摘要
为研究在浅水湖泊的外源污染源控制工作中控氮(N)的必要性,通过室外模拟实验,探究了N负荷升高对浅水湖泊沉水植物生长的影响。实验设置低N组(输入氮磷比为5∶1)和高N组(输入氮磷比为100∶1)两个N负荷水平,同时选择不同生长型的两种沉水植物——莲座型苦草(Vallisneria natans)和冠层型穗花狐尾藻(Myriophyllum spicatum)作为实验对象。结果表明:N负荷升高对苦草生长产生了明显的抑制作用,表现为高N组苦草的相对生长率、生物量、根长、株数和叶片数等指标均显著低于低N组。与苦草不同,N负荷升高对穗花狐尾藻的胁迫作用不显著,两种N浓度下穗花狐尾藻的生物量、相对生长率、节间距、株高和株数均无明显差异。总体而言,N负荷升高显著降低了沉水植物的总生物量,实验结束时高N组沉水植物的总生物量(115.86 g?m~(-2))是低N组(321.98 g?m~(-2))的36.0%。研究表明,N负荷升高会对沉水植物的生长产生胁迫,但是不同沉水植物对N负荷升高的响应具有种间差异。从湖泊管理和生态修复的角度,本研究支持外源N、P均需要控制的观点。
N and P are key factors that limit phytoplankton growth in freshwater lakes. Controlling external P loading is a widely recognized measure for lake restoration, but the necessity of limiting N inputs remains under debate. Here, we conducted a mesocosm experiment with a duration of 28 d to explore the effects of external N loading on the growth of submerged macrophytes with contrasting growth types of rosette(Vallisneria natans)and canopy(Myriophyllum spicatum). There were mixed plantings of both macrophytes(density ratio:1∶1)in each mesocosm. Our experiment design included one treatment with two levels of N inputs(high N group:N∶P=100∶1; low N group:N∶P=5∶1). The results showed that high N inputs greatly inhibited the growth of V. natans, which had a significantly lower relative growth rate,biomass, root length, and number of plants and leaves in the high N group compared with those in the low N group. However, there were no significant differences in the relative growth rate, biomass, internodal length, total height, and number of plants of M. spicatum between the two N loading treatments, thereby indicating that N loading did not have a significant effect on the growth of M. spicatum. Overall, the total biomass of the two submerged macrophytes in the high N group(115.86 g?m~(-2))was only 36.0% of that in the low N group(321.98 g?m~(-2)),thereby indicating that high external N loading had a significant negative effect on submerged macrophytes. Our study suggested that high N inputs can greatly reduce submerged macrophytes in shallow lakes, but the effects are species-specific. From the perspective of lake management and restoration, our study supported the view that both N and P should be controlled.
引文
[1]吴雅丽,许海,杨桂军,等.太湖水体氮素污染状况研究进展[J].湖泊科学,2014,26(1):19-28.WU Ya-li,XU Hai,YANG Gui-jun,et al.Progress in nitrogen pollution research in Lake Taihu[J].Journal of Lake Sciences,2014,26(1):19-28.
[2]Vitousek P M,Aber J D,Howarth R W,et al.Human alteration of the global nitrogen cycle:Sources and consequences[J].Ecological Applications,1997,7(3):737-750.
[3]Smith V H,Schindler D W.Eutrophication science:Where do we go from here?[J].Trends in Ecology&Evolution,2009,24(4):201-207.
[4]Baulch H M.Asking the right questions about nutrient control in aquatic ecosystems[J].Environmental Science&Technology,2013,47(3):1188-1189.
[5]Schindler D W.Eutrophication and recovery in experimental lakes:Implications for lake management[J].Science,1974,184(4139):897-899.
[6]María A,González S,Jeppesen E,et al.Does high nitrogen loading prevent clear-water conditions in shallow lakes at moderately high phosphorus concentrations?[J].Freshwater Biology,2005,50(1):27-41.
[7]Schindler D W,Hecky R E,Findlay D L,et al.Eutrophication of lakes cannot be Controlled by reducing nitrogen input:Results of a 37-year whole-ecosystem experiment[J].Proceedings of the National Academy of Sciences of the United States of America,2008,105(32):11254-11258.
[8]Wang H,Wang H.Mitigation of lake eutrophication:Loosen nitrogen control and focus on phosphorus abatement[J].Progress in Natural Science:Materials International,2009,19(10):1445-1451.
[9]Welch E.Should nitrogen be reduced to manage eutrophication if it is growth limiting?Evidence from Moses Lake[J].Lake&Reservoir Management,2009,25(4):401-409.
[10]Elser J J,Bracken M E,Cleland E E,et al.Global analysis of nitrogen and phosphorus limitation of primary producers in freshwater,marine and terrestrial ecosystems[J].Ecology Letters,2007,10(12):1135-1142.
[11]Conley D J,Likens G E.Ecology controlling eutrophication:Nitrogen and phosphorus[J].Science,2009,323(5917):1014-1015.
[12]Scott J T,Mccarthy M J.Nitrogen fixation may not balance the nitrogen pool in lakes over timescales relevant to eutrophication management[J].Limnology&Oceanography,2010,55(3):1265-1270.
[13]Paerl H W,Xu H,Mccarthy M J,et al.Controlling harmful cyanobacterial blooms in a hyper-eutrophic lake(Lake Taihu,China):The need for a dual nutrient(N&P)management strategy[J].Water Research,2011,45(5):1973-1983.
[14]Hilt S,Gross E M.Can allelopathically active submerged macrophytes stabilise clear-water states in shallow lakes?[J].Basic&Applied Ecology,2008,9(4):422-432.
[15]Moss B.Engineering and biological approaches to the restoration from eutrophication of shallow lakes in which aquatic plant communities are important components[J].Hydrobiologia,1990,200/201(1):367-377.
[16]Jeppesen E,Meerhoff M,Jacobsen B A,et al.Restoration of shallow lakes by nutrient control and biomanipulation-the successful strategy varies with lake size and climate[J].Hydrobiologia,2007,581:269-285.
[17]Moss B.The Broads:The People′s Wetland[M].London:Harper Collins Publishers,2001.
[18]Moss B,Jeppesen E,S?ndergaard M,et al.Nitrogen,macrophytes,shallow lakes and nutrient limitation:Resolution of a current controversy?[J].Hydrobiologia,2013,710:3-21.
[19]Cao T,Ni L,Xie P,et al.Acute biochemical responses of a submersed macrophyte,Potamogeton crispus L.to high ammonium in an aquarium experiment[J].Journal of Freshwater Ecology,2004,19(2):279-284.
[20]Nimptsch J,Pflugmacher S.Ammonia triggers the promotion of oxidative stress in the aquatic macrophyte Myriophyllum mattogrossense[J].Chemosphere,2007,66(4):708-714.
[21]Su S,Zhou Y,Qin J G,et al.Physiological responses of Egeria densa to high ammonium concentration and nitrogen deficiency[J].Chemosphere,2012,86(5):538-545.
[22]章宗涉.水生高等植物-浮游植物关系和湖泊营养状态[J].湖泊科学,1998,10(4):83-86.ZHANG Zong-she.Macrophyte-phytoplankton relationship and lake trophic status[J].Journal of Lake Sciences,1998,10(4):83-86.
[23]高汾,张毅敏,杨飞,等.水位抬升对4种沉水植物生长及光合特性的影响[J].生态与农村环境学报,2017,33(4):341-348.GAO Fen,ZHANG Yi-min,YANG Fei,et al.Growth and photosynthetic fluorescence characteristics responses of four submersed macrophytes to rising water level[J].Journal of Ecology and Rural Environment,2017,33(4):341-348.
[24]段德龙,于金金,杨静,等.伊乐藻与狐尾藻、苦草和金鱼藻的竞争研究[J].河南农业科学,2011,40(8):149-152.DUAN De-long,YU Jin-jin,YANG Jing,et al.Research on competition of Elodea nuttallii with Myriophyllum verticillatum,Vallisneria natans and Ceratophyllum demersum[J].Journal of Henan Agricultural Sciences,2011,40(8):149-152.
[25]闵奋力,左进城,刘碧云,等.穗状狐尾藻与不同生长期苦草种间竞争研究[J].植物科学学报,2016,34(1):47-55.MIN Fen-li,ZUO Jin-cheng,LIU Bi-yun,et al.Competition between Myriophyllum spicatum L.and Vallisneria natans(Lour)Hara at different growth stages[J].Plant Science Journal,2016,34(1):47-55.
[26]李启升,李永吉,韩燕青,等.水深对沉水植物苦草(Vallisneria natans)和穗花狐尾藻(Myriophyllum spicatum)生长的影响[J].湖泊科学,2019,31(4).LI Qi-sheng,LI Yong-ji,HAN Yan-qing,et al.Effects of water depth on growth of submerged macrophytes Vallisneria natans and Myriophyllum spicatum[J].Journal of Lake Sciences,2019,31(4).
[27]Gu J,He H,Jin H,et al.Synergistic negative effects of small-sized benthivorous fish and nitrogen loading on the growth of submerged macrophytes-Relevance for shallow lake restoration[J].Science of the Total Environment,2018(610/611):1572-1580.
[28]金相灿,屠清瑛.湖泊富营养化调查规范[M].二版.北京:中国环387境科学出版社,1990.JIN Xiang-can,TU Qing-ying.Lake eutrophication investigation specification[M].2nd Edition.Beijing:China Environmental Science Press,1990.
[29]Li K Y,Liu Z W,Gu B H.Compensatory growth of a submerged macrophyte(Vallisneria spiralis)in response to partial leaf removal:effects of sediment nutrient levels[J].Aquatic Ecololgy,2010,44(4):701-707.
[30]文明章,李宽意,王传海.水体的营养水平对苦草(Vallisneria atans)生长的影响[J].环境科学研究,2008,21(1):74-77.WEN Ming-zhang,LI Kuan-yi,WANG Chuan-hai.Effects of nutrient level on growth of Vallisneria atans in water[J].Research of Environmental Sciences,2008,21(1):74-77.
[31]Cao T,Xie P,Ni L Y,et al.The role of NH+4toxicity in the decline of the submersed macrophyte Vallisneria natans in lakes of the Yangtze River basin,China[J].Marine and Freshwater Research,2007,58(6):581-587.
[32]潘琦,邹国燕,宋祥甫.硝氮胁迫对不同沉水植物生理生长的影响[J].上海环境科学,2010,29(1):16-20.PAN Qi,ZOU Guo-yan,SONG Xiang-fu.Effects of nitrate-nitrogen stress on the growth and physiological indices of two submerged macrophytes[J].Shanghai Environmental Sciences,2010,29(1):16-20.
[33]黎慧娟,倪乐意.浮游绿藻对沉水植物苦草生长的抑制作用[J].湖泊科学,2007,19(2):111-117.LI Hui-juan,NI Le-yi.The effects of chlorophyta on the growth of submersed macrophyte Vallisneria natans:A laboratory experiment[J].Journal of Lake Sciences,2007,19(2):111-117.
[34]Yu Q,Wang H Z,Li Y,et al.Effects of high nitrogen concentrations on the growth of submersed macrophytes at moderate phosphorus concentrations[J].Water Research,2015,83:385-395.
[35]Kang C X,Takahiro K,Hao A M,et al.Oxidative stress responses of submerged macrophyte Vallisneria asiatica to different concentrations of cyanobacteria[J].Chinese Journal of Oceanology&Limnology,2015,33(2):364-371.
[36]He H,Kang Y,Liu Z.Nitrogen inputs enhance phytoplankton growth during sediment resuspension events:A mesocosm study[J].Hydrobiologia,2015,744(1):297-305.
[37]张雪,郑建伟,周茂飞,等.外源氮磷负荷比增加对刺苦草(Vallisneria spinulosa)生长的影响[J].湖泊科学,2017,29(4):880-886.ZHANG Xue,ZHENG Jian-wei,ZHOU Mao-fei,et al.Effect of increasing nitrogen/phosphorus ratio in loading on the growth of Vallisneria spinulosa[J].Journal of Lake Sciences,2017,29(4):880-886.
[38]王爱丽,孙旭,陈乾坤,等.污水处理厂尾水中氨氮对穗花狐尾藻生长的影响[J].生态学杂志,2015,34(5):1367-1372.WANG Ai-li,SUN Xu,CHEN Qian-kun,et al.Effect of ammonia in the tailwater from wastewater treatment plant on the growth of Myriophyllum spicatum[J].Chinese Journal of Ecology,2015,34(5):1367-1372.