Abstract:The vertical distribution characteristics of the pore water nitrogen concentration of the sediment from Dianchi Lake are studied, the nitrogen diffusion flux at its sediment-water interface was estimated quantitatively based on Fick diffusion law, and its influencing factors were also discussed. The results show: The total dissolved nitrogen of the sediment pore water from Dianchi Lake was mainly in the form of NH4+-N, accounting for 72.30%, With the increasing depth its concentration presented an increasing trend; followed by dissolved organic nitreogen (DON), accounting for 24.59%, with the increasing depth the concentration presented a trend of first increasing then decreasing gradually stabilized. NO3--N accounted for a lower proportion, and the concentration with depth increasing showed a decreasing trend. The amount of the NH4+-N diffused at sediment-water interface was between 12.73 and 59.74mg/m2·d [With an average of 30.18mg/(m2 ·d)]. The amount of the NH4+-N released was 3305.04t per year for the whole lake, and those of Caohai, Northern, Northeast and South of Waihai were large, average 35mg/(m2·d). Their spatial distribution presented decreasing trend from the north region to the south region gradually, the amount of the DON released was 1147.55t annual, which had a similar spatial distribution with NH4+-N. The amount of the NO3--N diffusion flux was from -2.70 to 0.27mg/(m2·d) [with an average of -0.50mg/(m2·d)], and its releasing trend was from the overlying water to the sediment. Compared with other lakes in our country, the sediment from Dianchi Lake with the larger nitrogen concentration, its NH4+-N fluxes at sediment-water interface was higher, so there was the larger effect on the ammonia concentration of the overlying water. That was significantly positively correlation between its NH4+-N fluxes from the sediment with its total nitrogen, organic matter, exchangeable nitrogen and ammonia nitrogen content of exchangeable in sediment, so the NH4+-N released of the sediment from Dianchi Lake was mainly influenced by its exchangeable nitrogen, particularly ammonia nitrogen content. The potential risk of the DON release from sediment was large, which was correlated with its values of C/N in sediment significantly at the same time.
汪淼, 严红, 焦立新, 王圣瑞, 刘文斌, 罗洁, 罗正乾. 滇池沉积物氮内源负荷特征及影响因素[J]. 中国环境科学, 2015, 35(1): 218-226.
WANG Miao, YAN Hong, JIAO Li-Xin, WANG Sheng-Rui, LIU Wen-Bin, LUO Jie, LUO Zheng-Qian. Characteristics of internal nitrogen loading and influencing factors in Dianchi Lake sediment. CHINA ENVIRONMENTAL SCIENCECE, 2015, 35(1): 218-226.