岱海水体氮、磷时空分布特征及其差异性分析

通过2018~2019年调查数据及历史相关监测资料，分析了岱海上覆水中氮、磷时空分布特征及主要影响因素，并探讨了氮形态、磷形态的时空分布差异性.结果表明，岱海上覆水总氮和总磷常年处于较高水平，尤其是总氮浓度明显高于全国其他湖泊.岱海上覆水总氮浓度在3.29~4.99 mg·L^-1之间，平均值为（3.93±0.33） mg·L^-1；总磷浓度在0.063~0.163 mg·L^-1之间，平均值为（0.111±0.023） mg·L^-1.上覆水中总氮和总磷浓度在春季、夏季呈现湖心深水区明显高于周边，秋季呈自东向西递减的趋势，而在冬季则呈现南部浅水区高于北部区域的趋势.上覆水中氮和磷营养盐均以溶解态为主，溶解态总氮和溶解态总磷占总氮和总磷的比例高达86.62%和77.84%，且溶解态氮以硝态氮为主导、溶解态磷则以有机磷为主要形态.研究中发现，湖水浓缩和内源营养盐释放是造成水体高总氮和总磷的主要原因，建议结合工程措施进行内源治理和生态修复，以防止水质进一步恶化.

Temporal and Spatial Distribution Characteristics and Difference Analysis of Nitrogen and Phosphorus in Daihai Lake

Based on the historical monitoring survey data from 2018 to 2019, the temporal and spatial distribution characteristics and main influencing factors of nitrogen and phosphorus in the overlying water in Daihai Lake were analyzed, and the differences of the temporal and spatial distribution were discussed. The results showed that the content of total nitrogen and total phosphorus in the overlying water was at a high level, especially the total nitrogen content was obviously higher than that in other lakes in China. The content of total nitrogen ranged from 3.29 mg·L^-1 to 4.99 mg·L^-1, with a mean value of (3.93±0.33) mg·L^-1; the content of total phosphorus ranged from 0.063 mg·L^-1 to 0.163 mg·L^-1, with a mean value of (0.111±0.023) mg·L^-1. In spring and summer, the content of total nitrogen and total phosphorus in the overlying deep water from the middle of the lake was significantly higher than that in the surrounding area. In autumn, the contents decreased from east to west, and in winter, the contents in the shallow water of the southern area were higher than that in the northern area. Nitrogen and phosphorus in the overlying water were mainly in the dissolved state, and the proportions of total dissolved nitrogen and phosphorus were 86.62% and 77.84%, respectively. The dissolved nitrogen was dominated by nitrate, whereas dissolved phosphorus was dominated by organic phosphorus. The concentration of lake water and the release of endogenous nutrient salts are the main reasons for the high total nitrogen and phosphorus. To prevent further deterioration of water quality, it is suggested to carry out endogenous treatment and ecological restoration in combination with engineering measures.