| Marine
Water Quality Monitoring in Hong Kong
Marine
Water- Our Valuable Resource
[Photo of a scene of Hong Kong's marine water]Hong
Kong is a thriving port with a population of nearly 7 million people.
It relies heavily on the sea for navigation, recreation, seafood
production, and supply of flushing and cooling water. The sea surrounding
us is also the home of diverse forms of marine life ranging from
microscopic algae to dolphins. Hong Kong is fully committed to protecting
its marine environment.
The Environmental
Protection Department (EPD) of the Hong Kong SAR Government monitors
the water quality of some 1,700 sq km of the territory's marine
waters. The monitoring programme serves the following purposes:
- indicate the
state of health of marine waters;
- assess compliance
with the statutory Water Quality Objectives (WQOs);
- reveal long-term
changes in water quality;
- provide a basis
for the planning of pollution control strategies.
Marine
Water Quality Monitoring
EPD's marine monitoring
programme covers about 90 water and 60 sediment sampling stations
in the open sea, semi-enclosed bays and typhoon shelters.
[Map of Marine water monitoring stations in Hong Kong]
[Photo of the Dr. Catherine Lam]Marine
monitoring is carried out on board a scientific vessel, the Dr.
Catherine Lam, which is equipped with a satellite-aided differential
global positioning system (DGPS) for accurate location of sampling
stations at sea.
[Photo of marine monitoring work]A
range of physical and chemical parameters, including temperature,
pH, salinity, turbidity and dissolved oxygen, are measured in
situ by a conductivity-temperature-depth (CTD) profiler and
the data are relayed to a computer. In addition, water and sediment
samples are collected and sent to the laboratories for the analysis
of some 40 parameters such as nutrients, metals, organics and coliform
bacteria. Water quality monitoring is generally conducted once a
month whereas sediment quality monitoring is done twice a year.
Water
Quality Objectives
Hong Kong is divided
into 10 Water Control Zones (WCZs) and each WCZ has a set of Water
Quality Objectives (WQOs). The rates of annual compliance with the
key WQOs (i.e. dissolved oxygen, ammonia, total inorganic nitrogen
and E.coli) are assessed based on all the data collected
during the year.
| Parameter
|
Objective
|
| Dissolved
Oxygen (depth-average) |
Not
less than 4mg/L in 90% of the samples |
| Dissolved
Oxygen (bottom) |
Not
less than 2mg/L in 90% of the samples |
| Unionized
Ammonia |
Annual
mean not exceeding 0.021mg/L |
| Total
Inorganic Nitrogen |
Ranging
from annual mean of not exceeding 0.1mg/L in Southern Water
Control Zone to not exceeding 0.7mg/L in Deep Bay Water Control
Zone |
| E.coli
|
Annual
geometric mean not exceeding 610/100mL in secondary contact
recreational areas |
More
Information on Marine Water Quality and Hong Kong's Environment
Detailed information
on Hong Kong's marine water quality is found in the annual report
Marine Water Quality in Hong Kong. This
report is available in public libraries and Environmental
Resource Centres, and can be downloaded from EPD's Marine Water
Quality Web Page.
Other information
on Hong Kong's environment can be obtained from EPD's homepage (http://www.epd.gov.hk).
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