春季渤海湾营养盐分布及潜在性富营养化评价

根据2011年5月对渤海湾海域20个站位海水营养盐的调查结果，分析该海区海水营养盐的分布特征，并进行了潜在性富营养化评价．研究发现，调查海域NO3--N质量浓度为150．5～276.3ug/L，NO2--N质量浓度为4．072．29．490ug／L，NH4＋-N、PO4 3-- P和SiO3 2-Si质量浓度分别为47．55～194．80ug／L、4．73～26．35ug／L和170．2—544．1ug/L．整体上，各类无机氮呈现出表底层差异不大、沿岸浓度高、外海浓度低的特点；断面分布呈现出由东向西逐渐升高的趋势，SiO23 2- -Si相反，NO3- -N、NH4--N和SiO2 3--Si质量浓度呈现出由北向南逐渐升高的趋势，而NO2--N、VO4 3--P质量浓度出现北高南低的情形．渤海湾连续站显示出一定的营养盐浓度随潮汐的韵律变化，其中NO3--N、NO2--N和NH4＋-N质量浓度变化相对较明显，低潮较高潮期间营养盐浓度高．营养盐与盐度的相关性不很显著．NO3 --N是溶解无机氮（DIN）的主要组成形式，占平均DIN含量的69．56％；该海区主要以磷限制为主，并已经逐渐从P限制向P、Si共同限制方向发展，这与潜在性富营养化评价结果一致．

Distribution of Inorganic Nutrients and Potential Eutrophication Assessment in Bohai Bay in Spring

Based on the nutrient data of 20 stations from Bohai Bay in May 2011, the distribution of major inorganic nutri- ents in Bohai Bay and seawater potential eutrophication were analyzed. The results show that NO3--N concentration in the investigated sea area ranged from 150.5 to 276.3 ug/L,NO2--N concentration ranged from 4.072 to 29.49 ug/L,and the concentrations of NH4-N, PO34--P as well as SiO23 -Si ranged from 47.55 to 194.8 ug/L, 4.73 to 26.35 ug/L and 170.2 to 544.1 ug/L, respectively. In general, nutrient concentrations decreased from near-shore to offshore but exhibited little variations between the surface and bottom within the water column. The concentration of all DIN species gradually increased from the east to the west while the concentration of SiO2/-Si displayed an inverse trend. The concentrations of NO3--N, NH4＋-N and SiO3 2 - -Si progressively went up from the north to the south, opposing the patterns of NO2-N and pO4 3--P. Time-series of data indicated that the nutrient concentration, particularly that of DIN, synchronized the diurnal tidal fluctuations in the studied area, being lower at high tides and higher at low tides. Nutrient concentrations were not significantly correlated to salinity. NO3-N was the dominant DIN species, accounting for on average 69.56% of the total DIN. The Bohai ecosystem seemed to be evolving from P-limitation to combined P- and Si-limitation, which is in line with our assessment of the potential eutrophication in this area.