裸土风蚀型开放源起尘机制研究进展

中国北方多个城市空气颗粒物来源解析结果表明,开放源是空气颗粒物污染的主要来源,裸土风蚀型开放源是主要的排放源类.对裸土风蚀型开放源起尘机制进行了诠释,提出了裸土风蚀型开放源、裸土风蚀起尘、裸土风蚀尘的概念,并对裸土风蚀型开放源的风蚀影响因素进行了研究,为城市空气质量达标及空气颗粒物污染防治提供科学参考.     

二重源解析技术及其系统实现

化学质量平衡是被广泛用于空气质量管理的受体模型之一.由于混合源(城市扬尘)和单一源因颗粒物源谱的严重共线性,采用美国环境保护署推荐使用的EPA-CMB8.2,无法定量解析出各排放源初始态和扬尘态颗粒物的贡献值和分担率.针对这一问题,完善和规范了二重源解析技术原理,开发了具有二重源解析功能的NKCMB3.0.对鞍山市样品污染物来源解析的试验结果表明,二重源解析技术在对混合源和单一源同时进行源解析时是有效的.     

宁波市大气可吸入颗粒物PM1o和PM2.5的源解析研究

在宁波市布设4个代表性点位,于2010年春季、夏季和冬季进行大气PM10和PM2.s的采样,同时采集了多种颗粒物源样品,建立了PM10、PM2.5和源样品的化学成分谱.采用化学质量平衡模型(CMB)对宁波市PM10、PM2.5进行源解析.结果表明,城市扬尘、煤烟尘、机动车尾气尘是宁波市PM10、PM2.5的3大污染源,...     

基于SWAT模型的观澜河流域城市面源污染负荷量化及影响效应评估

随着我国城市区域污水收集、截污系统的完善与水质净化厂出水标准的提高,点源污染逐步得到控制,城市面源污染对河流水质的影响越来越凸显。针对当前城市内河流集水区域城市面源污染负荷难以量化、对水体水质影响效应难以解析等问题,以深圳市观澜河流域为研究对象,通过对流域的现场勘察调研与地表累积物采样研究,来修正流域土地利用类型数据与SWAT模型的城镇数据库,构建流域城市面源污染评价模型。结果表明：SWAT模型城镇数据库中地表沉积物最大累积量(DIRTMX)、地表沉积物中总氮含量(TNCONC)、地表灰尘累积半饱和时长(TNALF)与地表灰尘总磷含量(TPCONC)对TN与TP负荷的模拟最为敏感;建立的SWAT模型对观澜河流域径流量、TP与TN模拟验证期的纳什效率系数(E_NS)分别为0.79、0.7、0.67,决定系数(R²)分别为0.81、0.77、0.81,模型拟合结果较好。应用SWAT模型分析了2018年观澜河流域TN和TP的城市面源污染时空分布特征：TN和TP输出最高值为13.31~14.91 t·km⁻²和1.69~1.86 t·km⁻²;8月份观澜河流域降雨径流污染最为严重,TN和TP负荷分别为2.15 t·km⁻²与0.24 t·km⁻²。上述评估结果可为区域城市面源污染的负荷量化与影响效应评估提供参考。     

光散射颗粒物监测仪在环境空气监测中的适用性

为了研究光散射颗粒物监测仪在环境空气监测中的适应性,参照《环境空气颗粒物(PM10和PM2.5)连续自动检测技术要求及检测方法》(HJ 653-2013),在北京秋季使用PQ200(滤膜采样器)对DustTrak8530、LD-6S、HBKLW-2共3种光散射仪器进行比对测试.结果表明,3种光散射仪器的平行性都达标;在监测PM10时,3种仪器与PQ200的线性相关系数都达标,斜率只有HBKLW-2达标,截距除HBKLW-2略微超标外都与标准相差较远;在监测PM2.5时,3种仪器与PQ200的线性相关系数都达标且优于PM10,斜率只有HBKLW-2和LD-6S达标,截距绝对值相比PM10有所减小,但只有HBKLW-2达标;经校正因子修正后,3种仪器与PQ200的线性回归斜率达标、相关系数不变、监测PM2.5的截距相比PM10更加接近标准值,故光散射仪器更加适用于环境空气PM2.5监测.     

A review of the impact of fireworks on particulate matter in ambient air

To determine the impact of fireworks (FW) and firecrackers (FC) on particulate matter (PM) in ambient air, we reviewed evidence related to ambient PM during FW/FC periods; specifically, PM concentration, size, morphology, chemical components, including water-soluble ions and trace metals, and associated human health risks caused by exposure to FW/FC PM were reviewed. A large body of research suggests that outdoor ambient PM levels increase significantly during FW/FC displays. Furthermore, FW/FC PM remains suspended in the air, contributing to high PM concentrations for a long period. Increased PM from burning FW and FC mainly comprises fine and ultrafine spherical particles. Elevated levels of various trace metals, ions, elemental carbon (EC), organic carbon (OC), and organics in PM are present during FW/FC periods.Implications: Unique physical and chemical properties of ambient PM during short-term FW/FC burning can lead to a substantial increase in adverse health effects compared with during non-FW/FC periods. Further epidemiological and toxicological research into the potential health effects resulting from exposure to various pollutants from FW/FC is vital. Geographical distributions of PM concentrations during FW displays highlight the importance of implementing PM controls at the regional level and formulating stricter protective environmental legislation, particularly in Asian (e.g., India, China, or Taiwan) where festivals are not the only periods celebrated with FW/FC.     

Seasonal variation of the size distribution of urban particulate matter and associated organic pollutants in the ambient air

Size-segregated samples of urban particulate matter (<0.95, 0.95–1.5, 1.5–3.0, 3.0–7.5, >7.5 μm) were collected in Thessaloniki, northern Greece, during winter and summer of 2007–2008, in order to study the size distribution of organic compounds such as polycyclic aromatic hydrocarbons (PAHs), aliphatic hydrocarbons (AHs) including n-alkanes and the isoprenoids pristane and phytane, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs). All organic compounds were accumulated in the particle size fraction <0.95 μm particularly in the cold season. Particulate matter displayed a bimodal normalized distribution in both seasons with a stable coarse mode located at 3.0–7.5 μm and a fine mode shifting from 0.95–1.5 μm in winter to <0.95 μm in summer. Unimodal normalized distributions, predominant at 0.95–1.5 μm size range, were found for most organic compounds in both seasons, suggesting gas-to-particle transformation after emission. A second minor mode at larger particles (3.0–7.5 μm) was observed for C₁₉ and certain OCPs suggesting redistribution due to volatilization and condensation.     

Identification and source apportionment of polycyclic aromatic hydrocarbons in ambient air particulate matter of Riyadh, Saudi Arabia

In an effort to assess the occurrence and sources of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of Riyadh, Saudi Arabia, PM₁₀ samples were collected during December 2010. Diagnostic PAH concentration ratios were used as a tool to identify and characterize the PAH sources. The results reflect high PM₁₀ and PAH concentrations (particulate matter (PM)?=?270–1,270 μg/m³). The corresponding average PAH concentrations were in the range of 18?±?8 to 1,003?±?597 ng/m³ and the total concentrations (total PAHs (TPAHs) of 17 compounds) varied from 1,383 to 13,470 ng/m³ with an average of 5,871?±?2,830 ng/m³. The detection and quantification limits were 1–3 and 1–10 ng/ml, respectively, with a recovery range of 42–80 %. The ratio of the sum of the concentrations of the nine major non-alkylated compounds to the total (CPAHs/TPAHs) was 0.87?±?0.10, and other ratios were determined to apportion the PM sources. The PAHs found are characteristic for emissions from traffic with diesel being a predominant source.     

Nonlinear analysis and prediction of coarse particulate matter concentration in ambient air

This study attempts to characterize and predict coarse particulate matter (PM10) concentration in ambient air using the concepts of nonlinear dynamical theory. PM10 data observed daily from 1999 to 2002 at a site in Mumbai, India, was used to study the applicability of the chaos theory. First, the autocorrelation function and Fourier power spectrum were used to analyze the behavior of the time-series. The dynamics of the time-series was additionally studied through correlation integral analysis and phase space reconstruction. The nonlinear predictions were then obtained using local polynomial approximation based on the reconstructed phase space. The results were then compared with the autoregressive model. The results of nonlinear analysis indicated the presence of chaotic character in the PM10 time-series. It was also observed that the nonlinear local approximation outperforms the autoregressive model, because the observed relative error of prediction for the autoregressive model was greater than the local approximation model. The invariant measures of nonlinear dynamics computed for the predicted time-series using the two models also supported the same findings.     

Feasibility of using low-cost portable particle monitors for measurement of fine and coarse particulate matter in urban ambient air

Exposure to ambient particulate matter (PM) is known as a significant risk factor for mortality and morbidity due to cardiorespiratory causes. Owing to increased interest in assessing personal and community exposures to PM, we evaluated the feasibility of employing a low-cost portable direct-reading instrument for measurement of ambient air PM exposure. A Dylos DC 1700 PM sensor was collocated with a Grimm 11-R in an urban residential area of Houston Texas. The 1-min averages of particle number concentrations for sizes between 0.5 and 2.5 µm (small size) and sizes larger than 2.5 µm (large size) from a DC 1700 were compared with the 1-min averages of PM_2.5 (aerodynamic size less than 2.5 µm) and coarse PM (aerodynamic size between 2.5 and 10 µm) concentrations from a Grimm 11-R. We used a linear regression equation to convert DC 1700 number concentrations to mass concentrations, utilizing measurements from the Grimm 11-R. The estimated average DC 1700 PM_2.5 concentration (13.2 ± 13.7 µg/m³) was similar to the average measured Grimm 11-R PM_2.5 concentration (11.3 ± 15.1 µg/m³). The overall correlation (r²) for PM_2.5 between the DC 1700 and Grimm 11-R was 0.778. The estimated average coarse PM concentration from the DC 1700 (5.6 ± 12.1 µg/m³) was also similar to that measured with the Grimm 11-R (4.8 ± 16.5 µg/m³) with an r² of 0.481. The effects of relative humidity and particle size on the association between the DC 1700 and the Grimm 11-R results were also examined. The calculated PM mass concentrations from the DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM_2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM_2.5.

Implications: The performance of a low-cost particulate matter (PM) sensor was evaluated in an urban residential area. Both PM_2.5 and coarse PM (PM_10-2.5) mass concentrations were estimated using a DC1700 PM sensor. The calculated PM mass concentrations from the number concentrations of DC 1700 were close to those measured with the Grimm 11-R when relative humidity was less than 60% for both PM_2.5 and coarse PM. Particle size distribution was more important for the association of coarse PM between the DC 1700 and Grimm 11-R than it was for PM_2.5.     

A wind tunnel simulation of the erosion of soil: Effect of soil texture,sandblasting, wind speed,and soil consolidation on dust production

This experiment was undertaken to see if a wind tunnel could be used to investigate fine particle (d < 25 μm) production by wind erosion. The effects of sandblasting, wind speed, soil consolidation and soil surface texture were separated. Results for loose soil showed that wind speed was of primary importance whereas surface texture and sandblasting had little effect. Surface crust effectively eliminated fine particle emission and greatly limited coarse particle emission. The effectiveness of the surface crust in preventing wind erosion seemed to be related to the modulus of rupture of the soil. Sand fluxes in the wind tunnel tests agreed with field observed fluxes but fine particle fluxes differed between wind tunnel and field observations.     

Uncertainty associated with the gravimetric measurement of particulate matter concentration in ambient air

This work applied a propagation of uncertainty method to typical total suspended particulate (TSP) sampling apparatus in order to estimate the overall measurement uncertainty. The objectives of this study were to estimate the uncertainty for three TSP samplers, develop an uncertainty budget, and determine the sensitivity of the total uncertainty to environmental parameters. The samplers evaluated were the TAMU High Volume TSP Sampler at a nominal volumetric flow rate of 1.42 m³ min^–1 (50 CFM), the TAMU Low Volume TSP Sampler at a nominal volumetric flow rate of 17 L min^–1 (0.6 CFM) and the EPA TSP Sampler at the nominal volumetric flow rates of 1.1 and 1.7 m³ min^–1 (39 and 60 CFM). Under nominal operating conditions the overall measurement uncertainty was found to vary from 6.1 x 10^–6 g m^–3 to 18.0 x 10^–6 g m^–3, which represented an uncertainty of 1.7% to 5.2% of the measurement. Analysis of the uncertainty budget determined that three of the instrument parameters contributed significantly to the overall uncertainty: the uncertainty in the pressure drop measurement across the orifice meter during both calibration and testing and the uncertainty of the airflow standard used during calibration of the orifice meter. Five environmental parameters occurring during field measurements were considered for their effect on overall uncertainty: ambient TSP concentration, volumetric airflow rate, ambient temperature, ambient pressure, and ambient relative humidity. Of these, only ambient TSP concentration and volumetric airflow rate were found to have a strong effect on the overall uncertainty. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically.

Implications:?This work addresses measurement uncertainty of TSP samplers used in ambient conditions. Estimation of uncertainty in gravimetric measurements is of particular interest, since as ambient particulate matter (PM) concentrations approach regulatory limits, the uncertainty of the measurement is essential in determining the sample size and the probability of type II errors in hypothesis testing. This is an important factor in determining if ambient PM concentrations exceed regulatory limits. The technique described in this paper can be applied to other measurement systems and is especially useful where there are no methods available to generate these values empirically.     

PM2.5在线监测样品采集的除湿调温系统及其性能

根据国家标准要求,PM2.5的监测需要对采集的颗粒物在15~30℃范围内某一温度下、（50±5）%的相对湿度下进行恒重。因此,PM2.5在线监测时,宜对样品进行即时除湿、调温处理。设计、制作了一套数控气体除湿调温装置,研究了影响该装置运行效果的因素,以优化系统运行的主要参数。结果表明：随着样品气在除湿调温系统内停留时间增长,其除湿量也相应增大,停留时间为27 s时除湿达到平衡;干燥气与样品气的流量比对样品气的除湿有重要影响,流量比从0.5增大到1.17时,除湿率随流量比的增大而上升,流量比为1.17时除湿率最大,达到50.97%,流量比增大到1.33以后直到2.0,随着流量比的增大除湿率反而逐渐降低;系统运行参数的优化设置,即样品气在除湿调温系统内停留时间为27 s,干燥气与样品气流量比的最大值设置为1.17,通过改变干燥气与样品气的流量比来实现对除湿量的精确控制;对含湿量在63.70 g·m-3以下的样品气进行除湿调温处理都可使样品气出气的含湿量符合PM2.5监测的国家标准要求,该除湿系统可满足我国PM2.5日常在线监测对样品气处理的需求。