Dynamics of dissolved, colloidal and particulate phosphorous: A case study in Danshuei tributary-Estuary, northern Taiwan
Abstract
Estuary delivery of phosphorous to the ocean is not well quantified because of uncertainties about the fate of dissolved organic phosphorous, colloidal phosphorous, nano-particles and particle/FeOOH-bound P. To address such concerns, truly dissolved (<1 kDa), Colloidal (1 kDa~0.1 μm, 0.1 μm~0.4 μm) and various particulate (>0.4 μm) fractions of both inorganic and organic phosphorous in waters of Danshuei Tributary, the largest, macro tidal, mountainous estuary in northern Taiwan, were investigated at both dry and wet seasons. Despite hydrological conditions, the colloidal phosphorous (CP) accounted for ~30% in average of total dissolved phosphorous (TP). Truly dissolved phosphate as in reactive phosphate (DIP) were only 84±13%, more than 16±13% were in organic fraction (DOP). In colloidal fraction, 66±27% were molybdate-reactive phosphate (CIP), organic phosphate (COP) accounted for 34±23%. The total dissolved phosphate concentration ranged from 0.21 to 16.9μM. The loading rate of TP from the estuary to the ocean was close to 0.1 Gmol/year and the reactive phosphate only accounted for ~80%. Approximately 50% particulate phosphorous was associated with surface-adsorbed phase. Strong correlation between surface-bound phosphorous and iron was found, ratio close to 1:2, implying that Fe-oxyhydroxide particles act as both a sorbent and carrier. It was found that the interactions of the Fe, S, and P cycles have important effects on phosphate availability and distribution along salinity gradient.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFMOS31A1624W
- Keywords:
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- 4235 OCEANOGRAPHY: GENERAL / Estuarine processes;
- 4807 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Chemical speciation and complexation;
- 4809 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Colloids;
- 4845 OCEANOGRAPHY: BIOLOGICAL AND CHEMICAL / Nutrients and nutrient cycling