大亚湾冬季沉积物中叶绿素含量与分布

Chlorophyll content and its distribution in the sediments of Daya Bay,South China in winter

2012年2月(冬季)对大亚湾海域沉积物叶绿素a(Chl-a)及其降解产物脱镁叶绿酸(Pha-a)的含量与分布进行了研究,并探讨了环境因子(水深、温度、透明度、粒度、营养盐、TOC)对表层沉积物Chl-a含量分布的影响。结果表明:Chl-a和Pha-a是同源的,随沉积物深度增加二者皆呈递减趋势,个别站位Chl-a和Pha-a出现许多小突跃,这可能与生物扰动和环境变化有关;表层(0～1cm)Chl-a和Pha-a的含量变化范围分别为0.98～1.55μg·g-1和3.97～6.65μg·g-1,平均含量分别为1.24和5.55μg·g-1。Chl-a含量变化是各种环境因子共同作用的结果,其中最主要的影响因素是沉积物底质颗粒的大小,高比例砂含量的底质能为底栖藻类提供更多的生存空间,但不利于沉积物中Pha-a的保存;比较了沉积物与上层水体中平均Chl-a相对含量,并与其他海域相比较,发现该海域沉积物中Chl-a含量较高,与水体Chl-a含量比值为50.28%～150.79%,近海沉积物中底栖初级生产力不可忽视。

In February（winter）,2012,an investigation was conducted on the chlorophyll a（Chl-a） and phaeopigments（Pha-a） contents and their distribution in the sediments of Daya Bay,and the relationships of the Chl-a in surface layer of the sediments with the environmental variables（water depth,temperature,transparency,granularity,nutrients,and TOC） were analyzed.The Chl-a and Pha-a in the sediments had the same source.The contents of Chl-a and Pha-a decreased significantly with increasing sediment depth,and there were several leaps in the vertical distribution of Chl-a and Pha-a,which might reflect the effects of bioturbation and environmental change.The Chl-a and Pha-a contents in the surface layer（0-1 cm） of the sediments varied from 0.98 to 1.55 μg·g-1 and from 3.97 to 6.65 μg·g-1,respectively,with the mean contents being 1.24 μg·g-1 for Chl-a and 5.55 μg·g-1 for Pha-a.The most important factor affecting the Chl-a content was the particle size of the sediments.The high proportion of sand in the sediments would provide more living space for microphytobenthos,but this type of sediments would save less Pha-a.The comparison between the Chl-a content in the sediments and in the upper water as well as in the other marine areas showed that the ratio of the Chl-a content in the sediments and in the upper water ranged from 50.28% to 150.79%,suggesting that the primary productivity in the sediments of coastal area should not be ignored.