A novel assessment considering spatial and temporal variations of water quality to identify pollution sources in urban rivers

Abstract

It’s vital to explore critical indicators when identifying potential pollution sources of urban rivers. However, the variations of urban river water qualities following temporal and spatial disturbances were highly local-dependent, further complicating the understanding of pollution emission laws. In order to understand the successional trajectory of water qualities of urban rivers and the underlying mechanisms controlling these dynamics at local scale, we collected daily monitoring data for 17 physical and chemical parameters from seven on-line monitoring stations in Nanfeihe River, Anhui, China, during the year 2018. The water quality at tributaries were similar, while that at main river was much different. A seasonal ‘’turning-back” pattern was observed in the water quality, which changed significantly from spring to summer but finally changed back in winter. This result was possibly regulated by seasonally-changed dissolved oxygen and water temperature. Linear mixed models showed that the site 2, with the highest loads of pollution, contributed the highest (β = 0.316, P < 0.001) to the main river City Water Quality Index (CWQI) index, but site 5, the geographically nearest site to main river monitoring station, did not show significant effect. In contrast, site 5 but not site 2 contributed the highest (β = 0.379, P < 0.001) to the main river water quality. Therefore, CWQI index was a better index than water quality to identify potential pollution sources with heavy loads of pollutants, despite temporal and spatial disturbances at local scales. These results highlight the role of aeration in water quality controlling of urban rivers, and emphasized the necessity to select proper index to accurately trace the latent pollution sources.

Positive effects of COVID-19 lockdown on river water quality: evidence from River Damodar, India

“…The majority of the large world rivers are polluted by anthropogenic activities such as non degradable agriculture fertilizers and untreated industrial sewage discharge into rivers 13 . The river water quality is also declined gradually through toxic materials and excess nutrients supply from agrarian fields 14 . CPCB 15 reported that around 38,000 million liters per day untreated sewage and wastewater are discharged into the Indian River systems.…”

Temporal and Spatial Water Quality Assessment of the Geumho River, Korea, Using Multivariate Statistics and Water Quality Indices

“…The KWQI ranges from 0 to 100, with a higher value representing cleaner water. In this assessment, KWQI values were divided into the following ve grades: excellent (80-100), good (60-79), fair (40-59), poor (20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39), and very poor (0-19).…”

“…With increasing industrialization and urbanization worldwide, the management of rivers in metropolitan areas is becoming more important [18][19][20] . In the case of the Geumho River in South Korea, the upstream section is relatively clean while nonpoint pollution sources discharge into the river under certain rainfall conditions.…”

Analysis of the Influence of Anthropogenic Factors of the Urbanized Territory of Poltava Region (Ukraine) on the State of River Water

“…Multiparametric spatial and temporal study of water quality Nanfeihe River (China), conducted by the authors [Yang et al, 2021], indicates the need for careful selection of proper index to accurately trace the latent pollution sources of urban rivers. Thus, the City Water Quality Index is more informative than the Water Quality Index in determining potential pollution sources with heavy loads of pollutants.…”