Earth Science Frontiers ›› 2022, Vol. 29 ›› Issue (4): 448-454.DOI: 10.13745/j.esf.sf.2021.11.29

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Distribution and evaluation of nitrogen, phosphorus and organic matter in sediments of the middle reaches of the Chaobai River

CHI Minghui1,2(), QIN Yanwen1,2, YANG Chenchen1,2, WEN Quan1,2, SUN Ning1,2, ZHU Huailin1,2, ZHANG Lei1,2,*()   

  1. 1. State Key Laboratory of Environmental Benchmarking and Risk Assessment, Beijing 100012, China
    2. Institute of Water Ecology and Environment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
  • Received:2021-05-06 Revised:2021-11-08 Online:2022-07-25 Published:2022-07-28
  • Contact: ZHANG Lei

Abstract:

The Chaobai River is a significant river that flows through Beijing, Hebei, and Tianjin areas. Taking the middle reaches of the Chaobai River as the study area, this paper sought to assess the level of nutrient pollution (organic matter, nitrogen and phosphorus) in the river sediments. One hundred thirty samples were collected from the study area and the organic matter (OM) content, total nitrogen (TN) and total phosphorus (TP) in the surface sediments were determined. Subsequently, the sources and distribution patterns of the three pollutants were analyzed, and the regional ecological risks were evaluated using a combination of organic pollution index and organic nitrogen pollution index. It was found in that (1) the OM content in the surface sediments varied from 0.17% to 13.15%, averaging 5.32%; TN ranged from 0.005-1.028 g/kg, averaging 0.192 g/kg; and TP ranged from 0.367-4.825 g/kg, averaging 1.662 g/kg. (2) Correlation analysis indicated that OM content was weakly correlated with TP or TN, while TN and TP were strongly correlated. TN and TP came from similar sources—mainly external sources, which is different from OM content. According to TOC/TN analysis, OM content was mainly affected by algae, phytoplankton and plants lack of fiber bundles. (3) According to organic pollution index evaluation results, 60% of surface sediment samples were clean (i.e., pollution free), 33.85% were relatively clean, 4.62% were almost clean, and 1.54% containd organic polutants. Organic pollution mainly occurred at the entrances of the Yunchaojian River and Tianjiazhuang drainage trunk canal into the Chaobai estuary. The organic nitrogen assessment results showed that the study area was generally free from organic nitrogen pollution and had a good overall pollution ranking.

Key words: Chaobai River, surface sediments, organic matter, nutrients, pollution characteristics, evaluation

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