沿海城市降水中总汞及汞同位素特征研究
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摘要
大气汞沉降是汞从排放源进入地表系统最主要的迁移途径,利用汞同位素追踪汞在大气中的迁移转化规律及潜在来源对研究汞的生物地球化学循环具有重要意义.本研究于2012—2013年对厦门市小坪、坂头、鼓浪屿和洪文站点降水中总汞(THg)浓度和汞同位素的变化特征进行了研究.结果表明,厦门降水中THg浓度为1.0～59.4 ng·L~(-1),大气THg湿沉降量为13.1μg·m~(-2)·a~(-1).厦门冷、暖季降水中THg浓度相当,但由于暖季丰沛的降水量,导致暖季THg的湿沉降量约为冷季的2.5倍.降水样品中均表现出负的偶数汞同位素质量分馏(δ~(202)Hg,-2.2‰～-1.5‰)、正的奇数汞同位素非质量分馏(Δ~(199)Hg,0.08‰～0.22‰),以及轻微偏正的偶数汞同位素非质量分馏(Δ~(200)Hg,0.01‰～0.07‰).厦门降水中奇数汞同位素非质量分馏是大气汞液相光致还原反应的结果.偶数汞同位素非质量分馏不明显与其处于较低的纬度有关.厦门降水中δ~(202)Hg接近于厦门当地及贵州燃煤烟气中的δ~(202)Hg值,表明厦门降水中汞可能受到本地或传输过来的燃煤排放的影响.
Atmospheric mercury(Hg) deposition is the predominant pathway of mercury transferring from emission sources to terrestrial ecosystems.Tracing the transport and transformation of Hg in the atmosphere and the potential sources of atmospheric Hg with mercury isotope signature is of great significance for the research on the biogeochemical cycle of Hg.To investigate the characteristics of total mercury(THg) and Hg isotopic composition in precipitation in a coastal city, the precipitation samples were collected simultaneously at Xiaoping, Bantou, Hongwen, and Gulangyu sites in Xiamen, China during 2012—2013 in this study.The concentrations of THg in precipitation samples were in the range of 1.0～59.4 ng·L~(-1), and wet deposition flux was 13.1 μg·m~(-2)·a~(-1).The concentration of THg in precipitations in warm season was comparable to that in cold season.The wet deposition flux of THg in warm season was 2.5 times higher than that in cold season due to the abundant precipitation amount.All precipitation samples displayed negative mass-dependent fractionation of even isotopes(δ~(202)Hg,-2.2‰～-1.5‰), positive mass-independent fractionation of odd isotopes(Δ~(199)Hg, 0.08‰～0.22‰), and slightly positive mass-independent fractionation of even isotopes(Δ~(200)Hg, 0.01‰～0.07‰).These results suggested that photoreduction in droplets induced odd Hg isotope anomalies, while little mass-independent fractionation of even Hg isotopes in Xiamen was probably related to low latitude.The δ~(202)Hg of precipitation samples was close to that of coal-burning flue gas in Xiamen and Guizhou, which indicated that Hg in precipitation might be affected by both local emission of coal-fired plant and transportation of coal combustion emission.
Atmospheric mercury(Hg) deposition is the predominant pathway of mercury transferring from emission sources to terrestrial ecosystems.Tracing the transport and transformation of Hg in the atmosphere and the potential sources of atmospheric Hg with mercury isotope signature is of great significance for the research on the biogeochemical cycle of Hg.To investigate the characteristics of total mercury(THg) and Hg isotopic composition in precipitation in a coastal city, the precipitation samples were collected simultaneously at Xiaoping, Bantou, Hongwen, and Gulangyu sites in Xiamen, China during 2012—2013 in this study.The concentrations of THg in precipitation samples were in the range of 1.0～59.4 ng·L~(-1), and wet deposition flux was 13.1 μg·m~(-2)·a~(-1).The concentration of THg in precipitations in warm season was comparable to that in cold season.The wet deposition flux of THg in warm season was 2.5 times higher than that in cold season due to the abundant precipitation amount.All precipitation samples displayed negative mass-dependent fractionation of even isotopes(δ~(202)Hg,-2.2‰～-1.5‰), positive mass-independent fractionation of odd isotopes(Δ~(199)Hg, 0.08‰～0.22‰), and slightly positive mass-independent fractionation of even isotopes(Δ~(200)Hg, 0.01‰～0.07‰).These results suggested that photoreduction in droplets induced odd Hg isotope anomalies, while little mass-independent fractionation of even Hg isotopes in Xiamen was probably related to low latitude.The δ~(202)Hg of precipitation samples was close to that of coal-burning flue gas in Xiamen and Guizhou, which indicated that Hg in precipitation might be affected by both local emission of coal-fired plant and transportation of coal combustion emission.
引文
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Huang S Y,Sun L M,Zhou T J,et al.2018.Natural stable isotopic compositions of mercury in aerosols and wet precipitations around a coal-fired power plant in Xiamen,southeast China[J].Atmospheric Environment,173: 72-80
Malinovsky D,Latruwe K,Moens L,et al.2010.Experimental study of mass-independence of Hg isotope fractionation during photodecomposition of dissolved methylmercury[J].Journal of Analytical Atomic Spectrometry,25(7):950-956
Mead C,Lyons J R,Johnson T M,et al.2013.Unique Hg stable isotope signatures of compact fluorescent lamp-sourced Hg[J].Environmental Science & Technology,47(6):2542-2547
Rolison J M,Landing W M,Luke W,et al.2013.Isotopic composition of species-specific atmospheric Hg in a coastal environment[J].Chemical Geology,336(1):37-49
Sherman L S,Blum J D,Keeler G J,et al.2012.Investigation of local mercury deposition from a coal-fired power plant using mercury isotopes[J].Environmental Science & Technology,46(1):382
Sonke J E,Heimbürger L E,Dommergue A.2013.Mercury biogeochemistry: Paradigm shifts,outstanding issues and research needs[J].ComptesRendus Geoscience,345(5/6):213-224
Sun R,Heimbürger L E,Sonke J E,et al.2013.Mercury stable isotope fractionation in six utility boilers of two large coal-fired power plants[J].Chemical Geology,336(1):103-111
Tang S,Feng C,Feng X,et al.2017.Stable isotope composition of mercury forms in flue gases from a typical coal-fired power plant,Inner Mongolia,northern China[J].Journal of Hazardous Materials,328:90
Wang Y M,Wang D Y,Meng B,et al.2012.Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas,Chongqing,China[J].Atmospheric Chemistry & Physics Discussions,12(4):10243-10272
Wang Z,Chen J,Feng X,et al.2015.Mass-dependent and mass-independent fractionation of mercury isotopes in precipitation from Guiyang,SW China[J].Comptesrendus - Géoscience,347(7/8):358-367
Xu L,Chen J,Yang L,et al.2014.Characteristics of total and methyl mercury in wet deposition in a coastal city,Xiamen,China: Concentrations,fluxes and influencing factors on Hg distribution in precipitation[J].Atmospheric Environment,99:10-16
Xu L,Chen J,Yang L,et al.2015.Characteristics and sources of atmospheric mercury speciation in a coastal city,Xiamen,China[J].Chemosphere,119:530-539
Yin R,Feng X,Chen J.2014.Mercury stable isotopic compositions in coals from major coal producing fields in china and their geochemical and environmental implications[J].Environmental Science & Technology,48(10):5565-5574
Yuan S L,Zhang Y,Chen J B,et al.2015.Large variation of mercury isotope composition during a single precipitation event at Lhasa City,Tibetan Plateau,China[J].Procedia Earth & Planetary Science,13:282-286
Zheng W,Hintelmann H.2010a.Nuclear field shift effect in isotope fractionation of mercury during abiotic reduction in the absence of light[J].Journal of Physical Chemistry A,114(12):4238-4245
Zheng W,Hintelmann H.2010b.Isotope fractionation of mercury during its photochemical reduction by low-molecular-weight organic compounds[J].Journal of Physical Chemistry A,114(12):4246-4253
Blum J D,Sherman L S,Johnson M W.2014.Mercury isotopes in earth and environmental sciences[J].Annual Review of Earth & Planetary Sciences,42(1):249-269
Chen J B,Hintelmann H,Feng X B,et al.2012.Unusual fractionation of both odd and even mercury isotopes in precipitation from Peterborough,ON,Canada[J].Geochimica Et Cosmochimica Acta,90(1):33-46
Eduardovna K G,Samuilovich R G,Sergeevna Y V.2013.The UNEP global mercury assessment: Sources,emissions and transport[J].Principyèkologii,1(4):36001
Fu X W,Feng X,Dong Z Q,et al.2010.Atmospheric gaseous elemental mercury (GEM) concentrations and mercury depositions at a high-altitude mountain peak in south China[J].Atmospheric Chemistry & Physics,10(5):2425-2437
Gale T K,Lani B W,Offen G R.2008.Mechanisms governing the fate of mercury in coal-fired power systems[J].Fuel Processing Technology,89(2):139-151
Gratz L E,Keeler G J,Blum J D,et al.2010.Isotopic composition and fractionation of mercury in Great Lakes precipitation and ambient air[J].Environmental Science & Technology,44(20):7764-70
Guo Y,Feng X,Li Z,et al.2008.Distribution and wet deposition fluxes of total and methyl mercury in Wujiang River Basin,Guizhou,China[J].Atmospheric Environment,42(30):7096-7103
Huang J,Kang S,Zhang Q,et al.2012.Wet deposition of mercury at a remote site in the Tibetan Plateau: Concentrations,speciation,and fluxes[J].Atmospheric Environment,62(15):540-550
Huang S,Yuan D,Lin H,et al.2017.Fractionation of mercury stable isotopes during coal combustion and seawater flue gas desulfurization[J].Applied Geochemistry,76:159-167
Huang S Y,Sun L M,Zhou T J,et al.2018.Natural stable isotopic compositions of mercury in aerosols and wet precipitations around a coal-fired power plant in Xiamen,southeast China[J].Atmospheric Environment,173: 72-80
Malinovsky D,Latruwe K,Moens L,et al.2010.Experimental study of mass-independence of Hg isotope fractionation during photodecomposition of dissolved methylmercury[J].Journal of Analytical Atomic Spectrometry,25(7):950-956
Mead C,Lyons J R,Johnson T M,et al.2013.Unique Hg stable isotope signatures of compact fluorescent lamp-sourced Hg[J].Environmental Science & Technology,47(6):2542-2547
Rolison J M,Landing W M,Luke W,et al.2013.Isotopic composition of species-specific atmospheric Hg in a coastal environment[J].Chemical Geology,336(1):37-49
Sherman L S,Blum J D,Keeler G J,et al.2012.Investigation of local mercury deposition from a coal-fired power plant using mercury isotopes[J].Environmental Science & Technology,46(1):382
Sonke J E,Heimbürger L E,Dommergue A.2013.Mercury biogeochemistry: Paradigm shifts,outstanding issues and research needs[J].ComptesRendus Geoscience,345(5/6):213-224
Sun R,Heimbürger L E,Sonke J E,et al.2013.Mercury stable isotope fractionation in six utility boilers of two large coal-fired power plants[J].Chemical Geology,336(1):103-111
Tang S,Feng C,Feng X,et al.2017.Stable isotope composition of mercury forms in flue gases from a typical coal-fired power plant,Inner Mongolia,northern China[J].Journal of Hazardous Materials,328:90
Wang Y M,Wang D Y,Meng B,et al.2012.Spatial and temporal distributions of total and methyl mercury in precipitation in core urban areas,Chongqing,China[J].Atmospheric Chemistry & Physics Discussions,12(4):10243-10272
Wang Z,Chen J,Feng X,et al.2015.Mass-dependent and mass-independent fractionation of mercury isotopes in precipitation from Guiyang,SW China[J].Comptesrendus - Géoscience,347(7/8):358-367
Xu L,Chen J,Yang L,et al.2014.Characteristics of total and methyl mercury in wet deposition in a coastal city,Xiamen,China: Concentrations,fluxes and influencing factors on Hg distribution in precipitation[J].Atmospheric Environment,99:10-16
Xu L,Chen J,Yang L,et al.2015.Characteristics and sources of atmospheric mercury speciation in a coastal city,Xiamen,China[J].Chemosphere,119:530-539
Yin R,Feng X,Chen J.2014.Mercury stable isotopic compositions in coals from major coal producing fields in china and their geochemical and environmental implications[J].Environmental Science & Technology,48(10):5565-5574
Yuan S L,Zhang Y,Chen J B,et al.2015.Large variation of mercury isotope composition during a single precipitation event at Lhasa City,Tibetan Plateau,China[J].Procedia Earth & Planetary Science,13:282-286
Zheng W,Hintelmann H.2010a.Nuclear field shift effect in isotope fractionation of mercury during abiotic reduction in the absence of light[J].Journal of Physical Chemistry A,114(12):4238-4245
Zheng W,Hintelmann H.2010b.Isotope fractionation of mercury during its photochemical reduction by low-molecular-weight organic compounds[J].Journal of Physical Chemistry A,114(12):4246-4253
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