摘要
研究塔玛亚历山大藻(Alexandriumtamarens)和锥状斯式藻(Scrippsiellatrochoidea)两种赤潮藻对海水中汞的富集和甲基化的影响,探讨赤潮藻对硫铁还原地杆菌GeobactersulfurreducensPCA (G. sulfurreducens PCA)汞生物甲基化的抑制作用。实验结果表明,不同种类藻对汞的耐受性不同,高浓度HgCl2 (≥25μg/L)抑制锥状斯式藻的生长,而对塔玛亚历山大藻的影响较小。两种藻均可有效地富集无机汞,但直接进行汞甲基化的效果不显著。FTIR分析发现,藻细胞表面分泌的大量羧基、氨基和羟基等官能团是富集汞的主要位点。汞-藻-菌实验中,当HgCl2初始浓度为10ug/L时,G. sulfurreducensPCA驱动的汞生物甲基化效率可达(6.38±0.4)%,在G. sulfurreducensPCA与塔玛亚历山大藻共存的实验组中,汞甲基化效率为(1.04±0.44)%,G. sulfurreducensPCA与锥状斯式藻的实验组中汞甲基化效率低至(0.76±0.05)%,两种赤潮藻的加入抑制了G.sulfurreducens PCA的汞生物甲基化。
The effect of two red-tide algae of Alexandrium tamarens and Scrippsiella trochoidea on mercury(Hg)adsorption and methylation were investigated. The inhibitory effect of two algae on biomethylation of Geobacter Sulfurreducens(G. sulfurreducens) PCA were demonstrated. The growth of Scrippsiella trochoidea was inhibited under exposure to high concentration of HgCl2(≥25 μg/L), but less affecting Alexandrium tamarens. Significant adsorption of Hg2+ was observed onto algal cells, whilst negligible amount of methylmercury(MeHg) was produced by two algae directly. FTIR spectra revealed that hydroxyl, carboxyl and amino groups were major binding sites for Hg2+ adsorption. In Hg-algae-bacteria tests, at initial HgCl2 concentration of 10 μg/L, a maximum mercury methylation efficiency of(6.38±0.4)% was obtained by pure G. sulfurreducens PCA culture as a control,but the efficiency reduced to(1.04±0.44)% with G. sulfurreducens PCA and Alexandrium tamarens coexisting, and a much lower efficiency of(0.76±0.05)% was detected with G. sulfurreducens PCA and Scrippsiella trochoidea coexisting. These results suggested that two red-tide algae inhibited mercury biomethylation of G. sulfurreducens PCA.
引文
[1]Zhang L,Wong M H.Environmental mercury contamination in China:sources and impacts.Environment International,2007,33(1):108-121
[2]Ullrich S M,Tanton T W,Abdrashitova S A.Mercury in the aquatic environment:a review of factors affecting methylation.Critical Reviews in Environmental Science and Technology,2001,31(3):241-293
[3]Li W C,Tse H F.Health risk and significance of mercury in the environment.Environmental Science and Pollution Research,2015,22(1):192-201
[4]Streets D G,Hao J M,Wu Y,et al.Anthropogenic mercury emissions in China.Atmospheric Environment,2005,39(40):7789-7806
[5]Celo V,Lean D R,Scott S L.Abiotic methylation of mercury in the aquatic environment.Sci Total Environ,2006,368(1):126-137
[6]Bravo A G,Bouchet S,Guédron S,et al.High methylmercury production under ferruginous conditions in sediments impacted by sewage treatment plant discharges.Water Research,2015,80:245-255
[7]Gilmour C C,Podar M,Bullock A L,et al.Mercury methylation by novel microorganisms from new environments.Environmental Science&Technology,2013,47(20):11810-11820
[8]Zhao L,Chen H,Lu X,et al.Contrasting effects of dissolved organic matter on mercury methylation by Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132.Environmental Science&Technology,2017,51(18):10468-10475
[9]Lin H,Morrell-Falvey J L,Rao B,et al.Coupled mercury-cell sorption,reduction,and oxidation on methylmercury production by Geobacter sulfurreducens PCA.Environmental Science&Technology,2014,48(20):11969-11976
[10]Yang Z,Fang W,Lu X,et al.Warming increases methylmercury production in an Arctic soil.Environmental Pollution,2016,214:504-509
[11]Berndt M E,Rutelonis W,Regan C P.A comparison of results from a hydrologic transport model(HSPF)with distributions of sulfate and mercury in a mineimpacted watershed in northeastern Minnesota.Journal of Environmental Management,2016,181:74-79
[12]Mazrui N M,Jonsson S,Thota S,et al.Enhanced availability of mercury bound to dissolved organic matter for methylation in marine sediments.Geochimica et Cosmochimica Acta,2016,194:153-162
[13]Pickhardt P C,Fisher N S.Accumulation of inorganic and methylmercury by freshwater phytoplankton in two contrasting water bodies.Environmental Science&Technology,2007,41(1):125-131
[14]Gray J E,Hines M E.Biogeochemical mercury methylation influenced by reservoir eutrophication,Salmon Falls Creek Reservoir,Idaho,USA.Chemical Geology,2009,258(3/4):157-167
[15]Regnell O,Tunlid A,Ewald G,et al.Methyl mercury production in freshwater microcosms affected by dissolved oxygen levels:role of cobalamin and microbial community composition.Canadian Journal of Fisheries&Aquatic Sciences,1996,53(7):1535-1545
[16]Guillard R R L,Ryther J H.Studies of marine planktonic diatoms:I.Cyclotella nana Hustedt,and Detonula confervacea(Cleve)Gran.Canadian Journal of Microbiology,1962,2(8):229-239
[17]蒋红梅,冯新斌,梁琏,等.蒸馏-乙基化GC-CVAFS法测定天然水体中的甲基汞.中国环境科学,2004,24(5):57-60
[18]440/5-84-026,Water Quality for Mercury[S].Washington DC:Office of Water,US Environmental Protection Agency,1985
[19]Vázquez G,González-álvarez J,Freire S,et al.Removal of cadmium and mercury ions from aqueous solution by sorption on treated Pinus pinaster bark:kinetics and isotherms.Bioresource Technology,2002,82(3):247-251
[20]Zeroual Y,Moutaouakkil A,Zohra D F,et al.Biosorption of mercury from aqueous solution by Ulva lactuca biomass.Bioresource Technology,2003,90(3):349-351
[21]Cain A,Vannela R,Woo L.Cyanobacteria as a biosorbent for mercuric ion.Bioresource Technology,2008,99(14):6578-6586
[22]Carro L,Anagnostopoulos V,Lodeiro P,et al.Adynamic proof of mercury elimination from solution through a combined sorption-reduction process.Bioresource Technology,2010,101(23):8969-8974
[23]Gu B,Bian Y,Miller C L,et al.Mercury reduction and complexation by natural organic matter in anoxic environments.Proceedings of the National Academy of Sciences,2011,108(4):1479-1483
[24]Benoit J M,Gilmour C C,Heyes A,et al.Geochemical and biological controls over methylmercury production and degradation in aquatic ecosystems.Biogeochemistry of Environmentally Important Trace Elements,2003,835:262-297
[25]邹嫣,司友斌,颜雪,等.Geobacter sulfurreducens对汞的甲基化及其影响因素研究.环境科学,2012,33(9):3247-3252
[26]Hollweg T A,Gilmour C C,Mason R P.Mercury and methylmercury cycling in sediments of the midAtlantic continental shelf and slope.Limnology and Oceanography,2010,55(6):2703-2722
[27]Zhao L,Chen H,Lu X,et al.Contrasting effects of dissolved organic matter on mercury methylation by Geobacter sulfurreducens PCA and Desulfovibrio desulfuricans ND132.Environmental Science&Technology,2017,51(18):10468-10475