藻华聚集的环境效应:对凤眼莲生态学性状的影响

Environmental Effects of Algae Blooms Cluster: The Impact on Ecology Character of the Eichhornia crassipes

化肥的过量使用,工业、生活污水的直排以及农业径流等多种因素,导致当前中国的主要河流、湖泊等均出现了因氮磷过量累积而造成的水体富营养化现象;而伴随该现象发生的是周期性水体蓝藻水华,对水生态环境以及当地居民生活、社会生产活动等造成了严重的不良影响。而在各种治理蓝藻水华和水体富营养化的措施中,原位种养水生植物因具有生态、环保和投入少等优点而成为首选措施。然而,在水生植物种植过程中,蓝藻大量聚集后将会对植物的生态性状产生何种影响,需要深入研究。通过研究藻华聚集后对水生植物的生理生态的影响,有助于揭示藻华规模性爆发引起水生植物消亡的深层机制和更好地发挥植物的水体生态修复功能。以凤眼莲为研究对象,探究不同蓝藻水华聚集下对凤眼莲生态学性状的影响及植物的应答响应。结果表明:藻华聚集后2 h内植物根区水体溶氧会被耗尽,Eh降至-200 m V,形成厌氧、强还原环境从而对凤眼莲产生胁迫作用;植物叶片、根系中N、P及可溶性糖含量上升,K含量下降,表明凤眼莲对环境胁迫有较强的应答响应;添加60 g·L^(-1)处理的根系活力持续增强,添加120 g·L^(-1)处理的根系活力在胁迫的前3 d增加、随后呈快速下降的变化趋势;植物根系长度、生物量和根系/茎叶比值呈持续下降趋势,表明在超过了凤眼莲的抗逆能力后,就开始出现根活性降低、生物量下降、K^+含量下降等对逆境胁迫的应答现象,植物的新陈代谢受阻,植物开始死亡,表明藻华聚集后水体生态环境恶化,对凤眼莲产生的重度胁迫是导致植物死亡的主要原因。

Eutrophication phenomenon in rivers, lakes and other water bodies in our county is becoming more and more serious as excessive nutrients (mainly nitrogen and phosphorus) accumulated during the last 30 years as the effects of excessive fertilizer using, industry and domestic sewage direct discharge, and agricultural runoff, etc. algae bloom (commonly known as cyanobacterial bloom, or blue-green algae bloom) is breaking out period in these water bodies with the deterioration of water quality ,and it has bad impact to the water ecological environment, local residents’ life, social production activities. The planting the aquatic plants in situ, among a variety of governance measures of algae blooms and purification of contaminated water, has the advantage of ecological, environmental protection and low cost as being the better choice. However, it need for further study how affect the plant’s ecological traits after the algae blooms accumulated in the root district of aquatic plants. So it is help to reveal the deep mechanism of aquatic plant die through studying the influence on the changes of biological and ecological index caused by the algae bloom large-scale gathered, and also to benefit to better play the role of the purification of polluted water of aquatic plants. In this study, the changes of ecology character ofEichhornia crassipesand its biological and ecological response were studied with the different concentration of algae cells gathered by the simulation experiment. Results showed that the dissolved oxygen would be exhausted in 2h after algae cells gathered, and the Eh decreased to -200 mV, the water environment became the anaerobic and reductive and formed the environmental stress to theEichhorniacrassipes. The concentration of Nitrogen, Phosphorus, dissolved sugar in plant leaf and root increased, however, the concentration of K+ in plant decreased quickly during the experiment, after the algae cells aggregated, it showed that the aquatic plant came into being the response to the stress environment. The root vigor of treatment group 1 continued to increase, but the treatment group 2 quickly rose to 0.68μg·g-1·h-1 during the 3 d, and then decreased to 0.14μg·g-1·h-1 to the end. The root length, plant biomass and root/stem leaf ratio of the plant decreased during the experiment, indicated theEichhornia crassipes had the ecological response to the adversity stress of the algae cells accumulated, which manifested the concentration of root vigor, plant biomass, K+ dropped. So the deterioration of water ecological environment posing the strong stress to the Eichhornia crassipesis the main reason of the die for the death of aquatic plant.