流量对三峡库区嘉陵江重庆主城段藻类生长的影响

Effect of Runoff on Algal Growth in Reach of Jialing River in City Zone of Chongqing

对于三峡库区,大部分一级支流都具备产生富营养化的营养水平,在水温和光照等气候条件适宜藻类生长的3—5月,水文条件成为影响藻类生长繁殖和诱发富营养化的关键因素.3—5月恰是水库坝前泄水的消落时段,水文条件与一般的湖泊、河流和水库等显著不同.针对三峡水库特殊的水文情势,通过现场水质采样,应用质量守恒原理,研究了3—5月上游来水流量对嘉陵江重庆主城段藻类生长的影响.结果表明:流量对河段的藻类密度和质量净增量有显著影响,3月因较低的来水流量和较小的大坝泄水量使藻类密度和质量净增量最大,5月当流量接近或超过历史同期水平时,河段的藻类质量净增量为负,而当流量偏枯较大时,藻类质量净增量为正.

In most of the first-order tributaries of Yangtze River in the Three Gorges Reservoir, the nutritional state has reached an extent needed for eutrophication. The hydrological condition becomes the key factor which impacts algal growth and induces eutrophication when climate condition, such as water temperature and illumination, is suitable for algal growth in period of Match to May. While at the time, the hydrological condition in this reservoir is significantly different from that in general lakes, rivers and reservoirs because of releasing water at the dam. Aiming at the special hydrological situation in period of water level decline from Match to May before flood season of the Three Gorges Reservoir, the effect of runoff on algal growth in reach of Jialing River in city zone of Chongqing was studied by analyzing water samples and by applying the principle of mass conservation. The resuhs show that the relationship between runoff and algal growth is obvious. There are the most algal density and the mass increment in March due to lower runoff and less drainage at darn. As runoff in May accesses or excesses that of the corresponding period in history, the mass inerement of algal in the reach is negative, but, as runoff is very lower, it is positive.