中文摘要：

为分析闽江河口营养盐的季节变化及混合行为,于2014年8月、11月及2015年1月、5月采集了河口水域13个站位的表层水样,测定了硝酸氮、亚硝酸氮、氨氮、活性磷酸盐及活性硅酸盐5项营养盐指标.调查结果表明：不同季节,硝酸氮均为溶解无机氮（DIN）的主要存在形态,其质量浓度冬季最高,夏季最低,亚硝酸氮冬季较低,氨氮夏季较低,DIN的季节变化主要受浮游生物生长消亡、氮循环及流量控制;活性磷酸盐春季及夏季低于秋季和冬季,季节变化主要受控于流量、悬浮物质量浓度及浮游生物的生长消亡;活性硅酸盐秋季远低于其他3个季节,季节变化主要受控于地表输入量及生物消耗和分解.河口混合行为方面,硝酸氮不同季节均呈现保守行为,亚硝酸氮较为复杂,特别是11月表现为质量浓度随盐度的增大而增大,氨氮夏季淡水端有去除现象,DIN与硝酸氮相似;活性磷酸盐夏季呈现保守行为,秋季受河口缓冲效应、人类活动及化学生物过程共同作用而表现为质量浓度随盐度增大而增大,冬季与秋季相似,春季大致呈保守行为;活性硅酸盐夏季、冬季和春季呈现保守行为,秋季随盐度变化不大.除此之外,河口营养盐结构有失调现象,大部分站位N/P（摩尔比）值超过22,Si/P（摩尔比）值超过22,总体表现为磷限制.

英文摘要：

In order to study seasonal variations and mixing behaviors of nutrients at the Min River Estuary,surface water samples were collected at 13 stations at the estuary in August and November of 2014 and January and May of 2015.The results showed that the main form of dissolved inorganic nitrogen（DIN）was NO3 --N in all four seasons,with the highest NO3 --N in January and the lowest in August.The content of NO2 --N and NH4 ＋-N was the lowest in January and August,respectively.Seasonal variations of DIN were mainly controlled by the growth and death of plankton,the nitrogen cycle and also the runoff.The average concentration of PO4 3--P in August and May was lower than in November and January.Its seasonal variations were mainly controlled by the runoff, suspended matter（SPM）and the growth and death of plankton.SiO3 2--Si was far lower in November than in other months and its seasonal variations were mainly controlled by the input of runoffs and the absorption and decomposition by plankton.NO3 --N was conservative in various seasons.NO2 --N showed quite complicated mixing patterns,especially in autumn when the concentration in-creased with the increasing salinity.NH4 ＋-N showed a trend of removal across the lower salinity gradient in August.Overall,the mixing behavior of DIN was similar to that of NO3 --N.PO4 3--P was conservative in August and roughly conservative in May,but increased with the increasing salinity in November and January due to buffering effect,human activities,chemical and biological processes.SiO3 2--Si was conservative in May,August and January,and showed a non-significant change with the salinity due to a combined effect of great diatom use and physical mixing in November.In addition,nutrients in the Min River showed a limitation of phosphorus with N/P values more than 22 and Si/P values over 22 at most of the stations.