Chromophoric dissolved organic matter in the estuaries of populated and mountainous Taiwan
2013
Yang, Liyang | Hong, Huasheng | Chen, Chen-Tung Arthur | Guo, Weidong | Huang, Ting-Hsuan
Absorption and fluorescence of chromophoric dissolved organic matter (CDOM) in 16 Taiwan estuaries are reported for the first time, so as to examine the influence of catchment characteristics on the CDOM level and to study the estuarine behavior of CDOM. The absorption coefficient (a₃₅₀) in the freshwater end-member ranged from 0.15 to 12.5m⁻¹ among estuaries. The a₃₅₀ and fluorescence intensities correlated positively with population density and the chlorophyll a concentration, likely due to the additions of CDOM from anthropogenic activities and autochthonous production. The freshwater a₃₅₀ also correlated negatively with precipitation, headwater altitude and freshwater discharge. The a₃₅₀ generally decreased linearly with increasing salinity in most estuaries. Humic-like fluorescent components had intensities strongly correlated with a₃₅₀, while protein-like components received notable additions in five estuaries but were removed in another five estuaries. The absorption spectral slope (S₂₇₅–₂₉₅) and slope ratio (SR; 275–295nm slope: 350–400nm slope) generally increased with increasing salinity, likely reflecting a decrease in the average molecular weight. The contribution of protein-like components to the total fluorescence changed greatly among different estuaries, which was in part associated with river population density and precipitation. The results showed that both the catchment characteristics and estuarine biogeochemical processes contributed to the variations of CDOM level and composition in estuarine environments.
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