高温强太阳光照条件下蓝藻水华形成的实验研究(英文)

Experimental examination on cyanobacterial bloom formation under high water temperature and strong solar irradiance

富营养化和藻类水华尤其是蓝藻水华在全世界范围内的湖泊中都有发生,但富营养化和水面藻类水华出现之间没有等同关系. 目前人们对水华形成机制还不是很了解,对水华的具体形成过程也不是很清楚,因此若能通过一定的途径使没有形成水面水华的富营养水体出现水面水华就对水华形成机制的研究很有意义. 实验选用高温季节里,于 2007 年 8 月 28 日将室外塑料蓝桶中培育的浮游植物丰富的天然水体—其中含有类颤藻鱼腥藻但其并不占据优势,引入到无色透明玻璃瓶中. 实验初始水体的 chl-a、TN 和 TP 依次为 615.20mg?m-3、9.144mg?L-1和 0.453mg?L-1. 2007 年 8 月 29 日对各处理进行营养盐的梯度添加,添加的营养盐为 KNO3和 KH2PO4. 共有 4 个营养盐添加梯度,添加的 N/P(质量比)为 7:1,其中添加的 N 的梯度为(mg?L-1):0,0.5,1.0 和 2.0. 实验过程中测定了水温、光合有效辐射、氮磷营养盐、叶绿素 a 和浮游植物种类的数量变化. 结果表明实验过程中各处理的营养盐和 chl-a 含量均比开始时有下降,同时各处理中水面出现了类颤藻鱼腥藻水华,且类颤藻鱼腥藻的数量随处理中营养盐添加量的增多而升高. 这说明了含有少量鱼腥藻的高chl-a含量的天然水体在高温季节引入到透明玻璃容器中后能形成水表面鱼腥藻水华,玻璃容器中的高温强光照条件和营养盐的添加能促进鱼腥藻在竞争中取得优势. 本实验利用小玻璃容器,排除了鱼类、风浪、底泥等多个因素的影响,集中关注营养盐添加和高温强光照因子,成功重现了蓝藻表面水华的发生. 营养盐添加水平与浮游植物种间竞争并导致水体表面水华发生之间的关系在此实验中得到很好的体现. 虽然本实验不能揭示蓝藻水华形成的具体机制,但为蓝藻水华形成机制研究提供了便捷的途径而很有意义.

Eutrophication and algal blooms-especially Microcystis-blooms have been occurring in lakes worldwide and have been a strong research focus for lake ecosystems. Eutrophication of phytoplankton-dominated water means the increase of nutrients content and improvement of primary productivity, especially the development of phytoplankton biomass. And there are two significantly different performance of the improvement of phytoplankton biomass： with or without surface algal blooms. In other words, eutrophication is not equal to surface algal blooms. So, if a method of transferring the eutrophic water of no surface algal bloom to surface bloom can be found, it will be very helpful for the study on the mechanisms of algal bloom especially the harmful cyanobacterial blooms. So far, the knowledge for the mechanisms of algae blooms is inadequate, and the blooming process isn＇t clearly understood. The relationships of environmental characteristics supporting the development of cyanobacterial bloom are so complicated that how these interactions finally drive the bloom occur was unknown. During hot seasons, warmer temperatures are more favorable for growth of a larger number of algae species but competition for limiting nutrients is likely to increase. Our experiment took such measurement： high temperature and strong sunshine were supplied to the natural phytoplankton community in transparent glass jars without nutrient addition until a few days later, in order to observe the influence of them and the response of the phytoplankton community.