Physicochemical and nutritional features of Gleditsia japonica shell biochar under different pyrolysis conditions

Journal of Material Cycles and Waste Management - This study aimed to investigate the effects of pyrolysis temperature (200–700 °C) and duration (2 h, 4 h) on...     

矿化垃圾生物反应床处理含酚废水工艺研究

研究了矿化垃圾生物反应床处理含酚废水的工艺参数.矿化垃圾生物反应床在经过驯化后,形成了稳定的微生物系统,反应床对有机酚具有较高的去除率.有机酚的去除率受湿干比影响较大,随着配水速率的提高,反应床对有机酚的去除率逐渐下降,配水速率大于0.342 cm/min时,去除率急速下降.在进水有机酚质量浓度为20 mg/L,连续配水时间6 h,湿干比为1∶8,配水速率为0.254 cm/min的条件下,反应床出水可达到或接近国家三级排放标准.     

HMX粒度、粒度级配对混合传爆药性能影响的研究

通过喷射方法把主体炸药 HMX重结晶后 ,将其制成粗细不同的几种粒度药粉 ,并按粗细不同比例进行级配 ,随后采用 SSGT和爆速测试 ,研究了不同粒度及粒度级配对其混合传爆药冲击波感度和爆速的影响规律 ,并对其结果进行了理论分析。由于实验条件的限制 ,还不能达到按要求控制条件以细化出要求的各种粒径 ,所以实验所选的几种级配粒度是随机的 ,因而具有代表性。     

微乳法制备W/O型Fe3O4磁流体及其清除水面浮油模拟研究

应用复合乳化剂和助表面活性剂制备出稳定的油包水(W／O)型微乳液,利用拟三元相图和体系电导随组成的变化,探明了一定条件下形成W／O型微乳液的最佳体系,进而利用W／O型微乳液作为“微反应器”合成Fe2O4磁流体,应用TEM对制备的磁流体进行了表征．初步模拟了用磁流体清除水面浮油的实验,获得令人满意的结果。     

我国人居环境现状和改善对策

本文分析了我国人类环境现状及面临的主要问题,提出了改善人居环境的对策,研究制定法规政策和发展规划、计划,并切实实施,把住宅建设和城市基础设施建设放在重要位置,加强科技工作和国际合作工作。     

TOF–SIMS surface analysis of chemical components of size–fractioned urban aerosols in a typical heavy air pollution event in Beijing

Size–fractioned atmospheric aerosol particles were collected during a typical heavy air pollution event in Beijing. The organic and inorganic components on the surfaces of the samples were analyzed using time–of–flight secondary ion mass spectrometry(TOF–SIMS).The variation characteristics of the surface chemical composition and influencing factors were studied, and the possible sources of these chemical compositions were identified through principal component analysis. The results showed that inorganic components such as crustal elements and sulfate, and organic components such as aliphatic hydrocarbons and oxygen–containing organic groups were present. Some surface components, such as polycyclic aromatic hydrocarbons, heavy metals and fluorides may exert adverse effects on human health. The species and relative percentages of the chemical components varied with particle size, diurnal and pollution progress. During a heavy pollution event, the species and relative percentages of secondary components such as oxygen–containing organic groups and sulfurous compounds increased, indicating that particles aged during this event. The surface chemical composition of the aerosol particles was affected mainly by emissions from coal combustion and motor vehicles. In addition, air pollution, meteorological factors, and air mass transport also exerted a significant effect on the surface chemical composition of aerosol particles.     

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter(PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry(ICP-MS). The results indicated that the average concentration of PM, chromium(Cr), arsenic(As), cadmium(Cd) and lead(Pb) in PM was177.3 ± 33.2 μg/m~3, 37.3 ± 8.8 ng/m~3, 17.3 ± 8.1 ng/m~3, 4.8 ± 3.1 ng/m~3 and 141.6 ± 49.1 ng/m~3,respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1–2.1 μm, followed by 9–10 μm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of1.1–2.1 μm and 9–10 μm ranges while for Cr, only a single-mode at 4.7–5.8 μm was observed. PM(64.7%), As(72.5%), Cd(72.2%) and Pb(75.8%) were associated with the fine mode below 2.1 μm,respectively, while Cr(46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.     

Characterization of precipitation in the background of atmospheric pollutants reduction in Guilin: Temporal variation and source apportionment

Rainfall samples were collected from three observation sites in Guilin from 2013 to 2017, and the chemical composition characteristics of precipitation and the contribution made by different ion sources were analyzed when atmospheric pollutants levels were reduced. The results showed that acid gas emissions and atmospheric pollutant concentrations continued to decline during the study period. However, the change in the volume-weighted mean pH at the three sites suggested that acid rain pollution was not alleviated and began to deteriorate after 2015. The continuing downward trend for alkaline neutralizing ions (Ca²⁺, NH₄⁺) in precipitation indicated that the reduction in alkaline neutralizing substances in the atmosphere was an important factor that led to the deterioration in acid rain across Guilin. The principal component analysis and spearman correlation analysis indicated five sources of ions in precipitation. Quantitative assessment of these five sources indicated that fossil fuel combustion contributed the most ions concentration in precipitation at the three sites, followed by agriculture, terrestrial (crustal) sources, marine sources, and biomass burning. Long-distance airflow might affect the acidity, the electrical conductivity (EC), and ion concentrations in precipitation across Guilin. The airflow trajectory from the west and southeast directions corresponded to higher acidity and ion concentrations. According to the current air pollution control strategy planned by Guilin, reducing atmospheric coarse particles and NH₃ at the same time may potentially lead to further deteriorations in acid rain contents. Therefore, Guilin needs to develop more reasonable pollution prevention measures that synergistically control atmospheric pollutants and acid rain pollution.     

Analysis of Influences between the Energy Structure Change and Energy Intensity in China

In this article, based on the data of the energy statistics from 1980 to 2004, we analyze the relationship between the primary energy structures, technique, management, and the energy use per unit of GDP based on the path analysis approach and present the degree of the direct, indirect, and the overall influences of the primary energy structures on the energy use per unit of GDP. The results show that the technical change and management level play a decisive role in the energy use per unit of GDP, and the ratio of oil consumption was the major limiting factor to energy use per unit of GDP. We then found the model of the energy use per unit of GDP and the structures of the primary energy consumption, eliminated the multicollinearity in the model with the path analysis result, and finally, analyzed the influence of the primary energy structure on the energy conservation.     

主成分分析法优化治理黑臭水体的碳素纤维铺设密度

在治理黑臭水体的碳素纤维铺设密度优化研究中,借助统计学软件(SIMCA-P),以4个指标(COD、TP、NH3-N、TN)作为分析变量,探讨了单指标优化法与主成分分析法分析样本数据的差别。结果表明:单指标优化法可以确定4个指标各自的最优铺设密度,而主成分分析法能综合4个指标的信息进行分析,并优选出碳素纤维的最优铺设密度为40 cm2/L,为碳素纤维的综合运用提供参考依据。