基于2009年2月(冬季)、5月(春季)、8月(夏季)、11月(秋季)全太湖32个站点的化学耗氧量(COD)、生化需氧量(BOD)、溶解性总氮(DTN)、溶解性总磷(DTP)、浮游植物色素数据,分析了太湖COD、BOD的时空分布特征,并探讨了影响COD、BOD时空分布的因素.结果表明,2009年太湖COD值为3.40~6.16mg·L-1,平均值为(4.38±0.72)mg·L-1;BOD为0.64~5.93mg·L-1,平均值为(1.91±1.63)mg·L-1.COD值在秋冬季节较高,其值显著大于春夏季(p〈0.001);而BOD值冬季较高,其它季节都较低.COD与BOD的空间分布格局相似,呈现出自竺山湾、太湖西北沿岸区向梅梁湾区、湖心区、东南湖湾区依次递减的趋势.分类统计结果显示,河口沿岸区COD、BOD值显著高于开敞水域区(p〈0.001).相关性分析结果表明,COD、BOD与DTN、DTP、浮游植物色素的相关性存在季节性差异.夏季浮游植物色素浓度与COD、BOD相关系数最高,说明夏季浮游植物降解对水体内COD和BOD的贡献要高于其它季节.COD与BOD的时空分布特征主要受降雨量、河流输入、"引江济太"及太湖浮游植物活动等的影响.
The temporal-spatial distribution of chemical oxygen demand(COD),biochemical oxygen demand(BOD),and the relationships between COD,BOD and phytoplankton pigment,dissolved total nitrogen(DTN) and dissolved total phosphorus(DTP) concentrations are presented based on the conventional monitoring data of COD,BOD,phytoplankton pigment,DTN and DTP from four seasons(winter:February;spring:May;summer:August;autumn:November) in 2009 including 32 samplings in Lake Taihu.The results showed that the COD concentration ranged from 3.40 to 6.16 mg·L-1 with a mean value of(4.38 ± 0.72) mg·L-1 and the BOD concentration ranged from 0.64 to 5.93 mg·L-1 with a mean value of(1.91 ± 1.63) mg·L-1.COD concentrations in winter and autumn were significantly higher than those in spring and summer(ANOVA,p 0.001),while BOD concentration was higher in winter and lower in other seasons.A significant spatial difference was found in COD concentration and BOD concentration,decreasing from Zhushan Bay and the river inflows of northwest Lake Taihu to Meiliang Bay,and from the central lake to the southeast lake basin.Apparently,COD and BOD concentrations were higher in the mouths of inflowing rivers and in bays,compared with the concentration in open water in Lake Taihu(ANOVA,p 0.001).Seasonal differences of relationships between COD,BOD and DTN,DTP,phytoplankton pigment are discussed.The highest correlation between COD,BOD and phytoplankton pigment concentration found in summer indicated a more important contribution of phytoplankton degradation to COD and BOD in summer than other seasons.The temporal-spatial distribution characterizations of COD and BOD were affected by the rainfall,the river inflows,the hydraulic project"Yangtze River-Taihu Lake Water Transfer Project"and the degradation of phytoplankton blooms in Lake Taihu.