A comparison of eutrophication impacts in two harbours in Hong Kong with different hydrodynamics
Date
2009-09-03Author
Xu, J.
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Yin, K.
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Liu, H.
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Lee, Joseph H. W.
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Anderson, Donald M.
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Ho, Alvin Y. T.
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Harrison, Paul J.
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Metadata
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https://hdl.handle.net/1912/4275As published
https://doi.org/10.1016/j.jmarsys.2010.04.002Keyword
Eutrophication; Nutrients; Phytoplankton biomass; Dissolved oxygen; Sewage; Stratification; Hydrodynamics; Light limitationAbstract
Eutrophication impacts may vary spatially and temporally due to different
physical processes. Using a 22-year time series data set (1986-2007), a comparison of
eutrophication impacts between two eutrophic harbors, Victoria and Tolo Harbours, in
Hong Kong with very different hydrodynamic conditions was conducted. In the
highly-flushed Victoria Harbour (Victoria), the highest Chl a (13 μg L-1) occurred due
to stratification in summer as a result of the input of the eutrophic Pearl River
discharge, but the high flushing rate restricted nutrient utilization and the further
accumulation of algal biomass. In other seasons, vertical mixing induced light
limitation and horizontal dilution led to low Chl a (< 2 μg L-1) and no spring bloom.
Few hypoxic events (DO < 2 mg L-1) occurred due to strong tidal mixing. Therefore,
Victoria is resilient to nutrient enrichment. In contrast, in the weakly-flushed Tolo
Harbour (Tolo), year long stratification, the long residence times and weak tidal
currents favored algal growth, resulting in a spring diatom bloom and high Chl a (up
to 30 μg L-1) all year and frequent hypoxic events in summer. Hence, Tolo is
susceptible to nutrient enrichment and it responded to nutrient reduction since sewage
treatment resulted in a 32-38% decrease in algal biomass in Tolo, but not in Victoria.
A significant (11-22%) reduction in bottom DO in the both harbors after sewage
treatment was due to a decrease in the organic loading from sewage treatment or the
diversion.
Description
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 83 (2010): 276-286, doi:10.1016/j.jmarsys.2010.04.002.
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Suggested Citation
Preprint: Xu, J., Yin, K., Liu, H., Lee, Joseph H. W., Anderson, Donald M., Ho, Alvin Y. T., Harrison, Paul J., "A comparison of eutrophication impacts in two harbours in Hong Kong with different hydrodynamics", 2009-09-03, https://doi.org/10.1016/j.jmarsys.2010.04.002, https://hdl.handle.net/1912/4275Related items
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