Spatial Distribution Characteristics And Environmental Indications Of Organic Matter In Surface Sediment Of Xingyun Lake

Lakes are one of the important ecosystems on the land,which have a great impact on the production and life of the people in the region.In recent years,with the acceleration of urbanization and the rapid development of industry and agriculture,human activities have severely affected lakes,causing lake waters to deteriorate,lakes to fall,and ecological functions to deteriorate.In order to understand the impact of human activities and regional factors on the ecological environment of Xingyun Lake,this article collected 117 surface sediment samples from Xingyun Lake in Yunnan,analyzed the spatial distribution characteristics and influencing factors of organic matter,judged the source of materials,and carried out environmental assessment of the study area And repair strategies.The following conclusions were obtained initially:?1?The particle size of the surface sediments of Xingyun Lake indicates that the silt composition is the dominant particle size in the study area,and the variation range is 54.84%to 69.21%,with an average value of 60.09%.The percentage content of the clay component is 27.19%⁴6.79%,with an average value of 36.36%;the percentage content of sand components fluctuates from 0.06%¹7.34%,with an average value of 5.31%.By analyzing the L1 and L2 profiles,it is further proved that the content of fine particles is higher in the deep water area near the lake center;the content of coarse particles is higher in the shallow water area near the lakeshore,and the size of the particle size is related to the offshore distance and water depth.The basic principle.?2?The percentage of organic matter in the surface layer of Xingyun Lake ranges from 10.19%to 21.15%,with an average value of 17.02%.There is a high degree of correlation between organic matter content and water depth?R²>0.91?,indicating that the organic matter content increases with the steady increase of sedimentary environment.increase.The carbonate content fluctuates between 4.85%and 15.25%,with an average of 15.25%.The contents of TN and TP in the surface sediments of Xingyun Lake fluctuated between 3.31⁷.88mg/g and 1.99⁴.71mg/g,with the average values of 5.74mg/g and 3.63mg/g,respectively.The spatial distribution of TN content generally has the characteristics of concentric spatial distribution,and the spatial distribution of TP content is generally fan-shaped.The correlation between organic matter content and TN content was high?R²>0.93?.The surface sediment C/N is between 12.6 and 14.38,with small fluctuations,with an average value of 13.2,indicating that the study area is affected by the combined effects of internal and external sources,and is mainly affected by terrestrial sources.?3?The values of ?13C and ?15N in the surface sediments of Xingyun Lake fluctuated between-26.39�^-25.07�and 7.2�¹2�,with the average values of-25.64�and 10.5�.?¹³C has a negative correlation with water depth.?¹⁵N has a relatively high degree of correlation with water depth?R²=0.725?and has a significant positive correlation.?15N increases with the increase of water depth,which may have a strong relationship with the sedimentary environment and sedimentary dynamics.Big relationship.?4?Qualitative and quantitative analysis of organic matter sources such as C/N and organic carbon and nitrogen isotopes show that:the main organic matter pollution of Xingyun Lake is sewage generated by human activities,and a few have soil organic matter and aquatic vascular plants,and the contribution of organic matter source:?Sewage?>Fm?vascular plant?>Fsoil?soil?,so the source of organic matter in the study area is a mixed source of lake internal and terrestrial sources.?5?An environmental assessment of the surface sediments of the Xingyun Lake shows that the organic carbon,organic index,and organic nitrogen in the study area are between 1.25 to 3.11,0.43 to 1.73,and 0.14 to 0.48,and the average values are2.51,1.15,and 0.32.The spatial distribution of the three has a great correlation.The spatial distribution of organic carbon and organic nitrogen pollution has been consistent,and all of them have a concentric circle shape and decrease gradually.The organic pollution level of the sediments in the study area is more than 80%of the lake area.The clean area is mainly distributed to the southern end of the lake,while the organic nitrogen pollution is distributed throughout the lake,and the nitrogen pollution is serious.