Research on the Causes of Seasonal Low Dissolved Oxygen of Fuxi River in Zigong Urban Section
This paper collected the automatic monitoring water quality data for the past 10 years from a National Surface Water Assessment Cross-Section(Tanyansuo)of Fuxi River(a tributary of Tuojiang River),and investigated the water quality and sediment pollution by sampling along this river reach in 2021.An in-situ experiment on oxygen consumption rate of water and sediment was conducted in Tanyansuo cross-section as well.The temporal and spatial distribution characteristics of dissolved oxygen(DO)and the causes of seasonal low DO were researched by times series analysis,correlation analysis and numerical simulation.The results showed that:the lowest DO in the surface water of Tanyansuo was observed during late spring and early summer,and DO in daytime was higher than at night;the concentration of oxygen-consuming pollutants in the surface water of Tanyansuo was higher than that of other sections in the Tuojiang River Basin,which leading to relatively higher oxygen consumption intensity and lower DO;DO was low in downstream than that in upstream of the sewage treatment plant due to the low-oxygen drainage from the plant and bottom water of Jinzidang barrage;high content of organic matter in sediment of the river reach provided basis for microbial decomposition activity and consumption of DO when temperature increased in spring and summer,along with weak water temperature gradient brought by disturbance from drainage,promoted the formation of seasonal low DO phenomenon in the section.It is further confirmed by dissolved oxygen prediction model that temperature change and weak water temperature gradient was the main factor for the seasonal low DO of Tanyansuo.
urban riverdissolved oxygendistribution characteristicswater temperature gradientsedimentlow oxygen
NETL
NSTL
万方数据
