E-waste recycling induced polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzo-furans pollution in the ambient environment

Polybrominated diphenyl ethers (PBDEs) have been determined in 30 samples, including soil, biota and plant collected from an electronic waste recycling site and its vicinage towns. Polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) were also simultaneously analyzed in 20 samples. PBDEs were detected in all soil samples and the highest was up to 789 ng/g dry weight (dw). The toxic equivalency (TEQ) of PCBs and PCDD/Fs detected in E-waste recycling site is significant higher than those in the vicinage samples. Biota and plant were also contaminated with high level of PBDEs, PCBs and PCDD/Fs in this area. High levels of the three kinds of organic compounds in the environmental samples showed that the E-waste recycling have induced serious environmental problems.     

受损生态系统类型及影响其退化的关键因素

受损生态系统的退化是当前面临的一个全球性问题,对受损生态系统类型的确认有助于了解其退化机制,进而采取适当的修复和恢复措施。根据受损生态系统的表现可将其划分为3种类型,即结构受损类型、景观受损类型以及混合类型。在结构受损的生态系统类型中,重要物种(如关键种、建群种)的丧失以及种间关系的解构可能在退化过程中起重要作用,因此,关键种、建群种的恢复和保护对于生态恢复是十分关键的。边缘效应、岛屿效应、小种群效应(如Allee效应、近交、遗传漂变)等的强化则可能是导致景观受损类型的生态系统退化的主要因素,因此,针对这种受损生态系统,增加生态系统面积、 降低空间隔离程度、建立片断生态系统间的连接是需要关注的主要问题。     

云南省区域人才竞争力研究

随着知识经济社会的进入,人才成为了社会经济发展最为重要的推动因素,不同区域的发展状态越来越决定于其人才的总体实力,即人才竞争力。本文从区域比较的角度出发,构建人才竞争力评价体系和模型,运用主成分分析方法对云南人才竞争力的特征以及在全国的位次进行分析。研究表明,2007年云南省人才竞争力综合得分为-4.4558,在全国31个省区中排名第23位,导致竞争力较弱的主要原因是区域科技活动水平和经济发展水平低。     

热解含油污泥制备吸附材料浅析

介绍了含油污泥热解技术及热解实验方法,提出热解产生的残渣进行适当处理可成为具有吸附性的材料。进行了含油污泥热解正交实验,得出影响最大的因素分别是热解温度、热解时间、升温速率,并得出最佳的热解温度、热解时间、升温速率等。分析了含油污泥热解的机理,探讨了热解含油污泥制备吸附材料的活化改性,并在此基础上对所制备吸附材料的脱硫性和除油性进行了研究。     

A study on oxidative degradation of polyacrylamide in wastewater with UV/FENTON/C4H4O62−

The degradation of polyacrylamide (PAM) in simulate wastewater was studied in UV/Fenton/C₄H₄O₆^2? system. The factors such as molecular ratio of H₂O₂/Fe²⁺/C₄H₄O₆^2?, pH, and the dosage of Fenton reagent that could affect the PAM degradation in the UV/Fenton/C₄H₄O₆^2? system were investigated. The experimental results showed that adding C₄H₄O₆^2? to UV/Fenton system could form photosensitive ferrous complexes, which led to higher degradation efficiency of PAM. The degradation rate of PAM could be up to 95.2% under the following conditions: the concentration of H₂O₂, Fe²⁺, and C₄H₄O₆^2? were 22.5, 2.25, and 2.25 mmol/L, respectively (i.e., molecular ratio of H₂O₂/Fe²⁺/C₄H₄O₆^2? was 10:1:1), the pH value was 3.0.     

The determination and matching analysis of pinch point temperature difference in evaporator and condenser of organic rankine cycle for mixed working fluid

Exergo-economic analysis of the pinch point temperature difference (PPTD) in both evaporator and condenser of sub-critical organic Rankine cycle system (ORCs) are performed based on the first and second laws of thermodynamics. Taking mixture R13I1/R601a as a working fluid and the annual total cost per net output power Z as exergo-economic performance evaluation criterion, the effects of PPTD in evaporator ΔT_e, and the PPTD ratio of condenser to evaporator y, on the exergo-economic performance of ORCs are analyzed. Moreover, how some other parameters influence the optimal PPTD in evaporator ΔT_e,opt and the optimal PPTD ratio of condenser to evaporator y_opt are also discussed. It has been found that the exergo-economic performance of ORCs is remarkably influenced by ΔT_e and y, and there exists ΔT_e,opt and y_opt. In addition, ΔT_e,opt and y_opt are affected by heat transfer coefficient ratio of condenser to evaporator ß, the temperature of working fluid at dew point in condenser T_1a, and composition of R13I1/R601a: larger ß and T_1a lead to lower ΔT_e,opt and y_opt; by contraries, larger mass fraction of R13I1 makes ΔT_e,opt and y_opt increase, and y_opt increases linearly. The effects of the temperature of working fluid at bubble point in evaporator T_3a, mass flow rate of exhaust flue gas m_g, and inlet temperature of exhaust flue gas T_gi on ΔT_e,opt and y_opt are very slight. For comparison, three additional working fluids, namely R601a, R245fa, and 0.32R245fa/0.68R601a, are also taken into account.     

Structure optimization and annual performance analysis of the lens-walled compound parabolic concentrator

The primary lens-walled compound parabolic concentrator (lens-walled CPC) has a significant advantage of a larger half acceptance angle as a static solar concentrator, but it also has a drawback of a low optical efficiency. In order to overcome this drawback, in this article, series of structure parameters were investigated and compared to further improve the optical efficiency within the half acceptance angle combined with the material properties. The average optical efficiencies of the improved lens-walled CPCs could achieve more than 82% within the half acceptance angle of 35?. Experiments were adopted to verify the credibility and validity of the simulation. Moreover, annual performance of the lens-walled CPCs comparison with that of the mirror CPC for Nottingham was analyzed. Results show that the improved lens-walled CPC has a higher optical performance for actual building application.     

Rebound effect and its decomposition – an analysis based on energy types in China

Rebound effect derived from energy efficiency improvement has been widely invested. However, most of studies focus on the rebound effect of the energy composite level and neither distinguish nor compare different energy types. We compare the differences in energy saving and energy rebound between primary and secondary energy sources, and further decompose the rebound effect into production rebound part and final demand component. To do so, we add a module for rebound into a comparative state China-CGE model. We design and test two simulation scenarios using the model. In Scenario 1, all production sectors’ energy efficiency of using primary energy increases by 5%. In Scenario 2, all production sectors’ energy efficiency of using secondary energy increases by 5%. The results show that Scenario 2 leads to more GDP growth and more energy saving. Our scenarios show rebound effects range between 9.6% and 27.9%, and in general are higher when energy efficiency of using primary energy sources is improved. Our decomposition analysis shows that improving energy efficiency in production sectors would stimulates energy use of final demand. Indeed, the consumption side has significant contribution to rebound in secondary energy use, especially in crude oil and gas. This study reveals that improving efficiency of using secondary energy is better than improving that of primary energy, both in terms of economic impact and energy rebound. And complementary policies that prevent energy services prices from falling too much can be adopted to reduce rebound. Controlling residential energy use could also be effective in reducing rebound, this has particular implication to economies in which residential energy consumption are far from saturation.     

Food chain transfer of cadmium and lead to cattle in a lead–zinc smelter in Guizhou, China

Cadmium (Cd) and Lead (Pb) are environmental pollutants. Environmental samples and bovine tissues were collected from the areas around a lead–zinc smelter in Guizhou, China for Cd, Pb, zinc (Zn) and copper (Cu) analysis. Cd in soil (10 mg/kg) and feed (6.6 mg/kg) from the polluted areas was 10 times higher than the Chinese Standards, resulting in higher Cd in bovine kidney (38 mg/kg) and liver (2.5 mg/kg). Pb in feed (132 mg/kg) from the polluted area was much higher than unpolluted areas, causing higher Pb levels in bovine tissues. Environmental Zn was elevated, but bovine tissue Zn was normal. Cu in bovine liver decreased with increased Cd and Pb. Metals in drinking water and in bovine muscle were within the Standard range. Thus, in the areas of this lead–zinc smelter, the environment has been contaminated with Cd and Pb, which has been transferred to cattle through the food chain.