Non-point source mercury emission from the Idrija Hg-mine region: GIS mercury emission model

A mercury emission model was developed to estimate non-point source mercury (Hg) emissions occurring over the year from the Idrijca River catchment, draining the area of the world's second largest Hg mine in Idrija, Slovenia. Site-specific empirical correlations between the measured Hg emission fluxes and the parameters controlling the emission (comprising substrate Hg content, soil temperature, solar radiation and soil moisture) were incorporated into the mercury emission model developed using Geographic Information System technology. In this way, the spatial distribution and significance of the most polluted sites that need to be properly managed was assessed. The modelling results revealed that annually approximately 51 kg of mercury are emitted from contaminated surfaces in the catchment (640 km(2)), highlighting that emission from contaminated surfaces contributes significantly to the elevated Hg concentrations in the ambient air of the region. Very variable meteorological conditions in the modelling domain throughout the year resulted in the high seasonal and spatial variations of mercury emission fluxes observed. Moreover, it was found that mercury emission fluxes from surfaces in the Idrija region are 3-4 fold higher than the values commonly used in models representing emissions from global mercuriferous belts. Sensitivity and model uncertainty analysis indicated the importance of knowing not only the amount but also the type of mercury species and their binding in soils in future model development.     

PVC塑料型材老化试验与思考

本文针对PVC塑料型材老化现象,从引起PVC塑料型材老化的基本观点、人工老化试验、不同地区气候老化影响、老化导致变色的影响因素等方面进行了讨论,提出了解决PVC塑料型材老化现象意见.     

环保型吸水膨胀聚合物凝胶的合成与评价

吸水性聚合物用于三次采油的机理是依靠这种聚合物在高含水层孔道表面产生的吸附机理与在孔道中形成的动力捕集和物理堵塞作用,在水的浸泡下,吸水性聚合物形成凝胶膨胀体,对大孔道实行封堵,起到调整吸水剖面,提高驱油效率的目的。以丙烯酸(AA)、丙烯酰胺(AM)为原料合成高吸水性聚合物凝胶,研究合成条件对聚合物凝胶吸水性能的影响,确定最佳合成条件为:当丙烯酸含量达到总量的80%左右,交联剂用量占单体总固含量的0.4%、引发剂用量占单体总固含量的0.4%、pH为5~11。实验结果表明:该聚合物凝胶适用于高含水油田调剖堵水,且可以重复使用,对储层无伤害。     

SOMPROF: A vertically explicit soil organic matter model

Most current soil organic matter (SOM) models represent the soil as a bulk without specification of the vertical distribution of SOM in the soil profile. However, the vertical SOM profile may be of great importance for soil carbon cycling, both on short (hours to years) time scale, due to interactions with the soil temperature and moisture profile, as well as on long (years to centuries) time scale because of depth-specific stabilization mechanisms of organic matter. It is likely that a representation of the SOM profile and surface organic layers in SOM models can improve predictions of the response of land surface fluxes to climate and environmental variability. Although models capable of simulating the vertical SOM profile exist, these were generally not developed for large scale predictive simulations and do not adequately represent surface organic horizons. We present SOMPROF, a vertically explicit SOM model, designed for implementation into large scale ecosystem and land surface models. The model dynamically simulates the vertical SOM profile and organic layer stocks based on mechanistic representations of bioturbation, liquid phase transport of organic matter, and vertical distribution of root litter input. We tested the model based on data from an old growth deciduous forest (Hainich) in Germany, and performed a sensitivity analysis of the transport parameters, and the effects of the vertical SOM distribution on temporal variation of heterotrophic respiration. Model results compare well with measured organic carbon profiles and stocks. SOMPROF is able to simulate a wide range of SOM profiles, using parameter values that are realistic compared to those found in previous studies. Results of the sensitivity analysis show that the vertical SOM distribution strongly affects temporal variation of heterotrophic respiration due to interactions with the soil temperature and moisture profile.     

炼油厂废水处理站挥发性羰基化合物成分谱研究

选取广东某大型炼油厂废水处理站进行现场采样,采用PFPH衍生化-GC/MS联用技术分析挥发性羰基化合物(oVOCs)的组成特征和含量水平,研究了其源排放特征、化学反应活性.结果表明,在该废水处理站大气中共检测出20种挥发性羰基化合物,各化合物的浓度范围为0～68.80μg.m-3,各废水处理单元oVOCs总浓度均值为(253.02±124.5)μg.m-3.背景校正后的质量浓度表明,各废水处理单元的大气中14种挥发性羰基化合物均占到总含量的90%以上,其中己醛含量最高,浓度均值达到(44.74±20.89)μg.m-3,其次是2-丁酮和乙醛,浓度均值分别达到(30.47±12.94)μg.m-3、(23.51±14.57)μg.m-3.通过计算化学活性和大气寿命筛选出分子标志物,并建立了废水处理站的oVOCs源成分谱.     

Advances in emission control of diesel vehicles in China

Diesel vehicles have caused serious environmental problems in China. Hence, the Chinese government has launched serious actions against air pollution and imposed more stringent regulations on diesel vehicle emissions in the latest China VI standard. To fulfill this stringent legislation, two major technical routes, including the exhaust gas recirculation (EGR) and high-efficiency selective catalytic reduction (SCR) routes, have been developed for diesel engines. Moreover, complicated aftertreatment technologies have also been developed, including use of a diesel oxidation catalyst (DOC) for controlling carbon monoxide (CO) and hydrocarbon (HC) emissions, diesel particulate filter (DPF) for particle mass (PM) emission control, SCR for the control of NOx emission, and an ammonia slip catalyst (ASC) for the control of unreacted NH₃. Due to the stringent requirements of the China VI standard, the aftertreatment system needs to be more deeply integrated with the engine system. In the future, aftertreatment technologies will need further upgrades to fulfill the requirements of the near-zero emission target for diesel vehicles.     

Recent advances and perspectives towards emission inventories of mobile sources: Compilation approaches, data acquisition methods, and case studies

In recent years, great efforts have been devoted to reducing emissions from mobile sources with the dramatic growth of motor vehicle and nonroad mobile source populations. Compilation of a mobile source emission inventory is conducive to the analysis of pollution emission characteristics and the formulation of emission reduction policies. This study summarizes the latest compilation approaches and data acquisition methods for mobile source emission inventories. For motor vehicles, a high-resolution emission inventory can be developed based on a bottom-up approach with a refined traffic flow model and real-world speed-coupled emission factors. The top-down approach has advantages when dealing with macroscale vehicle emission estimation without substantial traffic flow infrastructure. For nonroad mobile sources, nonroad machinery, inland river ships, locomotives, and civil aviation aircraft, a top-down approach based on fuel consumption or power is adopted. For ocean-going ships, a bottom-up approach based on automatic identification system (AIS) data is adopted. Three typical cases are studied, including emission reduction potential, a cost-benefit model, and marine shipping emission control. Outlooks and suggestions are given on future research directions for emission inventories for mobile sources: building localized emission models and factor databases, improving the dynamic updating capability of emission inventories, establishing a database of emission factors of unconventional pollutants and greenhouse gas from mobile sources, and establishing an urban high temporal-spatial resolution volatile organic compound (VOC) evaporation emission inventory.     

Insight into the critical factors determining the particle number concentrations during summer at a megacity in China

To identify the critical factors impacting the number concentration of particles with the aerodynamic diameters less than 2.5 μm(PNC_(2.5)), the continuous measurement of PNC_(2.5),chemical components in PM_(2.5), gaseous pollutants and meteorological conditions were conducted at an urban site in Tianjin in June 2015. Results indicated that the average PNC_(2.5) was 2839 ± 2430 d N/dlog Dp 1/cm~3 during the campaign. Compared to other meteorological parameters, the relative humidity(RH) had the strongest relationship with PNC_(2.5), with a Pearson's correlation coefficient of 0.53, and RH larger than 30% influenced strongly PNC_(2.5).The important influence of secondary reactions on PNC_(2.5) was inferred due to higher correlation coefficients between PNC_(2.5) and SO_4~(2-), NO_3~-, NH_4~+(r = 0.78–0.89; p 0.01) and between PNC_(2.5) and ratios that represent the conversion of nitrogen and sulfur oxides to particulate matter(r = 0.42–0.49; p 0.01). Under specific RH conditions, there were even stronger correlations between PNC_(2.5) and NO_3~-, SO_4~(2-), NH_4~+, while those between PNC_(2.5) and EC, OC were relatively weak, especially when RH exceeded 50%. Principal component analysis(PCA) and Pearson's correlation analysis indicated that secondary sources, vehicle emission and coal combustion might be major contributors to PNC_(2.5). Backward trajectory and potential source contribution function(PSCF) analysis suggested that the transport of air masses originated from these regions around Tianjin(Liaoning, Hebei, Shandong and Jiangsu) influenced critically PNC_(2.5). The north of Jiangsu, the west of Shandong, and the east of Hebei were distinguished as major potential source-areas of PNC_(2.5) by PSCF model.     

Emission factors of particulate matter, CO and CO2 in the pyrolytic processing of typical electronic wastes

A self-designed experimental device was employed to simulate the pyrolytic dismantling process of selected electronic wastes(E-wastes), including printed wiring boards(PWBs)and plastic casings. The generated particulate matter(PM) of different particle sizes, carbon monoxide(CO) and carbon dioxide(CO_2) were determined, and the corresponding emission factors(EFs) were estimated. Finer particles with particle sizes of 0.4–2.1 μm accounted for78.9% and 89.3% of PM emitted by the pyrolytic processing of PWBs and plastic casings,respectively, and the corresponding EFs were 9.68 ± 4.81 and 18.49 ± 7.2 g/kg, respectively.The EFs of CO and CO_2 from PWBs and plastic casings were 55.9 ± 26.9 and 1182 ± 439 g/kg,and 133.6 ± 34.6 and 2827 ± 276 g/kg, respectively. Compared with other emission sources,such as coal, biomass, and traffic exhaust, the EFs of E-wastes were relatively higher,especially for PM. There were significant positive correlations(p 0.05) of the initial contents of carbon and nitrogen in PWBs with the related EFs of PM, CO, and CO_2, while the correlations for plastic casings were insignificant. The EFs of CO of PWBs were significantly positively correlated with the corresponding EFs of PM and the parent polycyclic aromatic hydrocarbons(PAHs); however, the same result was not observed for plastic casings.     

Review on fate of chlorine during thermal processing of solid wastes

Chlorine(Cl) is extensively present in solid wastes, causing significant problems during the thermal conversion of waste to energy or fuels, by combustion, gasification or pyrolysis.This paper introduces the analytical methods for determining the Cl content in solid materials and presents the concentrations of Cl in various types of wastes, as reported in literature. Then, it provides a comprehensive analysis on the Cl emission behavior and Cl species formed during the thermal processing of the inorganic and organic Cl sources. The challenges resulted from the reactions between the formed Cl species and the ferrous metals, the heavy metals and the organic matters are summarized and discussed, e.g., high temperature corrosion, heavy metal evaporation and dioxin formation. The quality degradation of products(oil, char and syngas) by Cl is analyzed. Finally, the available controlling methods of Cl emission, including pre-treatment(water washing, sorting,microwave irradiation and stepwise pyrolysis) and in-furnace(absorbents, co-treatment and catalysts) methods are assessed.