| Lake Ulansuhai is a typical cold and arid lake in northern China.It mainly discharges farmland backwaters from the Hetao irrigation area and the surrounding domestic sewage.It is an important part of the irrigation and drainage system in the Hetao irrigation area,and plays an important role in the development of the northwestern part of China.Due to the frequent human activities,the Lake Ulansuhai seawater body has become eutrophic,and the excessive input of exogenous nitrogen and phosphorus is the main reason for the eutrophication of the water body.Existing studies have shown that,among the imported exogenous nitrogen and phosphorus,atmospheric deposition has become one of the important acquisition methods.In order to further explore the impact of atmospheric deposition on the nutrition status of Lake Ulansuhai seawater body,the Lake Ulansuhai Sampling and analysis of dry and wet settlement once a month are conducted and the following conclusions are drawn:(1)The water quality indicators of Lake Ulansuhai in 2017-2019 are spatially higher in the northern lake area than in the south.In terms of time,the concentration changes of water quality indicators in 2017-2019 are more stable and compared with 2017 and 2018 Decrease the trend.The analysis of the nutrition status of Lake Ulansuhai from 2014 to 2016 shows that the eutrophication of Lake Ulansuhai springs is generally higher than that of other seasons,and the nutritional status has a tendency to reduce.(2)Sampling and analysis of the nitrogen and phosphorus dry and wet deposition in the Lake Ulansuhai in 2018-2019 found that the atmospheric TN settlement in the Lake Ulansuhai was dominated by wet deposition.The dry and wet deposition of TN in summer was significantly higher than that in other seasons,and the winter was lower in spring and summer.The TN settlement in autumn is mainly wet settlement,and the winter is mainly dry settlement.Atmospheric TP settlement is different from TN.At every season,atmospheric TP settlement is dominated by dry deposition.During the study period,the atmospheric TN sedimentation flux was 7.8 times of TP,and the Lake Ulansuhai sedimentation method was dominated by TN sedimentation.Correlation analysis of TN and TP wet deposition fluxes and precipitation found that atmospheric TN and TP wet deposition increased with the increase of precipitation,and the two showed a significant positive correlation.The analysis of nitrogen and phosphorus forms of wet deposition samples obtained in 2018-2019 shows that NH3-N dominates the wet deposition of various forms of nitrogen in the Lake Ulansuhai.The wet deposition flux of each form of nitrogen is high in summer and low in winter.The analysis of phosphorus-form wet sedimentation shows that the Lake Ulansuhai is dominated by DTP wet sedimentation throughout the year,and the seasonal characteristics of DTP and DIP are the lowest in summer and winter.(3)The sedimentation of TN and TP increased the concentration of TN and TP in the water body,which did not have a great impact on its spatial distribution.The concentration still decreased from north to south,and the concentration at the drain(112)was higher than other lakes.The estimation of the contribution rate of TN and TP sedimentation to the nutritional status of the lake found that the contribution of nitrogen and phosphorus sedimentation were the highest in winter and the lowest in autumn.Although atmospheric deposition has a certain contribution to the lake,the contribution rate is very small.Compared with the drainage input,atmospheric deposition is not the main way for lakes and lakes to obtain exogenous nitrogen and phosphorus. |
PDF Full Text Request