基于空间插值的长江口邻近海域春季悬浮物和叶绿素a空间分布分析

Spatial distribution analysis of total suspended matter and chlorophyll-a in the adjacent waters of the Yangtze River Estuary in spring

针对目前利用实测数据对长江口邻近海域水质状况进行分析研究相对偏少的情况,基于“淞航”号2018年春季航次对该海域的综合观测,利用实验室水样分析数据对船载温盐深仪(CTD)的测量数据进行校正,并对该区域2018年春季时节悬浮物(TSM)和叶绿素a(Chl-a)浓度的空间插值结果进行分析。研究结果表明:CTD观测数据与水样分析数据呈较强线性相关关系。反距离权重插值对TSM和Chl-a浓度空间分布具有整体最优的效果。TSM浓度在近岸和近海底较高,在观测区域内出现两个高值中心;Chl-a浓度在近岸海域较高,有较明显的片状高值结构,垂向上表层较高。TSM与Chl-a浓度分布在长江口南北表现出不同的特征,且两者具有一定的负相关性。长江径流、外海洋流、潮汐混合等水动力过程是影响该区域TSM和Chl-a浓度分布的主要因素。

Considering the relatively few studies utilizing in-situ data on this topic,this study uses the comprehensive observational data collected by the Songhang voyage in spring 2018,to analyze the spatial distribution of total suspended matter(TSM)and chlorophyll a concentrations after correcting shipboard CTD measurements against the laboratory water sample analysis data.The results show that there is a strong linear correlation between CTD measurements and water sample analysis data.The inverse distance weight interpolation has the overall optimal effect on the spatial distribution of TSM concentration and chlorophyll a concentration.The TSM concentration is higher in the nearshore areas and in the bottom water near the seabed,and there are two high-value centers in the observation area;the chlorophyll a concentration is higher in the nearshore areas with obvious flake high-value structure,and higher in the vertical upper surface layer.The distributions of TSM concentration and chlorophyll a concentration in the north and south of the Yangtze River Estuary show different characteristics and negative correlation.The hydrodynamic processes including the runoff of the Yangtze River,ocean currents,and tidal mixing are the main factors affecting the distribution characteristics of TSM concentration and chlorophyll a concentration in the area.