蓝藻水华对太湖水柱反硝化作用的影响
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摘要
反硝化作用是湖泊水体最主要的脱氮过程,对减轻湖泊的氮素污染和富营养化控制具有重要意义.蓝藻水华暴发和衰亡可能会通过改变水体氮素循环途径及微环境来促使反硝化作用直接在水柱中发生,加速氮的去除.为了验证这一假设,取太湖湖水添加不同生物量的蓝藻和连续10 d的NO_3~--N、PO_4~(3-)-P营养盐,进行蓝藻生长与降解对反硝化影响的模拟实验,测定蓝藻水华期水体藻类生物量和各形态氮浓度的动态变化,同时利用~(15)N同位素添加培养结合膜进样质谱仪(MIMS)实时定量测定反硝化速率.结果表明,蓝藻在生长期吸收氮素转变为颗粒氮,在衰亡期藻细胞通过降解矿化释放了大量的NH_4~+-N,继而转化为NO_3~--N,为反硝化作用提供底物,是大幅度促进水体反硝化作用的关键;反硝化速率(以N2计,下同)最高达到(1 614. 52±301. 57)μmol·(m~2·h)~(-1),是同时期最低蓝藻生物量组反硝化速率[(534. 45±242. 18)μmol·(m~2·h)~(-1)]的3倍,实验结束时添加初始蓝藻生物量倍数最高组的TN去除率达最高(40. 02%),是未添加蓝藻组TN去除率(17. 72%)的2. 26倍,说明蓝藻堆积会显著促进反硝化作用的强度,加速水体氮素的去除.蓝藻衰亡时反硝化速率的快慢受NH_4~+浓度的影响显著,表明附着在藻团的微生物的耦合硝化-反硝化作用是氮盐去除的主要途径.本研究结果表明,水华蓝藻生长期快速吸收氮素转变为颗粒氮,蓝藻死亡降解后通过耦合硝化-反硝化作用加速氮素去除,这可能是太湖夏季氮素浓度降低的原因之一.
Denitrification is the most important nitrogen removal process in lake waters,and is of great significance for mitigating nitrogen pollution and controlling eutrophication in lakes. The outbreak and decline of cyanobacterial blooms may promote denitrification directly in the water column by changing the nitrogen circulation pathway and microenvironment of the water body,and accelerate the removal of nitrogen. In order to verify this hypothesis,the cyanobacteria with different biomass and the NO_3~--N,PO_4~(3-)-P nutrient for 10 days were taken from Taihu Lake water to simulate the effects of cyanobacteria growth and degradation on denitrification.The dynamic changes of algal biomass and various forms of nitrogen concentration were simultaneously determined by~(15)N isotope addition culture combined with membrane inlet mass spectrometer( MIMS) for real-time quantitative determination of denitrification rate. The results showed that cyanobacteria absorbed nitrogen into particle nitrogen during the growth period. During the decay period,algae cells released a large amount of NH_4~+-N by degrading mineralization,which was then converted into NO_3~--N to provide a substrate for denitrification. That is the key to promoting denitrification in water; the denitrification rate( as N2) reaches( 1 614. 52 ± 301. 57)μmol·( m~2·h)~(-1),which is three times higher than the denitrification rate [( 534. 45 ± 242. 18) μmol·( m~2·h)~(-1)]of the lowest concentration cyanobacterial group at the same time. At the end of the experiment,the highest rate of TN removal was highest in the group with the highest initial biomass of cyanobacteria( 40. 02%),which was 2. 26 times of the TN removal rate( 17. 72%) in the control,indicating that cyanobacterial accumulation can significantly promote the intensity of denitrification and accelerate the removal of nitrogen in water. The rate of denitrification in the decline of cyanobacteria is significantly affected by the concentration of NH_4~+-N,indicating that the coupling of nitrification-denitrification of microorganisms attached to algae is the main route of nitrogen removal. The results study indicate that the cyanobacteria bloom rapidly during the growth period. Nitrogen is converted into particle nitrogen. The degradation of cyanobacteria is accelerated by coupled nitrification-denitrification,which may be one of the reasons for the decrease of nitrogen concentration in Taihu Lake.
Denitrification is the most important nitrogen removal process in lake waters,and is of great significance for mitigating nitrogen pollution and controlling eutrophication in lakes. The outbreak and decline of cyanobacterial blooms may promote denitrification directly in the water column by changing the nitrogen circulation pathway and microenvironment of the water body,and accelerate the removal of nitrogen. In order to verify this hypothesis,the cyanobacteria with different biomass and the NO_3~--N,PO_4~(3-)-P nutrient for 10 days were taken from Taihu Lake water to simulate the effects of cyanobacteria growth and degradation on denitrification.The dynamic changes of algal biomass and various forms of nitrogen concentration were simultaneously determined by~(15)N isotope addition culture combined with membrane inlet mass spectrometer( MIMS) for real-time quantitative determination of denitrification rate. The results showed that cyanobacteria absorbed nitrogen into particle nitrogen during the growth period. During the decay period,algae cells released a large amount of NH_4~+-N by degrading mineralization,which was then converted into NO_3~--N to provide a substrate for denitrification. That is the key to promoting denitrification in water; the denitrification rate( as N2) reaches( 1 614. 52 ± 301. 57)μmol·( m~2·h)~(-1),which is three times higher than the denitrification rate [( 534. 45 ± 242. 18) μmol·( m~2·h)~(-1)]of the lowest concentration cyanobacterial group at the same time. At the end of the experiment,the highest rate of TN removal was highest in the group with the highest initial biomass of cyanobacteria( 40. 02%),which was 2. 26 times of the TN removal rate( 17. 72%) in the control,indicating that cyanobacterial accumulation can significantly promote the intensity of denitrification and accelerate the removal of nitrogen in water. The rate of denitrification in the decline of cyanobacteria is significantly affected by the concentration of NH_4~+-N,indicating that the coupling of nitrification-denitrification of microorganisms attached to algae is the main route of nitrogen removal. The results study indicate that the cyanobacteria bloom rapidly during the growth period. Nitrogen is converted into particle nitrogen. The degradation of cyanobacteria is accelerated by coupled nitrification-denitrification,which may be one of the reasons for the decrease of nitrogen concentration in Taihu Lake.
引文
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[12]Pérez-Mayorga D M,Ladah L B,Zertuche-González J A,et al.Nitrogen uptake and growth by the opportunistic macroalga Ulva lactuca(Linnaeus)during the internal tide[J].Journal of Experimental Marine Biology and Ecology,2011,406(1-2):108-115.
[13]Picot B,Moersidik S,Casellas C,et al.Using diurnal variations in a high rate algal pond for management pattern[J].Water Science and Technology,1993,28(10):169-175.
[14]Livingstone D,Pentecost A,Whitton B A.Diel variations in nitrogen and carbon dioxide fixation by the blue-green alga Rivularia in an upland stream[J].Phycologia,1984,23(2):125-133.
[15]De Philippis R,Faraloni C,Margheri M C,et al.Morphological and biochemical characterization of the exocellular investments of polysaccharide-producing Nostoc strains from the Pasteur Culture Collection[J].World Journal of Microbiology and Biotechnology,2000,16(7):655-661.
[16]Nguyen M L,Westerhoff P,Baker L,et al.Characteristics and reactivity of algae-produced dissolved organic carbon[J].Journal of Environmental Engineering,2005,131(11):1574-1582.
[17]Xu H,Paerl H W,Qin B,et al.Determining critical nutrient thresholds needed to control harmful cyanobacterial blooms in eutrophic Lake Taihu,China[J].Environmental Science&Technology,2015,49(2):1051-1059.
[18]Xu H,Paerl H W,Qin B Q,et al.Nitrogen and phosphorus inputs control phytoplankton growth in eutrophic Lake Taihu,China[J].Limnology and Oceanography,2015,55(1):420-432.
[19]陈宇炜,高锡云,秦伯强.西太湖北部夏季藻类种间关系的初步研究[J].湖泊科学,1998,10(4):35-40.Chen Y Z,Gao X Y,Qin B Q.The Summer phytoplankton species composition in northern part of west Taihu Lake[J].Journal of Lake Sciences,1998,10(4):35-40.
[20]金相灿,屠清瑛.湖泊富营养化调查规范[M].(第二版).北京:中国环境科学出版社,1990.
[21]陈明华,谢良国,付志强,等.丙酮法和热乙醇法测定浮游植物叶绿素a的方法比对[J].环境监测管理与技术,2016,28(2):46-48.Chen M H,Xie L G,Fu Z Q,et al.Comparison of two methods for measurement of phytoplanktonic Chlorophyll-a[J].The Administration and Technique of Environmental Monitoring,2016,28(2):46-48.
[22]Binnerup S J,Jensen K,Revsbech N P,et al.Denitrification,dissimilatory reduction of nitrate to ammonium,and nitrification in a Bioturbated Estuarine sediment as measured with15N and microsensor techniques[J].Applied and Environmental Microbiology,1992,58(1):303-313.
[23]Nielsen L P.Denitrification in sediment determined from nitrogen isotope pairing[J].FEMS Microbiology Letters,1992,86(4):357-362.
[24]Weiss R F.The solubility of nitrogen,oxygen and argon in water and seawater[J].Deep Sea Research and Oceanographic Abstracts,1970,17(4):721-735.
[25]Cardinale B J.Cardinale reply[J].Nature,2011,477(7366):E3-E4.
[26]何东,张毅敏,杨飞,等.太湖藻源性颗粒物降解过程中营养盐转化及其生态效应[J].中国环境科学,2016,36(3):899-907.He D,Zhang Y M,Yang F,et al.The transformation of the nutrient in the degradation process of the phytoplankton-derived particulate organic matter and it's ecological effect[J].China Environmental Science,2016,36(3):899-907.
[27]李柯,关保华,刘正文.蓝藻碎屑分解速率及氮磷释放形态的实验分析[J].湖泊科学,2011,23(6):919-925.Li K,Guan B H,Liu Z W.Experiments on decomposition rate and release forms of nitrogen and phosphorus from the decomposing cyanobacterial detritus[J].Journal of Lake Sciences,2011,23(6):919-925.
[28]Treusch A H,Leininger S,Kletzin A,et al.Novel genes for nitrite reductase and Amo-related proteins indicate a role of uncultivated mesophilic crenarchaeota in nitrogen cycling[J].Environmental Microbiology,2005,7(12):1985-1995.
[29]李洁,张思凡,肖琳.微囊藻水华对水体中氮转化及微生物的影响[J].环境科学,2016,37(6):2164-2170.Li J,Zhang S F,Xiao L.Effect of water bloom on the nitrogen transformation and the relevant bacteria[J].Environmental Science,2016,37(6):2164-2170.
[2]徐徽,张路,商景阁,等.太湖梅梁湾水土界面反硝化和厌氧氨氧化[J].湖泊科学,2009,21(6):775-781.Xu H,Zhang L,Shang J G,et al.Denitrification and anammox on the sediment-water interface in the Meiliang Bay of Lake Taihu[J].Journal of Lake Sciences,2009,21(6):775-781.
[3]Wu G X,Zhai X F,Jiang C G.Effect of ammonium on nitrous oxide emission during denitrification with different electron donors[J].Journal of Environmental Sciences,2013,25(6):1131-1138.
[4]Galloway J N,Townsend A R,Erisman J W,et al.Transformation of the nitrogen cycle:recent trends,questions,and potential solutions[J].Science,2008,320(5878):889-892.
[5]Wollheim W M,Peterson B J,Thomas S M,et al.Dynamics of N removal over annual time periods in a suburban river network[J].Journal of Geophysical Research:Biogeosciences,2008,113(G3):G03038.
[6]Harrison J A,Maranger R J,Alexander R B,et al.The regional and global significance of nitrogen removal in lakes and reservoirs[J].Biogeochemistry,2009,93(1-2):143-157.
[7]Silvennoinen H,Liikanen A,Torssonen J,et al.Denitrification and nitrous oxide effluxes in boreal,eutrophic river sediments under increasing nitrate load:a laboratory microcosm study[J].Biogeochemistry,2008,91(2-3):105-116.
[8]Mulholland P J,Helton A M,Poole G C,et al.Stream denitrification across biomes and its response to anthropogenic nitrate loading[J].Nature,2008,452(7184):202-205.
[9]Fulweiler R W,Nixon S W.Net sediment N2fluxes in a southern New England estuary:variations in space and time[J].Biogeochemistry,2012,111(1-3):111-124.
[10]Trimmer M,Grey J,Heppell C M,et al.River bed carbon and nitrogen cycling:State of play and some new directions[J].Science of the total Environment,2012,434:143-158.
[11]Liu T,Xia X H,Liu S D,et al.Acceleration of denitrification in Turbid Rivers due to denitrification occurring on suspended sediment in oxic waters[J].Environmental Science&Technology,2013,47(9):4053-4061.
[12]Pérez-Mayorga D M,Ladah L B,Zertuche-González J A,et al.Nitrogen uptake and growth by the opportunistic macroalga Ulva lactuca(Linnaeus)during the internal tide[J].Journal of Experimental Marine Biology and Ecology,2011,406(1-2):108-115.
[13]Picot B,Moersidik S,Casellas C,et al.Using diurnal variations in a high rate algal pond for management pattern[J].Water Science and Technology,1993,28(10):169-175.
[14]Livingstone D,Pentecost A,Whitton B A.Diel variations in nitrogen and carbon dioxide fixation by the blue-green alga Rivularia in an upland stream[J].Phycologia,1984,23(2):125-133.
[15]De Philippis R,Faraloni C,Margheri M C,et al.Morphological and biochemical characterization of the exocellular investments of polysaccharide-producing Nostoc strains from the Pasteur Culture Collection[J].World Journal of Microbiology and Biotechnology,2000,16(7):655-661.
[16]Nguyen M L,Westerhoff P,Baker L,et al.Characteristics and reactivity of algae-produced dissolved organic carbon[J].Journal of Environmental Engineering,2005,131(11):1574-1582.
[17]Xu H,Paerl H W,Qin B,et al.Determining critical nutrient thresholds needed to control harmful cyanobacterial blooms in eutrophic Lake Taihu,China[J].Environmental Science&Technology,2015,49(2):1051-1059.
[18]Xu H,Paerl H W,Qin B Q,et al.Nitrogen and phosphorus inputs control phytoplankton growth in eutrophic Lake Taihu,China[J].Limnology and Oceanography,2015,55(1):420-432.
[19]陈宇炜,高锡云,秦伯强.西太湖北部夏季藻类种间关系的初步研究[J].湖泊科学,1998,10(4):35-40.Chen Y Z,Gao X Y,Qin B Q.The Summer phytoplankton species composition in northern part of west Taihu Lake[J].Journal of Lake Sciences,1998,10(4):35-40.
[20]金相灿,屠清瑛.湖泊富营养化调查规范[M].(第二版).北京:中国环境科学出版社,1990.
[21]陈明华,谢良国,付志强,等.丙酮法和热乙醇法测定浮游植物叶绿素a的方法比对[J].环境监测管理与技术,2016,28(2):46-48.Chen M H,Xie L G,Fu Z Q,et al.Comparison of two methods for measurement of phytoplanktonic Chlorophyll-a[J].The Administration and Technique of Environmental Monitoring,2016,28(2):46-48.
[22]Binnerup S J,Jensen K,Revsbech N P,et al.Denitrification,dissimilatory reduction of nitrate to ammonium,and nitrification in a Bioturbated Estuarine sediment as measured with15N and microsensor techniques[J].Applied and Environmental Microbiology,1992,58(1):303-313.
[23]Nielsen L P.Denitrification in sediment determined from nitrogen isotope pairing[J].FEMS Microbiology Letters,1992,86(4):357-362.
[24]Weiss R F.The solubility of nitrogen,oxygen and argon in water and seawater[J].Deep Sea Research and Oceanographic Abstracts,1970,17(4):721-735.
[25]Cardinale B J.Cardinale reply[J].Nature,2011,477(7366):E3-E4.
[26]何东,张毅敏,杨飞,等.太湖藻源性颗粒物降解过程中营养盐转化及其生态效应[J].中国环境科学,2016,36(3):899-907.He D,Zhang Y M,Yang F,et al.The transformation of the nutrient in the degradation process of the phytoplankton-derived particulate organic matter and it's ecological effect[J].China Environmental Science,2016,36(3):899-907.
[27]李柯,关保华,刘正文.蓝藻碎屑分解速率及氮磷释放形态的实验分析[J].湖泊科学,2011,23(6):919-925.Li K,Guan B H,Liu Z W.Experiments on decomposition rate and release forms of nitrogen and phosphorus from the decomposing cyanobacterial detritus[J].Journal of Lake Sciences,2011,23(6):919-925.
[28]Treusch A H,Leininger S,Kletzin A,et al.Novel genes for nitrite reductase and Amo-related proteins indicate a role of uncultivated mesophilic crenarchaeota in nitrogen cycling[J].Environmental Microbiology,2005,7(12):1985-1995.
[29]李洁,张思凡,肖琳.微囊藻水华对水体中氮转化及微生物的影响[J].环境科学,2016,37(6):2164-2170.Li J,Zhang S F,Xiao L.Effect of water bloom on the nitrogen transformation and the relevant bacteria[J].Environmental Science,2016,37(6):2164-2170.
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