北太湖水体固氮作用及其影响因子

为探究北太湖固氮作用,使用乙炔还原法对其水体的原位固氮作用和室内的N、Fe和Mo对鱼腥藻固氮速率的影响进行研究。结果发现:北太湖的年均固氮速率为3.08 ng/(L·h),并表现出明显的时空变化特征,梅梁湾水区的速率最高(2.75 ng/(L·h)),湖心区速率最低(1.38 ng/(L·h));固氮速率在夏季最高6.03 ng/(L·h)],春1.08 ng/(L·h)]、秋0.81 ng/(L·h)]次之,冬季最低6.97×10-5 ng/(L·h)]。进行相关分析发现:鱼腥藻的生长不受N、Fe和Mo影响(P>0.05);但N是控制鱼腥藻固氮速率的主要因素(P<0.01),而Fe和Mo含量对鱼腥藻的固氮作用并不产生显著影响(P>0.05)。北太湖水体的原位水温(P<0.01)、DTN(P<0.01)、蓝藻生物量和NO₃-(P<0.05)是导致水体原位固氮速率时空差异的主要原因。

NITROGEN FIXATION OF WATER COLUMN IN NORTH TAIHU LAKE AND ITS INFLUENCING FACTORS FACTORS

In order to study the nitrogen fixation of the water in North Taihu Lake and the influencing factors, with the acetylene reduction technique(ART),the nitrogen fixation rate in situ of the water column and the roles of nitrogen (N), iron (Fe) and molybdenum(Mo)in controlling nitrogen fixation rate of Anabaena spp indoor were studied. The results showed that the annual mean nitrogen fixation rate of North Taihu Lake was 3.08 ng/(L·h), with a obvious spatio-temporal variation. The highest rate appeared in Meiliang Bay (2.75 ng/(L·h)) and the lowest rate appeared in the Center of lake (1.38 ng/(L·h)) in space. The rate in summer (6.03 ng/(L·h)) was the highest, and then spring (1.08 ng/(L·h)) and autumn (0.81 ng/(L·h)),lowest in winter (6.97×10-5 ng/(L·h)). With the correlation analysis,the growth of Anabeana spp was not effected by nitrogen, iron and molybdenum (P>0.05). The nitrogen fixation rates were effected by nitrogen (P<0.01), other than iron and molybdenum (P>0.05). Temperature,DTN,the biomass of algae (P<0.01) and NO₃- (P<0.05) of water in situ were the main influencing factors of the spatio-temporal variation in the in situ nitrogen fixation rates.