洱海沉积物特征及其对上覆水的影响

Sediment Characteristics of Erhai Lake and Its Impact on the Overlying Water

为深入掌握洱海沉积物粒径特征及碳氮磷分布,评估沉积物氮磷营养盐释放对洱海湖体水质的影响,于2020年12月对洱海19个点位进行沉积物采样分析以及沉积物再悬浮模拟实验。结果表明:洱海沉积物厚度空间差异显著,西侧近岸区域粒径较大其余区域粒径较小;洱海沉积物中有机质的含量12.3~26.1 g/kg,均值为23.24±3.49 g/kg,有机质含量较高区域主要集中在湖心平台和东南部湖区;洱海沉积物中全氮含量2190~8340 mg/kg,均值为5172±982.6 mg/kg,氮主要分布在人类活动聚集区,氮高值区在南部湖区,总体呈南部>中部>北部;洱海沉积物中总磷含量607~1240 mg/kg,均值为904±189.8 mg/kg,磷高值区在湖心平台深水区,呈中部>南部>北部;洱海沉积物中氮磷营养盐内源性污染负荷释放对全湖水质影响不大。

In order to gain an in-depth understanding of the sediment particle size characteristics and the distribution of carbon,nitrogen and phosphorus in Erhai Lake,and to assess the impact of the release of nitrogen and phosphorus nutrients from the sediments on the water quality of Erhai Lake,the sediment samples of 19 points in the lake and sediments were analyzed in December 2020.The results of the resuspension simulation experiment showed that the thickness of the sediments has significant spatial differences,and the near-shore area to the west had a larger particle size and the rest areas had smaller particle sizes;the organic matter content of the sediments was between 12.3~26.1g/kg,and the average value was 23.24±3.49g/kg,the areas with high organic matter content were mainly concentrated in the lake platform and the southeast lake area;the total nitrogen content in the sediments was between 2190~8340mg/kg,the average value was 5172±982.6mg/kg,and the nitrogen was mainly distributed in the areas where human activities were concentrated,the areas with high nitrogen values were in the southern lake area,generally in the south>central>north.The total phosphorus content in the Lake sediments was between 607~1240 mg/kg,with an average value of 904±189.8 mg/kg,and the high phosphorus value area in the deep water area of the lake center platform,the order was central>south>north;the release of endogenous pollution load of nitrogen and phosphorus nutrients in the sediments of Erhai Lake had little effect on the water quality of the whole lake.