Identifying spatial distribution pattern of water quality in Masan Bay using spatial autocorrelation index and Pearson's r

Abstract

To identify the spatial distribution pattern of water quality in Masan Bay, Pearson's correlation as a common statistic method and Morans I as a spatial autocorrelation statistics were applied to the hydrological data seasonally collected from Masan Bay for two years (2004-2005). Spatial distribution of salinity, DO and silicate among the hydrological parameters clustered strongly while chlorophyll adistribution displayed a weak clustering. When the similarity matrix of Moran's I was compared with correlation matrix of Pearson's r, only the relationships of temperature vs. salinity, temperature vs. silicate and silicate vs. total inorganic nitrogen showed significant correlation and similarity of spatial clustered pattern. Considering Pearson's correlation and the spatial autocorrelation results, water quality distribution patterns of Masan Bay were conceptually simplified into four types. Based on the simplified types, Morans I and Pearson's r were compared respectively with spatial distribution maps on salinity and silicate with a strong clustered pattern, and with chlorophyll a having no clustered pattern. According to these test results, spatial distribution of the water quality in Masan Bay could be summed up in four patterns. This summation should be developed as spatial index to be linked with pollutant and ecological indicators for coastal health assessment.