太湖藻源性“湖泛”发生的过程以及环境影响研究

发布时间：2019-05-13 12:25

【摘要】：太湖位于长江三角洲南缘,为中国大型淡水湖泊之一。太湖流域作为中国经济最为繁荣的区域之一,人类活动密集,水体富营养化严重。湖泊的富营养化造成了蓝藻水华频发,水体生态系统的退化等一系列的问题,从20世纪90年代开始出现在太湖西部以及梅梁湾、贡湖湾等蓝藻水华爆发区的“湖泛”现象更是让湖泊富营养化的危害发生质变。“湖泛”是一类水华蓝藻大量聚集,并在一定气象水文条件下腐败分解,致使水体发黑发臭的现象。“湖泛”的发生和发展过程往往较为迅速,但对水生生态系统以及周边居民的生产生活影响较大,针对“湖泛”研究还很匮乏。为了掌握太湖藻源性湖泛的发展过程以及环境影响,对太湖湖泛的预警预报,应急处理等提供有力的理论支持,消除太湖潜在的湖泛发生风险,我们开展了一系列相关的野外试验及室内分析工作,获得了以下研究成果:1.对2013年6月22至2013年6月27日间发生在太湖贡湖湾沿岸的湖泛现象进行了应急采样,对水体理化指标以及浮游植物、溶解态异味物质等进行了检测,结果表明,湖泛现象的发生伴随着大量总氮、总磷以及铵态氮的释放,水体中嗅味物质尤其是挥发性含硫有机物的浓度升高,并远超过嗅觉阈值。对异味物质与环境因子的分析显示,水体中溶解态硫醚类异味物质的浓度与电导率、总悬浮物、总氮、总磷和铵态氮浓度显著正相关,和溶解氧浓度显著负相关。但是实验并没有建立蓝藻生物量与异味物质的相互关系,这可能与湖泛显现发生时大量蓝藻已经腐败有关。进一步的实验还需通过野外原位围隔模拟来进行。2.为了更好的获取太湖“湖泛”发生过程及其对环境影响的数据,我们于2014年6月至9月间在太湖梅梁湾进行了为期近40d的原位围隔模拟实验。实验围隔内添加了约10000 mg/L新鲜蓝藻,模拟出类“湖泛”的黑臭水体,其相关指标均到达或超过已有“湖泛”数据,表明模拟实验是成功的。通过实验,我们发现,在夏季的高温天气下,大量蓝藻的长时间聚集会引发“湖泛”,“湖泛”发生时水体溶解氧浓度接近0 mg/L,p H降至6.67,水体总氮、总磷分别高达约40 mg/L和10 mg/L。“湖泛”的发生导致大量的氮磷等营养盐被释放进入水体,引起水体营养盐的快速聚集和释放,加速了水体营养盐的循环速率。水体呈腐败状态,表现为低氧-缺氧的状态,水体呈弱酸性,发黑发臭,这样水质会严重破坏了水域生态系统的生物多样性,影响水生生物的生长繁殖。为防止藻源性“湖泛”的再次发生,在控制太湖营养盐输入的同时,应结合气象、遥感、现场巡查等多种手段,掌握蓝藻生长、漂流规律,避免蓝藻的大量聚集,对蓝藻已聚集区域尽早打捞,并做好现场增氧的准备。
[Abstract]:Taihu Lake, located in the southern margin of the Yangtze River Delta, is one of the large freshwater lakes in China. Taihu Lake Basin, as one of the most prosperous areas in China, has dense human activities and serious eutrophication. The eutrophication of lakes has caused a series of problems, such as the frequent occurrence of blue algae Shui Hua and the degradation of water ecosystem, which began to appear in the western part of Taihu Lake and Meiliang Bay in the 1990s. The phenomenon of "lake flooding" in Shui Hua outbreak area, such as Gonghu Bay, makes the harm of lake eutrophication change qualitatively. "Lake flooding" is a large number of Shui Hua blue algae accumulation, and corruption and decomposition under certain meteorological and hydrological conditions, resulting in black and smelly water bodies. The occurrence and development process of "lake flooding" is often relatively rapid, but it has a great impact on the aquatic ecosystem and the production and life of the surrounding residents, and the research on "lake flooding" is still scarce. In order to master the development process and environmental impact of algal lake flooding in Taihu Lake, to provide strong theoretical support for early warning and prediction and emergency treatment of Taihu Lake flooding, and to eliminate the potential risk of lake flooding in Taihu Lake, We have carried out a series of related field experiments and laboratory analysis work, and the following research results have been obtained: 1. The flood phenomena along the coast of Gong Lake Bay in Taihu Lake from June 22, 2013 to June 27, 2013 were sampled urgently. The physical and chemical indexes of the water body, as well as the dissolved odour substances, were detected. The results showed that The occurrence of lake flooding is accompanied by the release of a large number of total nitrogen, total phosphorus and ammonium nitrogen. The concentration of odor substances, especially volatile sulfur-containing organic compounds, increases and far exceeds the olfactory threshold. The analysis of odour substances and environmental factors showed that the concentration of dissolved thioethers in water was positively correlated with conductivity, total suspended matter, total nitrogen, total phosphorus and ammonium nitrogen, and negatively correlated with dissolved oxygen concentration. However, the experiment did not establish the relationship between cyanobacteria biomass and odorous substances, which may be related to the corruption of a large number of cyanobacteria when the lake appeared. Further experiments need to be carried out by field in situ enclosure simulation. 2. In order to obtain the data of the occurrence process of "lake flooding" in Taihu Lake and its impact on the environment, we conducted an in situ enclosure simulation experiment in Meiliang Bay of Taihu Lake from June to September 2014. About 10000 mg/L fresh blue algae were added to the enclosure of the experiment to simulate the black and smelly water body of "lake flooding". The related indexes reached or exceeded the existing "lake flooding" data, which showed that the simulation experiment was successful. Through the experiment, we found that under the high temperature weather in summer, the accumulation of a large number of blue algae for a long time will lead to "lake flooding". When the "lake flooding" occurs, the dissolved oxygen concentration in the water body decreases from 0 mg/L,p H to 6.67, and the total nitrogen in the water body. The total phosphorus is as high as 40 mg/L and 10 mg/L., respectively. The occurrence of "lake flooding" leads to the release of a large number of nutrients such as nitrogen and phosphorus into the water body, which leads to the rapid accumulation and release of nutrients in the water body, and accelerates the cycling rate of nutrients in the water body. The water body is corrupt, showing hypoxia-hypoxia state, the water body is weak acid, black and smelly, so the water quality will seriously destroy the biodiversity of the water ecosystem and affect the growth and reproduction of aquatic organisms. In order to prevent the recurrence of algal "lake flooding", while controlling the input of nutrients in Taihu Lake, we should combine meteorology, remote sensing, on-site inspection and other means to master the growth and drifting laws of blue algae and avoid the accumulation of blue algae. The cyanobacteria have been recovered as soon as possible and ready to increase oxygen on the spot.
【学位授予单位】：华中农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524

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