骆马湖水质时空变化特征

摘要

于2014年1—12月对骆马湖10个样点水体理化指标开展周年监测，分析水质现状和水体营养状态，并结合聚类分析等多元统计分析方法识别水质时空变化特征。结果表明，方差分析显示透明度、电导率、溶解氧、氮、磷及叶绿素a等多项指标均呈现显著的月份变化，空间差异分析表明仅水深在各样点间差异显著，表明骆马湖水质空间差异较小。各月份总氮、总磷、高锰酸盐指数、叶绿素a质量浓度的样点均值分别为0�71～2�08 mg · L－1、23�82～71�78μg·L－1、1�87～5�09 mg·L－1、4�49～10�83μg·L－1，骆马湖水质为Ⅲ～劣Ⅴ类，总氮是现阶段的主要污染物，综合营养状态指数（ TLI）表明骆马湖处于中营养～轻度富营养状态。聚类分析将12个月分为冬春季和夏秋季2个聚类组，冬春季透明度、溶解氧、总氮、硝态氮浓度显著高于夏秋季，而叶绿素a和总磷浓度则呈现相反的变化趋势。聚类分析将10个样点分为北部湖区和南部湖区2个聚类组，总氮、硝态氮浓度和电导率是导致湖区水质差异的主要指标，北部湖区上述指标显著高于南部湖区。%Water physicochemical parameters were monitored at 10 sites in Lake Luoma from January to December 2014, for assessment of quality and trophic status of the lake water and for analysis of spatio⁃temporal variation of the water quali⁃ty with multi statistical analysis methods, including cluster analysis. One⁃way ANOVA shows that secchi depth, conductiv⁃ity and concentrations of dissolved oxygen, nitrogen, phosphorus and Chl⁃a differed significantly from month to month, while spatial differentiation analysis reveals that only water depth varied remarkably between sites, indicating that water quality little varied spatially in the lake. The monthly mean value of TN, TP, CODMn and Chl⁃a varied in the range of 0.71-2.08 mg·L-1 , 23.82-71.78μg·L-1 , 1.87-5.09 mg·L-1 and 4.49-10.83μg·L-1 , respectively, indicating that Lake Luoma fell into the categories of Ⅲ-Ⅴ in water quality in 2014 according to the standard for surface water quality ( GB 3838-2002) , with TN being the principal pollutant. The comprehensive trophic level index ( TLI) indicates that the lake reached the mesotrophic to light eutrophic level. Cluster analysis divided the 12 months of a year into two clusters ( winter⁃spring group and summer⁃autumn group) . The former was apparently higher than the latter in secchi depth, DO, TN and NO3-⁃N, but lower in Chl⁃a and TP. Cluster analysis also divided the ten sampling sites into two groups, the north and the south groups. The former was significantly higher than the latter in TN, NO3-⁃N and conductivity, which were the main factors responsible for differentiation of water quality in the lake.