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摘 要:环境磁学具有简便、快捷、经济和无破坏性等特点,在大气颗粒物污染中发挥了重要作用。该研究总结了环境磁学在大气颗粒物污染中的研究进展,包括指示污染程度划分污染范围、分离污染源和示踪沉积过程、重建区域污染历史这3个方面。最后根据环境磁学本身的特点,指出环境磁学未来的发展方向是大气颗粒物重金属示踪及源解析。
关键词:环境磁学 大气颗粒物 重金属 磁学参数
中图分类号:X823 文献标识码:A文章编号:1672-3791(2021)06(a)-0048-06
Research Progress of Environmental Magnetism in Atmospheric Particulate Pollution
SU Zhihua
(School of Management Science and engineering, Guizhou University of Finance and Economics, Guiyang, Guizhou Province, 550025 China)
Abstract: Environmental Magnetism has the characteristics of simplicity, rapidity, economy and non-destructive, and plays an important role in atmospheric particulate pollution. This study summarizes the research progress of environmental magnetism in atmospheric particulate matter pollution, including indicating pollution degree, dividing pollution scope, separating pollution sources and tracing deposition process, and reconstructing regional pollution history. Finally, according to the characteristics of Environmental Magnetism, it is pointed out that the future development direction of Environmental Magnetism is heavy metal tracing and source analysis of atmospheric particulate matter.
Key Words: Environmental magnetism; Atmospheric particulate matter; Heavy metal; Magnetic parameters
大氣颗粒物是大气中存在的各种固态和液态颗粒状物质的总称,根据粒径不同可分为总悬浮颗粒物(TSP)、可吸入颗粒物(PM10)和细颗粒物(PM2.5)等[1]。粒径是评估大气颗粒物毒性和危害性的重要参数,粒径越小通常对生物和环境的影响就越大。大气颗粒物可吸附各种重金属、有机化合物等有毒有害物质,是大气中多种污染物的“载体”和“催化剂”[2]。另外,大气颗粒物对光有吸收和散射效果,会引起大气能见度下降,并进一步诱发雾霾天气[3]。大气颗粒物的化学组成(尤其是微量重金属组分)决定了污染物的毒性效应,对人体健康具有特殊意义[4-5]。因此,研究大气颗粒物的组成成分及变化显得尤为重要。化学分析方法(比如AAS和ICP-MS)一直是分析大气颗粒物成分的传统方法,但该方法操作复杂,容易污染环境和经济成本较高,不适合进行实时动态监测和大范围使用[6-7]。
环境磁学通过研究环境中磁性矿物的变化规律,依据磁性参数的涵义研究环境过程与人类活动的关系,揭示环境变化的规律和驱动机制。伴随着磁学仪器的不断改良,磁学参数的测试越来越简便、快速、准确、无损和环保,对于监测大气颗粒物污染越来越有利[8-9]。各种环境系统均不同程度地含有外源性磁性污染物,其磁性特征与自然环境中原生和次生的磁性矿物在结构、形态、类型、浓度及粒径组成上均存在显著差异[8-10]。另外,环境介质中的磁性往往与赋存其上的重金属含量相关,磁性颗粒是重金属的强吸附剂和载体[11]。这两个要素是环境磁学监测大气颗粒物污染的理论基础。
1 主要的磁学参数
环境磁学通过对磁性矿物载体进行系统的磁参数测量,应用相关比值及岩石磁学实验判断样品中磁性矿物的含量、磁畴状态、种类及其组合关系,从而提取物质来源、形成环境、搬运过程和沉积作用等综合信息,进而判定污染情况。在所有的磁学参数中,磁化率是磁性矿物含量的重要替代指标,应用最为广泛。质量磁化率(χ)和低频率磁化率(χfd)通常可用来指示较为严重的污染[12]。另外,饱和等温剩磁(SIRM)可作为铁磁性矿物含量的粗略量度,特别是当样品磁性很弱时,SIRM可取代磁化率而成为大气微粒的指示器[13]。非磁滞剩磁(ARM)反映了磁性矿物颗粒的磁畴信息,由单畴晶粒的含量控制,χARM是单位偏转场下的单位质量非磁滞剩磁[14]。虽然χ、SIRM和ARM在某种程度上均可指示磁性矿物的含量,但SIRM和ARM还受到形状和粒度等因素的影响,而χ受粒度的影响最小(SP颗粒除外),测量最为方便,是反映磁性矿物含量常用指标[15]。χfd、ARM/χ、SIRM/χ、ARM/SIRM、Day图和FORC图是指示磁性矿物粒度的代用指标,ARM获得曲线和反向退磁曲线、磁化率随温度变化曲线(χ-T曲线)、剩磁温度变化曲线(J-T曲线)及磁滞回线(magnetic hysteresis loop)主要用于判别磁性矿物种类与组成[16]。 3.2 环境磁学未来的发展方向
介于化学分析得到的元素含量不能准确地反映污染物来源,而环境磁学可以通过分析样品磁性颗粒的种类、形貌及其磁学参数来反映其来源。因此,环境磁学未来的研究重点是探索环境磁学相对于地球化学在源解析方面的优势,重点关注颗粒物重金属源解析及示踪,将环境磁学与地球化学结合,并开展更深入的微观研究,例如电子探针、透射电镜、同步辐射等,以准确地了解磁性颗粒的微观结构与组成特征,从而获得更准确的源解析结果。
参考文献
[1] 汪蕊,丁建丽,马雯,等.基于PSCF与CWT模型的乌鲁木齐市大气颗粒物源区分析[J/OL].环境科学学报:1-10[2021-07-09].https://doi.org/10.13671/j.hjkxxb.2021.0044.
[2] OU J p,ZHENG L g,TANG Q, et al.Source Analysis of Heavy Metals in Atmospheric Particulate Matter in a Mining City[J].Environmental Geochemistry and Health, 2021(619–620):1-13.
[3] 曲金华,张志慧.阴霾天气的元凶——PM2.5[J].科技资讯,2012(35):140.
[4] 郑新梅,谢放尖,李文青.南京市电力行业大气颗粒物排放及减排对策分析[J].科技资讯,2015,13(32):118-119.
[5] 丁新航,梁越,肖化云,等.太原市采暖季清洁天与灰霾天PM2.5中水溶性无机离子组成及来源分析[J].环境化学,2019,38(6):1356-1366.
[6] LI H m,QIAN X,HU W,et al.Chemical Speciation and Human Health Risk of Trace Metals in Urban Street Dusts from a Metropolitan City,Nanjing,SE China[J].Science of the Total Environment, 2013(456-457):212-221.
[7] ZHANG C X,QIAO Q Q,PIPER J D A, et al.Assessment of Heavy Metal Pollution from a Fe-smelting Plant in Urban River Sediments Using Environmental Magnetic and Geochemical Methods[J].Environmental Pollution,2011,159(10): 3057-3070.
[8] HAY K L,DEARING J A,BABAN S M J,et al.A Preliminary Attempt to Identify Atmospherically-derived Pollution Particles in English Topsoils from Magnetic Susceptibility Measurements[J].Physics and Chemistry of the Earth,1997,22(1):207–210.
[9] LI X L,YANG Y,YANG J X,et al.Rapid Diagnosis of Heavy Metal Pollution in Lake Sediments Based on Environmental Magnetism and Machine Learning[J].Journal of Hazardous Materials,2021(416):26-163.
[10] BLUNDELL A,DEARING J A,BOYLE J F,et al.Controlling factors for the spatial variability of soil magnetic susceptibility across England and Wales[J].Earth-Science Reviews,2009,95(3-4):158-188.
[11] WANG G,OLDFIELD F,XIA D S,et al.Magnetic Properties and Correlation with Heavy Metals in Urban Street Dust:A Case Study from the City of Lanzhou,China[J].Atmospheric Environment,2011,46:289-298.
[12] 閆慧,吴国玺,李京忠,等.许昌市路尘磁化率空间分布特征及其污染指示意义[J].热带地理,2013,33(2):219-223.
[13] HUNT A.The Application of Mineral Magnetic Methods to Atmospheric Aerosol Discrimination[J]. Physics of the Earth and Planetary Interiors,1986, 42(1-2):10-21.
[14] Evans M E,Heller F.Environmental Magnetism: Principles and Applications of Enviromagnetics[M]. london Acdemic Press,2003:69-74. [15] 刘青松, 邓成龙, 潘永信. 磁铁矿和磁赤铁矿磁化率的温度和频率特性及其环境磁学意义[J].第四纪研究,2007,27(6):955-962.
[16] 尹刚,胡守云,闫海涛.不同环境污染载体的磁学研究及其应用特点[J].地球物理学进展,2012,27(5):1947-1956.
[17] WEBER S,HOFFMANN P,ENSLING J,et al. Characterization of Iron Compounds from Urban and Rural Aerosol Sources[J].Journal of Aerosol Science,2000,31(8):987-997.
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[19] 聂燕,王新,王博,等.西北典型工矿型城市街道尘埃重金属污染的环境磁学响应[J].环境科学,2015,36(9):3438-3446.
[20] WU Y F,SHI Y,ZHANG N,et al. Pollution Levels, Characteristics, and Sources of Polycyclic Aromatic Hydrocarbons in Atmospheric Particulate Matter Across the Hu Line in China.A Review[J].Environmental Chemistry Letters,2021(2):1-16.
[21] ZHANG C X,HUANG B C,LI Z Y, et al.Magnetic Properties of High-Road-Side Pine Tree Leaves in Beijing and Their Environmental Significance[J].Chinese Science Bulletin,2006,51(24):3041-3052.
[22] 曹丽婉,胡守云,APPEL E,等.临汾市树叶磁性的时空变化特征及其对大气重金属污染的指示[J].地球物理学报,2016,59(5):1729-1742.
[23] ROBERTSON D,TAYLOR K,HOON S.Geochemical and Mineral Magnetic Characterisation of Urban Sediment Particulates,Manchester,UK[J].Applied Geochemistry,2003,18(2):269-282.
[24] GODDU S R,APPEL E,JORDANOVA D,et al. Magnetic Properties of Road Dust from Visakhapatnam (India)-relationship to Industrial Pollution and Road Traffic[J]. Physics and Chemistry of the Earth,2004,29(13):985-995.
[25] 李勇,邹长明,姚洁.不同源区大气降尘的磁学性质及其环境意义[J].华东师范大学学报:自然科学版,2016(4):158-168.
[26] 陈姣,王冠.环境磁学在城市地表灰尘重金属污染研究中的应用[J].中国环境监测,2016,32(3):99-104.
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[29] OLDFIELD F.Toward the Discrimination of Fine-grained Ferrimagnets by Magnetic Measurements in Lake and Near-shore Marine Sediments[J].Journal of Geophysical Research: Earth Surface,1994, 99(B5):9045-9050.
[30] MORRIS W A,VERSTEEG J K,MARVIN C H, et al.Preliminary Comparisons between Magnetic Susceptibility and Polycyclic Aromatic Hydrocarbon Content in Sediments from Hamilton Harbour, Western Lake Ontario[J].Science of The Total Environment,1994,152(2):153-160.
[31] 張春霞,黄宝春,骆仁松,等.钢铁厂附近树木年轮的磁学性质及其环境意义[J].第四纪研究,2007,27(6):1092-1104.
[32] MA M M,HU S Y,CAO L W,et al.Atmospheric Pollution History at Linfen (China) Uncovered by Magnetic and Chemical Parameters of Sediments from a Water Reservoir[J].Environmental Pollution, 2015(204): 161-172.
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关键词:环境磁学 大气颗粒物 重金属 磁学参数
中图分类号:X823 文献标识码:A文章编号:1672-3791(2021)06(a)-0048-06
Research Progress of Environmental Magnetism in Atmospheric Particulate Pollution
SU Zhihua
(School of Management Science and engineering, Guizhou University of Finance and Economics, Guiyang, Guizhou Province, 550025 China)
Abstract: Environmental Magnetism has the characteristics of simplicity, rapidity, economy and non-destructive, and plays an important role in atmospheric particulate pollution. This study summarizes the research progress of environmental magnetism in atmospheric particulate matter pollution, including indicating pollution degree, dividing pollution scope, separating pollution sources and tracing deposition process, and reconstructing regional pollution history. Finally, according to the characteristics of Environmental Magnetism, it is pointed out that the future development direction of Environmental Magnetism is heavy metal tracing and source analysis of atmospheric particulate matter.
Key Words: Environmental magnetism; Atmospheric particulate matter; Heavy metal; Magnetic parameters
大氣颗粒物是大气中存在的各种固态和液态颗粒状物质的总称,根据粒径不同可分为总悬浮颗粒物(TSP)、可吸入颗粒物(PM10)和细颗粒物(PM2.5)等[1]。粒径是评估大气颗粒物毒性和危害性的重要参数,粒径越小通常对生物和环境的影响就越大。大气颗粒物可吸附各种重金属、有机化合物等有毒有害物质,是大气中多种污染物的“载体”和“催化剂”[2]。另外,大气颗粒物对光有吸收和散射效果,会引起大气能见度下降,并进一步诱发雾霾天气[3]。大气颗粒物的化学组成(尤其是微量重金属组分)决定了污染物的毒性效应,对人体健康具有特殊意义[4-5]。因此,研究大气颗粒物的组成成分及变化显得尤为重要。化学分析方法(比如AAS和ICP-MS)一直是分析大气颗粒物成分的传统方法,但该方法操作复杂,容易污染环境和经济成本较高,不适合进行实时动态监测和大范围使用[6-7]。
环境磁学通过研究环境中磁性矿物的变化规律,依据磁性参数的涵义研究环境过程与人类活动的关系,揭示环境变化的规律和驱动机制。伴随着磁学仪器的不断改良,磁学参数的测试越来越简便、快速、准确、无损和环保,对于监测大气颗粒物污染越来越有利[8-9]。各种环境系统均不同程度地含有外源性磁性污染物,其磁性特征与自然环境中原生和次生的磁性矿物在结构、形态、类型、浓度及粒径组成上均存在显著差异[8-10]。另外,环境介质中的磁性往往与赋存其上的重金属含量相关,磁性颗粒是重金属的强吸附剂和载体[11]。这两个要素是环境磁学监测大气颗粒物污染的理论基础。
1 主要的磁学参数
环境磁学通过对磁性矿物载体进行系统的磁参数测量,应用相关比值及岩石磁学实验判断样品中磁性矿物的含量、磁畴状态、种类及其组合关系,从而提取物质来源、形成环境、搬运过程和沉积作用等综合信息,进而判定污染情况。在所有的磁学参数中,磁化率是磁性矿物含量的重要替代指标,应用最为广泛。质量磁化率(χ)和低频率磁化率(χfd)通常可用来指示较为严重的污染[12]。另外,饱和等温剩磁(SIRM)可作为铁磁性矿物含量的粗略量度,特别是当样品磁性很弱时,SIRM可取代磁化率而成为大气微粒的指示器[13]。非磁滞剩磁(ARM)反映了磁性矿物颗粒的磁畴信息,由单畴晶粒的含量控制,χARM是单位偏转场下的单位质量非磁滞剩磁[14]。虽然χ、SIRM和ARM在某种程度上均可指示磁性矿物的含量,但SIRM和ARM还受到形状和粒度等因素的影响,而χ受粒度的影响最小(SP颗粒除外),测量最为方便,是反映磁性矿物含量常用指标[15]。χfd、ARM/χ、SIRM/χ、ARM/SIRM、Day图和FORC图是指示磁性矿物粒度的代用指标,ARM获得曲线和反向退磁曲线、磁化率随温度变化曲线(χ-T曲线)、剩磁温度变化曲线(J-T曲线)及磁滞回线(magnetic hysteresis loop)主要用于判别磁性矿物种类与组成[16]。 3.2 环境磁学未来的发展方向
介于化学分析得到的元素含量不能准确地反映污染物来源,而环境磁学可以通过分析样品磁性颗粒的种类、形貌及其磁学参数来反映其来源。因此,环境磁学未来的研究重点是探索环境磁学相对于地球化学在源解析方面的优势,重点关注颗粒物重金属源解析及示踪,将环境磁学与地球化学结合,并开展更深入的微观研究,例如电子探针、透射电镜、同步辐射等,以准确地了解磁性颗粒的微观结构与组成特征,从而获得更准确的源解析结果。
参考文献
[1] 汪蕊,丁建丽,马雯,等.基于PSCF与CWT模型的乌鲁木齐市大气颗粒物源区分析[J/OL].环境科学学报:1-10[2021-07-09].https://doi.org/10.13671/j.hjkxxb.2021.0044.
[2] OU J p,ZHENG L g,TANG Q, et al.Source Analysis of Heavy Metals in Atmospheric Particulate Matter in a Mining City[J].Environmental Geochemistry and Health, 2021(619–620):1-13.
[3] 曲金华,张志慧.阴霾天气的元凶——PM2.5[J].科技资讯,2012(35):140.
[4] 郑新梅,谢放尖,李文青.南京市电力行业大气颗粒物排放及减排对策分析[J].科技资讯,2015,13(32):118-119.
[5] 丁新航,梁越,肖化云,等.太原市采暖季清洁天与灰霾天PM2.5中水溶性无机离子组成及来源分析[J].环境化学,2019,38(6):1356-1366.
[6] LI H m,QIAN X,HU W,et al.Chemical Speciation and Human Health Risk of Trace Metals in Urban Street Dusts from a Metropolitan City,Nanjing,SE China[J].Science of the Total Environment, 2013(456-457):212-221.
[7] ZHANG C X,QIAO Q Q,PIPER J D A, et al.Assessment of Heavy Metal Pollution from a Fe-smelting Plant in Urban River Sediments Using Environmental Magnetic and Geochemical Methods[J].Environmental Pollution,2011,159(10): 3057-3070.
[8] HAY K L,DEARING J A,BABAN S M J,et al.A Preliminary Attempt to Identify Atmospherically-derived Pollution Particles in English Topsoils from Magnetic Susceptibility Measurements[J].Physics and Chemistry of the Earth,1997,22(1):207–210.
[9] LI X L,YANG Y,YANG J X,et al.Rapid Diagnosis of Heavy Metal Pollution in Lake Sediments Based on Environmental Magnetism and Machine Learning[J].Journal of Hazardous Materials,2021(416):26-163.
[10] BLUNDELL A,DEARING J A,BOYLE J F,et al.Controlling factors for the spatial variability of soil magnetic susceptibility across England and Wales[J].Earth-Science Reviews,2009,95(3-4):158-188.
[11] WANG G,OLDFIELD F,XIA D S,et al.Magnetic Properties and Correlation with Heavy Metals in Urban Street Dust:A Case Study from the City of Lanzhou,China[J].Atmospheric Environment,2011,46:289-298.
[12] 閆慧,吴国玺,李京忠,等.许昌市路尘磁化率空间分布特征及其污染指示意义[J].热带地理,2013,33(2):219-223.
[13] HUNT A.The Application of Mineral Magnetic Methods to Atmospheric Aerosol Discrimination[J]. Physics of the Earth and Planetary Interiors,1986, 42(1-2):10-21.
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