珠江口广州海域叶绿素a分布特征及环境调控因素

于2009年5、8、10和12月对珠江口广州海域叶绿素a和环境相关因子进行了取样调查,分析了广州海域叶绿素a的时空变化特点及其分布的环境调控因素。结果表明,广州海域水体中叶绿素a变化范围为1.43～86.9μg/L,平均含量为20.7μg/L,最高值出现在夏季的N1站位,为86.9μg/L,最低值出现在春季的N8站位,为1.43μg/L。各站位叶绿素a年平均浓度从上游到下游表现出明显的递减趋势,以N1站位浓度最高(38.54μg/L),N7站位浓度最低(7.44μg/L),相差5.2倍。调查海域叶绿素a的季节变化明显,呈单峰型,总体上表现为夏季﹥秋季﹥冬季﹥春季。根据叶绿素a浓度对广州海域富营养化状态进行评价,15.6%的监测站位处于低度富营养化,50.0%处于中度富营养化,28.1%处于高度富营养化,6.3%处于过度富营养化,总的来讲,以中、高度富营养化状态为主体。叶绿素a浓度与NO3--N浓度、温度呈现出一定的正相关关系(分别为:r=0.374,p<0.05;r=0.502,p<0.01),与盐度、溶解氧呈现出一定的负相关关系(分别为:r=-0.433,p<0.05;r=0.455,p<0.01)。与国内其他近岸海域(河口)相比,珠江口广州海域叶绿素a浓度处于较高水平,仅低于深圳湾。

Distribution and environmental regulation of chlorophyll-a in Guangzhou sea area, Pearl River Estuary

The distribution of chlorophyll-a and the related environmental factors were investigated during May,August,October and December in 2006 in Guangzhou sea area,Pearl River Estuary.The results showed that the concentration of chlorophyll-a ranged from 1.43 μg/L to 86.9 μg/L,with an annual average of 20.7 μg/L.The maximum concentration of chlorophyll-a was 86.9 μg/L at station N1 in summer,and the minimum value was 1.43 μg/L at station N8 in spring.Annual-averaged chlorophyll-a concentration decreased downstream from 38.54 μg/L at station N1 to 7.44 μg/L at station N7.The concentration of chlorophyll-a varied in different seasons and had a single-peak pattern,with the highest concentration in summer.According to the concentration of chlorophyll-a in sea waters,eutrophication status of Guangzhou sea area was divided into four groups,hypereutrophication,high eutrophication,medium eutrophication and low eutrophication,which took up 15.6%,50%,28.1% and 6.3% of the total monitoring stations,respectively,for the whole year.Positive correlation between the chlorophyll-a concentration and nitrate concentration(r=0.374,p<0.05),and temperature(r=0.502,p<0.01) was found.However,the chlorophyll-a concentration showed negative correlation with salinity(r=-0.433,p<0.05) and dissolved oxygen(r=0.455,p<0.01).Compared with other domestic coastal sea areas(estuaries),the chlorophyll-a concentration in Guangzhou sea area of the Pearl River Estuary was at a high level,which was just after that of the Gulf of Shenzhen.