三峡库区大宁河回水段水华暴发时空分布特征分析

The Temporal and Spatial Distribution Characteristic of Algare Blooms in the Daninghe River

对三峡库区一级支流大宁河巫山段2004年到2008年常规监测、水华期间加密监测以及单个测点水华垂线24小时监测数据进行了统计、分析及评价。结果发现,该河段水华暴发具有明显的时空分布特征,时间上,全年各月份均有出现,但主要集中在3～6月,占观测频次的79%;24小时内叶绿素a含量在下午16:00～18:00时间段内达到最大值;空间上,总体呈现出离入长江口越近暴发的频次越高,回水河湾较平直河道,宽阔河段较狭窄河段更重的趋势,主要集中在大宁河的开阔河段(小三峡三个峡谷之间及其上、下游开阔河段);24小时内水华垂线分布明显,0.5～5m的叶绿素a含量上层高于下层,水面下30m及以下区域叶绿素a含量变化不显著。

In this paper,some analysis and assessments have been carried on data from the monthly monitoring from the 2004-2008,the density monitoring during the periods of algae blooming,and an hourly vertical sampling lasting a day when algae growing in the Daning River,the Three Gorges Reservoir region.The results indicated that the temporal and spatial distribution characteristic of algae blooming was quite notable,from a view of time,the phenomenon appeared every month,and the frequency was higher during the March to June and the highest concentration was observed generally in 16：00～18：00 in a day;in space,the frequency was higher in the confluence with the Yangtze River than upstream segments,and was higher in wider ones;for the depth ranging from 0.5m to 5m,the chlorophyll-a concentration decreased from the upper to the lower,and there were no obvious differences for the depth more than 30m.