Marine Water
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| Causes of marine and coastal water pollution | |
| Status of marine water pollution | |
| Response for marine water protection |
Causes of marine and coastal water pollution
Population concentrated in the Coastal zone
At present about 19 millions people inhabit the coastal quarters/districts. The Red River Delta is most densely populated. Population in the coastal zone, especially in the cities located along the coast such as Ha Long, Hai Phong, Qui Nhon, Vung Tau, Rach Gia, produce waste, which finds its way into the rivers and then it is transported to the sea.
Growth of industry and
urbanisation
In the last few years, the growth rate of industrial production as a percentage of GDP in the whole country, especially in the 3 triangular development zones was 10-15% per year. This growth involves production of waste water, much of which is not treated and flows into the rivers and then on to the coastal zone. A great amount of organic compounds, heavy metals and oil comprises the pollution load of such waste water. A significant amount of solid waste that is not collected also goes into rivers and the sea. A part of air pollutants also fall in to the marine water.
Port and marine transport
development
At
present there are 60 big and small ports located at estuaries and along
the coast, including 7 big ports. The Vietnamese flotilla is small and old
with average useful life of
16-17 years. In 2000, the capacity of the flotilla was 2 million
tons.
For the maintenance of ports it is necessary to dredge them regularly because most of the ports suffer from sedimentation. Dredging activities result in a change in the marine water quality.
Development of oil and gas
industry
Oil
exploration and production in Vietnam has been increasing over the years
as follows: 1996: 8.8 million tons, 1997: 10.1 million tons, 1998: 12.5
million tons, 1999: 15 million tons, 2000 (up to May only): 5.98 million
tons. Since 2000 along with exploitation of oil, natural gas has also been
exploited.
The
oil and gas industry development involves two kinds of pollution:
permanent pollution and oil
spills. The number of oil spills resulting from the oil and gas industry
and marine transportation are on the increase. There were 4 big and small
oil spills in 1997, which increased to 6 and 10 in 1998 and 1999,
respectively.
Together with the recorded oil spills, attention must also be paid to oil spills from non-identified sources. Almost all the coastal provinces of Vietnam (29 provinces) are facing this problem and the number of such oil spills has grown over the last few years. Although these spills are of moderate volume, 2-3 tons on average, some of them are of bigger scale as the ones in Do Son-Hai Phong (May 1994), and Ba Tri-Ben Tre (May 1995).
Pollution transported by river
flows
Rain
water run off and soil erosion
resulting mainly from deforestation, and waste water from
industrial, agricultural and urbanisation activities discharge in to
rivers and then flows into the sea. Pesticides used in Vietnam are nearly
5,662-6,000 tons/year. The total nutrient components that come to the sea
by river flows are shown in the following table (Table 4.2).
Table
4.2.
Nutrient fluxes of 6 river systems into the Vietnam Sea
(tons/year)
|
River
system |
NO3 |
PO4 |
|
Thai
Binh |
10,446.3 |
9,887.5 |
|
Red
River |
14,860.0 |
24,602.0 |
|
Han
|
2,475.0 |
36,3.0 |
|
Thu
Bon |
62.0 |
16.0 |
|
Sai
Gon-Dong Nai |
79,570.0 |
10,220.0 |
|
Mekong |
27,941.0 |
1,470.0 |
Source
: Pham Van Ninh - Environment Studies in Coastal Areas [2,
15]
Coastal tourism in Vietnam has grown rapidly in the last few years. Tourism centres such as Ha Long, Cat Ba, Do Son, Sam Son, Cua Lo, Thuan An, Da Nang, Quy Nhon, Nha Trang, Vung Tau, and Phu Quoc, have a high growth rate (for example, tourism of Vung Tau has a growth rate of 36.4% for 1992-1993, Do Son tourism in 2000 increased by 64% in comparison with 1998, and as expected in 2005 and 2010 will increase 400% and 1000%, respectively. Untreated waste water from hotels and restaurants, solid waste on many beaches, waste from tourism boats and ships, are all a source of serious pressure on the water quality in the above mentioned tourism areas.
Status of marine water
pollution
The
status of marine water pollution is assessed on the basis of analysis and
monitoring results of the National Monitoring System for marine region in
Vietnam from 1995 onwards. The assessment is also based on many other
surveys, studies and EIAs provided for many coastal projects. The main
results are as follows:
Temperature, salinity, pH, DO,
BOD
Temperature,
salinity, pH, DO, BOD all meet the permitted standards in
Vietnam.
Similar to salinity, suspended solids in the Southern and North marine areas are strongly influenced by the river flows. Especially in the Ba Lat river mouth, it reaches 986.8 mg/l with the average of 185.03 mg/l. At Dinh An and Rach Gia the maximum values reach 1950.1 mg/l and 604 mg/l, the average values are 305.1 mg/l and 166 mg/l respectively. These values exceed the standard values for the aquaculture use (50 mg/l) and for swimming (25mg/l). During the flood season in the above mentioned areas, the turbidity is higher than the standard value for other uses (200 mg/l). In the open sea, the water is not polluted by SS.
Nitrite concentration in marine water ranges from traces to 345 mg/l. In the Northern coast it is high and always over the permitted level for aquaculture ( 2 mg/l) and the level is showing an increase from 1996-1999. In the Central coast, it is low and shows a decreasing trend from 1996 to 1999. In the Southern coast, it recorded highest levels in two years ( 1996-1997) and is always over the permitted level. In the offshore areas, the nitrite content is low and stable.
In
the coastal waters the average value of NO3-
- N ranges from 44.0 to 375.53
mg/l.
The measured maximum value at Rach Gia is 1,080 mg/l
(the standard value is
500 mg/l
for swimming and aquaculture). In the flood season the NO3-
- N concentration at Dinh An and Rach
Gia exceeds 500 mg/l
and some times in Vung Tau, Phu Qui and Nha Trang it exceeds this norm. In
general in the areas influenced by river flows, NO3-
- N is
higher than in other areas. In the open sea and Con Dao regions NO3-
- N is
rather high. The average value is 651 mg/l
and 365 mg/l
respectively. At the other stations such as Bach Long Vi and Ca Mau. It
reaches 27.5 mg/l
and 29.5 mg/l
respectively.
In the coastal areas NO3- - N changes significantly with seasons. The average value at most of the stations during the flood season is higher than in the dry season. It is evidently caused by river flows. Nevertheless no clear trend was noted for the yearly average values for this parameter.
Phosphorous
- phosphate (PO43- - P
)
-
In the coastal waters
The
average values from many years of observation of PO43-
- P ranges from 4.03 to 53.63 mg/l.
In the central part of Vietnam it is higher than in the North and the
South.
It
is noted that from the North to Da Nang, and from Vung Tau to Rach Gia
average value of PO43-
- P during flood
season is higher than in dry season. In the area from Dung Quat to Nha
Trang it is contrary.
- In the open sea : PO43- - P concentration is rather small and maximum value does not exceed 30 mg/l. In the Bach Long Vi and oil exploitation areas it is less then 5 mg/l.
The
yearly average values of SiO2-Si are in the range of
206.6-2606.9 mg/l.
In
general, the maximum and average values of SiO2-Si at all
coastal stations in flood season are higher than in the dry season. It is
caused by river flows with high concentration of SiO2-Si.
Coastal waters in Vietnam contain excess of nutrient due to the high content of nitrogen (NO2-, NO3-), phosphate (PO43-) and silicate (SiO2) at certain time in several areas such as Ba Lat (in the North), Da Nang, Nha Trang (in the Central), Dinh An, Rach Gia (in the South).
Six
heavy metals are monitored at the coastal and open sea stations. They are
Cu, Zn, As, Cd, Pb, Hg.
Zinc (Zn) :
In the coastal zone, the yearly average values of Zn in the period
1996-1999 were in the range of 19.67-60.83 mg/l
(Fig. 4.10). It is higher than the permitted value for aquaculture use (10
mg/l).
The maximum value measured at Cua Luc, Sam Son, Do Son, Rach Gia already
exceed the standard value for all kind of uses (100 mg/l).
In the open sea also Zn concentration is high, ranging from 1 to 78.95
mg/l,
especially in Con Dao and Ca
Mau. In contrast to the
nutrient levels, Zn concentration in flood season is less than in the dry
season at most monitoring coastal stations.
At the Northern stations Zn concentration seems to increase with time, at the Central stations a reverse trend is observed, while at the Southern stations there is no such clear trend.
Copper (Cu) :
In the coastal zone, yearly average values of Cu (1996-1999) range from
4.00 to 11.68 mg/l.
The maximum is 50.90 mg/l
at Phu Quy station. The 1996-1999 average values of Cu exceed 10
mg/l,
and at 12 of the 15 stations this value already exceeds the limit(Table
4.11). Do Son, Sam Son, Phu Quy, Vung Tau and Dinh An, Cu exceed the
permitted value for all kinds of uses (20 mg/l).
The
concentration of As, Cd, Hg, Pb measured at all stations is within the
permissible range for all kinds of uses and there is no clear increasing
or decreasing trend.
Oil concentration in the coastal waters ranges from 0.003 to 20.150 mg/l. The highest values have been measured at Dinh An area. If 0.3 mg/l is considered the permissible value for coastal water, the measured maximum values at all stations already exceeds this value
Oil
content at open sea stations (mg/l)
|
Station |
Max. |
Min. |
Mean |
|
Bach
Long Vi |
0.400 |
0.100 |
0.220 |
|
Dau
khi |
0.556 |
0.540 |
0.531 |
|
Con
Dao |
0.227 |
0.020 |
0.102 |
|
Ca
Mau |
0.046 |
0.038 |
0.042 |
Source : National Marine Stations, NEA
Note:
All presented data are referred from
[20]
In
the open sea, oil content is in the 0.038-0.536 mg/l range. Only in the
oil exploitation area the oil content is higher than 0.500 mg/l. The other
regions have lower oil content.
The maximum and yearly average values do not follow a clear trend; they increase with time at several stations and decrease with time at others.
Results
of pesticides monitoring at the stations from Cua Luc to Quy Nhon show
that they are within the permissible range for all kinds of uses.
Total coliform total ranges from 0 to 201,500 MNP/100 ml, which means that the coastal water changes from very clean to very dirty. At Cua Luc, Nha Trang, Vung Tau, Dinh An and Rach Gia the coliform number is often higher than allowed (1000 MPN/100ml) for all kinds of uses. At other places such as Sam Son, Dung Quat, Quy Nhon the total coliform was higher than the permissible value by several times
Response for marine water
protection
-
Legislation system in Vietnam has significantly improved. After the Law on
Environment Protection, Maritime Law, Marine Production Law, and Oil and
gas Law have been adopted, including many articles concerning
environmental protection. Recently the Civil Law, which includes some
articles of environmental concern has been adopted. The above mentioned
laws are good for the environment but law enforcement is still restricted
due to a lack of legal instruments. So far, there is no environment fee
system, environmental fund, and even the state oil spill contingency
plan.
-
The community education programmes are being implemented for raising
awareness in order to keep the sea clean, especially the swimming beaches
and tourism centres. Unfortunately, this measure has not yielded much
results. The people, including decision-makers are still ignorant about
the marine environment and about its limited self cleansing
capacity.
-
Various projects for building waste treating plants (for solid and waste
water) have been initiated in Ha Long, Hai Phong, Nha Trang, Da Nang, and
Vung Tau but these will take time to become operational or need additional
investment. One of the difficulties is that the treatment facilities have
to work in cities with old and underdeveloped
infrastructure.
EIA
have been carried out for almost all the projects with foreign investment
in marine and coastal waters of Vietnam such as ports, refinery, ship
repairing and building, maintenance of channels, oil and gas drilling,
etc. But some of them do not honour their commitments of EIA. It is also
true for the domestic units for which the environment impact assessment
were carried out, but these are not realised due to economic reasons or
lack of investment decisions on having treatment facilities or for
renovations.
The
Integrated coastal zone Management concept that has recently started is of
interest. Various projects of ICZM are in the early stages of
implementation with funding from ADB, World Bank and IMO. Tourism of
Vietnam is also of strategic importance and environmental risks are taken
into account in its development.
-
The leaders of the cities located in watersheds (for example Ho Chi Minh
City, Nam Dinh, Thai Binh, Can Tho, etc) understand that it is necessary
to keep the river and ground water clean and in the future the quality of
the coastal water can be improved because of cleaner riverine water
discharged into the coastal zone. But in general, particular and effective
measures are lacking. Solid and waste water treatment before discharging
into watersheds is still in the initial stages of development and not
uniform for the whole country .
-
The National Monitoring Network of NEA is well established but it needs
improvement in terms of QA/QC, increase of monitoring sites and frequency.
It is necessary to have all coastal cities to conduct regular monitoring
and integrate the results into the National Monitoring
Network.
-
Preparation of the National Plan for Oil Spill Treatment for Government
Approval.
-
Reducing the population growth rate to below the annual rate of 1.7
%
-
A number of scientific studies have been carried out by national
scientific institutions and with international
supports.
- Several international conventions and treaties were ratified and brought into effect
Status
of international treaties in Vietnam
|
Signed |
*
International Convention for the Protection of Pollution by Oil from
Ships (Marpol Convention), 1997 *
Ramsar Convention on Protection of Wetlands,
1971 *
Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their
Disposal, 1989 *
United Nations Convention on the Law of the Sea,
1982 |
|
Not yet
signed |
*
Convention on the prevention of marine pollution by dumping of
wastes and other matter,
1972 |