天山天池夏季叶绿素a的分布及富营养化特征研究

Distribution of Chlorophyll-a and Eutrophication State in Tianchi Lake of Tianshan Mountains in Summer

2014年6~8月,对天山天池水体叶绿素a(Chl-a)的分布特征及其与环境因子的相关性进行分析,探讨了天池富营养化状态及成因.结果表明,天池夏季Chl-a浓度变化范围为2.11~4.06μg·L-1,平均值为(2.8±0.69)μg·L-1.不同监测断面Chl-a垂直剖面变化趋势相似,整体表现为表层(0~2 m)和深层(12 m以下)低,中上层(2~12 m)高的特点.天池Chl-a浓度与深度和电导率显著负相关,与水温、p H值、溶解氧、蓝绿藻细胞密度和TP显著正相关,与TN的相关性较小.夏季天池TN和TP平均浓度分别为0.27 mg·L-1和0.035 mg·L-1,超过国际上一般标准的富营养型湖泊的浓度,采用修正的卡尔森营养状态指数评价天池的营养化状况,其目前处于中度富营养化水平.究其原因,可能主要是水土流失导致的营养盐升高,以及水生生物组成改变引起的藻类大量繁殖引起的.所以需从生态恢复和生态管理的角度,进行天池水质和周边植被的保护和恢复,以减缓天池水体富营养化加剧的风险.

From June to August in 2014,the distributions of chlorophyll-a( Chl-a) and correlations with environmental factors were investigated,the eutrophication status and causes were discussed in Tianchi Lake of Tianshan Mountains.The results showed that the Chl-a concentrations ranged from 2.11 to 4.06 μg·L- 1with a mean value of( 2.8 ± 0.69) μg·L- 1in summer,the vertical distribution of Chl-a in different monitoring zones had a similar characteristic that the Chl-a concentration in epilimnionis( 2-12 m) was higher than those at the surface( 0-2 m) and hypolimnion( below 12 m).The Chl-a concentration had significant negative correlations with depth and conductivity,significant positive correlations with water temperature,p H value,the concentration of dissolved oxygen,the cell density of algae and TP,and less correlation with TN.The mean concentrations of TN and TP in Tianchi Lake in summer were0.27 mg·L- 1and 0.035 mg·L- 1respectively,both of which exceeded the international standards of general eutrophic lakes.The modified Carlson trophic state index was used to assess the eutrophication status of Tianchi Lake,which is currently at a moderate eutrophication level.The reasons might be the increased nutrients attributed to soil erosion,and algae blooms due to the changes in the composition of hydrobios.Therefore,it is important to use ecological restoration and management to protect the water quality and surrounding vegetation,which may mitigate the risk of eutrophication in Tianchi Lake.