三峡库区大宁河回水段水华暴发时空分布特征分析

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。

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

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.