Temporal and spatial distributions of phytoplankton and inorganic and organic nitrogen in Chongming Island

Abstract

为研究崇明岛河网浮游植物和无机、有机氮的时空分布特征及其相互关系,于2014年1、4、7和10月在崇明岛河网内选取界河、堡镇港、八滧港3条河道9个采样点采集浮游植物和表层水样,并选取崇西水闸作为对照点进行研究.结果表明:河网内浮游植物以绿藻和硅藻为主,其中水闸和堡镇港夏季裸藻生物量所占比例超过50%.八滧港总溶解性氮(TDN)的主要组分是溶解性无机氮,而水闸、界河和堡镇港溶解性有机氮(DON)在TDN中的比例在夏、秋季低于冬、春季,农田土壤释放可能是DON的重要来源.水温、溶解氧和化学需氧量是影响铵态氮浓度变化的重要环境因素.此外,通过冗余分析发现,铵态氮影响绿藻和裸藻分布,尿素影响甲藻分布.;To investigate the temporal and spatial distributions of phytoplankton, inorganic and organic nitrogen as well as their relationship, the phytoplankton and surface water samples were collected at nine sites in Rivers Jiehe, Baozhengang, and Bayaogang in Chongming Island in January, April, July and October of 2014, a sample in Chongxi gate site was also collected as control. These results indicated that the phytoplankton community was composed by chlorophyta and bacillariophyta, and the contribution of euglenophyta biomass was more than 50% in the Chongxi gate and River Baozhengang in summer. Dissolved inorganic nitrogen(DIN) constituted the major fraction of total dissolved nitrogen(TDN), and the percentages of dissolved organic nitrogen(DON) in TDN in the Chongxi gate, Rivers Jiehe and Baozhengang were lower in summer and autumn than those in winter and spring, the release from agriculture soil may be an important source of DON. The concentration of ammonium nitrogen was affected by water temperature, dissolved oxygen, and chemical oxygen demand. The redundancy analysis suggested that the distribution of Chlorophyta and Euglenophyta was affected by ammonium nitrogen, and the distribution of Pyrrophyta was affected by urea.