3.5.2重金属主成分分析
通过对重金属和有机质含量进行相关性分析，可初步得出不同单一重金属和有机质之间可能的共同污染来源。为了进一步探析，在对数据进行特异值标准化处理的基础上，利用SPSS19.0软件对重金属含量做主成分分析，结果如图5和图6所示。
图5 天津城市道路灰尘重金属含量主成分分析箱线图
Fig.5 Boxplot of enrichment factors for heavy metals in urabn street dust of Tianjin
图6 天津城市道路灰尘重金属平均主成分分析
Fig.6 Illustration of total metal concentrations in urabn street dust of Tianjin
in the system of two principal components
12
数据分析得出平均主成分分析中的第一主成分的积累贡献率为33.050%，第二主成分的积累贡献率为57.315%。如图6可知，重金属Cu、Ni、Pb在旋转空间成分图的第一主成分上呈显著正负荷；Cr在第二主成分上呈现明显的正负荷，Cd则呈明显负负荷。众所周知，由于Pb主要来源于工业排放等人类活动，因此分析得出第一主成分主要是人为因素（交通运输污染以及工业污染因素等）影响，第二主成分即以自然因素为主。由图5可知，重金属Cr、Cu、Pb和Ni的四分位距大小适中，不同采样点灰尘中重金属浓度分布较为均匀；而Cd和Cr则存在明显的异常值，其异常值主要是由于采样点位于南开三马路、新开路、黄河道等交通主要干道，汽车尾气排放以及交通运输携带物污染导致Cd和Cr等重金属浓度增加[29]。 4 结论
（1）天津市区和不同环区有机质变异系数较大，道路灰尘中有机质的空间分布差异较大。道路灰尘颗粒粒径表现为双峰，主峰对应粒径较小，且为非正态分布。
（2）天津城市道路灰尘重金属Cd、Cr、Cu、Ni和Pb的平均含量依次为0.99、121.41、100.62、43.35和61.48mg/kg，均超过天津土壤环境背景值；其中Cd、Cr和Cu的空间分布差异较大，Ni和Pb的空间分布差异较小。
（3）运用地积累指数Igeo法对天津城市道路灰尘中重金属进行综合污染评价，Cd、Cr、Cu、Ni和Pb分别为中度污染、无污染、偏中度污染、无污染和轻度污染；运用潜在生态风险指数法对道路灰尘重金属进行生态风险评价，结果表明全市重金属污染的潜在生态风险程度处于较高水平。
（4）通过对天津道路灰尘中重金属和有机质进行相关性分析和主成分分析，辨析出重金属Cu、Ni和Pb主要受人为因素影响，交通尾气排放和工业污染为其主要来源，且以多因子复合影响为主。
参考文献
[1] De-Miguel E, Llamas J F, Chcoan E, et al. Origin and patterns of distribution of trace elements in street dust: unleaded petrol and urban lead [J]. Atmospheric Environment, 1997, 31: 2733-2740. [2] Ferreira-Baptista L, De Miguel E. Geochemistry and risk assessment of street dust in Luanda, Angola: a tropical urban environment [J]. Atmospheric Environment, 2005, 39: 4501-4512.
[3] Kartal S, Aydin Z, Tokalioglu S. Fractionation of metals in street sediment samples by using the BCR sequential extraction procedures and multivariate statistical elucidation of the data [J]. J Hazard mater, 2006, 132(1): 80-89.
13
[4] Duzgoren-Aydin N S, Wong C S C, Aydin A, et al. Heavy metal contamination and distribution in the urban environment of Guangzhou, SE China [J]. Environment Geochemistry and Health, 2006, 28: 375-391.
[5] Ahmed F, Ishiga H. Trace metal concentrations in street dusts of Dhaka city, Bangladesh [J].
Atmospheric Environment, 2006, 40: 3835-3844.
[6] 张菊,陈振楼,许世远,等. 上海城市街道灰尘重金属铅污染现状及评价[J]. 环境科学, 2006, 27(3): 519-523.
[7] Sindern S, Lima R F S, Schwarzbauer J, et al. Anthropogenic heavy metal signatures for the fast growing urban area of Natal (NE-Brazil) [J]. Environmental Geology, 2007, 52: 731-737.
[8] 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.
[9] Morton-Bermea O, Hernandez-Alvarez E, Gonzalez-Hernandez G, et al. Assessment of heavy metal pollution in urban topsoils from the metropolitan area of Mexico City [J]. J Geochem Explor, 2008, 07, 002.
[10] Filiz K, Hasan C. Determination of Cu, Pb, Zn, Ni, Co, Cd, and Mn in road dusts of Samsun City [J].
Environment Monitoring and Assessment, 2010, 168: 241-253.
[11] 王济,张一修,高翔,等. 城市地表灰尘重金属研究进展及展望[J]. 地理研究, 2012, 31(5):
881-830.
[12] 刘培桐,薛纪渝,王华东. 环境学概论[M].北京:高等教育出版社, 1995.
[13] Wood J M. Biological cycles for toxic elements in the environment [J]. Science, 1974, 183:
1049-1052.
[14] Stigliani W M, Doelman P, Salomons W, et al. Chemical time bombs-predicting the unpredictable [J].
Environment, 1991, 33(4): 4-9, 26-30.
[15] Charlesworth S M, Lees J A. The distribution of heavy metals in deposited urban dusts and
sediments, Coventry, England [J]. Environmental and Geochemistry and Health, 1999, 21: 97-115. [16] Shi Gui-tao Chen Zhen-lou, Xu Shi-yuan, et al. Potentially toxic metal contamination of urban soils
and roadside dust in Shanghai, China [J]. Environmental Earth Sciences, 2008, 156(2): 251-260. [17] Wei Bing-gan, Jiang Feng-qing, Li Xue-mei, et al. Contamination levels assessment of potential
toxic metals in road dust deposited in different types of urban environment [J]. Environmental Earth science, 2010, 61: 1187-1196.
[18] Kabata-Pendias A, Pendias H. Trace Metals in Soils and Plants, second edn [M]. CRC Press, Boca
14
Raton, Florida, 1992.
[19] Dockery D W, Pope C A. Acute respiratory effects of particulate air pollution [J]. Annual Reviews of
Public Health. Atomspheric Environment, 1994, 35: 2045-2051.
[20] Sadiq M, Mian A A. Nickel and Vanadium in air particulates at Dharahn (Saudi Arabia) during and
after the Kuwait oil fires [J]. Atmospheric Environment, 1994, 28: 2249-2253.
[21] Crosby D G. Environmental Toxicology and Chemistry [M]. Oxford University Press, New York,
1998.
[22] Aeliona C M, Davisa H T, McDermottb S, et al. Metal concentrations in rural topsoil in south
Carolina: Potential for human health impact [J]. Science of the Total Environment, 2008, 402: 149-156.
[23] 张一修,王济,秦樊鑫,等. 贵阳市道路灰尘和土壤重金属来源识别比较[J]. 环境科学学报, 2012,
32(1): 204-212.
[24] 田晖,周光理,郑巧东,等. 杭州城市灰尘迁移与粒径之间的关系研究[J]. 四川农业大学学报,
2006, 24(4): 422-425.
[25] 马旺海,曹斌,杨进峰,等. 城市重金属污染特征[J]. 中央民族大学学报:自然科学版, 2008, 17(1):
66-78.
[26] 王丽丽,刘敏,欧冬妮,等. 上海城市地表灰尘重金属粒级效应与赋存形态研究[J].华东师范大学:
自然科学版, 2009, 6: 64-70.
[27] He Ling-yan, Hu Min, Zhang Yuan-hang, et al. Chemical characterization of fine particles from
on-road vehicles in the Wutong tunnel in Shenzhen, China [J]. Chemosphere, 2006, 62(10): 1565-1573.
[28] Han Li-hui, Zhuang Guo-shun, Cheng Shui-yuan, et al. Characteristics of re-suspended road dust and
its impact on the atmospheric environment in Beijing [J]. Atmospheric Environment, 2007, 41(35): 7485-7499.
[29] Wei Bing-gan, Jiang Feng-qing, Li Xue-mei, et al. Spatial distribution and contamination assessment
of heavy metals in urban road dust from Urumqi, NW China [J]. Microchemical Journal 2009, 93, 147-152.
[30] 刘申,刘凤枝,李晓华,等. 天津公园土壤重金属污染评价及其空间分析[J]. 生态环境学报, 2010,
19(5): 1097-1102
[31] 郑小康,李春晖,黄国和,等.保定城区地表灰尘污染物分布特征及健康风险评价[J]. 环境科学
学报, 2009, 29(10): 2195-2202.
15
[32] 李如忠,周爱佳,童芳,等. 合肥市城区地表灰尘重金属分布特征及环境健康风险评价[J]. 环境科
学, 2011, 32(9): 2661-2668.
[33] 唐荣莉,马克明,张育新,等. 北京城市道路灰尘重金属污染的健康风险评价[J]. 环境科学学报,
2012, 32(8): 2006-2015.
[34] 杜佩轩,田晖,韩永明. 城市灰尘概念、研究内容与方法[J]. 陕西地质, 2004, 22(1): 73-79. [35] 常静,刘敏,侯立军,等. 城市地表灰尘的概念、污染特征与环境效应[J]. 应用生态学报, 2007,
18(5): 1153-1158.
[36] 史贵涛,陈振楼,张翠,等. 上海市饮用水源地周边环境中的重金属[J]. 环境科学, 2008, 29(7):
1797-1805.
[37] 梁涛,史正涛,吴枫,等. 昆明市街道灰尘重金属污染及潜在生态风险评价[J]. 热带地理, 2011,
31(2): 164-170.
[38] 李章平,陈玉成,杨学春,等. 重庆市主城区街道地表物中重金属的污染特征[J]. 水土保持学报,
2006, 20(1): 114-116, 138.
[39] Charlesworth S M, Everetta M, McCarthy R, et al. A Comparative study of heavy metal
concentration and distribution in deposited street dusts in a large and a small urban area: Birmingham and Coventry, West Midlands, UK [J]. Environment International, 2003, 29: 563-573. [40] Wang Ji, Chen Zhen-lou, Sun Xiao-jing, et al. Quantitative spatial characteristics and environmental
risk of toxic heavy metals in urban dusts of Shanghai, China [J]. Environmental Earth Sciences, 2009, 59: 645-654.
[41] Yasir Faiz, M. Tufail, M. Tayyeb Javed, et al. Road dust pollution of Cd, Cu, Ni, Pb and Zn along
Islamabad Expressway, Pakistan [J]. Microchemical Journal, 2009, 92: 186-192.
[42] 王利,陈振楼,陈晓枫,等. 上海内环高架沿线灰尘重金属污染分析与评价[J]. 环境监测管理与技
术, 2009, 21(5): 35-38.
[43] 程紫润,傅大放. 信号交叉口汽车尾气附加排放量分析[J].公路交通科技, 1993, 10(3): 67-71. [44] Lan Qing, Cui Kun-yan, Zeng Feng, et al. Characteristics and assessment of phthalate esters in urban
dusts in Guangzhou city, China [J]. Environmental monitoring and assessment, 2011, 10: 1107. [45] Shi Gui-tao, Chen Zhen-lou, Bi Chun-juan, et al. Comprehensive assessment of toxic metal in urban
and suburban street deposited sediments (SDSs) in the biggest metropolitan area of China [J]. Environmental Pollution, 2010, 158: 694-703.
[46] 史贵涛,陈振楼,王利,等. 上海城市公园灰尘重金属污染及其潜在生态风险评价[J]. 城市环境与
城市生态, 2006, 19(4): 40-43.
16
[47] 彭景,李泽琴,侯家渝. 地积累指数法及生态危害指数评价法在土壤重金属污染中的应用与探讨
[J]. 广东微量元素科学, 2007, 14(8): 13-17.
[48] 林俊杰,刘丹,方伟,等. 万州道路灰尘重金属空间分布及污染评价[J]. 环境科学与技术, 2011, 10:
89-92.
[49] 康丹. 西安城市公园不同粒径土壤中重金属污染研究[D]. 西安:陕西师范大学, 2010.
[50] 许宇慧,唐亚,张朝生. 四川省九寨沟景区道路灰尘及土壤重金属含量评价[J]. 山地学报, 2010,
28(3): 288-293.
[51] 王利. 上海高架道路沿线街道灰尘中重金属分布及污染评价[D]. 上海:华东师范大学, 2007.
17