格布点调研了环境辐射水平。北京原野γ辐射及宇宙射线室外剂量率按网点加权均值分别为５６．２及３２．３ｎＧｙ·ｈ＾－１,全市土壤中＾２３８Ｕ,＾２３２Ｔｈ,＾２２６Ｒａ,＾４０Ｋ及＾１３７Ｃｓ含量按面积加权均值分别为１９．４,３４．１,２１．４,６２２及８．３Ｂｑ·ｋｇ＾－１,各类水体水中Ｕ,Ｔｈ及＾２６Ｒａ,＾４０Ｋ浓度范围分别是０．１２－８．９４,０．０２－０．６６μｇ·Ｌ＾－１及６．     

基于复杂网络的地铁运营风险传导规律研究

地铁是特大城市有效解决通勤交通、实现交通低碳化的首选交通运输设施系统,极大地缓解了城市交通运行压力。但是伴随着地铁运营的网络化建设和规模的日趋庞大,导致安全事故频发,地铁运营风险传导也呈现出网络化特征。基于复杂网络理论,对地铁运营风险传导网络的基本规律进行了研究。结果表明:地铁运营风险传导网络中存在一些度很大的节点,而这些度很大的节点又与其临近的节点之间有很强的聚集程度,容易导致风险传导的发生,进而导致严重的后果。该研究可为地铁运营管理部门制定风险防范措施提供依据。     

Trends and development of steel demand in China: A bottom–up analysis

With economic development, the Chinese steel industry has rapidly expanded over the past three decades. However, this expansion has resulted in many problems, such as increasing energy consumption and excessive environmental pollution. Therefore, it is important to analyze the future steel demand in China. This study presents changes in steel production and apparent steel consumption in the years 1998–2010. Steel is mainly consumed by construction, machinery, automobiles, shipbuilding, railways, petroleum, household appliances and containers, and these nine industries are analyzed separately using stock based models. The study suggests steel demand in China will rise from 600 million t in 2010 to a peak of 753 million t in 2025, and then gradually decrease to 510 million t in 2050. The construction industry is the largest steel consumer, although its share of total steel demand will decrease in the future. Steel demand in automobile manufacturing, by contrast, will increase rapidly before 2035, and its share will increase from 6.0% in 2010 to 19.0% in 2050. Sensitivity analysis on the four major impact factors such as saturation levels, lifetime distributions, GDP and urbanization rate shows that saturation levels of different products greatly affect long-term and short-term steel demands, while GDP and lifetime distributions, especially the lifetime distribution of buildings, mainly affect the short-term and long-term steel demands, respectively.     

Electrochemical disinfection using the gas diffusion electrode system

A study on the electrochemical disinfection with H_2O_2 generated at the gas diffusion electrode (GDE) from active carbon/poly-tetrafluorcethylene was performed in a non-membrane cell. The effects of Pt load and the pore-forming agent content in GDE, and operating conditions were investigated. The experimental results showed that nearly all bacterial cultures inoculated in the secondary effluent from wastewater treatment plant could be inactivated within 30 min at a current density of 10 mA/cm~2. The disinfection improved with increasing Pt load. Addition of the pore-forming agent NH_4HCO_3 improved the disinfection, while a drop in the pH value resulted in a rapid rise of germicidal efficacy and the disinfection time was shortened with increasing oxygen flow rate. Adsorption was proved to be ineffective in destroying bacteria, while germicidal efficacy increased with current density. The acceleration rate was different, it initially increased with current density. Then decreased, and finally reached a maximum at a current density of 6.7 mA/cm~2. The disinfection also improved with decreasing total bacterial count. The germicidal efficacy in the cathode compartment was approximately the same as in the anode compartment, indicating that the contribution of direct oxidation and the indirect treatment of bacterial cultures by hydroxyl radical was similar to the oxidative indirect effect of the generated H_2O_2.