大气湿沉降对太湖水质及叶绿素a的影响

Effect of Wet Deposition on Water Quality and Concentration of Chlorophyll a in Lake Tai

在太湖梅梁湾近岸水域进行了大气湿沉降原位围隔研究,分析并对比了湖泊水体和围隔内的溶氧量、温度、氮磷营养盐的浓度和叶绿素a(Chla)等指标在降雨前后的变化情况。结果表明,湿沉降以N沉降为主,P沉降浓度相对较低,其中N沉降中NH3-N含量较高;接收湿沉降围隔内水体TN与TP通过雨水的稀释作用分别有59.9%和29.9%的下降,远高于未接受湿沉降围隔内水体TN和TP分别为16.1%和13.3%的下降幅度,而太湖湖体在降雨前后TN和TP则表现为不同程度的上升,分别上升42.3%和19.3%;降雨结束前后,叶绿素a浓度的变化程度为太湖湖体>围隔组1(接受湿沉降)>围隔组2(不接受湿沉降),表明太湖北部水域在秋季高水温期的湿沉降可能会导致水体富营养化程度加剧。

Abstrat： In situ study by enclosure method was used to compare parameters including the amount of dissolved oxygen in the lake water and mesocosm, temperature, concentration of nutrients and chlorophyll a （Chla） at Meiliang Bay, Lake Tai before and after rainfalls in water body and enclosures. The results showed that wet deposition was mainly affected by N deposition which contains higher NH3-N. P wet deposition showed relatively lower concentration. TN and TP in wet deposition receipt enclosures by 59.9% and 29.9% decline, respectively. Rainfall dilution was much more than those in wet deposition non-receipt ones by 16.1% and 13.3% decline. Meanwhile, TN and TP in lake water were increased by 42.3% and 19.3% after raining. Chlorophyll-a variance was in order of lake water〉 enclosure 1-treatment （receipt wet deposition）〉 enclosure 2-treatment （non-receipt wet deposition）after rainfalls, indicating eutrophication in northern Lake Tai area may be enhanced by wet deposition during high water temperature period at autumn.