Distribution of Bioactive Trace Metals in the Osaka Bay

Abstract

Among the trace components found in seawater, metals that serve as the active centers of metalloenzymes involved in metabolism within organisms are referred to as bioactive trace metals. To date, investigations into the distribution of bioactive trace metals have primarily been conducted in open ocean areas, with relatively few analytical studies focusing on coastal regions that are more susceptible to the influence of river water. Therefore, this study examined the distribution of nine bioactive trace metal elements (Al, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) in Osaka Bay. Dissolved metals exhibited a significant negative correlation with salinity and a significant positive correlation with nutrients, suggesting influences from riverine sources and planktonic activity. Among exchangeable particulate metals, Mn, Co, Ni, Cu, Zn, and Cd showed significant positive correlations with one another, indicating a common supply source. Al and Fe showed strong positive correlations in both the exchangeable particulate metals and total dissolved metals, suggesting that Fe, like Al, originates primarily from crustal sources.