氮磷增加对水源水库嗅味物质影响的模拟研究

Nitrogen and phosphorus enrichment influencing odor compounds production in drinking reservoir

我国水源水库经常发生嗅味物质超标问题,威胁到城市供水安全.嗅味物质产生往往与某些藻类的异常增殖有关,而氮、磷是藻类异常增殖的关键物质基础,揭示氮、磷营养盐输入增加对水库嗅味物质产生的影响有助于水源水库水质风险的精准防控.本研究以太湖流域水源水库沙河水库为例,在夏季蓝藻水华易发期开展原位氮、磷添加的湖沼学实验,探讨氮、磷输入对水库浮游植物群落结构及2-甲基异莰醇(2-MIB)、β-环柠檬醛等嗅味物质浓度的影响.结果表明,沙河水库夏季藻类生长受到氮、磷共同限制,氮、磷同时添加显著促进了蓝藻生长,进而增加了水体2-MIB等嗅味物质浓度;氮、磷添加还增加了微囊藻在蓝藻中的占比,并增加了β-环柠檬醛等嗅味物质浓度.统计分析表明,2-MIB浓度变化与蓝藻门的假鱼腥藻生物量变化密切相关;β-环柠檬醛的产生与藻类的衰亡过程联系紧密.本研究表明,氮、磷输入促进蓝藻异常增殖是太湖流域水源水库嗅味物质产生的一种机制,控制外源氮、磷输入,维持水库生态系统健康,是预防嗅味物质超标等水质风险的重要途径.

The odor compounds over-limitation often occur in drinking water reservoirs in China,threatening the safety of urban water supply.The production of odor compounds is often associated with the abnormal proliferation of some algae.Nitrogen and phosphorus are the key material basis for the abnormal proliferation of algae and thus revealing the influence of nitrogen and phosphorus input increase on the production of odor compounds in reservoirs is helpful for the precise prevention and control of water quality risks in source reservoirs.Taking Shahe Reservoir,a drinking water reservoir in Taihu Basin as a case,a in-situ limnological experiment was conducted to investigate the effects of nitrogen and phosphorus additions on phytoplankton community structure and the concentrations of 2-Methylisoborneol(2-MIB)andβ-cyclocitral in the reservoir during the cyanobacterial bloom prone period in summer.The results showed that algal growth was limited by both nitrogen and phosphorus in the reservoir during summer.The combined addition of nitrogen and phosphorus significantly stimulated the growth of cyanobacteria,thereby increasing the concentration of 2-MIB and other odor compounds in the water.Furthermore,Nitrogen and phosphorus addition increased the proportion of Microcystis to total cyanobacterial cell density and the concentration ofβ-cyclocitral Statistical analysis showed that the changes of 2-MIB concentration were closely related to the biomass changes of Pseudanabaena in Cyanophyta..The production of β-cyclocitral is closely related to the process of algae biomass decline and death.This study indicated that the abnormal proliferation of cyanobacteria promoted by nitrogen and phosphorus inputs was a mechanism for the production of odor compounds in the source reservoirs of the Taihu Lake Basin.Consequently,controlling the input of exogenous nitrogen and phosphorus to maintain the reservoir ecosystem health is an important way to prevent water quality risks such as excessive odor compounds.