Based on the nutrients and related simultaneous observation data in May and October of 2007 in the north part of the Liaodong Bay, the distribution and structure features of nutrients and its influencing factors were studied. The results showed that DIN was most abundant in spring and autumn, in turn SiO3-Si and PO4-P were relatively lower in this area. In spring DIN and SiO3-Si contents were slightly higher than in autumn, and PO4-P content was slightly lower than in autumn. The maximum nutrients values in the two seasons were recorded near the mouth of Liaohe River, and the minimum one was in the area eastern of Huludao. In the estuary region, the nutrients were universally higher than other regions. Furthermore, the nutrients concentration in the surface water was generally higher than that in the bottom. The distributions of three kinds of nutrients were similar in the Liaodong Bay, showing a "S" shape in spring, but a hook-shaped distribution in autumn in this area. The nutrients concentrations in spring and autumn were exceeded the threshold for phytoplankton growth. The primary production might be limited by phosphate in most of the waters in spring, but in autumn it was only be limited in a small part of the area near the mouth of the Liaohe River and Shuangtaizi River. In addition, the average N/P ratio of the waters in the two seasons was 66, increasing 55% compared with that of 43 in 1998, far greater than 16. Si/P and Si/N ratios were continuing to decrease, therefore the nutrients structure in whole area was seriously unbalanced. The terrigenous input due to human activities was the major nutrients source in Liaodong Bay, being the key factor affecting the imbalance of the nutrients structure. However the circulation and physical mixing during the period of investigation were the another two key factors affecting the nutrients con-centrition and distribution in the Liaodong Bay.%根据2007-05(春)和2007-10(秋)辽东湾北部海域营养盐的实测数据及相关同步观测资料,对该海域水体营养盐的分布、营养结构及其主要影响因素进行分析.结果表明:调查海域春、秋均以DIN最为丰富,其次SiO3-Si,PO4-P相对较少.春季DIN和SiO3-Si表底层浓度均略高于秋季的,而PO4-p浓度则略低于秋季的.春、秋3种营养盐浓度最高值均位于辽河口附近海域,而最低值则均位于葫芦岛以东近岸海域,河口区营养盐的浓度普遍高于非河口区的.此外,营养盐表层平均浓度均高于底层的.调查海域表底层各项营养盐分布趋势较为一致,春季各营养盐呈现“S”型走向的分布特征,而秋季在双台子河口存在向南延伸的高浓度营养盐水舌,并呈现弯钩状.春、秋季各营养盐浓度均高于浮游植物生长的阈值.按照化学计量限制的评估方法,春季绝大部分海域属于磷限制,而秋季仅部分海域属于磷限制,且主要集中在辽河口与双台子河口附近海域.此外该海域2个季节N/P平均为66,比1998年的43又升高55％,已经远远大于16,Si/P和Si/N持续降低,整个海域营养盐结构失衡比较严重.人类活动导致陆源营养盐输入是辽东湾北部海域营养盐的主要来源,也是其水体营养结构失衡的关键原因所在,而调查期间的环流状况以及淡咸水的物理混合作用则是影响辽东湾北部海域营养盐浓度、分布趋势的另外2个关键因素.
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