千岛湖水体叶绿素a与相关环境因子的多元分析

1999年1月至2000年12月对千岛湖水体的叶绿素a和理化因子进行了为期2年的逐月监测，对监测数据进行了多元逐步回归分析，找出与叶绿素a显著相关的环境因子，建立了多元回归方程．同时分析了叶绿素a含量的时空分布情况，并应用修正的卡尔森营养状态指数(TSI)对各监测点位的营养状态进行了排序．结果表明，湖区各监测点叶绿素a含量时空差异较大，新安江来水中叶绿素a含量变化较大．在5～30mg·m^-3之间，湖区内部监测点叶绿素a含量基本在5mg·m^-3以下，春季和秋季含量高于冬季和夏季含量．东南出水湖区大坝、密山和姥山点位的TSI<37。属贫营养型。其余湖区的TSI<53，为中营养型，与20世纪90年代中期的调查一致．湖区内部各监测点位的叶绿素a与理化因子关系比较复杂．在不同的监测点位。对藻类有显著影响的环境因子各有不同，但水温、总磷表现为正相关，透明度则表现为负相关．

Multianalysis between chlorophyll-a and environmental factors in Qiandao Lake water

In this paper, the regression equation between chlorophyll-a (Chla) and some environmental factors was calculate by multiple stepwise regression, based on the monthly monitoring data in the Qiandao Lake from Jan. 1999 to Dec. 2000, and modified Carlson trophic state index for all the sampling sites was also analyzed. The results indicated that the spatial and temporal distribution of chlorophyll a in the sampling sites were varied strongly, the concentration of chlorophyll a in the Xin'an river changed from 50 mg.m-3 to 30 mg.m-3, but that in the lake was under 5 mg.m-3. The modified Carlson trophic state index (TSIM) for the sampling sites in southeast of the lake was under 37 (belonging to olligotrophic), and the others were under 53 (belonging to mesotrophic). In different sampling sites, the significant environmental affecting factors for chlorophyll a were different. However, the relationships between chlorophyll a and water temperature and total phosphorus were positive, and that between chlorophyll a and diaphaneity was negative.