DISTRIBUTION AND ENRICHMENT OF PARTICULATE TRACE-METALS IN THE SOUTHERN EAST CHINA SEA

This study investigates the distribution and enrichment of trace metal s in suspended and sinking particulate matter from southern East China Sea (ECS) north of Taiwan during the period of April 1992 to April 19 93. According to these results, concentrations of suspended particulat e matter (SPM) in the inner shelf of southern ECS, the upwelling-influ enced shelf break, and Kuroshio water are 1.2 (surface)-4.2 (bottom) m g/l, ca. 0.3-0.5 mg/l, and 0.1-0.3 mg/l, respectively, reflecting vari ous influences of terrestrial inputs. A benthic nepheloid layer (BNL), apparently owing to resuspension of local and/or remote bottom sedime nts, formed over the shelf region. Temporal Variation in trace metal c ontents and enrichment in suspended matter from the shelf region refle ct the variability of metal inputs from Chinese rivers, particularly f rom Changjiang runoff. The abundance of a particulate metal is largely determined by the SPM content. Hence, the abundant profiles of most p articulate metals closely correspond to the distribution pattern of SP M. However, concentrations of most particulate metals (except for Al a nd Fe), based on the dry weight of SPM, increase from the China coasta l water to the Kuroshio water. The enriched metals are more likely to have derived from terrestrial inputs, rather than solely from biologic al accumulation. In addition, a decrease in metal contents and an incr ease in salinity confirm the transport of suspended particulate metals from the ECS shelf to the open ocean. Such an occurrence is verified by the feature of metal plume in the intermediate layer (550-800 m) of Kuroshio water. Moreover, the sinking particles collected from sedime nt traps deployed on the upper slope are relatively enriched in lithog enic matter and trace metals. Terrestrial inputs apparently control th e distribution of most trace metals in suspended and sinking particula tes in the southern ECS.