 |
|
|
According to the agreement
signed between the HKSAR Government and Guangdong
Authorities, the Dongjiang water supplied to Hong
Kong should conform to the national standard set out in
the Environmental Quality
Standards for Surface Water. The raw water after purification
by Hong Kong's water treatment works is suitable for
drinking. The Guangdong Authorities have carried
out the following measures in recent years so
as to assure the quality of Dongjiang raw water
transferred to Hong Kong :
- Sewage treatment
plants are being built along the
Dongjiang to reduce pollution.
- Factories which may pollute the
Dongjiang are being removed.
- The intake of Dongjiang
water has been moved upstream in 1998 where
the water quality is better.
- The Bio-nitrification Plant at the
Shenzhen Reservoir has been commissioned since early 1999.
- A dedicated aqueduct from the
Dongjiang intake to Shenzhen Reservoir has been
completed. The entire system was put into operation
in late June 2003.
- The project to intercept waste water
flowing into the Shenzhen Reservoir has been completed
since late 2004.
- Discharge of polluted water from
Shima River has been diverted and no longer
flows into Dongjiang commencing early 2005.
Significant improvement in Dongjiang
water quality is observed after the implementation of
the above measures.
The media have reported
on the water quality in specific areas along
the Dongjiang. Pollution in specific areas
does not significantly affect the overall
quality of raw water transferred to Hong Kong
as the flow volume of the Dongjiang is huge.
These reports do not fully reflect the water
quality of the Dongjiang main stream.
To enable the public
in Hong Kong to understand the actual situation,
the Environmental Protection Bureau of Guangdong
Province has recently provided the following
table of water quality data for samples taken in 2007
from the East Bank Section of Dongjiang's main stream
upstream from the intake of Dongjiang water at Taiyuan Pumping Station.
|
| Item |
Temperature
(oC) |
pH |
Dissolved
Oxygen |
Permanganate
Value |
Chemical
Oxygen
Demand |
5-Day
Biochemical
Oxygen
Demand
(BOD5) |
Ammoniacal
Nitrogen |
Total
Phosphorus |
| January |
16.9 |
7.17 |
7.10 |
1.37 |
13 |
1.0 |
0.467 |
0.027 |
| March |
19.4 |
7.53 |
6.53 |
1.93 |
11 |
1.0 |
0.465 |
0.07 |
| May |
26.2 |
7.06 |
6.83 |
2.07 |
7 |
1.0 |
0.467 |
0.067 |
| July |
29.1 |
7.3 |
6.48 |
2.07 |
8 |
1.8 |
0.37 |
0.083 |
| September |
27.3 |
7.76 |
6.57 |
1.93 |
5 |
1.7 |
0.423 |
0.08 |
| November |
22.8 |
7.29 |
6.43 |
1.43 |
7 |
2.2 |
0.402 |
0.077 |
| Yearly Mean |
23.6 |
7.30 |
6.66 |
1.80 |
9 |
1.4 |
0.432 |
0.067 |
|
GB3838-2002
Type II
Standard
for Surface
Water (<=) |
- |
6 - 9 |
>=6 |
4 |
15 |
3 |
0.5 |
0.1 |
|
| |
| Item |
Copper |
Zinc |
Fluoride |
Selenium |
Arsenic |
Mercury |
Cadmium |
| January |
0.001 |
0.025 |
0.2 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| March |
0.001 |
0.025 |
0.27 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| May |
0.001 |
0.025 |
0.3 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| July |
0.001 |
0.025 |
0.23 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| September |
0.001 |
0.025 |
0.26 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| November |
0.001 |
0.025 |
0.29 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
| Yearly Mean |
0.001 |
0.025 |
0.26 |
0.00012 |
0.004 |
0.00002 |
0.0005 |
|
GB3838-2002
Type II
Standard
for Surface
Water (<=) |
1.0 |
1.0 |
1.0 |
0.01 |
0.05 |
0.00005 |
0.005 |
|
| |
| Item |
Chromium
(VI) |
Lead |
Cyanide |
Volatile
Phenols |
Petroleum
Hydrocarbons |
Anionic
Surfactants |
Sulfide |
Faecal
Coliforms
(no./L) |
| January |
0.002 |
0.005 |
0.002 |
0.001 |
0.01 |
0.02 |
0.002 |
1332 |
| March |
0.002 |
0.005 |
0.002 |
0.001 |
0.04 |
0.02 |
0.010 |
1584 |
| May |
0.002 |
0.005 |
0.002 |
0.001 |
0.01 |
0.02 |
0.008 |
1163 |
| July |
0.002 |
0.005 |
0.002 |
0.001 |
0.03 |
0.02 |
0.016 |
1624 |
| September |
0.002 |
0.005 |
0.002 |
0.001 |
0.03 |
0.02 |
0.005 |
1330 |
| November |
0.002 |
0.005 |
0.002 |
0.001 |
0.037 |
0.02 |
0.008 |
1733 |
| Yearly Mean |
0.002 |
0.005 |
0.002 |
0.001 |
0.027 |
0.02 |
0.008 |
1447 |
|
GB3838-2002
Type II
Standard
for Surface
Water (<=) |
0.05 |
0.01 |
0.05 |
0.002 |
0.05 |
0.2 |
0.1 |
2000 |
|
| |
| Note : Except pH and where specified, all units are in mg/L. |
|
|
For further information
on Dongjiang water quality, please visit the homepage
of the Environmental Protection Bureau of Guangdong
Province at www.gdepb.gov.cn.
With the water quality analysis
system at the Muk Wu Pumping Stations where we
receive Dongjiang water, WSD monitors the water
quality round the clock to operate the treatment
processes at treatment works accordingly so as
to ensure that the treated water quality complies
with the World Health Organization Guidelines
for Drinking-water Quality. The water is safe
for consumption. Regarding the Dongjiang water
quality at Muk Wu Pumping Stations, please visit
the web page "Dongjiang
Water Quality as received in Hong Kong at Muk
Wu Pumping Station".
|
|
|
|
|
| |
|
|
|
|
