Channel: Marine chemistry http://www.jto.ac.cn EN-US http://www.jto.ac.cn/EN/1009-5470/current.shtml http://www.jto.ac.cn 1009-5470 http://www.jto.ac.cn/EN/10.11978/2021173 To investigate the influencing factors of transformable total nitrogen (TTN) and its release potential, this paper used a graded leaching method to classify nitrogen in the Bohai Sea surface sediments into ion exchange nitrogen (IEF-N), weak acid extractable nitrogen (WAEF-N), strong alkali extractable nitrogen (SAEF-N), strong oxidizer extractable nitrogen (SOEF-N) and non-transformable nitrogen (NTN) states, the effects of sediment particle size and organic matter on the amount of released nitrogen were also investigated, and the effects of TTN release in sediment on dissolved inorganic nitrogen (DIN) and Chl a in the overlying water were examined. The results showed that the order of the content of each TTN was SOEF-N > SAEF-N > IEF-N > WAEF-N, the release amount was IEF-N > SAEF-N > SOEF-N > WAEF-N, and the release ratio was IEF-N > WAEF-N > SAEF-N > SOEF-N, respectively, 69.83% of IEF-N, 64.93% of WAEF-N, 56.27% of SAEF-N, and 29.56% of SOEF-N will be released again. Pearson correlation results showed that the release of SOEF-N in the sediment was negatively correlated with silt content, but is positively correlated with sand content; SOEF-N was negatively correlated with both Chl a and dissolved inorganic nitrogen (DIN) in the overlying water, indicating that the release of SOEF-N has less effect on the Chl a and DIN in the overlying water, while waters of surface and bottom had extremely strong positive correlations (r=0.803, P<0.01; r=0.831, P<0.01), respectively, which may imply that there is no significant stratification of surface and bottom waters in this study area.

]]>