白洋淀湿地水华暴发阈值分析

Threshold analysis of water blooms in Baiyangdian wetlands

水体富营养化阈值分析可为控制水华暴发,确定合理的污染物控制水平提供科学依据。以白洋淀湿地为例,利用2000—2009年水质监测数据,选择表征水体富营养化的主要指标进行主成分聚类分析,划分出低溶氧高营养型和不稳定型2类水域;并针对不同水域类型,以叶绿素a为因变量,以pH值、水温、透明度(SD)、CODcr、总氮(TN)、总磷(TP)、氨氮、硝氮和溶解态无机磷为自变量,采用逐步回归方法,分别建立了水质指标与叶绿素a的多元线性关系式,以此确定了白洋淀湿地水体水华暴发阈值。根据叶绿素a为30μg·L-1为水华暴发的临界值,白洋淀低溶氧高营养型水域CODcr应控制在37.31mg·L-1,不稳定型水域TP应控制在0.12mg·L-1。

Threshold analysis of water body eutrophication can provide scientific basis for controlling water bloom and defining pollutants rational control level.Taking the Baiyangdian wetlands as the case,and by using 2000-2009 water quality monitoring data,the main indices characterizing the water body eutrophication of the wetlands were clustered by principal component analysis,and,using chlorophyll a as dependent variable,and water pH,temperature,transparency,CODcr,total nitrogen,total phosphorus,ammonia nitrogen,nitrate nitrogen,and dissolved inorganic phosphorus as independent variables,the multiple linear relationship of chlorophyll a and water quality indices was established by stepwise regression to determine the thresholds of water blooms in the wetlands.The Baiyangdian wetlands could be categorized into two kind water areas,i.e.,low dissolved oxygen and high nutritional,and unstable.With 30 μg·L-1 of chlorophyll a as the threshold of water bloom,the CODcr concentration in the low dissolved oxygen and high nutritional water area should be controlled at 37.31 mg·L-1,and the total phosphorous concentration in the unstable water area should be at 0.12 mg·L-1.