Cycling and Fates of Bioactive Elements (C, N, P, Si, Fe, Zn) in the
Upper Oceans of Kuroshio Sphere (II)
黑潮圈上層海洋生物源要素之循環與宿命(二)
Jia-Jang Hung (洪佳章)
Institute of Marine Geology and Chemistry, National Sun Yat-Sen University,
Kaohsiung, Taiwan
Purpose: Understanding the linkages between particle dynamics and cycling and fates
of bioreactive elements in the upper layer of northern South China Sea.
Summary:
The sediment traps were deployed in the northern South China Sea (NSCS)
to study the vertical fluxes and carbon and nutrient cycling in the NSCS basin and
their possible relations to external forcing changes. Particle fluxes vary spatially and
temporally and are apparently related to terrestrial inputs and monsoon-effected
processes. Both biogenic and lithogenic fluxes were generally higher during the
northeast (NE) monsoon season than during the southwest (SW) monsoon season.
The rain ratio (Corg/Cinorg) also appears to be greater (>1) in those shallow traps closer
to the Taiwan Island. Fluxes decrease generally with depth for biogenic components
(OM, carbonate, opal) but increase with depth for lithogenic components (Al2O3).
Most lithogenic materials appear to be derived from lateral transport below the
surface layer, and the deep fluxes show a decreasing trend with distance away from
the Taiwan Island. Carbonate dominates the biogenic fluxes in the upper layer and
may play as the major ballast in the transportation of biogenic materials through the
water column. Fluxes of Corg range from 0.69 to 77 mg m-2 d-1 , which are closely
correlated with the fluxes of opal ( 0.94-133 mg m-2 d-1) and carbonate (4.6-293 mg
m-2 d-1). However, the positive correlations between Corg (or carbonate) fluxes and
lithogenic fluxes (0.6-4978 mg m-2 d-1) display with different modes supporting the
lateral fluxes of lithogenic materials. Organic nitrogen and phosphorus decayed
preferentially over organic carbon as the biogenic components descend through water
columns. Microelements associated with biogenic materials (eg. Cd & Zn) also
display a significant decrease in contents with depth, showing a rapidly cycling in
water columns. The NSCS reveals a variable efficiency in drawing down CO2 and
transporting materials through water columns in different spaces and monsoon
seasons.
 hydro-stations
 trap sites
Fig. 1 Sampling locations in the northern South China Sea.
Fig. 2. Vertical fluxes of TOC under the influence of Kuroshio intrusion in the
northern South China Sea.