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.     

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.     

安太堡露天矿排土场表层岩土的径流特征与复垦种植研究

采用针孔式小型人工降雨机,分别模拟山西塞北高原90～60min,60～45min,45～30min,30～15min各时段降水量极大值,探讨大型露天矿排土场各种排土工艺下地表岩土的径流特征,以指导排土工艺和复垦种植。     

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。     

饮水型砷中毒病区人群砷暴露量及尿砷的季节变化

地下水高砷暴露的健康危害是环境与健康领域面临的巨大挑战。水砷含量及暴露人群饮水量参数的季节性变化可能影响饮水砷暴露评估的准确性。本研究选择内蒙古饮水砷中毒病区为研究区,测定丰水期(2013年5月)和枯水期(2013年12月)居民饮用水和尿液各形态砷(三价无机砷iAs~(3+)、五价无机砷iAs~(5+)、一甲基砷MMA~(5+)和二甲基砷DMA~(5+)+)含量,研究砷暴露量和尿砷的季节变化。结果表明,丰水期水砷含量(134.4±25.8)μg·L~(-1)显著低于枯水期的(163.2±38.1)μg·L~(-1),且丰水期水中iAs~(3+)的含量(58.9±51.2)μg·L~(-1)也显著低于枯水期的(100.1±49.0)μg·L~(-1)。研究人群丰水期通过饮水的摄砷量为313.1μg·d~(-1),低于枯水期的378.6μg·d~(-1)。此外,丰水期居民尿液总砷含量(218.6μg·L~(-1))显著低于枯水期(283.1μg·L~(-1))。丰水期女性居民尿液iAs、MMA~(5+)和总砷含量随当季饮水iAs~(5+)含量的升高而显著降低,枯水期女性尿液MMA5+含量随当季饮水iAs~(3+)及iAs含量的升高而显著升高。可见,病区居民饮水砷暴露量与尿砷含量具有明显的季节差异性,饮水砷与尿砷的关系受饮水砷形态、季节变化及性别等因素影响。     

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。     

Threat of heavy metal contamination in eight mangrove plants from the Futian mangrove forest,China

Mangrove plants play an important role in heavy metal maintenance in a mangrove ecosystem. To evaluate the characteristics of heavy metal contamination in the Futian mangrove forest, Shenzhen, China, eight heavy metals in mangrove sediments and plants were monitored, including essential elements such as Cu and Zn, and non-essential elements such as Cr, Ni, As, Cd, Pb and Hg. The results showed that the heavy metals exhibited the following scheme: Zn > As > Cu ≈ Cr > Pb > Ni > Cd ≈ Hg in sediment cores, among which Cd, As, Pb and Hg contents were nearly ten times higher than the background values. There was no significant difference in metal maintenance capability between native and exotic species. In mangrove plants’ leaves and stems, concentrations of Cu, Zn and As were higher than other heavy metals. The low bioconcentration factors for most heavy metals, except for Cr, implied the limited ability of heavy metal accumulation by the plants. Mangrove plants seem to develop some degree of tolerance to Cr. The factor analysis implies that anthropogenic influences have altered metal mobility and bioavailability.     

北京市东北城区夏季环境空气中苯系物的污染特征与健康风险评价

于2013年8月2日至31日,利用Airmo VOC在线分析仪开展了北京市东北城区环境空气中挥发性有机物(VOCs)的在线监测,分析了其中16种苯系物的污染水平、变化特征、来源及其臭氧形成潜势(OFP),并采用US EPA的健康风险评价模型对BTEX(苯、甲苯、乙苯、间-对二甲苯、邻二甲苯)和苯乙烯的人体健康风险进行了评价。结果表明,16种苯系物在观测期间总平均质量浓度为10.36μg·m-3,其中BTEX的质量浓度均值为7.45μg·m-3,约占总的苯系物质量浓度的72%。苯系物的质量浓度呈现明显的一次污染物日变化特征,即早晚较高,中午较低。苯与甲苯的质量浓度比值(B/T)平均为0.39,说明除机动车尾气外,涂料和溶剂的挥发释放对大气中苯系物也可能具有重要贡献。间-对二甲苯、1,2,4-三甲苯和甲苯的OFP值较高,对北京市大气臭氧光化学形成具有显著贡献。BTEX和苯乙烯对人体的非致癌风险危害商值在8.70E-05至3.76E-02之间,危害指数为6.19E-02,对暴露人群尚不存在明显的非致癌风险;而苯的致癌风险值为8.80E-06,超过了US EPA的建议值1.00E-06,显示苯对研究区居民身体健康存在潜在的致癌风险。