黎安港海水和沉积物中叶绿素a含量及与环境因子的关系分析

Analyses of chlorophyll a content in seawaters and sediments and its relationship with environmental factors in Li’an Lagoon

在2019年6月和9月对黎安港海域9个站点进行水质和沉积物采样调查,研究叶绿素a含量在潟湖内的空间分布,并探讨叶绿素a含量与相关环境因子的关系,为黎安省级海草特别保护区的海草资源保护与恢复提供基础数据及理论研究。结果表明:水体叶绿素a含量时空分布不均匀。6月,水体叶绿素a含量变化范围为3.34μg/L~14.64μg/L,均值为6.36μg/L;9月含量变化范围为12.20μg/L~21.62μg/L,均值17.61μg/L。总体上9月高于6月,空间分布特征为西南和北部偏高,东南部海草区和南部的港口门区偏低。沉积物叶绿素a含量变化范围为0.12μg/g~31.95μg/g,均值为5.71μg/g,表层沉积物叶绿素a呈北高南低的分布特征,柱状样叶绿素a随深度增加基本呈下降趋势。Pearson相关分析结果表明,6月,水质叶绿素a与无机氮和活性磷酸盐呈显著正相关,与水温和透明度相关性不显著;9月,与无机氮呈显著负相关,与其他因子相关性不显著;沉积物叶绿素a与水深、有机碳、总氮有关;说明营养物质和水下光照条件是影响浮游植物生长的主要因素。

We collected samples from nine sites at Li’an Lagoon in June and September,2019,to obtain the spatial distribution of chlorophyll a.Additionally,we considered the relationships between chlorophyll a content and environmental factors to provide basic data and theoretical research for the protection and restoration of seagrass resources in the provincial Seagrass Special Reserve of Li’an.The results revealed clear temporal and spatial differences in chlorophyll a.In June,the chlorophyll a content in water varied between 3.34 and 14.64μg/L with an average of 6.36μg/L.In September,chlorophyll a ranged from 12.20 to 1.62μg/L with an average of 17.6μg/L.Overall,chlorophyll a level in September was higher than that in June.Spatially,chlorophyll a concentration increased from southeast and south regions to southwest and north regions.The chlorophyll a content in sediments varied between 0.12 and 31.95μg/g with an average of 5.71μg/g.Chlorophyll a distribution in surface sediments was generally high in the north and low in the south.With the increase of depth,chlorophyll a in columnar samples showed a decreasing trend.Pearson’s correlation analysis indicated that chlorophyll a in the water was a significantly and positively correlated with inorganic nitrogen,and active phosphate in June,but was not significantly correlated with water temperature and transparency.In September,chlorophyll a was significantly and negatively correlated with inorganic nitrogen,but not significantly correlated with other nutrient concentrations.In sediment,chlorophyll a was related to water depth,organic carbon and total nitrogen.These findings suggested that nutrients and underwater light conditions are the main factors affecting the growth of phytoplankton in Li’an Lagoon.