An Heping, Environment Protection Office,
Bureau of Fisheries Management and Fishing Port Superintendent, Beijing.
Open sea culture of seaweed and mollusc is an important activity in parts of China. Above shows the long line culture of molluscs in north-east China.
The low per capita share of land resources in China makes it very difficult to satisfy the increasing need for animal protein by means of land alone, hence there is an increasing demand for aquatic products. China possesses vast seas and many rivers, lakes and reservoirs, but there is a very low rate of utilisation for aquaculture: 3 % for the sea and about 5 % of freshwater surface area. With progress in the development of culture technologies, the rate of utilisation of these resources will become higher. On the other hand, environmental pollution is increasingly becoming a hindrance to fisheries development. The ecological environment of the fisheries cannot be well-protected, and the steady development of fisheries and aquaculture promoted, until legislation concerned with the fisheries environment is improved, the monitoring network of the fisheries environment perfected and strengthened, and public awareness of the importance of environmental protection deepened. Today, the fisheries and aquaculture environment is suffering from worsening pollution problems and great damage has already been done. It is hoped that NACA can play its role in organising and co-ordinating environmental protection for fisheries and aquaculture in the Asia-Pacific region. The establishment of an aquaculture environment research centre is necessary for long-lasting, efficient protection of the fishery environment. This centre should conduct research, training and exchange of information on fisheries environmental protection. As a large fishing country, China is willing to contribute more in this field by undertaking the construction of an aquaculture environment research centre established under NACA. Our country has already set up monitoring networks for the fisheries environment to monitor the environment in fishing waters, and has made good progress in research work, which provides a good baseline of experience for our sponsorship of the centre. The quality of the environment has a close bearing on fisheries and cultivation. It is intended to improve regulation of fisheries environmental protection through the protection of spawning beds, breeding farms and compensation for fishery resources damaged by pollution. We also hope that NACA, FAO and other world organisations can finance and support this task.
Map of the People's Republic of China.
Fish culture technology development has made rapid strides in China and in 1992, the yield from aquaculture amounted to 7,760,000 tonnes. However, pollution of the fisheries environment has been increasing, giving rise to the loss of aquatic resources such as fish and shrimp. Pollution of river mouths affects the breeding of migratory fish and pollution of rivers running into seas has made red tides 30 times more frequent than in the 1970s. The area affected by red tides has expanded, doing great harm to the development of aquaculture along the coastline. With a view to protecting the fisheries environment, China set up a national network in 1985 to monitor the fisheries environment and investigate pollution. So far, 26 monitoring stations have been established. Some provinces have set up their own monitoring networks and stations, enhancing the overall capacity to monitor pollution.
The Bohai and Yellow Sea have been included in the national plan as the next fisheries development zones. Programmes for developing marine cultivation and the nearshore resources in North China, with Asian Development Bank loans, have entered the appraisal stage. Shandong and Liaoning have put forward their own slogan for the exploitation of marine resources, “a marine Shandong” and “a marine Liaoning”. Their goal is to equate the production value from marine exploitation with that of land industries. The marine production value in some counties along the Bohai has already contributed to more than half local gross production value. The quality of environmental protection has a direct bearing on the exploitation and utilisation of fisheries and breeding resources.
Since the United Nations Conference on Environment and Development, our country has made a series of policies to improve environmental protection. One of the ten policies on environment is to levy compensation fees for environmental resources and reduce environmental pollution by economic means. Regulations will be laid down on compensating fishery resources for environmental pollution and delimiting protective zones in fishing waters, to strengthen the administration of the fisheries environment. This report gives a general review and some specific information on monitoring systems for the aquatic environment in China and environmental issues affecting the development of coastal aquaculture around the Bohai and Yellow Sea in Northeast China. Special attention is given to coastal aquaculture because the Government of China is giving high priority to diversifying and increasing seafarming production along the coastline of China.
3. STATUS OF AQUACULTURE
3.1 Aquatic resources
China is confronted with large seas: the Bohai, Yellow, East and South Seas, the total area of seas being 3,543 million km2, including 1.5 million km2 of fish farms. The coastline totals over 32,000 km (around 18,000 km is mainland coastline, plus the coastlines of more than 6,500 islands). Shallow seas and mud flats cover an area of about 133,330 km2. At the present-day level of science, the water surface possible for artificial cultivation is 13,330 km2. By 1992, 4,490 km2 had been put into use: 779.4 km2 of shallow seas; 1,455 km2 of bays; and 2,756 km2 of mud flats. The surface area of inland freshwater totals 173,330 km2, and that of bottom lands, saline and barren land over 30,000 km2. By 1992, 39,770 km2 had been put into use: 14,720 km2 for ponds, 7,010 km2 for lakes, 3,210 km2 for rivers and 14,260 km2 for reservoirs.
In 1992, the total fisheries yield was 15.58 million tonnes, ranking the highest in the world with 6.91 million tonnes from marine fishing, 2.42 million tonnes from marine cultivation, 0.9 million tonnes from freshwater capture fisheries and 5.34 million tonnes from freshwater cultivation. Table 1 gives details of the production and value of aquaculture to the Chinese economy.
Table 1. Aquaculture production statistics for China, 1987–1992.
|Total production (tonnes)||4,584,697||5,321,900||5,745,894||6,183,179||6,530,516||7,760,000|
|Value (000s US $)||2,407,372||2,794,464||3,017,098||3,246,711||4,918,800||5,240,269|
|Production as % GNP||3.6||3.3||2.8||0.98||1.34||1.65|
|Export value (000s US $)||720,950||968,530||1,039,000||1,369,790||4,959,000||5,150,000|
3.2 Aquaculture species and systems
There are a wide range of species and aquaculture systems in China. Tables 2 and 3 give some details. For inland aquaculture, farming systems encompass: semi-intensive and intensive culture; polyculture and integrated farming; and culture in ponds, cages and pens. In coastal aquaculture, finfish are predominantly cultured in intensive cage culture systems, except for Mugil sp which are polycultured in coastal ponds. Pond culture is the main method of culturing shrimp, both in monoculture and polyculture. The culture of mollusc is by floating, mudflat and bottom culture using extensive methods. Seaweed culture is practised using extensive culture and by floating or bottom culture methods.
Table 2. Inland aquaculture species in China (1990 statistics).
(000s US $)
Key: H = Hatchery;
W = Wild;
L = Local;
E = Export;
N = Native;
I = Introduced.
There are also a number of exotic species introduced into China for aquaculture in both inland and coastal waters. A list is given in Table 4, the figures bracketed show the year of introduction and the country of origin (where known).
3.3 Legal framework for environmental management of aquaculture development
There are several environment protection laws which touch upon aquaculture, although these laws are not specifically drafted for aquaculture. The scope of the Fisheries Law of the People's Republic of China of 20/1/984 includes protection of fisheries and aquaculture environments. In general, there is more concern about the protection of aquaculture and fisheries from industrial pollution and eutrophication, than with protection of the environment from aquaculture development.
The Environment Division of the Bureau of Fisheries Management and Port Superintendence (Ministry of Agriculture) is planning to draw up further regulations on “Environmental Protection for Fisheries”, which will include aquaculture. This additional legislation may from part of the environmental law now being prepared by the National Environmental Protection Agency.
Table 3. Coastal aquaculture species in China (1990 statistics).
|Seed||Market||Native Exotic||Culture System|
|Finfish||Epinephelus sp.||43,345||nd||W||L/E||I||Intensive cage|
|Sparus macrocephalus||nd||nd||W/H||L/E||N||Intensive cage|
|Chrysophrys major||nd||nd||W/H||L/E||N||Intensive cage|
|Lates calcarifer||nd||nd||W/H||L/E||I||Intensive cage|
|Mugil sp.||nd||nd||W?||L/E||N||Pond, polyculture|
|Crustacean||Penaeus chinensis||186,181||914,573||W/H||L/E||N||SI. pond|
|P. penicillatus||-||N||SI, pc/mc pond|
|P. merguensis||-||N||SI, pc pond|
|P. japonicus||-||N||SI, mc pond|
|P. monodon||-||N||SI, pc/mc, pond|
|Metapenaeus ensis||-||N||Pond, pc, trad|
|M. affinis||-||N||Pond, pc, trad|
|Scylla serrata||W||L/E||N||Fattening in pond|
|Molluscs||Crassostrea gigas||82,354||288,961||W/H||L/E||I||Ext; floating|
|Pecten yessoensis||H||N||as above|
|Andara granosa||W||N||Ext, mudflat|
|Solen sp.||W||N||as above|
|Venerupis japonica||W||N||as above|
|Meretrix meretrix||W||N||as above|
|Ruenetupis philippinarum||W||N||as above|
|Ostrea plicatula||W/H||N||as above|
|Mactra veneriformis||W||N||as above|
|Chlamys farreri||W/H||N||Ext; floating|
|Argopecten irrediens||W/H||I||as above|
|Pecten yessoesis||H||N||as above|
|Haliotis discus hannai||H||N||as above|
|Sea cucumber||Stichopus japonicus selenka||H||N||Ext, bottom; stock enhancement|
|Seaweeds||Laminaria japonica||244,306||72,863||H||L/E||I||Ext; raft; long|
|Porphyra tenera||8,823||10,524||H||L/E||N?||as above|
|Undaria pinnatifada||N?||as above|
|Eucheuma sp.||L/E||N||Ext, bottom line|
|Gracilaria sp.||N||Ext, various|
|Misc algae||W/H||as above|
Key: H = Hatchery;
W = Wild;
L = Local;
E = Export;
N = Native;
I = Introduced;
Ext = Extensive;
pc = polyculture;
mc = monoculture;
SI = semi-intensive;
trad = traditional;
long = longline.
Table 4. Some exotic species introduced for culture into China
|Resource||Species (year, country of origin)|
|Inland Species||Ictalurus punctatus (1984, USA); Ictalurus nebulosus (1984, USA); Lepomis macrochir (1987, Japan); Labeo rohita; Clarias fuscus (1970s); Clarias lenther (1981); Catla catla (1973, Bangladesh); Pangasius sutchii (1978, Thailand); Cyprinus carpio (1982, Japan); Colossoma brachypomum (1985); Puntius gonionotus (1986; Thailand); Oxyeleotris marmorada (1988, Thailand); Corefonus sp. (1985, Japan); Blue tilapia (1981); Oreochromis mossambicus (1957, Vietnam); Clarias macrocephelus (1982, Thailand); Clarias batrachus (1978, Thailand); Oncorhynchus mykiss (1959, USA; 1983, Japan); Macrobrachium rosenbergii (1976, Japan); Scopthalmus maximus (1992, England).|
|Coastal Species||Crassostrea gigas (1979, Japan); Argopecten irradien (1981, USA), Giant kelp (1978, Mexico); Lates calcarifer.|
3.3.1 Legal framework governing access to aquaculture operations
Definition of aquaculture
Aquaculture is defined as the activity of acquiring products through artificial breeding and with aquatic plants and animals from water.
Laws and regulations
The following laws and regulations are relevant to aquaculture and/or the environment in China. The fisheries laws and regulations are designed to promote aquaculture development, management of capture fisheries resources and to maintain the quality of fisheries environments.
|Law of Regulation||Scope of Law or Regulation|
|1.||Fisheries Law of the People's Republic of China, 20/1/86.||1.||Protection and sustainable development of fisheries and aquaculture in China.|
|2.||Fisheries Water Quality Criteria 1/4/89.||2.||Defines water quality requirements for fishery environments.|
|3.||Protection of Wildlife 8/11/88.||3.||To protect endangered species, including 80 listed aquatic species|
|4.||Regulations on the Quarantine of Imported and Exported Animals and Plants, 4/6/82.||4.||To protect animal and plant resources, health and to strengthen quarantine.|
|5.||Marine Environment Protection Law, 26/12/82.||5.||Prevention of marine pollution, including aquaculture grounds.|
|6.||Environment Protection Law, 26/12/89.||6.||Protection of air, land and water environments.|
|7.||Law on Prevention and Control of Water Pollution 11/5/84.||7.||Water pollution control.|
|8.||Regulations on the Prevention of Vessel-Induced Sea Pollution 29/12/83.||8.||Prevention of pollution from marine vessels.|
|9.||Regulations on the Administration of Environmental Protection in the Exploration and Development of Offshore Petroleum, 29/12/83.||9.||Prevention of pollution during petroleum exploitation.|
|10.||Regulations on the Control over Dumping of Wastes in the Ocean, 6/3/85.||10.||Prevention of pollution from dumping of wastes in the Ocean|
Consent and authorisation
The Fisheries Law states that “the state shall encourage… the best use of suitable water surfaces and tidal flats to develop aquaculture”. Aquaculture operations on state owned water surfaces and tidal flats that have been designated for aquaculture are required under the Fisheries Law to apply for an operating licence. Small-scale pond culture on private land does not require an operating licence. Licences are required for using state and collectively owned land within the administrative division of a country. Applicants are required to apply to the government of that country.
3.3.2 Environmental management of aquaculture
Water quality, pollution control and monitoring
There are no set standards for effluent discharges from land-based fish farms. There is also no legal requirement for treatment of effluent from such farms. Under the Water Pollution Prevention and Control Law, it is prohibited (i) to deposit solid wastes and other pollutants on beaches and bank slopes below the highest water level of rivers, lakes, canals, channels and reservoirs (Decree No. 12, srt. 25) and (ii) to discharge pathogen-contaminated sewage unless it has been disinfected to meet the relevant national standards (id., art. 28). However, such regulations have not been applied to aquaculture. There are criteria that define acceptable water quality levels for all aquaculture and fishery environments, which are shown in Annex 1 to this paper.
The departments of fishery administration at various government levels are required (in art. 27 of the Fisheries Law) to monitor the pollution of fishery waters. The monitoring network of fisheries environmental protection is incorporated into a national environment monitoring network. The monitoring of fishery environments is co-ordinated at national level by the Bureau of Fisheries Management and Fishing Port Superintendence (of the Ministry of Agriculture), and undertaken at the national, provincial and local district or country level. The system covers aquaculture and fisheries environments. Further details of this fishery monitoring system are given in Section 5 of this report. There are also a number of other agencies involved in monitoring of the marine environment and major river systems. Together, these form an overall aquatic environment monitoring network.
Environmental impact assessment
Environmental impact assessments (EIA) are not normally carried out prior to the development of aquaculture farms. Aquaculture projects supported by such agencies as the World Bank and Asian Development Bank usually incorporate an EIA. According to the Environmental Protection Agency, EIA is implemented for certain industrial, construction and large scale development projects. In 1991, 22% of township and village industrial projects implemented an EIA (Environmental Protection, Agency, 1992).
Control of movement of fish and maintainance of biodiversity
There are no regulations regarding the transport of aquatic organisms from one area to another within China. However, the “Import and Export Animal and Plant Quarantine Regulations of the People's Republic of China” promulgated in 1982, stipulates that all animals and plants imported from and exported to other countries must be quarantined by the port animal and plant quarantine service. The “Port Quarantine Regulations for Freshwater Fishes” has subsequently been enacted.
There are also codes of practice for the introduction of new species. A number of new species have been introduced into China for aquaculture (e.g. Oreochromis mossambicus from Vietnam in 1957 and recently in 1992 the turbot (Scopthalmus maximus) from England to Qingdao - see Table 3). After introduction, species are confined to government stations where research is undertaken before distribution to farmers. Some wild stocks of important aquaculture species also receive protection. For example, catching of fry and spring spawning of Penaeus orientalis is prohibited. If a breeding parent is needed for cultivation, time limits are set by the local fishery administration for obtaining these from the wild. Other species, such as the fry of grouper (Epinephelus sp.) are also protected in this way.
The Law of Wild Animals Protection of the People's Republic of China assigns responsibility to the Bureau of Fisheries Management and Fishing Port Superintendence for the protection of endangered aquatic animals (of which there are 80 species listed under the “List of Wild Animals under State's Special Protection”).
Control of toxic or hazardous substances or pharmaceutical preparations in aquaculture
There are codes of practice for the use of some toxic substances in agriculture. For example, the use of mercurous nitrate and sodium pentochlorophenate has been banned because of their toxicity and persistence in aquatic environments. Codes of practice have been developed for the use of chemicals in aquaculture. There are also codes of practice for the use of pesticides in aquaculture. There are no regulations for antibiotics used in fish disease treatments.
The Water Pollution, Prevention and Control Law Decree No. 12 provides that competent central and local governments may define protected zones and take measures to ensure that the water quality in those protected zones complies with the standards for their designated uses with regard to important fishery water bodies (art. 12 Decree No. 12); (“Fishery water bodies” = “those parts of water bodies designated for the spawning, feeding, wintering, or migration passage of fish, or shrimps, and for breeding fish, shrimp, or shellfish, or growing algae” art. 43).
Article 13 of the Regulations for Implementation of the Fishery Law also states that the “natural spawning, breeding and feeding grounds of fish, shrimp, shellfish and algae as well as their major migration routes shall not be used as aquaculture grounds”.
Imported fish are initially quarantined under the legislation described above.
Product quality control
There are legal requirements for monitoring product quality, which are enforced by the Bureau of Fisheries Management. All aquaculture products should adhere to the following standards:
|sodium pentachlorophenate||<2 mg/kg|
There are no other standards relating to the quality of aquaculture products.
3.4 Institutional framework related to aquaculture and the environment
There are a number of institutes responsible for aquaculture and the environment in China. The National Environment Protection Agency under the State Council is in overall charge of environmental protection and is also the executive arm of the Environmental Protection Commission of the State Council.
The Bureau of Fisheries Management and Fishing Port Superintendance of the Ministry of Agriculture has the responsibility for dealing with environmental protection as it relates to fisheries and fisheries environments. The Environment Division of the Bureau of Fisheries Management provides training, co-ordination and supervision of a nation-wide network for monitoring of important aquaculture and fisheries environments. The Bureau also sets regulations, water quality criteria, commissions and implements research and supports the project for environmental monitoring of fishery environments.
The Sub-Society of Fisheries Ecology Environment Protection of the Chinese Society of Agriculture, Ecology and Environmental Protection, is responsible for drawing up strategies for fishery environment protection, organising academic exchange in the fields of fishery environment research, publishing the journal of Fishery Environment Protection and publicising fishery environmental affairs. Universities and Scientific Institutions are also involved in education and research related to the environment. The major institutions involved in the environmental management of aquaculture under the Ministry of Agriculture are shown below.
3.5 Government policy
The quality of the aquatic environment has a direct effect on the development of aquaculture. Industrial pollution and the irrational layout of cultivation will affect the healthy development of aquaculture. The existing environmental protection laws have regulations that forbid industry to pollute the culture environment, but no regulations to prevent cultivation from polluting the environment. This kind of pollution stands out in some highly culture-intensive areas. China is currently conducting investigations of this phenomenon so that regulations that prevent aquaculture from polluting the environment can be laid down.
|Bureau's of the Ministry of Agriculture||Major responsibilities|
|Bureau of Fisheries Management and Fishing Port Superintendence.||Environmental aspects of aquaculture and fisheries development.|
|Bureau of Aquatic Products.||Aquaculture planning and technology development.|
|Institutes with environmental responsibilities under the Bureau of Fisheries Management||Major Responsibilities|
|Centre of Environment Monitoring for Fisheries (Beijing).||Evaluating projects for environment monitoring for fishery.|
|Bohai Fishery Environment Monitoring Station (Beidaihe).||Environmental monitoring, protection and research in the Bohai (sea).|
|Yellow Sea Fisheries Research Institute (Qingdao).||As above, for Yellow sea and part of Bohai sea.|
|East China Sea Fisheries Research Institute (Shanghai).||As above, for East China Sea.|
|South China Sea Fisheries Research Institute (Guangzhou).||As above, for South China Sea.|
|Freshwater Fisheries Research Centre (Wuxi).||Aquaculture development and environmental monitoring and protection in Jiangsu province and lower Yangtse river.|
|Yangste River Fisheries Research Institute (Shashi).||As above, for Upper Yangste river.|
|Pearl River Fisheries Research Institute (Guangzhou).||As above, for Pearl river and delta.|
|Heilong River Fisheries Institute (Heilong).||As above, for Heilong river region.|
4. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: GENERAL REVIEW
This section gives a general overview of environmental issues in aquaculture development in China, including both positive and negative impacts.
Since the 1970s, environmental pollution has done great damage to fisheries leading to the extinction of fish and shrimp in some rivers and frequent pollution of the fisheries environment. Environmental protection laws have regulations which restrict industry from polluting the fishery environment. The last decade has witnessed the development of artificial breeding technology and large-scale cultivation which has in turn quickened the development of aquaculture, but this has been accompanied by eutrophication of highly intensive culture areas. This problem has attracted attention over the last two or three years. In some highly concentrated shrimp-breeding areas, such as the Pulandian Bay in Liaoning and Rushan and Dingzhi Bay in Shandong, the discharged waste water from shrimp farms has resulted in the eutrophication of surrounding waters, perhaps constituting one of causative factors of red tides. Attention is now increasingly being given to dealing with such problems, including studying and popularising the model of mixed and rotational culture to reduce the effects of cultivation on the environment.
4.1 Impacts of the external environment on aquaculture
4.1.1 Inland aquaculture
Floods and droughts have affected aquaculture in some areas. Land reclamation has resulted in some loss of sites for inland aquaculture. The build up of solid matter and garbage can have serious local impacts on fisheries environments, and sometimes aquaculture. Of the 590 million tonnes of solid wastes produced in China in 1991, 10 million tonnes were estimated to have been discharged into rivers. Mining and low water availability have also been identified as problems for inland aquaculture in some areas. There are no problems of acid soils in inland areas, but sometimes water and soils are considered too alkaline. Furthermore, water shortages (particularly severe in the north east of China - 19% of the nation's water resources are to the north of the Yellow river where 64% of China's cultivated land is located) have affected aquaculture and fisheries.
The expanding industrial production in China has led to significant water pollution problems. At present the principal source of water pollution in China is industrial waste water, of which the most hazardous contents are organic pollutants, toxic chemicals and heavy metals (China's Country Report for UNCED, 1992). In 1991, the country's total waste water discharge reached 33.6 billion tonnes, of which 23.6 billion tonnes was derived from industry. An estimated 80% of the total is discharged into rivers, lakes and seas without treatment.
In 1991, surveys of water pollution in 532 rivers showed that 82% were contaminated to various degrees. Water quality of the major rivers was relatively good but river sections running through cities were seriously polluted. Of the 43,562 km of seven major rivers surveyed, 45% met Grade I and Grade II water quality standards, 11% met Grade III and 44% met Grade IV and V. In terms of fisheries, fish are nearly extinct in 2,000 km, and 20,000 km failed to reach the water quality standard for fisheries (Table 5).
Table 5. Water quality in the seven major rivers of China (EPA, 1992).
|River system||Length surveyed|
|Water quality||Major pollutants|
|9,193||54%-Grade I and II||Suspended matter, oxygen consuming matter, ammonia nitrogen, volatile phenols.|
|30%-Grade IV and V|
|7,048||29%-Grade I and II||Suspended matter, ammonia nitrogen, petrochemicals, oxygen consuming matter.|
|67%-Grade IV and V|
|Pearl river||5,496||57%-Grade I and II||Suspended matter, chlorides, ammonia nitrogen, oxygen consuming matter.|
|16%-Grade IV and V|
|Huaihe||1,333||5% - Grade I and II||Ammonia nitrogen and oxygen consuming matter.|
|30% -Grade III|
|65% - Grade IV and V|
|Songhua river||2,412||19% - Grade I and II||Oxygen consuming matter, volaitile phenols, ammonia nitrogen.|
|23% - Grade III|
|58% - Grade IV and V|
|Haihe river||6,460||9% - Grade I and II||Ammonia nitrogen, volatile phenols and oxygen consuming matter.|
|91% - Grade IV and V|
|Liaohe river||1,711||6% - Grade I and II||Ammonia nitrogen, volatile phenols and oxygen consuming matter.|
|94% - Grade IV and V|
The effect of this pollution on fisheries and aquaculture is serious. An estimated 200,000 tonnes of fish are lost annually as a result of industrial pollution, around 70% of the loss coming from inland fisheries (capture fisheries and aquaculture combined). In 1991, according to statistics complied in 16 provinces and municipalities, there were 251 pollution incidents causing losses of more than Yuan1 10,000 each, and a total direct loss of Yuan 140 million (Table 6). Of these, 73% were in aquaculture representing a loss of Yuan 120 million. In 1992, the losses have risen sharply, which could reflect a serious deterioration in the fishery environment in China.
Table 6. Pollution damage to aquaculture and fisheries in China.
|Year||Number of incidents||Economic loss (Yuan)||Percent of economic loss to aquaculture|
Some rivers (or parts of rivers) are seriously polluted, such as Nengjiang River, a branch of Heilongjiang River in which fish mortalities resulting from water pollution have occurred more than 10 times since 1958. It has also been estimated that industrial pollution caused losses of 1,620,000 kg adult fish, 160,000 kg fingerlings and 260,000 fry in Hubei Province from 1978 to 1985. Environmental pollution also caused an estimated loss of US $ 338,800 to the fisheries of Hunan Province in 1986. The chronic or indirect effects of pollution on fisheries is undetermined.
Hypernutrification and eutrophication are the most serious problems affecting major lakes and reservoirs. During a survey of the nation's 26 major lakes between 1986 and 1989, suspended solids, organic matter, COD and BOD all exceeded water quality standards. The following lakes were surveyed: Dianchi lake; Jingbo lake; Taihu; Chaohu; Dianshanhu; Xuanwuhu; West Lake; Daminghu; and East Lake. Between 1986 and 1989, only 11.1% of lakes and 7.4% of reservoirs were considered “non-contaminated” or “moderately contaminated”. According to the Environmental Protection Agency (1992), water quality in large reservoirs is better than in lakes, with 14 out of 16 monitored meeting grade I and grade II water quality standards.
Eutrophication of freshwater lakes and reservoirs may have a positive impact on production from some capture fisheries and cage and pen culture of Chinese carps.
Human and agricultural wastes
Increasing urbanisation and population growth have led to serious problems of aquatic environmental pollution in China. It has been found that lakes near urban areas are likely to suffer from eutrophication, microbial contamination, low oxygen levels, phytoplankton blooms, heavy metal pollution and pesticide pollution. Local fish culture operations could consequently also suffer adverse effects. These problems are projected to continue in the near future.
Some severe localised effects of petrochemical discharges have been noted in inland waters, and petrochemical pollution is important in some river systems.
According to the Environmental Protection Agency (1992), the effects of man-made radiation are small, with only a few areas slightly polluted. There is no evidence that such pollution has affected fisheries and aquaculture in any way.
1 (calculated from 1 US $ = 5.8 Yuan)
4.1.2 Coastal aquaculture
Floods and typhoons have caused some damage to coastal aquaculture operations. In some areas, siltation and accumulation of solid waste may also result in problems for culture farms.
Water quality of most open sea areas is good, but poor in some coastal areas, estuaries and bays. The main sources of pollution are petrochemicals, organic substances, nutrients and heavy metals. According to the Environmental Protection Agency (1992), the main pollutants in coastal sea waters are ammonia, nitrite and nitrate nitrogen and oils. In 1991, the coastal waters most seriously affected by nitrogen pollution were Changjiang river estuary, Hangzhou bay, Zhoushan island, and the Pearl river delta. Those seriously affected by oils were the Haikou bay and the Pearl river delta.
Over the past few years, some sea waters have become more eutrophic. This has led to increasing numbers of red tide incidents. In 1991, there were 38 reported incidents of red tides, of which 24 were in the East China Sea, 12 in the South China Sea and 2 in the Bohai Sea. In 1990, there were 34 red tides. In 1992, 50 red tides were reported. The effect of red tides on fisheries is a rather complicated problem. On the whole, it occurs more often in the East and South Sea than in the Bohai and Yellow Sea. Recently, the frequency and size of red tides in the latter two seas have increased dramatically. The annual incidence of red tide is now about 30 times as many as the average for 1961–1980. It is very difficult to make accurate statistics of the times of red tides and their effects on fisheries.
From what is known, the effects of red tides on coastal aquaculture have been severe. In August 1987, the phytoplankton species Noctiluca aciatillans bloomed in Changsi County, Zhejing Province causing damage to Laminaria farms. In August 1989, a Gymnodinium sp bloom in the Bohai devastated shrimp farms around the Bohai, causing an estimated Yuan 400 million worth of damage to Penaeus chinensis farmers. The most severe effects were felt in shrimp farms along the coast of Hubei province, but farms in Shandong province were also affected. More recently, in June 1990, a Cochlodinium sp bloom affected finfish farms in Quanzhau Bay, Fujian Province. Red tides are considered one of the most serious dangers to coastal aquaculture, causing direct mortalities due to asphyxiation or the release of toxins.
Problems of nutrient enrichment, eutrophication and resulting phytoplankton blooms are considered a severe problem for coastal farms. Related problems of low dissolved oxygen and microbial contamination have also been recorded. The overuse of pesticides and fertilisers on nearby farms may have had significant local impacts on coastal aquaculture, although this has not been studied. All these problems are expected to continue or even intensify in future.
Oil spills have been recorded and have had severe localised impacts on coastal aquaculture. For example, between 1987 and 1989 there were severe shellfish mortalities in Laizhou bay in Shandong province, affecting mainly Arca subcrenata. The total loss was around 10,000 tonnes worth around 1 million Yuan.
Radioactive contamination does not present a danger to coastal aquaculture.
4.2 Contamination of aquaculture products
The most severe case of aquaculture product contamination occurred in 1988 just outside of Xiaomiaohong in Qidong Country in Jiangsu Province where some 370,000 people became infected with viral hepatitis A after consuming contaminated mogan clam (Anadara subcrenata). Samples of clam were tested positive for the virus and the Ministry of Agriculture subsequently imposed a ban on capture of clam stock from this area. The ban is still in force and has caused an estimated loss of more than 10 million Yuan to the local fishery economy every year. This economic figure does not include the costs to society caused by this severe incident.
Low levels of trace metals have also been recorded in aquaculture products. However, with the exception of a report of mercury residues in inland cultured finfish, these are generally not considered significant. In 1985, a survey was made of residues of 10 toxic substances in 14 species of economically important fish species cultured in 12 areas that support large aquaculture industries. The results show that all 10 toxic substances existed in fish from areas with serious local pollution, with some residues exceeding safe limits for human consumption. However, for most samples, the concentration of toxic substances was below safe limits and did not pose a health hazard.
4.3 Impacts of aquaculture on the environment
There is less information on the impact of aquaculture on the environment although there are concerns related to inland and coastal aquaculture. In general, environmental impacts from aquaculture are regarded as considerably less polluting or serious than industrial, construction or other large scale non-aquaculture developments. However, there are examples where aquaculture development has caused some impact on other fisheries and other sectors. There is also the recognition that self-pollution and other impacts can affect the long term sustainability of aquaculture.
4.3.1 Inland aquaculture
Water pollution and physical impacts
Development of pond fish culture has greatly contributed to the freshwater fisheries production in China, due to the increase in pond area and intensification. However, it is reported that the water depth of more than half of the fish production ponds does not exceed 1 m; and due to negligence in repair and intensification (which will tend to produce more silt), ponds have become silted in some areas limiting the depth to 50–70 cm. There are some 46,000 ha of such ponds in Jianxi and 80,000 ha in the densely cultivated Pearl river delta in Guangdong. Such problems have led to a deterioration of water quality in ponds (giving rise to disease problems) and there are also anecdotal reports of some environmental problems from indiscriminate dumping of silt in canals and rivers, particularly in the densely populated Pearl river and Yangtse river deltas.
In contrast, the “traditional” forms of integrated farming offer potential to reduce environmental impacts through recycling of potentially polluting agricultural wastes. Polyculture of several species of fish also provides a way of optimising environmental conditions in the pond. However, there are also reports that traditional forms of integrated culture are changing as farmers move to more intensive systems involving higher levels of supplementary feeding and fertilisation, giving higher economic returns. Although not well documented, such changes may also lead to some environmental impacts in the future.
Some information on the effects of intensification of fish culture practices exists for cage and pen culture. As a consequence of semi-intensive and intensive feeding practices in cage culture of fish in bays, water quality in some reservoirs is reported to have deteriorated, resulting in fish mortalities. Some of these problems are caused by poor site selection and high densities of cages, combined with poor water exchange. Others have been attributed to cage farming exceeding the “carrying capacity” of the site. A case of high mortality rate in cage culture of common carp has been reported from the 80 ha Shuimotan reservoir located in Sichiun province, West China. Cage culture started in 1988, but due to poor water exchange and the intensive cage farming practices, water quality deteriorated in 1991, leading to a loss of 70 tonnes of table sized common carp. As the reservoir has no external pollution sources, the high mortality was attributed to excess accumulation of unconsumed feed and faeces. Because of such problems, intensive cage culture has been discontinued in reservoirs designated for drinking water.
Interactions with capture fisheries
The use of wild seed for finfish culture, has had an adverse effect on the productivity and diversity of some natural populations, particularly the hairy crab, Eriocheir sinensis and eel, Anguilla japonica. Disease outbreaks in intensively farmed finfish are fairly common, and may act as a constraint to the development of the industry.
Interactions with other resource users
Intensive finfish farmers in particular experience some competition for space with local agriculture, industry, tourism and other aquafarmers. The problem is particularly acute near larger cities where recently there has been major economic development and diversification.
4.3.2 Coastal aquaculture
Water pollution and physical impacts
Pollution by poorly managed aquaculture activities has an effect on the external environment, but also causes problems for the farm itself. The major impacts of coastal aquaculture are eutrophication; sedimentation; decrease in oxygen levels; increase in nutrient levels and algal blooms; and release of solid matter, micro-organisms, and toxic metabolites. Most of these factors are particularly evident in shrimp ponds. This aspect is discussed in more detail in Section 5.
There is little known about environmental impacts of shellfish and seaweed farming, although impacts are thought to be negligible. It is known that overstocking of culture areas can lead to farms exceeding the “carrying capacity” of the environment. However, farmers normally use appropriate stocking densities to avoid such problems.
Interactions with capture fisheries
Coastal aquaculture, and shrimp farming in particular, has some impact on natural fish populations by reducing stocks of wild seed and resulting in reduced productivity and diversity of native species. However, such effects are small compared to the effects of industrial waste water and other pollution sources.
Interactions with other resource users
Competition with local industry for land, water and access to coastal aquaculture sites may provide problems for the fish farmer. Particularly in Guangdong province, there has been intense competition with other sectors to develop the aquaculture along the coastline. For example, in Zhouhai and Shenzen, areas previously used for pond culture have been developed for other businesses.
5. INTERACTIONS BETWEEN AQUACULTURE AND THE ENVIRONMENT: IN-DEPTH STUDY
This in-depth study covers two topics of importance related to aquaculture and the environment in China: a description of the fisheries environment monitoring network and the relationship between aquaculture and the environment in the Bohai. A discussion of the fishery environment monitoring network is necessary to understand the response to pollution problems discussed with respect to aquaculture in the Bohai.
5.1 Fishery environment monitoring network
The fishery environment monitoring network was established in 1985, and has come to consist of 25 monitoring stations: The central station, oceanic province and basin stations, and provincial stations. The locations of the stations are shown in Table 7.
Table 7. Monitoring stations in the fishery environment network.
|Central Station||Regional Station||Local Station|
|Centre of Environment Monitoring for Fishery (Beijing).||Heilong River (Harbin).||Heilongjiang Province (Qiqihar).|
|Harbin City (Harbin).|
|Jilin Province (Changchun).|
|Liaonin Province (Fresh) (Liaoyan).|
|Upper Yangtze Rover (Shashi).||Hubei Province (Wuhan).|
|Wuhan City (Wuhan).|
|Hunan Province (Changsha).|
|Lower Yangtze River (Wuxi).||Hunan Province (Fresh) (Wuhu).|
|Shanghai Municipality (Shanghai).|
|Pearl River and Delta (Guangzhou).||Guangdong Province (Guangzhou).|
|Bohai Bay (Qingdao).||Liaonin Province (Marine) (Dalian).|
|Dalian Bay (Dalian).|
|Yellow Sea (Qingdao).||Shandang Province (Yantai).|
|East Sea (Shanhai).||Zhejian Province (Zhoushan).|
|Fujian Province (Xiamen).|
|Beijing Municipality (Beijing).|
The main function of the network is to monitor the resources and environment in important fishing waters under its jurisdiction, conduct studies on environmental pollution, submit reports about the condition of the fisheries environment, present reports about the loss in fishery resources to the local fishery administration as an evidence for verdicts concerning pollution incidents. At present, because of the unpunctuality of investigations and evidence-finding, the complicated task of identifying pollutants and the difficulty in calculating economic loss to fishery resources, the compensations for fishery resource loss remains very low. Between 1990 and 1991, the average compensation for pollution incidents amounted to between 5.9% and 13% of the total economic loss (Table 8). However, most of the compensation given was for aquaculture.
There is a need to improve the monitoring work of the existing 25 monitoring stations and set up more at the district and municipal level before making them members of the national fishery environment monitoring station. Monitoring stations at the provincial level need to guide the monitoring of the environment of culture farms as part of the national environment monitoring system so as to make the environment monitoring network function more efficiently.
Table 8. Compensation for pollution damage to aquaculture and fisheries in China.
|Year||Economic loss (Yuan)||Percent to aquaculture||Rate of compensation (%)|
(Source: Bureau of Fisheries Management and Port Superintendence).
5.2 Aquaculture and the environment in the Bohai
Background to aquaculture in the Bohai
The Bohai is China's northernmost sea, with the line between Mount Laotie and Penglai Corner at its border (Figure 1). Here lies the Bohai Channel, which is 102 km wide. The Bohai covers an area of 77,000 km2, with three big bays. On the north is Liaodong Bay into which run the Liaohe River, Raoyang River, the Big and Small Ling Rivers. On the south is the Laizhou Bay into which flows the Xingqing River, Wei River and Beijiao River. The Bohai is the shallowest sea of its kind, with a mean depth of 18 m. Over half of the sea is less than 20 m deep. It is also the chief spawning and bait-finding area for marine fishes and shrimps as well as a fishing ground in the north, suitable for the development or enhancement of fish, shrimps and shellfishes.
The cultivation yield of the Bohai makes up 64% of the national yield, with 69% for prawns; 99% for scallops; 95% for mussels; and 71 % for kelp. In 1990, the export value of Dalian and Shandong Province alone was US $ 330 million, making up 25% of the export value of China's aquatic products. The development of marine cultivation has promoted the development of fishing baits, breeding, processing and foreign trade and provided jobs for about 1 million surplus rural labourers. The fishery production value in many coastal counties makes up over 10% of the local gross production value and exceeds the latter in some counties, the highest percentage being 50 percent. Fisheries development has greatly accelerated economic development in the coastal area. Each of the provinces is taking advantage of the reform and opening drive in an effort to make the fishery production value reach or surpass the local gross agricultural production value in the next century.
Figure 1: Bohai and Yellow Sea.
In spite of its fishery importance, there are areas of the bay with serious pollution problems. Organic pollution is the heaviest, followed by oil pollution. Coastal eutrophication is producing an increasingly greater effect on enhancement, culture, breeding, as well as on fisheries. These problems are attracting more and more attention.
Impacts of environment on aquaculture
The highest yield of economic fishes and shrimps in the Bohai reached 300,000 tonnes. The coastal mud flats possess rich shellfish resources. The Liaodong Bay alone produces more than 10,000 tonnes of economic shellfish annually. With the industrial development of coastal cities, poisonous waste water from factories was discharged into the Bohai through various river courses, polluting most of the rivers to different extents. The environment along the banks, at river mouths and inland bays has worsened remarkably. The mass mortality of fishes, shrimps and shellfishes occurs frequently. At some river mouths, migratory fishes and shrimps no longer exist, and the neritic shellfish resources are decreasing. The frequent red tides in recent years has also had some effect on cultivation, with the worst in 1989, when shrimp cultivation suffered a loss of 400 million Yuan as a result of a bloom of Gymnodinium sp.
Environmental impacts of aquaculture
The development of aquaculture in the Bohai has led to some environmental impacts. The impact of the discharge of shrimp pond waste water into the sea on coastal eutrophication is obvious in some areas, especially in some bays with highly concentrated cultivation farms. The problem of eutrophication normally stands out between July and August when the amount of feed used is highest. The quality of coastal water is sometimes restored to normal levels after the harvest of shrimp. Table 9 gives some information on the water quality in Dingzhi Bay where there is a large concentration of shrimp culture ponds (see also Figure 2). In some areas, ponds have been built into estuaries. These physical changes, combined with the nutrients and organic material released from farms, have had some detectable effects on benthic fauna.
Table 9. Water quality changes in Dingzhi Bay (Bohai). Shrimp are cultured from May until September (results show the range for 9 sampling stations).
|COD (mg/l)||T (°C)||DO (% saturation)|
The significance of these environmental changes have not been assessed in detail, however, recent problems with outbreaks of shrimp disease are thought to be related to changes in environmental conditions. The problems are reported to be worse in areas with large-scale cultivation of shrimp. Although further information is required, it appears that disease problems are less where integrated farming (e.g. shrimp and molluscs) is practised (see next section).
One study has compared the amount of COD (chemical oxygen demand) released by shrimp ponds with that from other sources. The results (Table 10) show that in Liaoning and Shandong provinces the amount of COD discharged from shrimp ponds has increased since 1983, but that the percentage is still low compared to other sources (mainly industrial and domestic).
Figure 2: Shrimp pond areas (shaded) in Dingzhi Bay.
Table 10. Chemical oxygen demand (COD) from shrimp farming in Liaoning and Shandong provinces in comparison with industrial and domestic discharges.
|1983||Shrimp pond area (ha).||54,000||12,020|
|COD from shrimp culture (tonnes/yr).||2,223.7||4,949.8|
|COD from industrial and domestic discharges (tonnes/yr).||1,227,372||312,760|
|% of total COD contributed by shrimp ponds.||0.18%||1.6%|
|1988||Shrimp pond area (ha).||467,000||816,400|
|COD from shrimp culture (tonnes/yr).||19,235.2||33,619|
|COD from industrial and domestic discharges (tonnes/yr).||1,579,618||653,217|
|% of total COD contributed by shrimp ponds.||1.2%||5.1%|
Environmental management of aquaculture
The problem of pollution and aquaculture has been recognised and efforts are being made to properly quantify the impacts and derive solution. Several methods have been tried, or are under consideration, to reduce the impacts of aquaculture on water quality or to reduce impacts of environmental pollution on aquaculture.
One method involves the proper design and lay-out of culture farms, including separate water supply and drainage canals. There is also a need to allocate areas for mixed culture - including integrated culture methods to reduce the impacts associated with monoculture. It is recognised that monoculture, particularly shrimp culture, is likely to lead to disease and environmental problems and there is a need to mix different culture methods in the same area to avoid such problems. It is necessary to promote integrated seafarming, involving mixed cultivation of many species. Several methods are being developed (Table 11). These methods need to be further developed in order to achieve better economic and environmental returns.
Table 11. Integrated seafarming model methods, including practical and experimental combinations.
|Yellow Sea||Laminaria sp. (or Undaria sp.) - seacucumber (or abalone).||In commercial use - method for using the upper water column and bottom zone.|
|Yellow Sea||Laminaria-scallops (Chalmys sp. and Argopecten sp.).||As above.|
|Bohai/Yellow Sea||Shrimp - clam (several species).||Experimental - but shown to increase shrimp production when cultured together in ponds.|
|Zhoujiang||Shrimp cockle (Arca sp.).||As above.|
|Fujian||Shrimp-fish-oyster (Crassostrea sp.).||As above.|
|Guangdong||Shrimp - Argopecten irradians.||As above.|
6. COUNTERMEASURES FOR DEALING WITH ENVIRONMENTAL PROBLEMS
The following countermeasures to protect aquaculture from the adverse effects of pollution and red tides are proposed:
To strengthen the agency for fishery environmental protection with a network of monitoring stations. In China, the Chinese Network for Monitoring Environment for Fishery works in this capacity. To improve the work of this network, improved monitoring systems and analysis and interpretation of monitoring data are required. Further environmental monitoring around aquaculture farms is required so that levels of environmental degradation are known and red tide events can be predicted.
To improve methods for determining compensation in environmental pollution incidents. It is important to determine the “real” effects of pollution on fisheries so that disputes between claimants and polluters can be fairly resolved.
To draw up further laws and regulations specifying water quality criteria that prevent pollution of the aquatic environment for aquaculture. There is also a need to take fishery interests fully into consideration when evaluating the impacts of projects involving the aquatic environment, and for further research to provide a scientific basis for aquatic environmental protection.
To ensure that technical and management personnel dealing with environmental protection in aquaculture and fisheries are fully trained.
In China, the Sub-Society of Fisheries Environment Protection of the Society of Agriculture, Ecology and Environmental Protection has been established to raise the level of academic research on the aquatic environment and to ensure distribution and exchange of this information. The work of this society could be further strengthened.
There is also a need to promote integrated seafarming, e.g. molluscs and shrimp culture together. Integrated seafarming has the potential to make optimum use of aquatic resources and to reduce environmental impacts.
Countermeasures to prevent contamination of fish products, such as methods of depuration and detoxification, are currently being investigated. Meanwhile, the Regulation of Ecology Management about Shellfish has been drawn up. This regulation aims to restrict the discharge of sewage into culture areas, including environmental monitoring.
7. FUTURE AQUACULTURE DEVELOPMENT AND RECOMMENDATIONS
Having identified the cures and prevention above, a national/regional aquaculture/environment programme is required to counter the environmental problems in aquaculture development. The following recommendations are given.
The establishment of a research centre for aquaculture environments in the Asia-Pacific region. The findings of research, monitoring technology and other methods from developed countries may be introduced to promote the steady development of aquaculture in the region. This centre should be responsible for training, research and exchange of information and data at the regional level.
A systematic study of the multi-pattern cultivation (integrated seafarming), including environmental protection, aquatic product yields and economic benefits.
A study of ways to strengthen legislation for compensation of fish kills/damage for fishery resources affected by industrial pollution is required to strengthen the compensation system. There is a need to consider the development of protected zones for fisheries and aquaculture environments. Industry in some developed districts often develops at the cost of the fisheries environment. Experience in legislation in some developed countries can be referred to so as to perfect the legal system concerning the fisheries environment in China. Although the current environmental laws involve the fisheries and cultivation environment, specific regulations on these matters need to be developed.
A strategic study of the environmental management of aquaculture and fisheries development. With regard to the importance of the fisheries economy and the graveness of the environmental problems in the Bohai, there is a need for a co-operative study with other institutions to develop a more integrated approach to the management of the coastal zone environment in the Bohai. Support from an appropriate international organisation is requested for this study.
Further training of state-level officials is necessary to improve the country's policy making ability in fishery environments.
Regional exchange of information and experiences between scientists and managers working in aquaculture/fisheries and the environment must be promoted through regular meetings of concerned individuals.
EPA (1992). Report on the state of the environment in China 1991. National Environmental Protection Agency, China.
State Standard of the People's Republic of China. Standard of Water Quality for Fisheries. Issued by the National Environmental Protection Agency on August 12, 1989 Put into effect on March 1, 1990.
This standard is specifically laid down to implement the Environmental Protection Law, Water Pollution Prevention Law, Marine Environmental Protection Law and Fishery law of the People's Republic of China, prevent and control the water pollution of fishery waters, and guarantee the normal growth and propagation of fishes, shrimps, shellfishes, phycophyta and the quality of aquatic products.
1. The theme, content and the range of application
This standard applies to the spawning, feeding ground and over winter ground, migration pathways of fishes and shrimps as well as to such seas, fresh water fishery waters and the breeding and nursery areas of aquatic products.
2. Requirement of water quality for fishery
3. Protection of fishery water quality
4. Implementation of this standard
5. Monitoring of water quality
Standard of Water Quality for Fishery
|Items||Value of Standard|
|1.||Colour, offensive smell, smell.||Fish, shrimp, shell fish and kept should not have odd colour, odd offensive smell|
|2.||Floating material.||No oil film and floating foam should appear on the water surface|
|3.||Suspended material (mg/l).||The amount added to human beings should not surpass 10, and the suspending materials sunk to the bottom of the water should not be harmful to fish, shrimp and shellfish|
|4.||pH value.||Freshwater 6.5–8.5, sea water 7.0–8.5|
|5.||Soluble oxygen.||In successive 24h, above 16 h should be higher than 5 mg/l, and the other time should not be lower than 3 mg/l, as for fish of Salmonidae type any time except during periods of water freezing should not be lower than 4mg/L.|
|6.||Biochemical oxygen demand (5 days, 20°C).||should not surpass 5 mg/l, frozen period should not surpass 3 mg/l.|
|7.||Total colonial bacillus.||should not be greater than 5000/L (and should not surpass 500 pieces/L)|
|8.||Mercury.||< 0.0005 mg/l.|
|9.||Cadmium.||< 0.005 mg/l.|
|10.||Lead.||< 0.05 mg/l.|
|11.||Nobelium.||< 0.1 mg/l.|
|12.||Copper.||< 0.01 mg/l.|
|13.||Zinc.||< 0.1 mg/l.|
|14.||Nickel.||< 0.05 mg/l.|
|15.||Arsenic.||< 0.05 mg/l.|
|16.||Cyanide compound.||< 0.005 mg/l.|
|17.||Sulphur compound.||< 0.2 mg/l.|
|18.||Fluorinated compound.||< 1 mg/l.|
|19.||Unionised ammonia..||< 0.02 mg/l.|
|20.||Kjeldahl nitrogen.||< 0.05 mg/l.|
|21.||Volatised phenol.||< 0.005 mg/l.|
|22.||Yellow phosphorus.||< 0.001 mg/l.|
|23.||Petroleum.||< 0.05 mg/l.|
|24.||Acrylonitrile.||< 0.05 mg/l.|
|25.||Acryladehyde.||< 0.02 mg/l.|
|26.||BHC.||< 0.002 mg/l.|
|27.||DDT.||< 0.001 mg/l.|
|28.||Malathion.||< .005 mg/l.|
|29.||Pentachlorophenol.||< 0.01 mg/l.|
|30.||Rogor.||< 0.1 mg/l.|
|31.||Methamidophos.||< 1 mg/l.|
|32.||Parathion methyl.||< 0.0005 mg/l.|
|33.||Carbofuran.||< 0.01 mg/l.|