2008~2022年我国湖泊有机质相关指标时空演变

Spatiotemporal variations of indicators of organic matter from 2008 to 2022 in inland lakes of China

基于2008~2022年中国湖泊长时间序列水质数据,采用Mann—Kendall检验(M-K检验),Pearson相关分析以及主成分分析(PCA)等对有机质及相关营养指标在长时间序列上的变化规律,空间异质性特征及指标之间的相关关系进行研究.结果表明:2008~2022年,全国湖泊溶解氧(DO)浓度以每年0.19mg/L的速度增加(P<0.001),从2008年的7.09mg/L增加至2022年的10.04mg/L,高锰酸盐指数(COD-Mn)浓度从5.86mg/L下降至3.17mg/L,表明我国湖泊水环境质量整体改善.然而,化学需氧量(COD),COD-Mn,生化需氧量(BOD5)等近年来出现波动性变化且有增加趋势.相关性分析结果表明,COD-Mn与总磷(TP),氨氮(NH3-N)以及叶绿素(Chla)均呈现显著正相关性(r>0.50, P<0.05);BOD5与TP呈现显著正相关性(r=0.61, P<0.05);COD与TP(r=0.80,P<0.05)以及Chla(r=0.61,P<0.05)显著正相关,表明TP浓度和叶绿素浓度可能是影响我国湖泊有机质变化的关键因素.在空间尺度上,COD,COD-Mn与BOD5等有机质相关指标为影响全国湖泊水质空间异质性特征的主要因素,且有机质浓度较高的湖泊地理分布较为明显,主要集中于蒙新湖区和云贵高原湖区.

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.