Physico-chemical characterization and source tracking of black carbon at a suburban site in Beijing

Particles from ambient air and combustion sources including vehicle emission, coal combustion and biomass burning were collected and chemically pretreated with the purpose of obtaining isolated BC (black carbon) samples. TEM (transmission electron microscopy) results indicate that BC from combustion sources shows various patterns, and airborne BC appears spherical and about 50 nm in diameter with a homogeneous surface and turbostratic structure. The BET (Barrett–Emmett–Teller) results suggest that the surface areas of these BC particles fall in the range of 3–23 m²/g, with a total pore volume of 0.03–0.05 cm³/g and a mean pore diameter of 7–53 nm. The nitrogen adsorption–desorption isotherms are indicative of the accumulation mode and uniform pore size. O₂-TPO (temperature programmed oxidation) profiles suggest that the airborne BC oxidation could be classified as the oxidation of amorphous carbon, which falls in the range of 406–490°C with peaks at 418, 423 and 475°C, respectively. Generally, the BC characteristics and source analysis suggest that airborne BC most likely comes from diesel vehicle emission at this site.     

重庆市冬季PM_(2.5)及气态污染物的分布特征与来源

利用重庆市大气污染物监测站2013年冬季(2013年11月—2014年1月)的实测数据,分析PM2.5及相关气态污染物(SO2、NO2、O3)的时空特征,并采用轨迹聚类与PSCF(潜在源贡献因子)分析污染物来源.结果表明:除ρ(O3)以外,其他3种污染物质量浓度的月际变化趋势基本一致,均呈12月升高、1月降低的特征;污染物空间分布不均,其中ρ(PM2.5)和ρ(NO2)在工业区和人口密集区较高,ρ(SO2)南高北低,ρ(O3)城区低于郊区.ρ(SO2)、ρ(NO2)与ρ(PM2.5)均呈显著正相关,其中ρ(SO2)与ρ(PM2.5)的R(相关系数)在城、郊区分别为0.71、0.65,ρ(NO2)与ρ(PM2.5)在城、效区的R分别为0.73、0.56;而ρ(O3)与ρ(PM2.5)未表现出显著相关.ρ(SO2)、ρ(NO2)与ρ(PM2.5)的相关性高低可在一定程度上说明二次气溶胶的污染程度,ρ(O3)与ρ(PM2.5)的相关性受到PM2.5来源和污染程度的影响.轨迹分析结果显示,重庆市2013年冬季主要受东北方向气流影响;聚类分析表明,重庆市11月没有表现出明显的PM2.5外来输送特征,但12月和1月的PM2.5外来输送特征明显,并且不同方向的气流污染物浓度差异也较大.PSCF分析发现,重庆市冬季PM2.5、SO2、NO2、O3主要来源于本地和周围城市局地传输,同时还受南宁、贵阳、遵义、达州等地的影响.     

预处理对小球藻吸附Cd(Ⅱ)、Pb(Ⅱ)和Cu(Ⅱ)的影响

为了研究不同预处理方式对小球藻藻体吸附Cd2+、Pb2+和Cu2+的影响,文章将经过高温灭菌、Ca(NO3)2溶液浸泡和HNO3溶液浸泡预处理的小球藻藻体冷冻干燥,然后在单、两和三组份重金属离子溶液中进行吸附实验。结果表明,在单一系统中,经过Ca(NO3)2溶液浸泡过的藻体吸附效果较好;在混合系统中,冷冻干燥的藻体吸附效果较好。小球藻藻体对重金属吸附动力学曲线表明,在单一或混合系统中,高温灭菌的藻体对Cd2+、Pb2+的吸附于360 min内基本达到平衡,Ca(NO3)2或HNO3溶液浸泡过的藻体对Cd2+、Cu2+的吸附于360 min内基本达到平衡。运用红外光谱仪和扫描电镜对吸附重金属离子前的藻体进行表征。结果表明,不同预处理藻体细胞的功能性基团和形态结构存在着差异,进而影响其对Cd2+、Pb2+、Cu2+的吸附能力。     

污染源监督性监测中比对监测技术要求研究

为了加强环境监督管理,实现对重点监控企业的动态监控,《污染源自动监控管理办法》要求所有重点监控企业安装污染源自动监控设备.同时《国家重点监控企业污染源自动监控设施考核规程》中要求环境监测站对国家重点监控企业的污染源在线监测系统定期进行比对监测,在每季度进行污染源监督性监测的同时,采用标准方法对污染源在线监测系统进行比对监测,并根据监测的结果对污染源在线监测系统数据的有效性做出判断.     

Temporal variability of atmospheric particulate matter and chemical composition during a growing season at an agricultural site in northeastern China

This study presents the observations of PM_(10) and PM_(2.5) concentrations at an agricultural site from April to October 2012 in Dehui city,China.Ambient air was sampled by filter-based samplers and online PM monitors.The filter samples were analyzed to determine the abundance of ionic/inorganic elements,organic carbon(OC) and elemental carbon(EC).The daily PM_(10) concentrations varied significantly over the monitoring period,with an average of168 ± 63(in the range of 52-277) μg/m~3 during the land preparation/planting period(26 April-15 June),85 ± 65(36-228) μg/m~3 during the growing season(16 June-25 September),and 207 ±88(103-310) μg/m~3 during the harvest period(26 September-31 October).PM_(2.5) accounted for44%,56%and 66%of atmospheric PM_(10) during these periods,respectively.The PM_(10) diurnal variation showed a distinct peak from 16:00 to 21:00(LST) during the growing and harvesting seasons,while a gradual increase throughout the daytime until 17:00 was observed during tilling season.Mineral dust elements(Al,Ca,Fe,and Mg) dominated the PM_(10) chemical composition during the tilling season;OC,NO_3~-,SO_4~(2-) and NH_4~+ during the growing season;and carbonaceous species(i.e.,OC and EC) during the harvesting season.Our results indicate that the soil particles emitted by farm tillage and organic matter released from straw burning are the two most significant sources of PM_(10) emissions contributing to the recurring high pollution events in this region.Therefore,development of agricultural PM inventories from soil tillage and straw burning is prioritized to support air quality modeling.     

基于模糊专家系统的垃圾焚烧底灰重金属污染风险评价

垃圾焚烧处理技术可以实现城市生活垃圾减量化,但底灰中重金属的存在与迁移转化会形成持续的潜在风险。针对重金属Cu、Cr、Pb和Cr对环境的潜在风险进行分析,将模糊专家系统引入潜在生态风险指数法中。首先将重金属的富集系数作为输入,然后应用知识库和推理机制来实现重金属对环境危害快速、不确定信息的准确推理,最后对城市生活垃圾焚烧底灰中重金属对环境的潜在风险进行评价。实验结果验证,该方法能够更快速、准确地做出适当的决定,为底灰的安全处置和再利用提供理论基础。     

人工湿地应用于富营养化景观水体修复

以某会议中心1号和2号人工湿地为研究对象,研究了人工湿地对富营养化景观水体的净化效果。结果表明:1号和2号人工湿地对COD、TN和TP均具有较好的处理效果,植物的差异对湿地污染物去除效果的影响不明显。TP的去除主要依靠基质的作用。湿地的前段和中段是整个湿地COD和TN去除的主体,且前段的去除率高于中段。     

Assessment of Bisphenol A (BPA) neurotoxicity in vitro with mouse embryonic stem cells

The adverse effects of environmental pollution on our well-being have been intensively studied with many in vitro and in vivo systems. In our group, we focus on stem cell toxicology due to the multitude of embryonic stem cell (ESC) properties which can be exerted in toxicity assays. In fact, ESCs can differentiate in culture to mimic embryonic development in vivo, or specifically to virtually any kind of somatic cells. Here, we used the toxicant Bisphenol A (BPA), a chemical known as a hazard to infants and children, and showed that our stem cell toxicology system was able to efficiently recapitulate most of the toxic effects of BPA previously detected by in vitro system or animal tests. More precisely, we demonstrated that BPA affected the proper specification of germ layers during our in vitro mimicking of the embryonic development, as well as the establishment of neural ectoderm and neural progenitor cells.     

Trends of the sunshine duration and diffuse radiation percentage on sunny days in urban agglomerations of China during 1960–2005

The long-term observational data of sunshine duration (SD) and diffuse radiation percentage (defined as diffuse solar radiation/total solar radiation, DRP) on sunny days during 1960–2005 were analyzed in 7 urban agglomerations and the whole of China. The results show that the sunny sunshine duration (SSD) has decreased significantly except at a few stations over northwestern China in the past 46 years. An obvious decrease of the SSD is found in eastern China, with the trend coefficients lower than − 0.8. Accompanied by the SSD decline, the sunny diffuse radiation percentage (SDRP) in most stations shows obvious increasing trends during the 46 years. The averaged SDRP over China has increased 2.33% per decade, while the averaged SSD shows a decrease of − 0.13 hr/day per decade. The correlation coefficient between SDRP and SSD is − 0.88. SSD decreased over urban agglomerations (small to large city clusters) in the past 46 years, especially in large cities and medium cities, due to the strong anthropogenic activities and air pollution represented by aerosol option depth (AOD) and tropospheric column NO₂ (TroNO₂). On the regional scale, SSD has an opposite trend from SDRP during 1960 to 2005, and the variation trends of regional mean values of SSD and SDRP in southeastern China are more pronounced than those in northwestern China.     

海河干流浮游植物调查及环境影响因子研究

为研究海河干流汛期富营养化状况,于2013年8月对海河干流进行了浮游植物调查和水质监测,并采用冗余分析(RDA),研究了浮游植物群落与环境因子的关系.结果表明,浮游植物共计5门37种(属),优势种为水华微囊藻(Microcystis flos-aquae)、微小色球藻(Chroococcus minutus)、颤藻属(Oscillatoria sp.)、钝顶螺旋藻(Spirulina platensis)和梅尼小环藻(Cyclotella meneghiniana).浮游植物丰度范围为583.00～12 021.00×104 cells·L-1,生物量范围为4.01 ～45.70 mg·L-1,以蓝藻为主,海河干流处于重富营养状态.RDA分析结果表明,硝酸盐氮是显著影响海河干流浮游植物丰度变化的主要环境因子.控制营养盐的输入是防治海河干流蓝藻水华的主要措施.