The spatiotemporal variations of indicators of organic matter,as well as the correlation of indicators were studied based on the water quality monitoring data in inland lakes of China from 2008 to 2022 by using Mann-Kendall test(M-K test),Pearson correlation analysis and principal component analysis(PCA)analysis.Results showed that from 2008 to 2022,the concentration of dissolved oxygen(DO)increased at a rate of 0.19mg/L per year(P＜0.001),from 7.09mg/L to 10.04mg/L.In addition,the concentration of permanganate index(COD-Mn)decreased from 5.86mg/L to 3.17mg/L,which indicated that the water quality of lakes in China has significantly improved.However,concentrations of chemical oxygen demand(COD),COD-Mn,biochemical oxygen demand(BOD5)showed an increasing trend of fluctuation,which should be paid much more attention.The results from correlation analysis demonstrated that the concentration of COD-Mn was significantly positively correlated with total phosphorus(TP),ammonia nitrogen(NH3-N)and chlorophyll(Chla)(r＞0.50,P＜0.05),BOD5was significantly positively correlated with TP(r=0.61,P＜0.05),and COD was significantly positively correlated with TP(r=0.80,P＜0.05)and Chla(r=0.61,P＜0.05).All these results revealed that the concentration of TP and chlorophyll might be critical factors affecting the organic matter concentration.Spatially,organic matter related indicators including COD,COD-Mn and BOD5 were dominant factors to determine the spatial heterogeneity of water quality in lakes of China.Moreover,the geographical distribution of lakes with high organic matter concentration is more concentrated,mainly concentrated in Mengxin Lake and Yunnan-Guizhou Plateau Lake.
维普
万方数据