Author(s): Su-Duan Hu; Tian-Xiang Wang; Shi-Guo Xu; Guang-Yu Su; Yue-Nan Yu
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Keywords: No Keywords
Abstract: Nitrogen is an important index in reservoir environment. Sediment has gradually become a key factor affecting water quality. Based on the field investigation and laboratory simulation, the spatial distribution, fractions and adsorption/release characteristics of nitrogen in sediments were studied by taking Biliuhe reservoir as a case study. The results indicate that the concentration of total nitrogen (TN) in sediments of Biliuhe reservoir was high, which varied from 1153 to 3320 mg/kg. The average concentration was respectively 2725 mg/kg and 1538mg/kg in the water covered zone and water-level fluctuating zone. TN increased gradually from the entrance to the dam agreeing with the change of the hydraulic gradient. The amount of nitrogen released in 24 hours (the initial concentration of TN in the overlying water is 0mg/L) ranged from 56.1 to 171.33mg/kg and accounted for2.64–6.62% of TN in sediments. Therefore, the nitrogen in sediments had a potential risk of release. The maximum adsorption capacity in 24 hours was between 108.22 and 698.95 mg/kg. The adsorption efficiency ranged from 10.932 to 63.992L/kg in the water covered zone and 15.363 to 33.237l/kg in water-level fluctuating zone. In the water covered zone, the critical adsorption and release concentration range of sediments was 3.29-10.12mg/L which was in high risk of release and greater than that of the overlying water in most cases. While the critical adsorption and release concentration range of sediments was 1.22-2.23mg/L in water-level fluctuating zone, which was less than the overlying water and the release risk was low. This paper mainly studied the spatial distribution of nitrogen and the adsorption and release characteristics of sediment under different overlying water conditions, while the effect of water microenvironment was not considered which will be studied in the future.
Year: 2018