摘要
水华暴发是一个多因素综合作用的结果,如温度、光照、氮磷营养盐、微量元素、CO_2等。其中CO_2作为藻类光合作用的底物,对藻类生长和水华暴发影响重大。大量化石燃料的燃烧及森林绿地面积的锐减,在增加大气中CO_2来源的同时减少了CO_2的吸收源,导致大气中CO_2浓度剧增,有人预计到21世纪末,CO_2浓度将倍增。大气CO_2浓度的增加对藻类光合作用及水华暴发的影响令人关注。
本试验以普遍存在于我国各地水体中的水华优势种铜绿微囊藻为材料,设置了7个CO_2浓度,研究CO_2浓度变化对铜绿微囊藻生长及光合活性的影响。试验结果显示,随着CO_2浓度增加,铜绿微囊藻的生物量及叶绿素a浓度呈现出先升高后降低的趋势。CO_2浓度在400～6400μL/L范围内,藻的生长得到促进,浓度继续升高则会对生长产生抑制作用,铜绿微囊藻生长的最适CO_2浓度在800μL/L左右。不同浓度CO_2条件下生长的铜绿微囊藻叶绿素荧光活性和光合放氧速率都存在显著性差异(P<0.05)。
高浓度(25600μL/L)CO_2环境为光合作用提供了充足的碳源,藻类碳浓缩机制CCMs下调,固碳所需能量减少,饱和光强降低。铜绿微囊藻受极高浓度CO_2胁迫,叶绿素合成受阻,光能的吸收、传递,尤其是转化受限,影响藻细胞内的电子传递过程,最大电子传递速率ETRmax降低。此外,高浓度CO_2条件下,铜绿微囊藻的暗呼吸速率增强,维持细胞基本生理活动所需能量增加,光合作用合成的能量仅有很少一部分用于细胞生长繁殖和叶绿素合成,能量不足可能是铜绿微囊藻光合色素合成受阻及生长被抑制的原因之一。
透射电镜扫描结果显示,高浓度CO_2条件下生长的铜绿微囊藻与对照组(400μL/L)相比,外部结构没有显著变化,但细胞内类囊体数目减少,且出现不规则排列,与正常细胞差异显著,表明藻细胞的光合机构受到损伤。
CO_2浓度的适当增加会促进藻类生长,浓度过高反而会产生抑制作用。高浓度CO_2对铜绿微囊藻的抑制作用主要是由于细胞光合机构受损,叶绿素合成受阻所致。
Water bloom, which occurred frequently and strongly, has been seriously affected people’s life and its occurring mechanism & treatment methods were paid more attention by scholars in the world. Water bloom is a combined result of multiple factors such as temperature, light, nutrients, trace element, carbon dioxide, etc. As a substrate, carbon dioxide (CO_2) plays an important role in algae’s photosynthesis. Atmospheric CO_2 has risen dramatically as a result of human activities such as fossil fuel burning and deforestation, it was estimated that the concentration of CO_2 in atmosphere will be doubled at the end of 21st century. Effects of elevated CO_2 on algae’s photosynthesis were worth to be concerned.
Seven different CO_2 concentrations were set in this experiment to study the effects of CO_2 on Microcystis aeruginosa’s growth and physiological activity. Results showed that biomass and chlorophyll a content of Microcystis aeruginosa increased firstly and then decreased with the increase of atmospheric CO_2. Algal growth was promoted at the range of 400～6400μL/L CO_2 concentration, the optimum CO_2 concentration for growth of Microcystis aeruginosa was about 800μL/L. Under different CO_2 concentration, Microcystis aerugonisa’s biomass, chlorophyll fluorescence and oxygen evolution rate were significantly different (P<0.05). High CO_2 provided sufficient carbon soure for algal photosynthesis, the carbon-concentrating mechanism (CCMs) weak down and energy required reduced so that the saturated light intensity decreased. By stress of high ,synthesis of chlorophyll a was blocked and limited light absorption, transmission & transformation especially, which would influence the electron-transfer process, leading to the lower of the maximum electron transport rate ETRmax. In addition, under high CO_2 condition, Microcytis aeruginosa’s dark respiration rate increased, then energy needed to maintain algal physiological activity increased and there was little erergy used for cell growth and reproduction. Lack of energy maybe the main reseason for block of the biosynthesis of chlorophyll a. Compared with the control , Microcystis aeruginosa, which was under high CO_2 (25600μL/L) condition, its external structure has not changed, but inner structure of cell were significantly different from the control cells, the number of thylakoid reduced and arranged irregularly. It indicated that algal photosynthetic apparatus has been damaged.
Appropriate increase of atmospheric CO_2 will promote algae growth, in contrast, excessively high CO_2 will cause inhibition. Effects of high CO_2 inhibited the growth of Microcystis aeruginosa mainly due to the damage of photosynthetic apparatus and block of chlorophyll a synthesis. The optimal CO_2 concentration (800μL/L) to the growth of Microcystis aeruginosa would be helpful to understanding the occurring mechanism of Microcystis aeruginosa bloom.
引文
1.钱奎梅,陈宇伟,宋晓兰.太湖浮游植物优势种长期演化与富营养化进程的关系.生态科学.2008,27(2):65-70
2. N. Lisette, De Senerpont, Domos, et al. Climate-induced shifts in an experimental phytoplankton community: a mechanistic approach. Hydrobiologia. 2007,584: 403-413
3.朱伟,万蕾,赵联芳.不同温度和营养盐质量浓度条件下藻类的种间竞争规律.生态环境. 2008,17(1):6-11
4.康丽娟,刘永梅,李敦海,等.不同盐度下水华束丝藻对CO_2浓度倍增的生理响应.水生生物学报. 2007,31(5):671-674
5. W J Adelman, J F Fohlmeister, J J Sasner, et al. Sodium channel blocked by aphantoxin obtained from the blue-green algae, Aphanizomenon flos-aquae. Toxin. 1981,20(2):513-516
6.刘其根,陈立侨,陈勇.千岛湖水华发生与主要环境因子的相关性分析.海洋湖沼通报. 2007,1:117-124
7.崔力拓,李志伟.氮、磷营养盐组成对铜绿微囊藻生长的影响.河北渔业. 2006,5:12-15
8.刘永梅,刘永定,李敦海,等.氮磷对水华束丝藻生长及生理特性的影响.水生生物学报. 2007,31(6) :774-779
9.邱昌恩,况琪军,刘国祥,等.不同氮浓度对绿球藻生长及生理特性的影响.中国环境科学. 2005,25(4):408-411
10.邹迪,肖琳,杨柳燕,等.不同氮磷比对铜绿微囊藻及附生假单胞菌磷代谢的影响.环境化学. 2005,24(6): 647-650
11.胡章喜,徐宁,李爱芬,等.氮磷比率对3种典型赤潮藻生长的影响.水生生物学报. 2008,32(4):484-489
12.谢平论蓝藻水华的发生机制-从生物进化、生物地球化学和生态学观点第九章蓝藻水华的成因
13.王得玉,冯学智,周立国,等.太湖蓝藻暴发与水温的关系的MODIS遥感.湖泊科学. 2008,20(2):173-178
14.陈桥,韩红娟,翟水晶,等.太湖地区太阳辐射与水温的变化特征及其对叶绿素a的影响.环境科学学报. 2009,29(1):199-206
15.刘玉生,韩梅,梁占彬,等.光照、温度和营养盐对滇池微囊藻生长的影响.环境科学. 1994, 8(6):7-11
16.林兴权,潘彩萍,王波.紫外光辐照抑制蓝藻生长的研究.中国给水排水. 2007, 23(7):94-97
17.颜润润,逄勇,王珂,等不同培养条件下扰动对两种淡水藻生长的影响.环境科学与技术.2007,30(3):10-13
18.高月香,张永春.水文气象因子对藻华爆发的影响.水科学与工程技术. 2006, 2:10-12
19.顾启华,赵林,谭欣.铜绿微囊藻·螺旋鱼腥藻和水华束丝藻竞争优势的研究.安徽农业科学.2007,35(7):1990-1991,203
20.吕秀平,张栩,康瑞娟,等. Fe3+对铜绿微囊藻生长和光合作用的影响.北京化工大学学报. 2006,33 (1):27-30
21.张伟,阎海,吴之丽.铜抑制单细胞绿藻生长的毒性效应.中国环境科学. 2001,21(1):4-7
22.邱昌恩六种常见重金属对藻类的毒性效应概述.重庆医科大学学报. 2006,31(5):776-779
23.王海明,王宁,袁信芳,等.不同形态Fe对铜绿微囊藻生长及其生物可利用性的影响.农业环境科学学报. 2007,26(3):1029-1032
24.张铁明,杜桂森,杨忠山,等.锌对2种淡水浮游藻类增殖的影响.西北植物学报.2006,26(8):1722-1726
25.连民,刘颖,俞顺章.氮、磷、铁、锌对铜绿微囊藻生长及产毒的影响.上海环境科学.2001,20(4):166-171
26.毕东苏,钱春龙. Hg2+和Cr(VI)对富营养化水体中藻类生长的毒性效应.安徽农业科学.2007,35(26):8306-8308
27. Climate Change 2007 The Physical Science Basis
28. U. Riebesell. Effects of CO_2 enrichment on marine phytoplankton. Journal of Oceanography. 2004,60: 719-729
29. K.G..Schulz, U. Riebesell, B. Rost. et al. Determination of the rate constants for the carbon dioxide to bicarbonate inter-conversion in pH-buffered seawater system. Marine Chemistry. 2006, 100:53-65
30. YF Song, BS Qiu. The CO_2-concentrating mechanism in the bloom-forming cyanobacterium Microcystis aeruginosa (Cyanophyceae) and effects of UVB radiation on its operation. Journal of Phycology. 2007,43:957-964
31. Z Chen, HM Cheng, XW Chen. Effect of Cl- on photosynthetic bicarbonate uptake in two cyanobacteria Microcystis aeruginosa and Synechocystis PCC5803. Chinese Science Bulletin. 2009,54(7):1197-1203
32. HY Wu, DH Zou, KS Gao. Impacts of increased atmospheric CO_2 concentration on photosynthesis and growth of micro- and macro-algae. Science in China Series C: Life Science. 2008,51(12):1144-1150
33. MR Badger, GD Price. CO_2 concentrating mechanisms in cyanobacteria: molecular components, their diversity and evolution. Journal of Experimental Botany . 2003,54:609-622
34. BS Qiu, KS Gao. Effects of CO_2 enrichment on the bloom-forming cyanobacterium Microcystis aeruginosa (Cyanophyceae): Physiological responses and relationships with the availability of dissolved inorganic carbon. Journal of Phycology. 2002,38:721-729
35. J. A. Raven. Inorganic carbon concentrating mechanisms in relation to the biology of algae. Photosynthesis Research. 2003, 77:155-171
36. Swan S.W. Cot, Anthony K.C.So,George S.Espie. A Multiprotein Bicarbonate Dehydration Complex Essential to Carboxysome Function in Cyanobacteria. Journal of Bacteriology. 2008,190(3):936-945
37. SS Wang, YD Liu, YD Zou, et al. Modulation and adaptation of carbonic anhydrase activity in Microcystis spp. Under different environmental factors. Acta Ecologica Sinica. 2006,26(8):2443-2448
38. LJ Kang, XJ Chen, XJ Pan, et al. Effect of elevated bicarbonate concentration growth, chlorophyll a fluorescence and ultra-structure of Microcystis aeruginosa (cyanobaterium). Fresenius Environmental Bulletin. 2009,18(5):687-693
39. HH Hu, KS Gao. Impacts of CO_2 enrichment on growth and photosynthesis in freshwater and marine diatoms. Chinese Journal of Oceanology and Limnology. 2008,26 (4):407-414
40. A.Engel, K.G..Schulz, U.Riebesell, et al. Effects of CO_2 on particle sizedistribution and phytoplankton abundance during a mesocosm bloom experiment (PeECE II). Biogeosciences. 2008,5:509-521
41. I.Emma Huertas.Gabriel Navarro,Susana Rodríguez-Gálvez, et al.Temporal patterns of carbon dioxide in relation to hydrological conditions and primary production in the northeastern shelf of the Gulf of Cadiz (SW Spain). Deep-Sea Research II .2006, 53:1344-1362
42. S. Rabouille, J.M. Thébauit, M.J.Salen?on. Simulation of carbon reserve dynamics in Microcystis and its influence on vertical migration with Yoyo model. C.R.Biologies. 2003, 326:349-361
43. A. Bourret, Y.Martin, M.Troussellier. Modelling the response of microbial food web to an increase of atmospheric CO_2 partial pressure in a marine Mediterranean coastal ecosystem (Brusc Lagoon,France). Ecological Modelling .2007, 208:189-204
44. FX Fu, YH Zhang, M.E. Warner, et al. A comparison of future increased CO_2 and temperature effects on sympatric Heterosigma akashiwo and Prorocentrum minimum. Harmful Algae. 2008, 7:76-90
45.《水和废水监测分析方法》编委会编水和废水监测分析方法(第四版)[M].北京:中国环境科学出版社.2002,120-124
46. G M Bertoni, A Pissaloux, P Morard, et a1.Bicarbonate-pH relationship with iron chlorosis in white lupine. J Plant Nutr.1992,15:1 509-1 518
47. J M McCray, J E Matocha. Effects of soil water levels on solution bicarbonate , chlorosis and growth of sorghum. J Plant Nutr.1992,15:1 877-1 890
48. X Yang, V Rmheld, H Marschner. Effect of bicarbonate on root growth and accumulation of organic acids in Zn-inefficient and Zn-efficient rice cultivars (Oryza sativaL.). Plant and Soil.1994,164:1-7
49.陈莲花,刘雷.叶绿素荧光技术在藻类光合作用中的应用.江西科学. 2007,25(6):788-790,806
50.康丽娟,潘晓洁,常锋毅,等. HCO3-碱度增加对铜绿微囊藻光合活性和超微结构的影响.武汉植物学研究. 2008,26(1):70-75
51.杨威,孙凌,袁有才,等.碱度水平对铜绿微囊藻和四尾栅藻生长和竞争的影响.农业环境科学学报. 2007,26(4):1264-1268
52.杨苏文,姜霞,金相灿. HCO3-对铜绿微囊藻、四尾栅藻和小环藻增长特性及竞争行为的影响.生态环境. 2007,16(2):347-351
53.李晓,冯伟,曾晓春.叶绿素荧光分析技术及应用进展.西北植物学报. 2006,26(10):2186-2196