Assessment of Nutrient and Heavy Metal Pollution in Channel Dredged Sediments in the middle and lower reaches of the Yangtze basin

¹ Tianjin Research Institute for Water Transport Engineering, Key Laboratory of Environmental Protection in Water transport Engineering, Ministry of Transport, Tianjin 300456, China
² Tianjin Key Lab of Marine Resource & Chemistry, Tianjin Marine Environmental Protection and Restoration Technology Engineering Center, Tianjin University of Science & Technology, Tianjin 300457, China

^* Corresponding author’s e-mail: 529202551@qq.com

Abstract

There was a large amount of dredged materials produced stably in the Yangtze waterway each year. How to dispose these dredged materials was a major technical problem in the field of port and waterway engineering. The dredged materials were valuable resource, and the utilization of dredged materials in landscape can be an important direction in the future. To analyze the feasibility of dredging for landscaping, the waterway dredged sediments from middle and lower reaches of the Yangtze River basin, such as Dongting Lake, Chenglingji section, Zhenjiang section, Nantong section and Taihu Lake were collected, and the nutrient characteristics, heavy metal content and pollution degree were analyzed. The results showed that the pH, moisture content, petroleum hydrocarbons, organic matter and available P in Yangtze River waterway dredging sediments were 7.28~7.74, 3.75~28.27%, 14.21~121.84 ppm, 1.88~5.29% and 16.96~65.38 ppm respectively, which were moderate pollution and suitable for plants growth. The content of available N and available K content were 67.12~87.97 ppm and 2.78~20.11 ppm, which were too low to meet the needs of plant growth. Extra sources of nitrogen and potassium should be added into the sediments when reused. Dredged sediments were contaminated by heavy metals Cu, Pb and Zn, the evaluation results showed that their enrichment effect was not obvious, which won’t affect the sediment utilization. Dredged sediments were widely contaminated by Cd (0.05~2.68 mg/kg), and there was a certain enrichment effect, so some Cd hyperaccumulators should be planted to remediate Cd in dredged sediments.