The contents of total nitrogen (TN)

total phosphorus (TP) and total organic carbon (TOC) in 16 sampling points of the Weihe River and its tributary channels were studied

and the possible sources of sediments were studied by C/N and N/P ratio methods. The status of sediment pollution is evaluated by the organic pollution index method. The study shows that the TN content in the sediment is between 0.069~3.839 g/kg

66.1% of sample content is below the average 0.639 g/kg; the TP content is between 0.453~1.841 g/kg

62.7% of sample content is below the average. 0.713 g/kg; TOC content is between 0.772~25.221 g/kg

62.3% of sample content is below the average value of 5.609 g/kg. The organic matter in the sediments of the Weihe River in Shaanxi Province is mainly affected by endogenous sources

and is dominated by algae and phytoplankton. The source of phosphorus in sediments is mainly external input. The N/P values of all sampling points from 2014 to 2016 were less than the Redfield ratio

which may be related to the biogeochemical processes of carbon

nitrogen and phosphorus in sediments. In November 2016

there were external sources of organic matter in partical rivers such as Linjia Village

Wolongsi Bridge

Changxing Bridge

Xingping

Caotan and Qingjiang River. In 2015

the organic index and the organic nitrogen index changed in the same period

namely before the flood