Sciences marines : recherche et développement

Abstrait

Tracing the Variability of Dissolved Organic Matter Fluorescence in the East China Sea in the Red Tide Season with use of Excitation-emission Matrix Spectroscopy and Parallel Factor Analysis

Weihong Zhao, Lisha Lv and Hui Miao

From the end of March to the end of May, 2011, five cruises were carried out to survey the red tide occurrence in the Zhejiang coast of the East China Sea where the red tides occurred each spring and there was a trend for community succession from diatoms to dinoflagellates. Using Excitation Emission Matrix Spectrum(EEMs) combined with Parallel Factor Analysis (PARAFAC) examine the fluorescent components feature of dissolved organic matter (DOM) sampled from the East China Sea in the red tide season. Three fluorescent components were identified by PARAFAC, including tyrosine-like component C1(230,280/320), tryptophan-like component C2(240,305/355) and humic-like component C3(270,340/480). The result showed that the fluorescence intensity of C1 was relatively high and changed along with the succession of red tides, besides, the weak correlation coefficient with salinity and the particularity of its source suggested that phytoplankton activity was the important factor in fluorescence intensity change of C1. The fluorescence intensities of component C2 and C3 were relatively low and changed not very significant, but its good linearity with salinity indicated that the terrestrial input was the important sources of two components during the algae dispersion. Lower Fluorescence Index (FI) (<1.4) also tested the terrestrial distribution.
Nevertheless, correlation coefficient with salinity was slightly decreasing showed the effects of biological activity had increased during the outbreak of dinoflagellate. Higher (>0.8) Biological Index (BIX) and lower Humification Index (HIX) (<2) inferred that biological activity intensively in the red tide season in the East China Sea would contribute the CDOM in the water.