Journal of East China Normal University(Natural Science) ›› 2020, Vol. 2020 ›› Issue (1): 150-158.doi: 10.3969/j.issn.1000-5641.201841032

• Estuary and Coastal Research • Previous Articles     Next Articles

Spatiotemporal variations and influencing factors of organic carbon content in the urban rivers of Shanghai

ZHU Kun, WU Ying, Qi Lijun   

  1. State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China
  • Received:2018-11-12 Published:2020-01-13

Abstract: Surface water samples were collected monthly from four sites in Suzhou River and Huangpu River from December 2015 to December 2016. We analyzed the concentration of dissolved organic carbon (DOC) and particulate organic carbon (POC) along with total suspended matter (TSM) and stable carbon isotope (δ13C) to understand the spatial and temporal variations in Suzhou River and Huangpu River. During the dry season, the DOC concentration of upstream sections of Suzhou River (4.52 ±0.48 mg·L-1) was higher than the downstream sections (3.66 ±0.32 mg·L-1), while there was no significant difference between the upstream and downstream sections during the flood season. Different retention times for DOC transportation for the upstream sections relative to the downstream sections might be a major factor for the spatial distribution of DOC. The δ13C (-29.1‰ ±1.0‰) during the flood season was more negative than the dry season (-28.1‰ ±0.6‰), indicating the significant contribution from plankton in the flood season. The mass fraction of POC (POC%) showed no significant differences between the flood and dry seasons, but the POC% in the dry season (6.01% ±2.27%) was still higher than the flood season (4.10% ±0.99%). The DOC concentration and POC% in Huangpu River showed no obvious differences the upstream and downstream sections; however, DOC showed higher concentration during the winter and lower concentration during the summer. The lower TSM (79.1 ±26.4 mg·L-1) and more negative δ13C (-28.1‰ ±0.9‰) in the flood season suggested that the Huangpu River was affected mainly by the water discharge from Taihu Lake during the flood season; POC% in the flood season was higher than the dry season. DOC was the dominant fraction of organic carbon in the two rivers, and the difference in the water self-purification capacity between two urban rivers resulted in the difference of DOC/POC variation range. The gradual decrease in the DOC concentration of the Huangpu River during the period from 2005-2016 indicates that the third phase of sewage treatment projects achieved initial effectiveness in controlling organic pollution of the Huangpu River, but the high concentration of total organic carbon (TOC) indicates that the organic pollution in Huangpu River was still at a relative high level.

Key words: Huangpu River, Suzhou River, stable carbon isotope, dissolved organic carbon, particulate organic carbon

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