Temporal and spatial dynamics of dissolved oxygen and formation of hypoxia in typical reaches of Dongjiang River estuary
To clarify the causes of hypoxia in the southern tributary of the Dongjiang River and provide scientific basis for water management,this study measured water quality of the main river sections during spring and summer in 2019.The measurement re-sults showed that the dissolved oxygen in the southern tributary of the Dongjiang River dropped from 6.93 mg/L in the middle rea-ches at Daojiao Town to 4.08 mg/L at the estuary.Correlation analysis indicated that dissolved oxygen was significantly negatively correlated with water temperature,and positively correlated with salinity,and had a significant negative correlation with nutrients such as ammonium nitrogen and total phosphorus.The increase of nutrients was spatially significantly overlapped with the reduction of dissolved oxygen,especially during the summer.The main cause of hypoxia in the southern tributary of the Dongjiang River was the mixed influence of physical,chemical,and biological factors.The increase in water temperature and nutrients accelerated oxy-gen consumption in the middle and lower reaches of the water body.The narrowing of the river channel at confluences and poor light penetration in downstream waters led to insufficient replenishment of dissolved oxygen,and thus caused frequent hypoxia at the low-er reaches Shatian Sisheng section.
Southern tributary of the Dongjiang Riverdissolved oxygenhypoxianutrientsPearl River
万方数据
维普
