Wen Yan, Shan Bao-Qing, Zhang Wen-Qiang
State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
University of Chinese Academy of Sciences, Beijing 100049, China.
Huan Jing Ke Xue. 2021 Jun 8;42(6):2839-2847. doi: 10.13227/j.hjkx.202011122.
The distribution of inorganic nitrogen across the sediment-water interface in Baiyangdian Lake, the largest shallow lake in North China, was examined during the low temperature period. Furthermore, the influence of inorganic nitrogen diffusion flux in sediment porewater on the overlying water quality was analyzed. The results showed that the mean TN concentration in the surface water ranged from 4.83 to 8.23 mg·L, the mean NH-N concentration ranged from 0.21 to 0.34 mg·L, and the mean NO-N concentration ranged from 0.01 to 2.75 mg·L. TN exceeds the Class V water quality standard for surface water, indicating serious pollution. The mean TN content of the sediments ranged from 681 to 4365 mg·kg, of which TON was the main form of TN, accounting for 61.6%-93.1%. NH-N was the main form of TIN, with a mean content ranging from 28.9 to 116.3 mg·kg, and a mean NO-N content of between 5.2 and 23.7 mg·kg, which is relatively low. The NH-N concentration in the porewater was 3 to 16 times that of the overlying water, showing a gradual accumulation trend. The diffusion flux ranges of NH-N, NO-N, and NO-N across the sediment-water interface were -0.55-4.09, -1.44-3.67, and -0.88-0.04 mg·(m·d), respectively. There was still a potential release risk during the low temperature period. A large amount of NH-N accumulated in the sediments during the low-temperature period, which may affect the quality of the overlying water after the temperature rises. Therefore, studying the distribution of nitrogen across the sediment-water interface, and the risk of internal release of inorganic nitrogen during the low temperature period, is of great significance for improving water quality in Baiyangdian Lake and understanding the internal nitrogen pollution of shallow lakes.
在低温期对白洋淀（华北最大的浅水湖泊）沉积物 - 水界面无机氮的分布进行了研究。此外，分析了沉积物孔隙水中无机氮扩散通量对上覆水质的影响。结果表明，地表水总氮（TN）平均浓度为4.83至8.23mg·L，氨氮（NH₃ - N）平均浓度为0.21至0.34mg·L，硝态氮（NO₃ - N）平均浓度为0.01至2.75mg·L。TN超过地表水Ⅴ类水质标准，表明污染严重。沉积物中TN平均含量为681至4365mg·kg，其中有机氮（TON）是TN的主要形态，占61.6% - 93.1%。氨氮是无机氮（TIN）的主要形态，平均含量为28.9至116.3mg·kg，硝态氮平均含量在5.2至23.7mg·kg之间，相对较低。孔隙水中氨氮浓度是上覆水的3至16倍，呈逐渐积累趋势。氨氮、硝态氮和亚硝态氮（NO₂ - N）穿过沉积物 - 水界面的扩散通量范围分别为 - 0.55 - 4.09、 - 1.44 - 3.67和 - 0.88 - 0.04mg·(m²·d)。在低温期仍存在潜在释放风险。低温期沉积物中积累了大量氨氮，温度升高后可能影响上覆水水质。因此，研究氮在沉积物 - 水界面的分布以及低温期无机氮的内源释放风险，对于改善白洋淀水质和了解浅水湖泊内部氮污染具有重要意义。
