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Trace metals play an important role in biogeochemical cycling in ocean systems. However, because the use of trace metal clean sampling and analytical techniques has been limited in coastal China, there are few accurate trace metal data for that region. This work studied spatial distribution of selected dissolved trace metals (Ag, Cu, Co, Cd, and Ni) and Cu speciation in the southern Yellow Sea (SYS) and Bohai Sea (BS). In general, the average metal (Cu, Co, Cd, and Ni) concentrations found in the SYS were lower by a factor of two than those in BS, and they are comparable to dissolved trace metal concentrations in coastal seawater of the United States and Europe. Possible sources and sinks and physical and biological processes that influenced the distribution of these trace metals in the study region were further examined. Close relationships were found between the trace metal spatial distribution with local freshwater discharge and processes such as sediment resuspension and biological uptake. Ag, owing to its extremely low concentrations, exhibited a unique distribution pattern that magnified the influences from the physical and biological processes. Cu speciation in the water column showed that, in the study region, Cu was strongly complexed with organic ligands and concentrations of free cupric ion were in the range of 10−12.6–10−13.2mol L−1. The distribution of Cu‐complexing ligand, indicated by values of the side reaction coefficient α′, was similar to the Chl adistribution, suggesting that in situ biota production may be one main source of Cu‐complexing organic ligand. Spatial distribution of selected trace metals in Yellow Sea was revealed, and their concentrations were half those of the Bohai SeaSignificant correlations were found between dissolved Cu, Cd, Co, and Ni concentrations and salinity; the distribution of Ag was uniqueCu speciation in seawater was studied and in situ biota production may be one main source of the strong organic Cu‐complexing ligands

Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size fractions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid extractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (Nso)) are obtained by the sequential extraction. The results show that the contents and the distributions of the extractable nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distributions of Nie, Nsoand total nitrogen (TN) present positive correlations with fine particles content, while Nwaand Nsadoes not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.