Abstract:
Intact sediment cores from the Yellow River were studied for denitrification rate (De) based on benthic fluxes of molecular nitrogen (N
2) by a laboratory incubation study; meanwhile correlation between sediments De and concentration of dissolved organic carbon (DOC) and nitrate, and sediment oxygen consumption rate (SOC) was discussed.The mean value of De for the control treatment was 14.81±9.43 μg N/m
2/h.For the extragenousnitrogen addition treatment, the highest De was investigated in N1 level (4.5 mg/L) with a mean value of 21.99±12.45 μg N/m
2/h.For the extragenouscarbon addition treatment, the highest De was investigated in C1 level (2.4 mg/L) with a mean value of 24.33±14.38 μg N/m
2/h.In theory, sediment denitrification rate up to peak, when concentration of nitrate and DOC in overlying water was 9.8 and 4.0 mg·L
-1 respectively; the optimal C/N for sediment denitrification was 2.3.Correlation between De and SOC showed different patterns depending on nitrate and DOC level.Our study investigated that De was significant positively related to SOC under lower nitrate and DOC level, while negativelyrelated to SOC under higher DOC and lower nitrate level; however, no significant correlation between De and SOC was investigated when overlying water showed higher nitrate and lower DOC level.