Spatial patterns of concentrations of Cu, Zn, Cd, and Pb in marine sediments from Japanese port areas

We examined the spatial patterns of concentrations of trace metals Cu, Zn, Cd, and Pb in marine sediments as well as the physicochemical properties (total organic carbon, particle size, and water content) of those sediments from port and coastal areas of Japan. The samples we studied were from three datasets: a Japan-wide dataset and two datasets from local port areas. Principal component analysis showed that the relationships among the trace metal concentrations were nearly one-dimensional but differed among the three datasets, whereas the relationships among physicochemical properties were similar for the three datasets. Linear model analyses showed positive relationships between total organic carbon and the concentrations of trace metals, although their slopes differed by locality and according to carbon to nitrogen ratios. The spatial patterns of the trace metals were related to those of the organic matter present. However, local effects, including differences of carbon to nitrogen ratios, appear to drive the differences in the spatial patterns of the trace metal concentrations among local ports. We believe that the knowledge obtained from this study will contribute to understanding the mechanisms that control the spatial distribution of trace metals Cu, Zn, Cd, and Pb in sediments in port areas.