应用化学提取法评价大气颗粒物中重金属的生物有效性

以广州市楼顶降尘为研究对象,在分析其粒度分布和重金属总量的基础上,采用单一化学提取法（DWLP、TCLP）和多级化学提取法（SEP）研究了大气颗粒物中4种重金属元素的生物有效性。结果表明：样品中96％以上颗粒小于100μm,其中10μm和2．5μm以下颗粒分别占33％和11％。大气颗粒物中重金属含量很高,Cu、Pb、Zn和Cd的平均含量分别为362．43、1033．81、830．32和5．80mg／kg,是广东省环境土壤背景值的17～64倍。单一提取法中,TCLP的提取效率明显高于DWLP,表明pH值是影响大气颗粒物中重金属释放的主要因素。SEP法结果显示,Zn和Cd的生物可利用态比例远高于Cu和Pb。经DWLP和TCLP法提取后,颗粒物中重金属的总含量有不同程度的降低,生物可利用态所占比例明显增加。通过综合分析,发现SEP此其他两种方法更适用于评价大气颗粒物中重金属的生物有效性。     

Radioactive particles in dose assessments

Radioactive particles present a novel exposure pathway for members of the public. For typical assessments of potential doses received by members of the public, habit surveys and environmental monitoring combine to allow the assessment to occur. In these circumstances it is believed that the probability of encounter/consumption is certain. The potential detriment is assessed through sampling the use of environmental monitoring data and dose coefficients such as that in ICRP 60 [ICRP, 1990. 1990 Recommendations of the international commission on radiological protection. Publication 60. Annals of the ICRP 21 (1-3)]. However, radioactive particles often represent a hazard that is difficult to quantify and where the probability of encounter is less than certain as are the potential effects on health. Normal assessment methodologies through sampling and analysis are not appropriate for assessing the impact of radioactive particles either prospectively or retrospectively. This paper details many of the issues that should be considered when undertaking an assessment of the risk to health posed by radioactive particles.     

冲缝筛管结垢速率模拟研究*

为对防砂过程中因地层物性影响而导致冲缝筛管出现结垢问题进行准确的过程分析,基于FLUENT平台利用现场数据建立流道中的化学反应和沉积结垢的数值模型,评估管道缝宽、环境压力、温度、离子浓度与流速对冲缝筛管结垢速率的影响规律。结果表明:筛管结垢速率与管内温度和离子浓度成正相关,与管内流体流速成负相关,但环境压力影响不大,同时结垢主要产生在冲缝台阶以及冲缝套与打孔基管的接触面上,对产液的过流面积存在较大影响;结合正交分析得到4个敏感因素的主次顺序为:管内温度、管内流速、反应物浓度、环境压力,并确定最小结垢的组合方案;通过DPM模型探究CaCO3颗粒的沉积规律,得到管内的沉积情况,并建立多因素垢层厚度的计算模型。在实际生产中为降低筛管结垢对油井产能的影响,可以通过降低管内的温度、离子浓度及适当地增大流速来抑制结垢过程的发生。     

A preliminary study on pollution characteristics of surfactant substances in fine particles in the Beibu Gulf Region of China

The pollution characteristics of surfactant substances in fine particles (PM_2.5) in spring were studied in the Beibu Gulf Region of China, 68 samples of PM_2.5 were collected at Weizhou Island in Beihai City from March 12 to April 17, 2015. The Anionic Surfactant Substances (ASS) and Cationic Surfactant Substances (CSS) in the samples were analyzed using Byethyl Violet Spectrophotometry and Disulfide Blue Spectrophotometry, respectively. Combined with the data from backward trajectory simulation, the effects of air pollutants from remote transport on the pollution characteristics of surfactant substances in PM_2.5 in the Beibu Gulf Region were analyzed and discussed. The results showed that the daily mean concentrations of ASS and CSS in spring in the Beibu Gulf Region were 165.20 pmol/m³ and 8.05pmol/m³, and the variation ranges were 23.21–452.55 pmol/m³ and 0.65–31.31 pmol/m³, accounting for 1.82‰ ± 1.65‰ and 0.12‰ ± 0.11‰ of the mass concentration of PM_2.5, respectively. These concentrations were lower than those in comparable regions around the world. There was no clear correlation between the concentrations of ASS and CSS in PM_2.5 and the mass concentrations of PM_2.5. Tourism and air transport had a positive contribution on the concentrations of ASS. The concentration of surfactant substances in PM_2.5 was significantly impacted by wind speed and wind direction. Atmospheric temperature, air pressure and precipitation had little effect on the concentrations of surfactant substances. Surfactant substances in PM_2.5 significantly impacted visibility. Results also showed that the main sources of surfactant substances were from the southern China and Southeast Asia.     

Size distribution and anthropogenic sources apportionment of airborne trace metals in Kanazawa, Japan

Aerosol samples were collected from Kanazawa, Japan to examine the size distribution of 12 elements and to identify the major sources of anthropogenic elements. Key emission sources were identified and, concentrations contributed from individual sources were estimated as well. Concentrations of elements V, Ca, Cd, Fe, Ba, Mg, Mn, Pb, Sr, Zn, Co and Cu in aerosols were determined with ICP-MS. The results showed that Ca, Mg, Sr, Mn, Co and Fe were mainly associated with coarse particles (>2.1 μm), primarily from natural sources. In contrast, the elements Zn, Ba, Cd, V, Pb and Cu dominated in fine aerosol particles (<2.1 μm), implying that the anthropogenic origin is the dominant source. Results of the factor analysis on elements with high EF_Crust values (>10) showed that emissions from waste combustion in incinerators, oil combustion (involving waste oil burning and oil combustion in both incinerators and electricity generation plants), as well as coal combustion in electricity generation plants were major contributors of anthropogenic metals in the ambient atmosphere in Kanazawa. Quantitatively estimated sum of mean concentrations of anthropogenic elements from the key sources were in good agreement with the observed values. Results of this study elucidate the need for making pollution control strategy in this area.     

Trace elements in atmospheric particulate matter over a coal burning power production area of western Macedonia, Greece

Total suspended particle (TSP) concentrations were determined in the Eordea basin (western Macedonia, Greece), an area with intensive lignite burning for power generation. The study was conducted over a one-year period (November 2000–November 2001) at 10 sites located at variable distances from the power plants. Ambient TSP samples were analyzed for 27 major, minor and trace elements. Annual means of TSP concentrations ranged between 47 ± 33 μg m⁻³ and 110 ± 50 μg m⁻³ at 9 out of the 10 sites. Only the site closest to the power stations and the lignite conveyor belts exhibited annual TSP levels (210 ± 97 μg m⁻³) exceeding the European standard (150 μg m⁻³, 80/779/EEC). Concentrations of TSP and almost all elemental components exhibited significant spatial variations; however, the elemental profiles of TSP were quite similar among all sites suggesting that they are affected by similar source types. At all sites, statistical analysis indicated insignificant (P < 0.05) seasonal variation for TSP concentrations. Some elements (Cl, As, Pb, Br, Se, S, Cd) exhibited significantly higher concentrations at certain sites during the cold period suggesting more intense emissions from traffic, domestic heating and other combustion sources. On the contrary, concentrations significantly higher in the warm period were found at other sites mainly for crustal elements (Ti, Mn, K, P, Cr, etc.) suggesting stronger influence from soil resuspension and/or fly ash in the warm months. The most enriched elements against local soil or road dust were S, Cl, Cu, As, Se, Br, Cd and Pb, whereas negligible enrichment was found for Ti, Mn, Mg, Al, Si, P, Cr. At most sites, highest concentrations of TSP and elemental components were associated with low- to moderate-speed winds favoring accumulation of emissions from local sources. Influences from the power generation were likely at those sites located closest to the power plants and mining activities.     

对喷流除尘技术在收集硫酸铵和硝酸铵粉尘中的应用研究

对喷流除尘技术利用粉尘颗粒在撞击区内来回振荡、相互碰撞并团聚的机理进行除尘.实验采用水平式对喷流除尘系统收集硫酸铵和硝酸铵的混合物粉尘,主要考察喷嘴气流速度、含尘浓度和喷雾化水润湿含尘气流对除尘效率的影响,并进行机理分析.实验表明,除尘效率随喷嘴风速的增大而升高,但喷嘴风速超过25～27 m/s后,反而下降;除尘效率随含尘浓度的增加而升高,但含尘浓度超过0 45～0.55 kg/m3后反而有所降低;喷雾化润湿含尘气流能显著提高除尘效率,最优耗水量为0.18～0.22 kg/kg粉尘,超过该值后无显著变化.实验确定的最优除尘条件为:喷嘴速度25～27 m/s、含尘浓度0.45～0.55 kg/m3、耗水量0.18～0 22 kg/kg粉尘,除尘效率最高可达96.8%.     

机动车排放颗粒物采集系统参数的研究和测试

机动车排放颗粒物是重要的空气污染物.笔者主要阐述了机动车排放颗粒物采集系统开发和研制过程中部分实验参数的研究和确定,同时给出了初步测试的结果,这些结果在一定程度上表征了机动车排入颗粒物的污染状况.      

交变电场中偶极荷电粒子电凝并的理论研究

根据碰撞理论 ,推导出偶极荷电粒子在交变电场中的电凝并系数 ,并利用 Williams求声凝并的方法 ,将其简化。若忽略粒子的惯性 ,则电凝并系数与交变电场的频率无关。     

Composition of the Saprotrophic Fungi in Calluna Heathland Soil and the Influence of Ammonium Nitrate Application

The composition of saprotrophic soil fungi in the mor layerof a Calluna-dominated, Danish heathland wasinvestigated after two years of fertilization with ammoniumnitrate (0, 35, 50 and 70 kg N ha^1- yr^-1) using asoil washing technique. The most frequently isolated generafrom the soil particles plated were Penicillium, Trichoderma, Mortierella and Mucor. Eightspecies of Penicillium were identified and Penicillium spinulosum was the most frequently isolated.The occurrence of dark, sterile fungi on the soil particleswas low. There were no measurable changes in the specificcomposition of the saprotrophic soil fungal groups due tothe nitrogen treatments, beside from an increasedoccurrence of Absidia californica. I conclude that adirect impact on the composition of the saprotrophic fungiin heathland soil is unlikely under enhanced nitrogen input.