Tung‐Yuan Ho1, Liang‐Saw Wen2, Chen‐Feng You3, Der–Chuen Lee4
1Research Center for Environmental Changes, Academia Sinica, Taipei, Taiwan
2Institute of Oceanography, National Taiwan University, Taipei, Taiwan
3Department of Earth Sciences, National Cheng Kung University, Tainan, Taiwan
4Institute of Earth Sciences, Academia Sinica, Taipei, Taiwan
Tóm tắt
We report the elemental composition (P, Si, Al, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn) in the size‐fractionated plankton and suspended particulate matter (SPM) in the surface waters of the South China Sea. The sizefractionated plankton were effectively and gently separated by gravity through a novel trace‐metal‐clean filtration device, equipped with 150‐, 60‐, and 10‐µm aperture nets in sequence to concentrate the plankton. P‐normalized metal quotas in the largest fraction, mostly composed of copepods, were close to or slightly lower than the average metal quotas obtained from previous field studies. However, the total metal quotas in the two smaller fractions were 8‐ to 40‐fold higher than the largest one, and they increased with decreasing sizes. The striking correlation between some essential metals and chlorophyll (Chl) in the SPM at the offshore site indicates that the majority of the metals were associated with algae. Nevertheless, the P‐normalized metal quotas also showed positive correlations with abiogenic Al and Mn, indicating that most of the metals associated with phytoplankton were from extracellular inorganic particles. Preliminary evidence suggests that the extracellular metals were originally derived from anthropogenic aerosols, which contain abundant dissolvable trace metals. The metal quotas of the zooplankton assemblages have a fairly consistent value as compared to observations from other regions, but algae larger than 10 mm carry overwhelming amounts of extracellular metals even in offshore areas. The stoichiometry concept for trace‐metal composition in marine plankton assemblages is unrealistic in the field.
