Arid Zone Research ›› 2021, Vol. 38 ›› Issue (6): 1534-1545.doi: 10.13866/j.azr.2021.06.05

• Water Resources and Utilization • Previous Articles     Next Articles

Analysis of water quality and eutrophication changes in Hulun Lake from 2011 to 2020

YU Haifeng1(),SHI Xiaohong1(),SUN Biao1,ZHAO Shengnan1,LIU Yu1,ZHAO Meili2   

  1. 1. Water Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, Inner Mongolia, China
    2. Wildlife Conservation Center of Inner Mongolia, Hohhot 010010, Inner Mongolia, China
  • Received:2021-04-24 Revised:2021-07-15 Online:2021-11-15 Published:2021-11-29
  • Contact: Xiaohong SHI E-mail:yhf970204@163.com;imaushixiaohong@163.com

Abstract:

In this study, Hulun Lake was taken as the research object, and water quality indicators measured in a long time series from 2011 to 2020 were selected. Interannual variations in Salinity (S), Electrical Conductivity (EC), Total Dissolved Solids (TDS), pH, Transparency (SD), Chlorophyll a (Chl.a), Dissolved Oxygen (DO), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP) were analyzed. The water quality and eutrophication degree of Hulun Lake from 2011 to 2020 were evaluated on the basis of the gray pattern recognition model and comprehensive nutrient state index. Combined with the actual situation of Hulun Lake, the water quality and eutrophication degree of Hulun Lake were examined from two aspects of external input and meteorological conditions. Results showed that S, TDS, and EC decreased from 2011 to 2020, and water salinity improved. pH was between 8.86 and 9.37, and water was weakly alkaline. TN and COD decreased, but TP did not. Grey Pattern Composite Index (GC) indicated that the best water quality of the decade was observed in 2012, and the worst water quality was documented in 2011. Overall, GC decreased from 4.01 in 2011 to 3.35 in 2020, indicating that water quality improved. Comprehensive Nutritional Status Index (TLI) implied that water underwent moderate eutrophication, severe eutrophication, and another moderate eutrophication from 2011 to 2020. TLI initially increased and subsequently decreased; in particular, it increased from 61.837 in 2011 to 71. 815 in 2016 and then decreased to 61.535 in 2020. Wind speed and water depth were the driving factors of eutrophication in Hulun Lake. At present, the main pollution in Hulun Lake is caused by nitrogen, phosphorus, and organic pollutants. The water quality of Hulun Lake can be enhanced by implementing effective measures, such as controlling the discharge of upstream sewage, strictly regulating the balance of grass and graziery, and improving the quality of water supply.

Key words: Hulun Lake, eutrophication, grey model, integrated nutritional status index method