常熟新建水源地湖泊轮叶黑藻和穗状狐尾藻的生长差异及对水环境的影响

GROWTH DIFFERENCES BETWEEN HYDRILLA VERTICILLATA AND MYRIOPHYLLUM SPICATUM AND THE EFFECTS ON WATER ENVIRONMENT IN NEWLY BUILT WATER SUPPLY LAKES IN CHANGSHU CITY

为了探明沉水植物群落构建对新建水源地湖泊水环境的作用效果,于2019年5—11月在常熟新建应急水源地湖泊比较研究了轮叶黑藻(Hydrilla verticillata)和穗状狐尾藻(Myriophyllum spicatum)两种沉水植物在人工栽种条件下的生长及对水质和叶绿素a(Chl.a)的影响。结果表明:两种沉水植物在试验湖泊均可正常生长,二者的生物量在5月至9月均呈上升趋势,但轮叶黑藻在5—7月处于快速生长期,而穗状狐尾藻在7—9月处于快速生长期;轮叶黑藻的衰亡期较穗状狐尾藻早,且衰亡过程持续时间短,11月轮叶黑藻完全衰亡,而穗状狐尾藻仍处于衰亡中期。两种沉水植物在生长期均可有效降低水体Chl.a浓度,对藻类生长起到抑制作用,但是在衰亡期会造成水体营养水平上升,Chl.a浓度升高。由总磷(TP)、总氮(TN)、高锰酸盐指数(CODMn)、Chl.a、溶解氧(DO)和透明度(SD)计算综合隶属函数值表明在两种沉水植物生长的高峰期,沉水植物组的水质状况优于对照组,衰亡期水质趋于恶化。Pearson相关分析表明轮叶黑藻生物量与Chl.a存在显著负相关关系,轮叶黑藻和穗状狐尾藻生物量与TP存在显著负相关关系。研究结果可为长江中下游湖泊生态修复过程中沉水植物选择、栽种和管理提供理论依据和借鉴参考。

In order to explore the effect of submerged macrophytes community construction on the water environment of newly built water supply lakes,a comparative study was conducted on the growth of Hydrilla verticillata and Myriophyllum spicatum under artificial planting conditions and their effects on water quality and chlorophyll a(Chl.a)in the newly built emergency water supply lake from May to November 2019 in Changshu City,Jiangsu Province,China.The results showed that the two kinds of submerged macrophytes could grow normally in the experimental lake,and their biomass showed an upward trend from May to September,but H.verticillata was in a rapid growth period from May to July,while M.spicatum was in a rapid growth period from July to September.The decay period of H.verticillata was earlier than that of M.spicatum,and the decay process was shorter.In November,H.verticillata withered completely,while M.spicatum was still in the middle stage of decay.The concentration of Chl.a could be effectively reduced during growth period of two submerged macrophytes,inhibiting phytoplankton growth,while the results were opposite during the period of decline in Autumn.The comprehensive membership function value calculated by total phosphorus(TP),total nitrogen(TN),chemical oxygen demand(CODMn),Chl.a,dissolved oxygen(DO)and Water transparency(SD)showed that the water quality of submerged macrophytes group was better than that of the control group during the period of vigorous growth,while deteriorating during decline period.Pearson analysis showed that the biomass of H.verticillata had a significantly negative correlation with Chl.a,and the biomass of H.verticillata and M.spicatum had a significantly negative correlation with TP.This study can provide theoretical support for selecting,planting and harvesting of submerged macrophytes during lake restoration in the middle and lower Yangtze River Basin.