湖北省典型流域片区地表水溶解氧时空变化及驱动因素

Spatio-temporal variation and driving factors of dissolved oxygen in surface water of typical watershed areas in Hubei Province

溶解氧(DO)是反映地表水水质状况的重要指标,是精准开展流域综合治理的关键参数之一。收集湖北省200座水质自动监测站2021—2022年地表水自动监测数据,研究DO时空变化特征并进行聚类分组,采用相关系数法、多元线性回归定量分析16个流域片区DO浓度变化的驱动因素,并提出流域治理建议。结果表明:1)时间上,湖北省地表水DO浓度存在显著季节性差异,表现为冬季>春季>秋季>夏季,其中5—10月存在显著昼夜变化。2)空间上,全省16个流域片区分为低氧区、中氧区和富氧区。低氧区为四湖片区和汉江下游片区,DO浓度和饱和度均较低,且夏季低氧发生频率高;富氧区集中在清江片区和汉江丹库以上片区,夏季易出现DO过饱和;其他流域片区为中氧区,DO饱和度稳定在较高水平。3)影响因素上,低氧区表现为复合型污染,富氧区主要受水生植物生长的影响,中氧区主要受水温影响。结合不同流域片区DO浓度变化特征,提出从“三水”统筹角度,分级分区开展流域系统化治理,即低氧区加强污染源头管控和过程控制,富氧区防控水华发生风险,中氧区严格排污总量控制。

Dissolved oxygen(DO)is an important indicator to reflect the quality of surface water,and it is one of key parameters for carrying out accurate comprehensive management of watersheds.Automatic monitoring data of surface water from 200 water quality automatic monitoring stations in Hubei Province from 2021 to 2022 were collected to study the spatial-temporal variation characteristics of DO and perform cluster grouping.The driving factors of DO variations of sixteen watershed areas were analyzed quantitatively by correlation coefficient method and multiple linear regression,and some suggestions for watershed management were proposed.The results indicated that:(1)DO concentration of surface water in Hubei Province showed significant seasonal difference as winter>spring>autumn>summer.Moreover,there was a significant diurnal variation from May to October.(2)Sixteen watershed areas in Hubei Province were divided into low oxygen zone,medium oxygen zone and rich oxygen zone.The low oxygen zone was mainly concentrated on Sihu area and the lower reaches of Hanjiang River area,with low DO concentration and saturation and high frequency of low DO occurrence in summer.The rich oxygen zone was mainly concentrated in Qingjiang area and the upper reaches of Danku Reservoir area of the Hanjiang River,with supersaturation in summer.The other watershed areas were medium oxygen zone,with stable saturation at a high level.(3)In terms of influencing factors,the low oxygen zone was characterized by compound pollution,the rich oxygen zone was affected by aquatic plant activities,and the medium oxygen zone was affected by temperature.Based on the characteristics of DO changes in different watershed areas,from the perspective of overall coordination of"three water"(water environment,water resource,water ecology),systematic watershed management methods should be set in a graded and partitioned manner,namely strengthening pollution source and process control in the low oxygen zone,preventing and controlling the risk of water blooms in the rich oxygen zone,and strictly controlling the total discharge in the medium oxygen zone.