桑沟湾海域叶绿素a的时空分布特征及其影响因素研究

2009年4月-2010年2月对山东荣成典型养殖海湾—桑沟湾海域水体中的叶绿素a（Chl-a）进行了6个航次的监测,分析该海区表底层海水中Chl-a的质量现状,探讨Chl-a在桑沟湾海区的时空分布特征,以及与水温和营养盐等主要环境因子的相关性。结果表明,桑沟湾海域表层海水Chl-a质量浓度范围为0.36～9.77μg L-1,平均值为2.17μg L-1;底层海水Chl-a质量浓度范围为0.40～7.46μg L-1,平均值为2.14μg L-1。Chl-a质量浓度的季节性变化呈现一定的模式,夏季〉秋季〉春季〉冬季。Chl-a的质量浓度在春季和冬季呈现由湾内向湾外递减的分布特征,而夏季和秋季则没有明显的分布规律。垂直分布上,夏季表层Chl-a质量浓度高于底层,冬季则是底层高于表层,春秋2季表底层垂直分布比较均匀。相关分析显示桑沟湾Chl-a与水温呈较显著正相关,但与营养盐溶解无机氮（DIN）不具显著意义的相关关系。总体看来,桑沟湾海域Chl-a的时空分布受养殖环境状况、水文环境及陆地径流和外源输入的共同影响,贝藻养殖活动及营养盐的陆源输入是影响Chl-a分布格局的重要因素。

The spatial and temporal distribution of chlorophyll-a and its influencing factors in Sanggou Bay

6 cruises were completed in the period from April 2009 to February 2010 to investigate and analyze the chlorophyll-a（Chl-a） status in the surface and bottom layer seawater of Sanggou Bay,a typical marine culture area in Rongcheng,Shandong.The spatial and temporal distribution of local Chl-a,and its relationships to the main environmental factors including water temperature and nutrients were discussed.Results showed that the Chl-a content varied between 0.40 and 7.46 μg L-1 with a mean value of 2.17 μg L-1 in the surface seawater.In the bottom seawater,the Chl-a content varied between 0.36 and 9.77 μg L-1 with a mean value of 2.14 μg L-1.With regards to seasonal variation,Chl-a content was the highest in summer,followed by autumn,spring and winter in sequence.The horizontal distribution of Chl-a showed that its content decreased from inner area to the outside of the bay in spring and winter.However,in summer and autumn,there was no obvious trend.As for vertical distribution,Chl-a content was higher in the surface seawater than that in the bottom seawater in summer and this trend was reversed in winter.In spring and autumn,Chl-a was evenly distributed vertically.Correlation analysis showed that the Chl-a content was positively related to water temperature,but when comparing the Chl-a content with dissolved inorganic nitrogen（DIN）,there was no obvious correlation between them.Overall,the Chl-a distribution and seasonal variation are significantly affected by marine cultures,hydrographic environments,land runoff and exogenous input into the bay.The kelp and shellfish cultures as well as the terrestrial nutrients input are important influence factors of Chl-a distribution pattern.