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.
作者
李启升
胡忠军
李永吉
何虎
韩燕青
靳辉
李宽意
LI Qi-sheng;HU Zhong-jun;LI Yong-ji;HE Hu;HAN Yan-qing;JIN Hui;LI Kuan-yi(National Demonstration Center for Experimental Fisheries Science Education,Shanghai Ocean University,Shanghai 201306,China;Centre for Research on Environmental Ecology and Fish Nutrion(CREEFN)of the Ministry of Agriculture,Shanghai Ocean University,Shanghai 201306,China;Shanghai Engineering Research Center of Aquaculture,Shanghai Ocean University,Shanghai 201306,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 210008,China;Yueyang Institute of Aquaculture,Yueyang 414001,China;Sino-Danish College,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《农业环境科学学报》
CAS
CSCD
北大核心
2019年第7期1589-1596,共8页
Journal of Agro-Environment Science
基金
水体污染控制与治理科技重大专项(2017ZX07203-005)
国家自然科学基金项目(31770509,41571086)
中国科学院135部署项目(NIGLAS2018GH04)
中国科学院科技服务网络计划重点项目(KFJ-STS-ZDTP-038-3)~~
关键词
氮负荷
沉水植物
浅水湖泊
苦草
穗花狐尾藻
nitrogen loading
submerged macrophytes
shallow lake
Vallisneria natans
Myriophyllum spicatum