Volatile organic pollutants in soil or groundwater migrate into buildings through the aeration zone, leading to the accumulation of indoor pollutants and endangering human health. To study the process and influencing factors of site vapor invasion, using benzene as an example, a one-dimensional J&E analytical model and a two-dimensional approximate analytical AAM model were used to explore the influence of soil property parameters on the vapor attenuation coefficient and indoor vapor attenuation coefficient at the bottom plate of polluted site buildings, And analyze the applicable conditions of the two models. The results show that the indoor vapor concentration (Cin) depends on the vapor concentration (Cck) at the building floor and the rate of soil gas entering the room (Qck) Indoor vapor attenuation coefficient in the J&E model（ α Sin) decreases first and then increases as the depth of the foundation increases, while the indoor vapor attenuation coefficient in the AAM model has been showing an upward trend. The presence of capillaries reduces the vapor attenuation coefficient by 1-2 orders of magnitude, and soil moisture can also effectively block the upward diffusion of vapor. Under low permeability soil conditions, the indoor vapor attenuation coefficients calculated by both models are around 10-4; Under high permeability soil conditions, convection is strong at the building floor, and the vapor concentration at the building floor in the J&E model decreases. The indoor vapor attenuation coefficient is around 10-3, and the vapor concentration at the building floor in the AAM model is a constant value. The indoor vapor attenuation coefficient increases linearly with the change of soil permeability coefficient, and is 1-2 orders of magnitude higher than the results of the J&E model. Research shows that, When there is strong convective action at the bottom of buildings in polluted sites or in sandy or loamy soil, it is more reasonable to use the J&E model; In weak convection or in silt or clay, the AAM model can be used instead of the J&E model to simplify the calculation process and facilitate site risk assessment. Pollutant vapors have strong penetration in sandy soil, while clay layers can effectively block the migration of vapors. In actual site risk management, soil replacement or surface covering with clay can be used to block the migration of vapors
PM2.5 is the main culprit causing haze in multiple provinces and cities in China. Clarifying its spatiotemporal distribution pattern and clarifying its influencing factors has profound implications for the comprehensive management of haze. Based on PM2.5 concentration data from 50 monitoring stations in Shaanxi Province in 2015, spatial data statistics, Kriging interpolation, and Morlet wavelet analysis were used to study the spatiotemporal distribution pattern of PM2.5 concentration in Shaanxi Province, And the grey correlation model was used to explore the influencing factors of PM2.5 concentration. The results showed that: ① the overall PM2.5 concentration in Shaanxi Province showed a seasonal variation pattern of 'high in winter, low in summer, and middle in spring and autumn', a monthly variation pattern of 'U-shaped' fluctuations, a daily variation pattern of periodic pulse fluctuations, and a temporal variation pattern of 'W-shaped' fluctuations; ② The concentration of PM2.5 in Shaanxi Province exhibits a spatial distribution characteristic of 'low in the north and high in the central and southern regions', with significant spatial agglomeration. High value areas in different seasons are concentrated in cities within the Guanzhong Basin with relatively low elevations. This is closely related to the difficulty of air diffusion within the basin, the high frequency of calm and stable weather, and the susceptibility to temperature inversion; ③ The indicator layer with the greatest impact on PM2.5 concentration in Shaanxi Province is the source of PM2.5 pollution (with a weight value of 0.49), followed by urbanization and land use (with a weight value of 0.37), and meteorological and topographic factors have the smallest impact (with a weight value of 0.15). The comprehensive correlation degree of each indicator layer in different cities varies greatly All indicator factors are strongly correlated with PM2.5 concentration. Precipitation, motor vehicle ownership, sulfur dioxide emissions, smoke (dust) emissions, built-up area, population density, and per capita GDP are the main factors affecting PM2.5 concentration in Shaanxi Province. The main factors affecting PM2.5 concentration in various cities have certain spatial differences. Research shows that human activities have a significant impact on PM2.5 in Shaanxi Province, especially with the rapid advancement of urbanization, The continuous growth of relevant indicators such as population, motor vehicles, energy consumption, and total industrial output value will further increase the diversity of PM2.5 sources and the emissions of related pollutants
To investigate the environmental behavior of PBDEs (polybrominated diphenyl ethers) in the atmosphere of Kunming, in March 2014, atmospheric TSP (total suspended particulate matter) and PM2.5 samples were collected from 8 sampling points in Kunming, and 13 homologues of PBDEs attached to them were measured using GC-MS technology, Furthermore, the distribution characteristics and potential risks of PBDEs on TSP and PM2.5 were analyzed. The results showed that the concentration of ∑ PBDE attached to TSP (total mass concentration of polybrominated diphenyl ethers) ranged from 21.10 to 175.00 pg/m3, while the concentration of ∑ PBDE attached to PM2.5 ranged from 17.50 to 149.00 pg/m3, accounting for approximately 35.31% to 85.14% of the ∑ PBDE concentration in TSP, Moreover, high brominated homologues (BDE-138~BDE-209) are more likely to adhere to PM2.5 than low brominated homologues (BDE-17~BDE-99), accounting for approximately 8.50%~61.60% of the concentration of ∑ PBDE. The potential impact on PBDEs in atmospheric particulate matter and the evaluation of air inhalation exposure doses indicate that the DEDay (respiratory daily exposure) of PBDEs in adults and children ranges from 5.28 to 43.75 and 6.90 to 57.23 pg/(kg · d), respectively, The TDI (total daily intake) ranges from 114.78 to 951.09 and 150.00 to 1244.13 pg/(kg · d), respectively, far below the minimum harmless level [1 mg/(kg · d)] The TDI of BDE-99 is 11.09~72.39 and 14.35~94.57 pg/(kg · d), respectively, which are lower than the minimum intake level [260 pg/(kg · d)]. Studies have shown that PBDEs on atmospheric TSP and PM2.5 in Kunming do not pose a health risk to humans
In order to understand the composition characteristics and pollution levels of atmospheric PM2.5 in the extremely arid region of China and the urban area of Hotan City, samples of atmospheric PM2.5 were collected from January to December 2014. Gas chromatography-mass spectrometry (GC-MS), ion chromatography (IC), inductively coupled plasma mass spectrometry (ICP-MS), and elemental analysis were used to analyze PAHs (polycyclic aromatic hydrocarbons), metal elements, and water-soluble inorganic ions The chemical components such as OC (organic carbon) and EC (elemental carbon) showed that the average annual concentration of PM2.5 in the urban area of Hotan City during the sampling period was (770.11 ± 568.01) μ G/m3, showing a trend of highest in summer and lowest in winter; Metal elements, water-soluble inorganic ions, OC, EC, and ∑ 16 PAHs (total polycyclic aromatic hydrocarbons) account for 15.292%, 9.789%, 4.246%, 0.331%, and 0.015% of the mass concentration of PM2.5, respectively. The source analysis of PAHs and metal elements, water-soluble inorganic ions, OC, EC in PM2.5 using PMF (orthogonal matrix factorization method) shows that the main sources of PAHs are coal and gasoline combustion emissions (13.91%), biomass combustion (33.98%) Natural gas combustion (52.11%); The main sources of metal elements, water-soluble inorganic ions, OC, and EC are soil dust (56.49%), oil combustion (25.49%), motor vehicle emissions (10.09%), and coal and biomass combustion (7.93%). Research shows that during the sampling period, dust has a significant impact on the atmospheric PM2.5 composition in the urban area of Hotan City, and is the main source of air pollution in the region
Pub Date : 2018-05-25DOI: 10.13198/j.issn.1001-6929.2018.03.12
李越洋, 姬亚芹, 王士宝, 张蕾, 赵静琦
为研究天津市春季道路降尘PM2.5中重金属污染特征及健康风险，于2015年3月22日-5月23日用降尘缸采集天津市主干道、次干道、支路、快速路道路两侧道路降尘样品，利用再悬浮系统将道路降尘中PM2.5悬浮至滤膜上，并用电感耦合等离子体质谱仪（ICP-MS）测定了PM2.5中7种重金属（Ni、Pb、Cd、As、Mn、Cu和Zn）的质量分数.结果表明：道路降尘PM2.5中Ni、Pb、Cd、As、Mn、Cu和Zn质量分数平均值分别为37.05、82.50、1.73、25.65、380.18、201.08和736.43 mg/kg；Igeo（地累积指数）显示，Cd属于强污染，Zn和Cu属于中到强污染，Pb属于中度污染，As属于轻度污染，Ni和Mn属于无污染；健康风险评价显示，手-口摄入是道路降尘PM2.5中重金属进入人体的主要途径，儿童的暴露剂量和非致癌风险均高于成人，总非致癌风险次序为As > Pb > Mn > Cu > Zn > Cd > Ni，其中儿童手-口途径As的暴露风险商（HQing）及非致癌总风险（HI）均为1.23，大于限值（1），对儿童存在非致癌风险；其他重金属非致癌总风险均低于限值，对人体无非致癌风险；道路降尘PM2.5中Ni、As和Cd通过呼吸途径对人体均无致癌风险.
To study the heavy metal pollution characteristics and health risks of PM2.5 in spring road dust in Tianjin, dust samples were collected from both sides of Tianjin's main, secondary, branch, and expressway roads using a dust collector from March 22 to May 23, 2015. The resuspension system was used to suspend PM2.5 in road dust onto the filter membrane, The mass fractions of seven heavy metals (Ni, Pb, Cd, As, Mn, Cu, and Zn) in PM2.5 were determined using inductively coupled plasma mass spectrometry (ICP-MS). The results showed that the average mass fractions of Ni, Pb, Cd, As, Mn, Cu, and Zn in PM2.5 were 37.05, 82.50, 1.73, 25.65, 380.18, 201.08, and 736.43 mg/kg, respectively; Igeo (Earth Accumulation Index) shows that Cd belongs to strong pollution, Zn and Cu belong to medium to strong pollution, Pb belongs to moderate pollution, As belongs to mild pollution, and Ni and Mn belong to no pollution; The health risk assessment shows that hand to mouth intake is the main pathway for heavy metals in road dust PM2.5 to enter the human body. Children's exposure dose and non carcinogenic risk are higher than adults, and the total non carcinogenic risk order is As>Pb>Mn>Cu>Zn>Cd>Ni. Among them, the exposure risk quotient (HQing) and non carcinogenic total risk (HI) of children's hand to mouth route As are 1.23, which is greater than the limit value (1), indicating a non carcinogenic risk for children; The total non carcinogenic risk of other heavy metals is below the limit, and there is no non carcinogenic risk to the human body; Ni, As, and Cd in road dust PM2.5 have no carcinogenic risk to humans through respiratory pathways
In order to explore the chemical characteristics and sources of water-soluble ions in the summer atmospheric particulate matter of typical "cluster" cities - Zibo City, PM2.5 and PM10 were simultaneously sampled in August 2016 at 6 urban points (Huantai, Zhangdian, Linzi, Zichuan, Boshan, Zhoucun), 2 suburban points (Yiyuan, Gaoqing), and 1 clean control point (Lushan) in Zibo City. The spatial distribution characteristics of atmospheric particulate matter mass concentration and 9 water-soluble ions were analyzed, And principal component analysis was used to explore the main sources of water-soluble ions in PM2.5 and PM10. The results showed that: ① The daily mean range of PM2.5 and PM10 mass concentrations at various points in Zibo during summer (excluding clean control points) was 57.2-112 and 77.4-163, respectively μ G/m3, the spatial distribution characteristics are as follows: urban points>suburban points>clean control points; The PM2.5/PM10 (mass concentration ratio) at each point ranges from 0.61 to 0.80, indicating that PM2.5 is the main source of atmospheric particulate matter pollution in summer in Zibo. ② The proportion of water-soluble ions in PM2.5 and PM10 is 53.3% and 48.5%, respectively, with secondary inorganic ions accounting for 91.4% and 83.7% of the total ion concentration, indicating that atmospheric particulate matter is mainly composed of secondary ions and mainly enriched in PM2.5; The molar concentration ratio of ∑ anions/∑ cations in PM2.5 is 1.07, while in PM10, the ratio is 0.87, indicating that PM2.5 is close to neutral while PM10 is weakly alkaline The ion sources at various points in Zibo during summer have certain spatial differences. The CD (divergence coefficient) between urban, suburban, and clean control points is higher than 0.2, while the CD value between urban points is lower than 0.2, indicating that the chemical properties of water-soluble ions between urban points are relatively similar. ④ Principal component analysis shows that the water-soluble ions in summer atmospheric PM2.5 in Zibo may mainly come from industrial sources, biomass boilers, coal combustion, secondary sources, road dust, and construction dust, while the ions in PM10 mainly come from road dust, construction dust, sea salt, and secondary sources. Research shows that particulate matter pollution in Zibo is severe and has obvious spatial distribution characteristics. The sources of water-soluble ions are complex, and zoning should be adopted Pollution prevention and control measures for multi-source control
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