Nitrogen Concentrations in Surface Water and Bottom Water of Tolo Harbour, Hong Kong, & Its Potential Effect on Marine Life

Madeleine Hsu

Authors

Madeleine Hsu Taft School

Keywords:

nitrogen, hypoxia, Eutrophication, surface water, bottom water

Abstract

The industrialization of Hong Kong has caused eutrophication in water systems. Specifically, Tolo Harbor, Hong Kong, located just one km from industrial and wastewater treatment facilities, such as the Tai Po Sewage Treatment Works, makes it highly vulnerable to pollution. The sewage facilities can introduce nitrogen-rich effluent into the ocean, and because Tolo is an enclosed harbor, limited mixing occurs, and pollutants tend to concentrate (Environmental Protection Department, 2022). As a result, the eutrophication present in Tolo Harbor could lead to hypoxic conditions, or oxygen deficiency, in its water. Through monthly sampling at five different locations within Tolo Harbor, the study asks the question: what are the trends between surface and bottom water NO2 and NO3 concentrations near the coast, and farther from the coast in Tolo Harbour? The findings of this study not only allow us to understand nitrogen dynamics in Tolo Harbour, but the final part of the study will present different species of marine organisms in Tolo Harbour such as corals, bivalves, fish, and echinoderms, and go into depth on how they are negatively affected by hypoxic conditions.

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