Water Quality

Toxic Substances Monitoring in Hong Kong

The Environmental Protection Department (EPD) initiated a Toxic Substances Monitoring Programme in 2004 to monitor and assess the extent of toxic substances pollution in the Hong Kong marine environment, including marine water, sediment and biota, and potential land-based pollution sources, such as sewage effluent as well as river water and storm runoff.

1. Why do we need to monitor toxic substances in the marine environment?

The EPD has been monitoring marine waters in Hong Kong since 1986, under the Routine Marine Monitoring Programme which covers over 90 stations and analyses over 80 physical, chemical and biological parameters regularly. However, there are other potentially toxic chemicals present in the environment which may be of some concerns to the ecosystem and public health. They can come from a variety of pollution sources such as domestic sewage, industrial discharges, river and storm runoff etc. To assess the presence of these potentially harmful chemicals in the marine environment of Hong Kong, the EPD conducted an investigation on toxic substances pollution in the territory during 1999-2003 entitled “The Toxic Substances Study”. The Study, based on extensive literature review, field measurement and toxicological testing, concluded that while the Hong Kong marine environment was not widely contaminated with toxic chemicals at levels of concern, a number of potentially problematic pollutants existed and warranted continued monitoring. Based on the findings of the study and taking into account the resources and man power constrains, a Toxic Substances Monitoring Programme was initiated in 2004, focusing on marine water, sediment, biota and potential pollution sources as well as storm water and sewage discharge.

2. What toxic substances are being monitored?

Since 2004, a list of 24 chemicals including those of potential concern to the local environment as identified in the 2003 Toxic Substances Study, as well as some priority toxic substances controlled internationally, have been included in the monitoring programme. The list of chemicals has been further extended with respect to new scientific evidences and international legislative requirements. Since 2010, a total of about 40 chemicals are being monitored. These include selected persistent organic pollutants (POPs) under the Stockholm Convention (e.g. dioxins, furans, PCBs, DDT, lindane, α–hexachlorocyclohexane, β–hexachlorocyclohexane, hexabromobiphenyl, commercial pentabromodiphenyl ether, commercial octabromodiphenyl ether, aldrin, chlordane, dieldrin, endrin, heptachlor, hexachlorobenzene, mirex, toxaphene, chlordecone, pentachlorobenzene and perfluorooctane sulfonic acid and etc), as well as tributyltin (TBT), polyaromatic hydrocarbons (PAHs), phenol, nonylphenol, nonylphenol ethoxylates, fluoride, metals including total and methyl mecury (Hg), Barium (Ba), Beryllium (Be), Cadmium (Cd), Copper (Cu), Selenium (Se), Silver (Ag), Thallium (Tl), Tin (Sn), Zinc (Zn) and a metalloid Arsenic (As).

3. What is the status of the overall levels of toxic substances in the local marine environment?

Our results show that the levels of toxic substances in most of the Hong Kong marine environment were generally low compared with other areas of the Pearl River Estuary, and largely within the range reported for coastal waters of the Mainland and other countries. In general, the levels of toxic substances in marine water, sediment and biota met local* and international standards**, i.e., USA, Canada, European Union, Australia and Japan for protection of marine life and human health***. Nevertheless, elevated levels of some chemicals such as selected heavy metals (e.g. Cu and Ag) were found in marine sediments at some localised “hot spots” associated with historical pollution as well as nonylphenol in sediments at areas near the discharge points of the, now obsoleted sewage screening plants in central Victoria Harbour.

The following sections present summary results of the monitoring programme.

Persistent Organic Pollutants Antifoulant Other Organic Pollutants Non-metallic inorganic Metals Metalloid
^ water includes marine water, domestic sewage, sewage treatment works’ effluent, river water and storm runoff.
^^ sediment includes marine sediment, river sediment and sewage treatment works’ sludge.
* Local standards refer to the standards for heavy metals in sediment stipulated in the Appendix A of the Works Bureau Technical Circular (Works) No. 34/2002 Management of Dredged / Excavated Sediment.
** International standards mainly refer to the standards developed/adopted by the National Oceanic and Atmospheric Administration (NOAA) and USEPA. If the standard of a chemical cannot be found from NOAA and USEPA’s list, the standard of other countries (Canada, European Union, Australia) are adopted for comparison.
*** The assessment of the impact on human health due to the levels of different chemicals in marine biota tissue is conducted based on the methodology promulgated by international and national regulatory agencies such as the World Health Organization (WHO), USEPA and Health Canada.



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