中文关键词沉水植物水环境蓝藻有机质营养盐利用率 英文关键词submerged plantswater environmentcyanobacteriaorganic matteravailable of nutrients

作者	单位	E-mail
康丽娟	中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008 中国科学院大学, 北京 100049	kanglijuan18@mails.ucas.ac.cn
许海	中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008	hxu@niglas.ac.cn
邹伟	中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008 中国科学院大学, 北京 100049
朱广伟	中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008
朱梦圆	中国科学院南京地理与湖泊研究所, 湖泊与环境国家重点实验室, 南京 210008
季鹏飞	江南大学环境与土木工程学院, 无锡 214122
陈洁	江南大学环境与土木工程学院, 无锡 214122

中文摘要 沉水植物的季节性死亡分解会引起水体环境的巨大改变，如大量释放有机碳和氮磷等植物营养素，进而可能引起浮游植物群落结构的显著变化.本文以菹草为例，调查了我国江淮中下游平原14个浅水湖泊中该物种春季生长期和夏季衰亡期水环境物理化学指标和浮游植物相关参数，并量化了菹草衰亡对水质和浮游植物群落结构的影响.结果表明，在春季，菹草的生长显著抑制了沉积物的悬浮，提高了水体的透明度，同时菹草在生长过程中，吸收了水体中的营养元素并将其储存在植株体内或输送到沉积物中，菹草的光合作用还显著提高了水体的溶解氧和pH.然而，夏季菹草的衰亡使得湖水变得十分浑浊，水体有机质含量显著上升.此外，本研究还发现夏季有草区与无草区浮游植物组成和蓝藻生物量差异显著，对应的蓝藻占总藻生物量的比值分别为18.96%和34.05%.菹草衰亡区的蓝藻表现出更大生物量的原因如下：一是植株体的分解为蓝藻提供了充足的有机质和氮磷物质，为蓝藻的增殖提供了营养来源；二是夏季菹草衰亡导致水体浊度增加，使得蓝藻在竞争中占据了更好生态位，使其具备更大的氮、磷营养盐利用效率. 英文摘要 The decomposition of submerged macrophytes is generally associated with dramatic changes in the water environment, such as the large release of nutrients (e.g., nitrogen and phosphorus) and organic carbon to the surrounding waters, which may result in significant changes in phytoplankton community structure. In this study, Potamogeton crispus, physicochemical variables, and phytoplankton samples were collected in 14 shallow lakes in the middle and lower Jianghuai Plain in spring (growing period of P. crispus) and summer (decomposition phase of P. crispus) of 2018. The effects of the decline of P. crispus on water quality and phytoplankton community structure were quantified. The results showed that water transparency increased significantly in spring because the growth of P. crispus inhibits sediment resuspension and macrophytes can transport the nutrients from the water column to the sediment. The values of dissolved oxygen and pH also increased significantly due the photosynthesis by macrophytes. In contrast, the decomposition of P. crispus during summer months caused a significant increase in water turbidity and organic matter. There were considerable differences in phytoplankton biomass and cyanobacterial biomass in the sites with or without P. crispus, and the corresponding ratios of cyanobacterial biomass to the total algal biomass were 18.96% and 34.05%, respectively. Higher values of cyanobacterial biomass were observed with the decomposition of P. crispus than its counterpart in summer because ① the decomposition of macrophytes provided sufficient organic matter and nutrient (nitrogen and phosphorus) resources for cyanobacterial growth; ② P. crispus decline in summer significantly increased water turbidity, which makes cyanobacteria occupy a better ecological niche and more efficiently utilize nitrogen and phosphorus.

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