-
作为典型的非点源污染,城市地表灰尘可通过重力等自身因素以及各种人为活动累积到地面或建筑物表面中,目前已经成为城市地表分布最为广泛的污染物载体之一[1].大气积尘作为地表灰尘的一种,其累积来源十分复杂,例如地表土壤扬尘可通过风力的水平迁移和自身重力导致的二次沉降使得积尘在水平与垂直方向上出现空间累积差异,交通排放的尾气颗粒物也可以在风力等作用下造成积尘的累积,王萧等[2]对北京市大气灰尘研究发现其来源也受到周围沙地的影响.
随着中国城市化进程加快,经济快速发展,各种能源消耗的增加所带来的大气污染会对城市和人类健康产生一系列不利影响.近年来,对于大气积尘重金属的研究主要为分析其污染特征、健康风险评价,来源解析等,主要的研究方法有地累积指数法[3]、富集因子法[4]、潜在生态健康评价法[5]、主成分分析法[6]、PMF[7]等方法.Wang等[8]通过富集因子法和因子分析法对2008—2009年北京市地面降尘来源研究发现,通过风蚀作用而使农田产生的土壤粉尘是其主要来源,建筑扬尘是第二贡献者,汽车尾气次之;刘玥等[9]用PMF法对地表灰尘的来源进行分析发现土壤、燃煤和交通是其主要污染源.稀土元素(REE)的化学性质较为稳定,在风化、搬运等作用中不易受到影响,可以作为示踪元素来研究大气降尘来源[10],目前对于稀土元素的研究多为其浓度、地球化学特征[11]和来源解析[12]等,Wang等[13]对厦门市PM2.5中稀土元素的分布及来源研究发现,稀土元素并非以当地天然土壤为主,并且城市PM2.5中的稀土元素主要来自汽油车和柴油车尾气,郊区PM2.5中的稀土元素主要来自汽油车尾气.
近年来,对于大气积尘中微量元素的研究大多数以近地面水平方向为主,在其垂直高度上的研究较少.马志强[14]对大气垂直污染物的分布研究中发现,人类日常的生活生产活动早已达到了100 m以上,导致在垂直高度上污染物进行累积.本文研究了北京市近地面不同高度上积尘的微量金属元素包括11种重金属和14种稀土元素污染水平和来源解析,揭示其在垂直高度微量金属变化特征,为研究积尘在垂直高度上的污染防治提供科学依据.
北京城区秋季不同高度积尘中微量元素污染特征及源解析
Characteristics and source analysis of trace element pollution in dust accumulated at different heights in Beijing
-
摘要: 为研究北京市城区大气积尘中微量元素在不同高度下的污染特征及来源,于2021年9—11月采集了积尘样品,用电感耦合等离子体质谱仪ICP-MS(8800)分析了11种重金属元素(Mn、Zn、Cu、Cr、Pb、V、Ni、As、Co、Mo、Cd)和14种稀土元素,采用地累积指数法、富集因子法、配分模式图和主成分分析法对其进行污染特征和来源分析.结果表明,11种重金属元素的浓度从低层至中层逐渐升高,低层与高层浓度相差不大,Zn元素浓度从中层至高层呈上升趋势,在高层出现最大值584.3 mg·kg−1,而V、Mn、Ni、Cu等元素浓度从中层至高层降低,14种稀土元素浓度均在中层最低,其浓度在所有高度下均未超出环境背景值.地累积指数结果表明, Cd元素在中层污染最为严重,污染等级为4级,Zn元素在高层污染最为严重,污染等级为2级,而As、Mn、Mo、Co、V污染程度均为无污染,但相对于低层与高层,中层污染指数较高.通过富集因子、配分模式图和主成分分析结果显示,14种稀土元素来源为自然源,11种重金属元素来源为地壳源、交通源和燃烧源.Abstract: To study the pollution characteristics and sources of trace elements in Beijing's atmospheric dust at different heights, dust samples were collected from November to December, 2021, and the contents of 11 heavy metals (Mn, Zn, Cu, Cr, Pb, V, Ni, As, Co, Mo, Cd) and 14 rare earth elements were analyzed by ICP-MS(8800). The results show that the contents of 11 heavy metal elements gradually increase from the lower layer to the middle layer, and the contents of the lower layer and the upper layer are not much different, while the maximum value of Zn element is 584.3 mg·kg−1 in the upper layer, and the concentrations of 14 rare earth elements are all in the middle layer and the bottom region, and their contents do not exceed the environmental background values at all heights. The results of the ground accumulation index show that Cd elements are the most polluted in the middle layer with pollution level 4, Zn elements are the most polluted in the upper layer with pollution level 2, while As, Mn, Mo, Co, V pollution levels are non-polluted, but the pollution index is higher in the middle layer compared to the lower and upper layers. The results of enrichment factors and principal component analysis show that 14 rare earth elements are from crustal sources and 11 heavy metals are from crustal, traffic and combustion sources.
-
Key words:
- dust accumulation /
- different heights /
- heavy metals /
- rare earth elements /
- pollution characteristics /
- sources
-
表 1 不同高度积尘重金属地累积指数
Table 1. Geoaccumulation index of heavy metals in dust at different heights
元素
Elements地累积指数
Ground Accumulation Index低层(6 m)
Low Level中层(17 m)
Middle Level高层(41 m)
High LevelV −0.80 −0.67 −0.91 Cr −0.26 0.16 −0.13 Mn −0.40 −0.31 −0.46 Co −0.85 −0.55 −1.02 Ni −0.04 0.40 0.03 Cu 1.40 1.93 1.41 Zn 1.55 1.70 1.88 As −0.58 −0.42 −0.63 Mo −1.42 −0.91 −1.10 Cd 3.02 3.46 2.99 Pb 1.14 1.24 0.93 表 2 不同高度积尘重金属地累积指数分级
Table 2. Grading of the geoaccumulation index of heavy metals in dust at different heights
元素
Elements地累积指数级别
Ground Cumulative Index Level低层(6 m)
Low Level中层(17 m)
Middle Level高层(41 m)
High LevelV 0 0 0 Cr 0 1 0 Mn 0 0 0 Co 0 0 0 Ni 0 1 1 Cu 2 2 2 Zn 2 2 2 As 0 0 0 Mo 0 0 0 Cd 4 4 3 Pb 2 2 2 表 3 不同高度积尘稀土元素特征参数
Table 3. Characteristic parameters of rare earth elements in dust at different heights
特征参数
Characteristic parameters低层(6 m)
Low Level中层(17 m)
Middle Level高层(41 m)
High LevelΣREE 179.24 176.36 184.32 ΣLREE 145.99 144.13 146.60 ΣHREE 33.26 32.23 37.72 ΣLREE/HREE 4.39 4.47 3.89 δEu 0.90 0.80 0.91 δCe 1.31 1.75 1.04 (La/Yb)N 11.75 9.17 11.65 (La/Sm)N 3.54 3.13 3.10 (Gd/Yb)N 2.07 1.92 2.42 表 4 不同高度积尘重金属主成分分析
Table 4. Principal component analysis of heavy metals in dust at different heights
变量元素
Variable elements因子负荷
Factor load1 2 3 V 0.57 0.48 0.51 Cr 0.47 0.68 −0.15 Mn −0.01 0.84 0.42 Co 0.80 0.39 0.11 Ni 0.87 0.26 −0.03 Cu 0.33 0.86 0.03 Zn 0.76 −0.12 0.27 As 0.83 0.31 0.26 Mo 0.25 0.92 0.17 Cd 0.17 0.11 0.87 Pb 0.61 0.29 0.06 特征值 3.8 3.4 1.4 方差贡献率% 34.3 31.3 12.6 累计贡献率% 34.3 65.6 78.2 -
[1] CHANG J, LIU M, HOU L J, et al. Concept, pollution character and environmental effect of urban surface dust[J]. Ying Yong Sheng Tai Xue Bao = the Journal of Applied Ecology, 2007, 18(5): 1153-1158. [2] 王萧. 北京市街道灰尘地球化学特征及物源分析[D]. 北京: 中国地质大学(北京), 2021. WANG X. Geochemical characteristics and source analysis of street dust in Beijing[D]. Beijing: China University of Geosciences, 2021 (in Chinese).
[3] LOSKA K, WIECHUŁA D, KORUS I. Metal contamination of farming soils affected by industry[J]. Environment International, 2004, 30(2): 159-165. doi: 10.1016/S0160-4120(03)00157-0 [4] WANG X H, BI X H, SHENG G Y, et al. Chemical composition and sources of PM10 and PM2.5 aerosols in Guangzhou, China[J]. Environmental Monitoring and Assessment, 2006, 119(1): 425-439. [5] NKANSAH M A, OPOKU F, ACKUMEY A A. Risk assessment of mineral and heavy metal content of selected tea products from the Ghanaian market[J]. Environmental Monitoring and Assessment, 2016, 188(6): 332. doi: 10.1007/s10661-016-5343-y [6] XIA D S, WANG B, YU Y, et al. Combination of magnetic parameters and heavy metals to discriminate soil-contamination sources in Yinchuan—a typical oasis city of Northwestern China[J]. Science of the Total Environment, 2014, 485/486: 83-92. doi: 10.1016/j.scitotenv.2014.03.070 [7] TAN J H, DUAN J C, CHAI F H, et al. Source apportionment of size segregated fine/ultrafine particle by PMF in Beijing[J]. Atmospheric Research, 2014, 139: 90-100. doi: 10.1016/j.atmosres.2014.01.007 [8] WANG R D, ZOU X Y, CHENG H, et al. Spatial distribution and source apportionment of atmospheric dust fall at Beijing during spring of 2008-2009[J]. Environmental Science and Pollution Research, 2015, 22(5): 3547-3557. doi: 10.1007/s11356-014-3583-3 [9] 刘玥, 郭文强, 武晔秋. 基于PMF模型的大同市城区公园地表灰尘中重金属污染评价及来源解析[J]. 环境化学, 2022, 41(5): 1616-1628. doi: 10.7524/j.issn.0254-6108.2021091103 LIU Y, GUO W Q, WU Y Q. Pollution assessment and source analysis of surface dust heavy metals in parks of Datong city based on Positive matrix factorization model[J]. Environmental Chemistry, 2022, 41(5): 1616-1628 (in Chinese). doi: 10.7524/j.issn.0254-6108.2021091103
[10] TANG Y, HAN G L, WU Q X, et al. Use of rare earth element patterns to trace the provenance of the atmospheric dust near Beijing, China[J]. Environmental Earth Sciences, 2013, 68(3): 871-879. doi: 10.1007/s12665-012-1791-z [11] 张棕巍, 于瑞莲, 胡恭任, 等. 泉州市大气降尘中稀土元素地球化学特征及来源解析[J]. 环境科学, 2016, 37(12): 4504-4513. ZHANG Z W, YU R L, HU G R, et al. Geochemical characteristics and source apportionment of rare earth elements in the dustfall of Quanzhou city[J]. Environmental Science, 2016, 37(12): 4504-4513 (in Chinese).
[12] GWENZI W, MANGORI L, DANHA C, et al. Sources, behaviour, and environmental and human health risks of high-technology rare earth elements as emerging contaminants[J]. Science of the Total Environment, 2018, 636: 299-313. doi: 10.1016/j.scitotenv.2018.04.235 [13] WANG S S, YU R L, HU G R, et al. Distribution and source of rare earth elements in PM2.5 in Xiamen, China[J]. Environmental Toxicology and Chemistry, 2017, 36(12): 3217-3222. doi: 10.1002/etc.3902 [14] 马志强, 王跃思, 孙扬, 等. 北京大气中常规污染物的垂直分布特征[J]. 环境科学研究, 2007, 20(5): 1-6. MA Z Q, WANG Y S, SUN Y, et al. Characteristics of vertical air pollutants in Beijing[J]. Research of Environmental Sciences, 2007, 20(5): 1-6 (in Chinese).
[15] 胡永兴, 宿虎, 张斌, 等. 土壤重金属污染及其评价方法概述[J]. 江苏农业科学, 2020, 48(17): 33-39. HU Y X, SU H, ZHANG B, et al. Soil heavy metal pollution and its evaluation methods: A review[J]. Jiangsu Agricultural Sciences, 2020, 48(17): 33-39 (in Chinese).
[16] 李友平, 刘慧芳, 周洪, 等. 成都市PM2.5中有毒重金属污染特征及健康风险评价[J]. 中国环境科学, 2015, 35(7): 2225-2232. LI Y P, LIU H F, ZHOU H, et al. Contamination characteristics and health risk assessment of toxic heavy metals in PM2.5 in Chengdu[J]. China Environmental Science, 2015, 35(7): 2225-2232 (in Chinese).
[17] ZOLLER W H, GLADNEY E S, DUCE R A. Atmospheric concentrations and sources of trace metals at the South pole[J]. Science, 1974, 183(4121): 198-200. doi: 10.1126/science.183.4121.198 [18] 李丽娟, 温彦平, 彭林, 等. 太原市采暖季PM2.5中元素特征及重金属健康风险评价[J]. 环境科学, 2014, 35(12): 4431-4438. LI L J, WEN Y P, PENG L, et al. Characteristic of elements in PM2.5 and health risk assessment of heavy metals during heating season in Taiyuan[J]. Environmental Science, 2014, 35(12): 4431-4438 (in Chinese).
[19] 孔春霞, 郭胜利, 汤莉莉. 南京市生活区夏秋季节大气颗粒物垂直分布特征[J]. 环境科学与管理, 2009, 34(11): 35-38. KONG C X, GUO S L, TANG L L. Vertical distribution characteristics of atmospheric particles in summer and autumn in Nanjing[J]. Environmental Science and Management, 2009, 34(11): 35-38 (in Chinese).
[20] 倪刘建, 张甘霖, 阮心玲, 等. 南京市不同功能区大气降尘的沉降通量及污染特征[J]. 中国环境科学, 2007, 27(1): 2-6. NI L J, ZHANG G L, RUAN X L, et al. The flux and pollution character of dust-fall in different functional zones of Nanjing[J]. China Environmental Science, 2007, 27(1): 2-6 (in Chinese).
[21] 张舒婷, 李晓燕, 陈思民. 贵阳市不同空间高度灰尘和重金属沉降通量[J]. 中国环境科学, 2015, 35(6): 1630-1637. ZHANG S T, LI X Y, CHEN S M. Vertical characteristics of deposition fluxes of dust and heavy metals of Guiyang City[J]. China Environmental Science, 2015, 35(6): 1630-1637 (in Chinese).
[22] 刘红年, 苗世光, 蒋维楣, 等. 城市建筑动力学效应对对流边界层影响的敏感性试验[J]. 气象科学, 2008, 28(6): 599-605. LIU H N, MIAO S G, JIANG W M, et al. The sensitivity study on the effect of city buildings’ dynamics on turbulence characteristic of convective boundary layer[J]. Scientia Meteorologica Sinica, 2008, 28(6): 599-605 (in Chinese).
[23] 谢华林, 张萍, 贺惠, 等. 大气颗粒物中重金属元素在不同粒径上的形态分布[J]. 环境工程, 2002, 20(6): 55-57, 5. doi: 10.3969/j.issn.1000-8942.2002.06.018 XIE H L, ZHANG P, HE H, et al. Distribution of heavy metal elements in the different diametral atmospheric particulate matters[J]. Environmental Engineering, 2002, 20(6): 55-57, 5 (in Chinese). doi: 10.3969/j.issn.1000-8942.2002.06.018
[24] 王章玮. 大气中的稀土元素及稀土农用对温室气体排放的影响[D]. 南宁: 广西大学, 2003. WANG Z W. Rare earth elements of atmosphere and effects of rare earth elements on emissions of greenhouse gases[D]. Nanning: Guangxi University, 2003 (in Chinese).
[25] 吴铎, 魏海涛, 赵瑞瑞, 等. 兰州市室内大气降尘环境磁学特征及其随高度变化研究[J]. 环境科学, 2014, 35(1): 79-84. WU D, WEI H T, ZHAO R R, et al. Magnetic properties of indoor dustfall at different heights in Lanzhou[J]. Environmental Science, 2014, 35(1): 79-84 (in Chinese).
[26] XIONG Q L, ZHAO W J, GUO X Y, et al. Distribution characteristics and source analysis of dustfall trace elements during winter in Beijing[J]. Huan Jing Ke Xue= Huanjing Kexue, 2015, 36(8): 2735-2742. [27] NARGIS A, HABIB A, ISLAM M N, et al. Source identification, contamination status and health risk assessment of heavy metals from road dusts in Dhaka, Bangladesh[J]. Journal of Environmental Sciences (China), 2022, 121: 159-174. doi: 10.1016/j.jes.2021.09.011 [28] 王利军, 卢新卫, 雷凯, 等. 宝鸡市街尘重金属元素含量、来源及形态特征[J]. 环境科学, 2011, 32(8): 2470-2476. WANG L J, LU X W, LEI K, et al. Content, source and speciation of heavy metal elements of street dusts in Baoji city[J]. Environmental Science, 2011, 32(8): 2470-2476 (in Chinese).
[29] GIOIA S M C L, BABINSKI M, WEISS D J, et al. An isotopic study of atmospheric lead in a megacity after phasing out of leaded gasoline[J]. Atmospheric Environment, 2017, 149: 70-83. doi: 10.1016/j.atmosenv.2016.10.049 [30] PAN H Y, LU X W, LEI K. A comprehensive analysis of heavy metals in urban road dust of Xi'an, China: Contamination, source apportionment and spatial distribution[J]. Science of the Total Environment, 2017, 609: 1361-1369. doi: 10.1016/j.scitotenv.2017.08.004 [31] AMATO F, PANDOLFI M, VIANA M, et al. Spatial and chemical patterns of PM10 in road dust deposited in urban environment[J]. Atmospheric Environment, 2009, 43(9): 1650-1659. doi: 10.1016/j.atmosenv.2008.12.009 [32] 息朝庄, 吴林锋, 张鹏飞, 等. 贵州省惠水土壤-灌溉水-雨水-大气降尘中Cd、As等微量元素特征及来源讨论[J]. 中国地质, 2023, 50(1): 192-205. XI C Z, WU L F, ZHANG P F, et al. Characteristics and sources of Cd and As trace elements in soil-irrigation-rainwater-atmospheric dust-fall in Huishui County, Guizhou Province[J]. Geology in China, 2023, 50(1): 192-205 (in Chinese).
[33] 刘进, 潘月鹏, 师华定. 华北地区农田土壤镉来源及大气沉降的贡献[J]. 农业环境科学学报, 2022, 41(8): 1698-1708. LIU J, PAN Y P, SHI H D. Atmospheric deposition as a dominant source of cadmium in agricultural soils of North China[J]. Journal of Agro-Environment Science, 2022, 41(8): 1698-1708 (in Chinese).