|JIANG Tao,ZHANG Sheng,ZHAO Shengnan,SHI Xiaohong,SUN Biao,TIAN Weidong,HAN Zhiming,LV Jie.Exchange characteristics of ammonia nitrogen at the water and sediment interface during the ice-sealing period in Lake Ulansuhai. J. Lake Sci.2019,31(1):81-87. DOI:10.18307/2019.0108
|为揭示冰封期氨氮（NH4+-N）在沉积物-水界面的迁移机制及内源性营养盐对全湖污染的贡献，于2018年2月初在乌梁素海湖区7个采样点采集了上覆水体与沉积物样品，得到了冰封期上覆水体与沉积物间隙水中的NH4+-N浓度，估算了沉积物-水界面NH4+-N的扩散通量.结果显示，上覆水体中NH4+-N浓度变化范围为0.55~1.60 mg/L，平均值为1.05 mg/L，0~5 cm表层沉积物间隙水中NH4+-N浓度是上覆水体中的10倍以上，其变化范围为6.64~18.63 mg/L，平均值为11.92 mg/L.估算沉积物间隙水NH4+-N向上覆水体的扩散通量为1.282~4.269 mg/（m2·d），表明在湖水冻结过程中，底泥沉积物接纳了大量的可溶性污染物成为内源污染源，会在冰封稳定期、融冰期和融冰后的一段时间内成为湖水的主要污染源.
|关键词: 冰封期 乌梁素海 沉积物 氨氮 内源污染源
|Exchange characteristics of ammonia nitrogen at the water and sediment interface during the ice-sealing period in Lake Ulansuhai
JIANG Tao, ZHANG Sheng, ZHAO Shengnan, SHI Xiaohong, SUN Biao, TIAN Weidong, HAN Zhiming, LV Jie
Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, P. R. China
|Lake Ulansuhai is the largest lake in the Yellow River Basin with an area of 293 km2. The average air temperature is 7.3℃ and the winter is about six months with a cumulative negative accumulated temperature about 610-800℃·day. The lake water usually starts freezing in the early November and melting in the end of March or in the early April of the following year. The lake is completely sealed by ice in terms of ice-sealing period for about 100-130 days with an ice thickness of 0.63 m in average. To get better understanding in the migration mechanism of ammonia nitrogen at the water sediment interface and the impact of endogenous nutrients on the lake environment during the ice-sealing period, the water and sediment samples were collected at seven sampling sites in early February of 2018 in Lake Ulansuhai. The concentrations of ammonia nitrogen of the water samples were analyzed. The diffusion flux of ammonia nitrogen at the water sediment interface was estimated. The results showed that the concentrations of ammonia nitrogen in the water ranged from 0.55 mg/L to 1.60 mg/L with an average of 1.05 mg/L. The concentrations of ammonia nitrogen in the pore water of 0-5 cm surface sediments were one order of magnitude greater than that in overlying water which ranged from 6.64 mg/L to 18.63 mg/L with an average of 11.92 mg/L. The diffusion flux of ammonia from the sediments to the water was 1.282-4.269 mg/(m2·d). This indicated that a large number of soluble pollutants had been transported to the sediments during the process of freezing. It would be the one of the dominated source of water pollution to the lake environment in the period of ice stability, during the period of ice thawing, and in a period of time after ice thawing.
|Key words: Ice-sealing period Lake Ulansuhai sediment ammonia nitrogen endogenous pollution