郑州市景观水体东风渠绿藻水华污染特征及营养盐效应

Contaminative characteristics and nutrient effect of green algae in the landscape waterbody of DongFeng River in Zhengzhou city

[目的]城市景观水体富营养化导致水质恶化是不少城市水环境的共性问题,研究景观水体水质与营养盐的关系,对控制水华爆发和改善景观水体质量具有重要意义。[方法]以郑州市东风渠为研究区域,对夏季绿藻水华爆发时和冬季水体中浮游藻类生物量叶绿素a(Chl.a)、脱镁叶绿素a(Dechla.)、营养盐浓度以及理化特性进行调查分析。[结果]夏季Chl.a平均值为29.76μg·L^(-1),冬季为23.72μg·L^(-1),夏季Dechla.平均值为18.13μg·L^(-1),冬季为19.32μg·L^(-1),Chl.a和Dechla.波动幅度冬季比夏季大,冬季河流中浮游藻类生物量有明显的空间异质性。在花园路桥东200米处(I-2#)Dechla.最大40.73μg·L^(-1),溶解氧(DO)最低1.48mg·L^(-1),此处水体污染最严重。夏季水体总氮(TN)平均值为226.08mg·L^(-1),总磷(TP)平均值为6.25mg·L^(-1),TP变化范围较小;冬季TN平均值为343.75mg·L^(-1),TP平均值为11.70mg·L^(-1),TP变化范围较大,有明显的空间异质性。夏季和冬季水质营养等级均为重度富营养,夏季绿藻水华爆发时Chl.a与pH和浊度(TB)呈显著正相关。冬季底泥中Chl.a浓度范围为3.21~10.74μg·g-1,平均值6.82μg·g-1,Dechla.浓度范围为11.24~19.33μg·g-1,平均值为13.81μg·g-1;底泥TN平均值14.35mg·g-1,TN沿水流方向从花园路到东明路变化趋势先下降后上升,在经三路桥西(I-2’#)最小12.66mg·g-1;底泥TP平均值6.56mg·g-1,TP沿水流方向逐渐降低。[结论]研究结果对绿藻水华污染控制有一定指导意义。

[Objective]The eutrophication of urban landscape water result is a common problem on deterioration of water quality.Studying the relationship between water quality and nutrient salt in landscape water is very important to control water blooming and improve water quality.[Methods]The Chlorophyll a（Chl.a）,Demagnesiumchlorophyll a.（Dechla.）,nutrient and physicochemical properties of samples collected from DongFeng river were investigated during algae blooming summer and winter.[Results]The result showed that average contents of Chl.a were 29.76μg·L-1 and23.72μg·L-1 in summer and winter,and Dechla were 18.13μg·L-1 and 19.32μg·L-1,respectively.The fluctuation ranges of Chl.a and Dechla.In winter was greater than that of in summer.The biomass of planktonic algae in winter had obvious spatial heterogeneity.In the sampling site I-2#,200 meters far from the east of HuaYuan road bridge,the content of Dechla was the highest（40.73μg·L-1）,and dissolved oxygen（DO）was the lowest（1.48 mg·L-1）among all cross sections,showing the most serious water pollution.The average contents of total nitrogen（TN）and total phosphorus（TP）were 226.08 mg·L-1 and 6.25 mg·L-1,respectively during summer,the content of TP was changed smoothly.The average contents of TN and TP were 343.75 mg·L-1 and 11.70 mg·L-1,respectively in winter,and TP content varied widely in the different sites,showed spatial heterogeneity in winter.Water quality maintained a high eutrophic level in summer and winter.Chl.a was positively correlated with pH and turbidity（TB）during＂water bloom＂.Inaddition,the variation ranges of Chl.a and Dechla.in winter sediment were 3.2110.74μg·g-1 and 11.2419.33μg·g-1,and their averages were 6.82μg·g-1 and 13.81μg·g-1,respectively.Average content of TN was 14.35 mg·g-1,it tended to decrease and then increase along the flow direction from HuaYuan road to the DongMing road,the minimum content of TN was 12.66 mg·g-1 located in the west of JingSan road bridge（I-2’#）.The average content of TP was6.56 mg·g-1,tended to decrease gradually from upper to downstream river along the flow direction.[Conclusion]The result of the study have some guiding significance for controlling the pollution of algae blooms.