广海湾海域营养盐时空分布及富营养化评价

依据2014年10月（秋季）和2015年4月（春季）的广海湾海域海洋环境调查结果，对盐度、营养盐和叶绿素等环境生态因子的时空分布特征进行了分析，采用富营养化指数法（EI）和营养质量状态指数法（NQI）评价海域的富营养化状态水平，研究了营养盐、氮磷比、浮游植物量及种群结构之间的联系。结果表明:广海湾海域春季营养盐分布呈近岸、湾顶向湾口下降的变化趋势；秋季广海湾海域营养盐呈西北海域低、东南海域高的趋势。营养盐分布与浮游植物之间相互影响，是一种相对动态变化关系。春、秋两季广海湾均呈现富营养化状态，分布呈近岸高、远海低的趋势，秋季的富营养化状态比春季严重。

Temporal and spatial distribution characteristics of nutrients and eutrophication assessment in Guanghai bay

The spatial and temporal distributions of environmental ecological parameters (including salinity, nutrients and chlorophyll a) were investigated in the Guanghai bay during two cruises in October 2014 (autumn) and April 2015 (spring). The state of eutrophication in this region were evaluated by eutrophication index (EI) and nutrient quality state index (NQI). The relationships among nutrients, the N/P ratio, phytoplankton biomass and population structure were discussed in order to provide an improved understanding of the influence of environmental factors on coastal eutrophication. The spatial distributions of nutrients displayed a declining trend from the coastal estuary toward the marine environment in spring. In autumn, the concentrations of nutrients were higher in the northwestern regions, compared with those in the southeastern area. These findings suggest an extremely dynamic cycling of nutrients that responds rapidly to changes in the phytoplankton biomass and community structure. Eutrophication occurred in Guanghai bay during spring and autumn, with a decreasing gradient from inshore to offshore sites. Eutrophication situation worsened obviously from spring to autumn.