Effects of water stability and thermal stratification on the vertical distribution of dissolved oxygen at Lake Qiandao
To provide substantial information of vertical distribution of dissolved oxygen(DO)at Lake Qiandao,oxycline depth(OD)and oxycline intensity(OI)were defined and calculated for January 2017 to February 2020.Lake Analyzer(LA)was used to calculate Schmidt Stability(St),Buoyancy frequency(N2),thermocline depth(thermD)and thermocline thickness(thermT)based on the high-frequency monitoring water quality(WQ)data and the meteorological data at Lake Qiandao for the same period.The results demonstrated that there were long-lasting thermal stratification and DO stratification from April to December through the year.Thermal stratifications showed obvious seasonality with stratifications initially formed during April-June,strengthened during July-September,and weakened during October-December.According to Spearman correlation analysis among the parameters for water stability,thermal stratification and vertical DO distribution,water stability was a key factor for vertical DO distribution,and the thermal stratification was a key factor for oxycline formation.Intensive thermal stratification decreased vertical DO exchange between the upper and lower layers,and promoted the oxycline formation.ThermD and OD was closely correlated with R2 of 0.81(N=25).Successful application of LA to Lake Qiandao showed that LA was a reliable and adaptive tool for quantitatively estimating the parameters for thermal and oxycline stratifications and water stability not only for Lake Qiandao but also for other lakes.
water stabilitythermal stratificationdissolved oxygenoxyclineLake AnalyzerLake Qiandao
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