天目湖2001～2002年环境调查及富营养化评价

2001年6月～2002年5月，中国科学院南京地理与湖泊研究所与溧阳市环保局对天目湖进行了为期一年每月一次的生态调查，在此基础上结合历史资料，探讨了天目湖有关理化参数、水质指标的分布变化规律、水环境现状、富营养化评价及其演化趋势。分析结果表明，温跃层随着季节的变化而呈现增强－稳定－减弱－消失的周期变化；近年来天目湖水质下降极为明显，已经不能完全达到Ⅱ类水标准；全湖透明度在0.5~2.4 m之间变化，年平均透明度为1.45 m；总氮在2001年至2002年周年平均值为0.54mg/L，总磷的平均值是0.03mg/L；年平均藻类个数为5 026万个/L，平均生物量为15.36 mg/L。湖泊达到中富营养化程度，随着渔业生产和游客的逐年增加，还有进一步加速恶化的趋势。

MAIN PHYSICAL AND CHEMICAL FACTORS IN TIANMUHU LAKE, WITH EVALUATION OF EUTROPHICATION FROM 2001 TO 2002

From June of 2001 to May of 2002, a one year joint study by Nanjing Institute of Geography and Limnology, CAS and Liyang Environmental Protection Bureau was undertaken in Tianmuhu lake. The characteristics of physical and chemical factors,their eutrophic trend and present situation of water quality and eutrophication were analyzed. The results showed that water quality decreased obviously in recent years following the increase of tourists and fishery. Thermocline turned up from March to October, and strengthened from March to May, then weakened from September to October. Water quality did not reach the second class of National surface water standard. Secci disc was in the range 0.5~2.4 m\+\{-1\} (average1.54 m-1). The annual average values of TN, TP were 0.54 mg/L and 0.003 mg/L, respectively. The average values of abundance and biomass of phytoplankton were 5.026×10\+7 cell/L and 15.36 mg/L, respectively. The lake is situated meso to meso eutrophication and the situation may become worse in the future without effective protection measures.