连续式磁性颗粒去除器在轧钢废水处理中的应用

连续式磁性颗粒去除器，是利用稀土永磁Ｎｄ－Ｆｅ－Ｂ为材质，处理含磁性颗粒废水的装置，其主要结构由动力传递，磁块组合体，磁条移动，设备本体，进出口流道及分离部件等组成，该文阐述了永磁分离机理，并通过磁性悬浮颗粒的理论驱进速度和最小捕获粒径的求解，探讨了提高砒生粒去除器捕 方法，实践证明，该装置用于冶金轧钢废水处理中，能代替传统的轧钢废水三级处理工艺，节约投资成本７０％，占地减少８５％，运行费用亦大幅     

Appraisal of measurement methods, chemical composition and sources of fine atmospheric particles over six different areas of Northern Belgium

Daily and seasonal variation in the total elemental, organic carbon (OC) and elemental carbon (EC) content and mass of PM_2.5 were studied at industrial, urban, suburban and agricultural/rural areas. Continuous (optical Dustscan, standard tapered element oscillating micro-balance (TEOM), TEOM with filter dynamics measurement system), semi-continuous (Partisol filter-sampling) and non-continuous (Dekati-impactor sampling and gravimetry) methods of PM_2.5 mass monitoring were critically evaluated. The average elemental fraction accounted for 2-6% of the PM_2.5 mass measured by gravimetry. Metals, like K, Mn, Fe, Cu, Zn and Pb were strongly inter-correlated, also frequently with non-metallic elements (P, S, Cl and/or Br) and EC/OC. A high OC/EC ratio (2-9) was generally observed. The total carbon content of PM_2.5 ranged between 3 and 77% (averages: 12-32%), peaking near industrial/heavy trafficked sites. Principal component analysis identified heavy oil burning, ferrous/non-ferrous industry and vehicular emissions as the main sources of metal pollution.     

Characteristics and mixing state of S-rich particles in haze episodes in Beijing

Direct individual analysis using Scanning Electron Microscopy combined with online observation was conducted to examine the S-rich particles in PM_2.5 of two typical polluted haze episodes in summer and winter from 2014 to 2015 in Beijing. Four major types of S-rich particles, including secondary CaSO₄ particles (mainly observed in summer), S-rich mineral particles (SRM), S-rich water droplets (SRW) and (C, O, S)-rich particles (COS) were identified.We found the different typical morphologies and element distributions of S-rich particles and considered that (C, O, S)-rich particles had two major mixing states in different seasons. On the basis of the S-rich particles’ relative abundances, S concentrations and their relationships with PM_2.5 as well as the seasonal comparison, we revealed that the S-participated formation degrees of SRM and SRW would enhance with increasing PM_2.5 concentration. Moreover, C-rich matter and sulfate had seasonally different but significant impacts on the formation of COS.

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基于稳定同位素示踪的流域颗粒有机物质来源辨析

为有效控制流域水质污染,保证饮用水水源的水质安全,通过采集和测定流域内土壤、植物以及河流断面水体悬浮颗粒有机质(POM)在枯水期和丰水期的碳、氮稳定同位素值和C/N比值,对石头口门水库汇水流域水体POM的来源进行研究.结果表明,水体中POM主要来源于土壤有机质,其贡献为69.2%,藻类等大型水生生物和浮游植物的贡献分别为23.1%和7.7%.流域水体中POM的来源存在时空差异.丰水期,浮游植物和藻类等大型水生植物的贡献均为15.4%,而枯水期后者的贡献提高到了30.8%.水体POM主要来源于双阳河和饮马河下游的土壤有机质,说明该区域土壤侵蚀较重,易发生非点源污染;岔路河和饮马河上游支流小黄河,水体POM以浮游植物的贡献占主导,其贡献分别为86.3%和94.8%,这些区域侵蚀较弱,非点源污染发生的风险小;大中型水库区域的POM主要由藻类等大型水生植物贡献,表明悬浮颗粒物在进入水库后可能发生了明显沉积.     

Association of the mutagenicity of airborne particles with the direct emission from combustion processes investigated in Osaka, Japan

The association of the direct-acting mutagenicity of soluble organic fraction of airborne particles toward Salmonella typhimurium YG1024 strain with the direct emission was investigated at a roadside and at a residential area in Osaka, Japan. The direct-acting mutagenicity was evaluated as mutagenic activity per unit volume of ambient air (rev m⁻³) and/or that per airborne particulate weight collected on a filter (rev mg⁻¹). The annual or diurnal changes of the mutagenicity of airborne particles at the residential site showed similar patterns to those of some gaseous pollutants such as NO₂ and SO₂, which were emitted from combustion processes. This result indicates that the mutagenicity is mainly attributable to the primary emissions. From the analysis of the relationship between the wind sector and the mutagenic intensity, rev m⁻³ and rev mg⁻¹ values were strongly affected by the emissions from the fixed sources and from the mobile sources, respectively. The rev m⁻³ value and concentration of 1-nitropyrene (1-NP) in unit per m³ at the roadside were a factor of 2.6 and 2.8 higher than those at the residential site, respectively, but the rev mg⁻¹ value and concentration of 1-NP in unit per mg at the roadside were substantially comparable to those at the residential area. These observations suggest that the characteristics of the airborne particles can be attributed to the automotive emissions even at the suburban area.     

中国大气颗粒物中金属元素环境地球化学行为研究

大气颗粒物金属污染已成为目前大气污染的研究热点之一。文章梳理、分析归纳了中国近年来大气颗粒中金属元素的环境地球化学方面的研究。目前研究较多的是Fe、Ca、Mg、Si等地壳元素和Cu、Pb、Cd、Zn、Hg等污染元素;大气颗粒物中对人体有害的Cu、Pb、Cd、As、Zn等污染较严重,而Cr、Mn、Co、Ni等污染较轻。大气颗粒物中金属含量随时间分布变化显著,总体上呈现冬季〉秋季〉春季〉夏季的特点,空间分布上一般北方燃煤城市大于南方一般城市;城市内部一般工业区〉交通区〉居民区〉郊区;金属元素在细粒径颗粒（〈2μm）中高,粗颗粒（〉2μm）中低,尤其以污染元素明显。污染元素与地壳元素的垂直分布规律差异较大。大气颗粒物中金属元素的富集程度与元素种类、区域类型、季节变化、粒径大小等有关。最后,提出应加强大气颗粒物中金属元素空间分布差异、时间分布的尺度及差异性研究;同时加强超细颗粒物的研究,以便建立大气颗粒物金属元素与人类健康关系的风险模型。     

空气细颗粒物(PM2.5)污染特征及其毒性机制的研究进展

细颗粒物(PM2.5)是指空气动力学直径≤2.5μm的颗粒物,其表面吸附大量的有毒有害物质,并可通过呼吸沉积在肺泡,甚至可通过肺换气到达其他器官.由于细颗粒物的重要性,美国EPA已经于1997年颁布了细颗粒物的空气质量标准,年均值为0.015mg/m3,日均值为0.065mg/m3,然而我国至今仍未制定细颗粒物空气质量标准.颗粒物上吸附的化学组分主要可分成自然来源及燃煤或燃油等人为污染来源两大类,特别是来自工业性和居住区燃煤及汽车燃油尾气.空气细颗粒物污染表现为形态各异、成分复杂等特征.细颗粒物有明显的毒性作用,可引起机体呼吸系统、免疫系统等较为广泛的损害.细颗粒物与心肺疾病密切相关,如增加入院率、急诊次数、呼吸疾病及症状增加、肺功能下降,甚至于过早死亡.简要概述了细颗粒物的污染特征及其毒性机制研究进展.     

厦门水库水体颗粒物分布特征及其与环境因子的关系研究

研究了厦门湖边水库、石兜-坂头水库水体颗粒物的分布特征及其与环境因子之间的关系。结果表明:(1)水体颗粒物平均含量以坂头库区最高,石兜库区次之,湖边水库最低,平均含量分别为31.9、27.7和23.1mg/L;在空间分布上,不同水库或库区、不同采样站位间,由于水体颗粒物的来源成因不同,其分布规律呈现出明显的差异。(2)从水体颗粒物与环境因子的关联度分析,湖边水库及石兜-坂头水库两个库区的水体颗粒物与总氮和总磷都有较大关联性。(3)利用Pearson积矩相关系数(两尾)进行检验,湖边水库及石兜-坂头水库两个库区的水体颗粒物均与总氮呈显著或极显著相关,与透明度呈显著负相关,与叶绿素a均呈负相关,与其它因子的相关规律性不明显。(4)水体颗粒物与环境因子的逐步回归分析表明,在不同的水库或库区,对水体颗粒物有显著影响的环境因子各不相同,湖边水库是高锰酸盐指数和总氮,石兜库区是高锰酸盐指数、总氮和总磷,坂头库区是pH、溶解氧和总磷。     

模拟烹饪油烟的粒径分布与扩散

烹饪油烟颗粒物粒径分布与扩散特性研究有助于解析其对室内空气质量和居民健康的影响,采用电子低压撞击器(ELPI)实时监测了油烟机开启和关闭状态下,模拟烹饪油烟发生处和3 m外位置处,0.03~10μm范围内油烟颗粒数浓度和质量浓度随粒径分布.油烟颗粒主要以655 nm以下的细颗粒为主.油烟机能够显著降低室内油烟浓度,开启油烟机后,油烟发生处颗粒数浓度从2.8×106个·cm-3降低到2.3×105个·cm-3,PM2.5(空气动力学直径≤2.5μm的颗粒)质量浓度从85.9 mg·m-3降低到6.2 mg·m-3.油烟机对PM10的净化效率高于PM2.5.油烟迅速从发生处扩散到3 m外,无通风状态下,总颗粒数浓度衰减达65%,PM2.5质量浓度衰减达75%.计算流体动力学(CFD)模拟了油烟机对油烟PM2.5质量浓度场扩散分布影响.红外摄像仪监测了油烟温度场分布扩散,以扇形向外扩散,伴随着油烟温度梯度降低.     

Modeling estuarine-shelf exchanges in a deltaic estuary: Implications for coastal carbon budgets and hypoxia

The export of wetland-derived materials to the coastal ocean (i.e., the “Outwelling” hypothesis) has received considerable attention over the past several decades. While a number of studies have shown that estuaries export appreciable amounts of nutrients and carbon, few studies have attempted to estimate the importance of estuarine sources for the coastal carbon budgets in river-dominated coastal ecosystems. A novel tidal prism model was developed to examine estuarine-shelf exchanges in the Barataria estuary, a deltaic estuary located in the north-central Gulf of Mexico. This estuary has been the site of a massive wetland loss, and it has been hypothesized that carbon export from the eroding coastal wetlands supports the development of a large hypoxic zone in the coastal Gulf of Mexico. The model results show that the Barataria estuary receives nitrogen through the tidal passes and releases carbon to the coastal ocean. The mean calculated tidal water discharge of 6930 m³ s⁻¹ is equivalent to about 43% of the lower Mississippi River discharge. The annual total organic carbon (TOC) export is 109 million kg, or 57 gC m² yr⁻¹ when prorated to the total water area of the estuary. This carbon export is equivalent to a loss of 0.5 m of wetland soil horizon over an area of 8.4 km², and accounts for about 34% of the observed annual wetland loss in the estuary between 1978 and 2000. Compared to the lower Mississippi River, the Barataria estuary appears to be a very small source of TOC for the northern Gulf of Mexico (2.7% of riverine TOC), and is unlikely to have a significant influence on the development of the Gulf's hypoxia.