Abstract
Urbanization and human activities have exerted a tremendous adverse influence on the water quality of the Licun River, Qingdao, China. In order to restore the water quality, a succession of measures have been carried out since 1996, mainly encompassing flood controlling, sewage intercepting and watercourse greening (before 2007), watercourse and point source control based on administrative region (2008–2017), as well as the comprehensive governance based on river basin (after 2018). In 2019, the amount of discharged industrial wastewater, chemical oxygen demand, and ammonia nitrogen decreased by 53.91%, 87.75% and 89.88%, respectively, compared with 2000. Such results indicate that continuous governance has achieved a quantitative effect, and that industrial discharge is not the main pollution source. In the present work, the Spearman rank correlation coefficient and river comprehensive pollution index methods were used to analyze the change trend of main pollutants. The water quality was improved continuously, and the reduction of total phosphorus and ammonia nitrogen was the key to upgrading water quality. Afterward, the emission of pollution sources was accounted for from viewpoints of the point source, non-point source and sludge. Finally, suggestions were put forward to improve the water quality of the Licun River and provide some reference for the urban river management in northern China.
Highlights
Urbanization and human activities have exerted a tremendous adverse influence on the water quality of the Licun River, Qingdao, China
Monitoring data show that total phosphorus (TP) concentration occasionally exceeds the standard, which should be paid more attention. KCOD remains stable at about 17% with little fluctuation and increases to 24.2% in 2020, while the monitoring data show that chemical oxygen demand (COD) concentration is stable and up to the standard
The first stage of river engineering governance encompasses flood control, sewage interception and greening; the second stage of river engineering and point source treatment is concentrated in the administrative region (2008–2017); the third stage of comprehensive treatment is based on the basin
Summary
Urbanization and human activities have exerted a tremendous adverse influence on the water quality of the Licun River, Qingdao, China. This suggested that previous governance schemes in improving the water quality of the Licun River have not worked effectively[1,2,3]. The quantitative changes in pollutant discharge and water quality under continuous governance are analyzed using the river comprehensive pollution index and Spearman rank correlation coefficient methods. Based on the calculation of pollution sources in the basin, the main pollutants production is clarified, and suggestions are put forward for pollution control, which will provide a reference value for the future governance of the Licun River and other rivers in northern China
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