中文摘要：

依据自20世纪60年代以来胶州湾营养盐调查与研究资料,系统分析了近40余年来胶州湾营养盐浓度与结构的长期变化规律,以及2000年以后胶州湾营养盐浓度与结构的变化特征。结果表明,近几十年来胶州湾各项营养盐浓度都呈现增加趋势,但不同种类营养盐浓度变化的时期并不相同。氨氮浓度到2001年达到顶峰,随后呈现下降趋势。而亚硝酸盐和硝酸盐含量的上升趋势在2000年之后尤为显著。磷酸盐和硅酸盐浓度的变化主要体现在20世纪90年代后期。与此同时,胶州湾营养盐的结构也发生了很大变化。总溶解无机氮中不同氮源的组成比例发生改变,2000年后氨氮在总溶解无机氮中所占的比例逐渐降低,硝酸盐所占比例逐渐增加。不同营养盐之间的比例亦发生变化,2000年以后氮磷比值开始下降,氮磷比严重失衡的状态得到缓解,硅氮比有所上升,但仍然低于Redfield比值。

英文摘要：

Based on data obtained from the Jiaozhou Bay ecosystem monitoring since the 1960＇s,long-term changes in nutrient concentrations and structures were investigated in this paper.Our results indicated that the concentrations of all five nutrients showed increasing trends during the last several decades.Among these nutrients,ammonium concentration increased gradually from the 1980＇s and reached a peak in 2001,then it decreased afterward.The increasing trends of nitrite and nitrate concentrations were significant from the 1990＇s,especially after 2000.Phosphate and silicate concentrations began to increase after 1998.Beside concentration,nutrient structures also changed dramatically.In dissolved inorganic nitrogen（DIN）,the proportion of ammonium decreased gradually after 2000,and that of nitrate increased accordingly.The N/P ratio began to decrease since 2000 from the previously high N/P ratio;at the same time,the Si/N ratio began to increase,although it was still lower than the Redfield value.The imbalance in nutrient structure was alleviated compared to the 1990＇s,however,it is still necessary to control the increase in DIN based on this study.