福建龙岩市龙潭湖甲藻水华成因的研究

The possible cause of a dinoflagellate bloom occurring in Longtan Lake

2009年12月初,在福建龙岩市龙硿洞风景名胜区龙潭湖首次发现拟多甲藻水华,最高细胞密度达到1.11×107cells.经过应急处置,甲藻和其他藻类被杀灭.监测发现,上游小溪和溶洞地下水营养物质均优于国家Ⅱ类标准,但入湖后,TN和TP浓度明显上升.结果表明,龙潭湖蓄水改变了小溪的自然流态,形成了营养盐的累积和甲藻的快速增殖;环境和水温度的明显升高,也起到了一定的促进作用;沉积物营养盐蓄积和内释放对甲藻水华具有重要的贡献,而TP可能是本次水华的主要限制因子.

In the early December, 2009, a dinoflagellate bloom caused by Peridiniopsis sp. was found for the first time in Longtan Lake, which is located in Long Kong Dong water-eroded cave scenery spot, Longyan City, Fujian Province. The cell density of the dinoflagellate reached as high as 1.11×107cells/L during the bloom. By a series of urgent disposal procedures, the blooming dinoflagellate as well as other microalgae was eventually eliminated, after which investigations were instantly carried out to explore the cause of the bloom. Nutrients concentrations in the upstream rivulet and the cave underground water did not exceed the levels of Class II water in National Criteria for groundwater water quality, but markedly increased in the lake water, especially the concentrations of TN and TP. Thus it was suggested that nutrient accumulation, hence the proliferation of dinoflagellate, had been accelerated due to the alteration of rivulet flow pattern by water impoundment in Longtan Lake, and therefore mainly accounting for the bloom event. Moreover, an unexpected temperature increase in the lake water right before and during the bloom may to some extent help to explain the bloom occurrence. The results indicated that endogenous release of nutrients accumulated in lake sediments had made great contribution to the outbreak of the dinoflagellate bloom, and TP might be a primary restriction factor for the bloom.