气候对巢湖东半湖水体环境变化的驱动效应

分析了小尺度气候变化对巢湖水体环境的影响,并揭示了水体营养生态对气候变化的响应机制。结果表明,年降雨量、年均温度、年日照时数变化稳定,平均值分别为1 176.2 mm,15.96℃和1 906 h,而高温天数(>35℃)年际变化显著(4~32 d/a)。调查期间总氮(TN)和总磷(TP)变化动态为开口向下的"凸"型抛物线形式,而高锰酸盐指数(CODMn)和叶绿素a(Chla)总体呈现为"凹"型曲线,水体总体呈现为中度营养状态。CCA分析发现巢湖区域的年降雨量、年均温度、年高温天数(>35℃)、年日照时数与湖水中TN,TP,CODMn和Chla呈显著相关性。其中TN,TP,CODMn和年日照时数对水体营养状态影响显著,贡献率分别为69%,45%,36%和27%。因此,可推测日照时数年际变化是导致水质变化的重要因素之一,气候因子与TN和TP在一定条件下对水体富营养化形成具有协同效应。

Driving Effects of Regional Climate on Dynamics of Water Environment in Eastern Half of Chaohu Lake

The small scale climate change and water environment in the eastern half of Chaohu Lake was investigated by canonical correspondence analysis(CCA)in 1987-2007.The results were showed as the follows.Annual precipitation,mean temperature per year,and yearly sunlight hours varied constantly in about twenty years with mean value of 1176.19mm,15.96,1906h,respectively.However,annual days of high temperature over 35 showed a significant difference among surveyed years,which ranged within 4~32d/a.Water circum stance of eastern half of Chaohu Lake displayed anonconsistent change with that of climate.In these years,Total nitrogen(T N)and total phosphor(T P)exhibited a convext rack of parabolacurve.The rest parameters like CODMn and Chla changed with the concave curve.It was deduced that eastern half of Chaohu Lake was evolving inmeso-trophic status by typical indicators such as eutrophication index(EI,mean 41.22 annually)and nutrient quality index(NQI,1.95~5.86).Relationship analysis indicated that climate factors were closely related with water indicators.Especially,T N,T P,CODMn,and sunlighthours contributed largely to mesoeutropho cation in eastern half of Chaohu Lake,whose influential coefficient was 69%,45%,36%,and 27%.In conclusion,the dynamic of sunlight hours for years will drive predominantly the variation of water quality of eastern half of Chaohu Lake.Especially,when coupling with high contents of T N and T P,the effects of climate factors will be more significant.