Water pollution in countries in Asia and the Pacific is caused mainly by domestic sewage, industrial effluents, and runoff from activities such as agriculture and mining. The severity of water quality problems in the region is summarized in Table 2.4.
The problem of pathogenic pollution is quite severe in South Asia, South-East Asia, the Pacific Islands, and China; only in industrial countries such as Japan, Australia, and New Zealand is the problem relatively minor. Pathogens generally come from domestic sewage that is discharged untreated into watercourses. South Asia and China are most severely affected by organic matter pollution, the main source of which is effluent from the pulp and paper and food industries.
Lake eutrophication is a significant but localized concern in a number of countries. A survey by UNEP and the International Lake Environment Committee (ILEC) shows that 54 per cent of the lakes in South-East Asia suffer from eutrophication problems (UNEP, 1994). This subregion's inland water bodies are also affected by the presence of pathogenic agents, while many rivers carry enhanced nutrient and pollutant loads resulting from changes in land use, industrialization, and urbanization.
Discharge of mine tailings and development of industrial areas with direct discharge of pollutants into neighbouring river systems has resulted in hot spots of heavy metal pollution throughout the region.
In the small island countries, salinization affects the ground-water resources severely due to the intrusion of sea water. In Thailand, the rapid lowering of the water table due to excessive extraction of ground water has caused the shallow aquifers in Bangkok to become contaminated with sea water. The overwithdrawal of ground-water reserves has also caused land subsidence in cities such as Bangkok and Jakarta. In Bangkok, for instance, land has subsided in some places by 0.5-0.6 metres over the last 20-25 years, which has aggravated the city's flood problems (ESCAP, 1995a). In countries like Bangladesh, salinity and sedimentation are occurring largely as a result of upstream water withdrawal.
The fresh-water withdrawals in Asia and the Pacific range from 15 to 1,400 cubic metres per person per year (WRI/UNEP/UNDP, 1994). Agriculture accounts for 60-90 per cent of the annual water withdrawal in most countries of the region, with the highest proportion in Afghanistan (99 per cent). (See Table 2.3.) The demands for domestic and industrial uses are increasing in the region due to the high rates of urbanization and industrialization. The demand for water will continue to rise in the region in parallel with population growth.
Fresh-water availability of below 1,000 cubic metres per capita per year indicates water scarcity. Singapore is already water-scarce, with considerably less than 1,000 cubic metres per capita of water available per year, while Iran and India are heading in that direction. India is among the countries projected to fall into the water-stress category before 2025. Its situation is well illustrated by the case of Rajasthan, which is home to 8 per cent of India's population but claims only 1 per cent of the country's total water resources. China is expected to only narrowly miss the water-stress benchmark by 2025 (WRI/UNEP/UNDP, 1992).
Atmosphere
One of the important implications of economic growth in Asia and the Pacific over the last three decades has been the increased demand for energy. The region, excluding Japan, Australia, and New Zealand, accounted for 21 per cent of the world's primary commercial energy demand in 1992 as compared with 51 per cent for members of the Organisation for Economic Co-operation and Development (OECD) and 28 per cent for the rest of the world. The growth in energy demand for the whole region was 3.6 per cent per year between 1990 and 1992, compared with an average 0.1 per cent growth of the whole world (ADB, 1994b). In particular, the region accounted for about 41 per cent of world coal consumption in 1993 (EIA, 1995).
The rapid growth in energy demand and especially the region's reliance on coal translate into a significant increase in air pollutants if appropriate technological interventions are not made (such as the use of scrubbers). Urban air pollution is a serious problem in many major cities of the region. Significant health threats also arise from indoor air pollution resulting from the use of low-quality solid fuels, such as coal, wood, crop residues, and dung for cooking and heating in lower-income urban households and in rural areas throughout the region.
Fly ash generated from the mining of coal is also a significant problem in the region, particularly in India, where the problem is as serious as acid rain is elsewhere. An estimated 35-40 million tons of fly ash are generated by thermal power plants every year, and only 2-3 per cent is being reused (India, 1993). Fly ash can be reduced through better washing techniques. In addition, it can be reused as fertilizer, to make bricks and roads, or to replace sand used to refill mines.
Transboundary air pollution is a problem that has accompanied economic growth and high energy consumption. The effects of coal burning tend to spread over a large area, resulting in acid deposition in areas near the coal burning plants as well as further away. The accumulation of fly ash adds suspended particulate matter into the air and leads to air quality deterioration. In addition, slash-and-burn agriculture leads to haze problems that extend beyond national boundaries. Unfortunately, only a limited number of quantitative analyses of transboundary air pollution have been done in the past.
Although acidification of the environment has until recently been regarded as a problem only in Europe and North America, the problem has also started to emerge in parts of Asia and the Pacific region. It has been estimated that 38 million tons of sulphur dioxide were emitted in 22 countries of Asia in 1990, almost 56 per cent more than in North America, and this is expected to be much higher in the coming decades if effective mitigation measures are not adopted (Shrestha et al., 1996). About 78 per cent of these emissions originated from North-East Asia (China, Republic of Korea, Japan, Hong Kong, Mongolia, and Chinese Taipei).
A study done in a project sponsored by the World Bank and the Asian Development Bank (Hettelingh et al., 1995) on acid rain and emissions reduction in Asia shows that the areas with critical loads of up to 320 milligrams per square metre per year (that is, areas that are most susceptible to acid deposition) are located in South China, the areas south-east of Thailand, Cambodia, and southern Vietnam. In 1990, the areas with an acid loading in large excess of critical loads were located in south-east China, north-east India, Bangladesh, Thailand, parts of Indonesia, South Korea, southern Japan, and small parts of the Philippines.
Biodiversity
The region encompasses parts of three of the world's eight biogeographic realms and includes the world's highest mountain system, the second largest rainforest complex, and more than half of the world's coral reefs. Five of the 12 "mega-diversity" countries identified by McNeeley et al. are in this region (McNeeley et al., 1990). The rainforests of South-East Asia contain some 10 per cent of the flora of the world. The region as a whole encompasses two thirds of the world's flora. Almost all the nations in the region (with the exception of Singapore and Brunei Darussalam) depend heavily on direct harvesting from nature.
The flora and fauna of the region are more threatened now than ever before. (See Figure 2.8.) The drive for increased agricultural production has resulted in the loss of genetic diversity. Land under rice cultivation rose between 1960 and 1970 by only 25 per cent, but production rose by 77 per cent due to the replacement of traditional varieties with higher-yielding, semi-dwarf varieties. By 2005, India is expected to produce 75 per cent of its rice from just 10 varieties compared with the 30,000 varieties traditionally cultivated. In Indonesia, 1,500 varieties of rice disappeared during the period 1975-90 (WRI/UNEP/IUCN, 1992). Terrestrial biodiversity loss in various ecosystems has been identified as a major concern, but losses have still to be quantified. Overall habitat losses have been most acute in the Indian sub-continent, China, Vietnam, and Thailand (ESCAP, 1995b).
The Indo-west Pacific is the centre of shallow-water marine biodiversity. Coastal habitat loss and degradation, combined with increased sediment, nutrient, and pollutant discharge into coastal areas, are a major cause of concern, particularly in the insular countries of the region. Thailand alone lost about 200,000 hectares of mangrove from 1961-93 (Government of Thailand, 1994). Conversion of mangroves to shrimp mariculture and unsustainable fishing practices such as blast fishing are widespread. Although the impacts of such practices on regional biodiversity are difficult to quantify, it has been estimated that the rates of loss of coral reef and mangrove habitats are among the highest in the world.
The underlying causes of losses of biological diversity in the region include international trade, particularly in timber (which results in forest habitat losses); population growth (leading to accelerated rates of land use change); poverty (in conjunction with demand leading to unsustainable consumptive use of "common access resources"); the introduction of non-native species (leading to destruction of predator/prey equilibrium); and improper use of agrochemicals (leading to loss of aquatic species). Other major reasons for biodiversity loss include loss of keystone species, extensive deforestation and habitat loss, increased trafficking in animals and animal body parts, large-scale conversion of land for agriculture, and the construction of large-scale dams.
Biological diversity is recognized as a legitimate issue at national and international levels in Asia and the Pacific, and there has been a considerable response (such as the implementation of the Convention on Biological Diversity and designation of protected areas). (See Figure 2.9.) However, patterns of unsustainable use and conflicting policies contribute to continued losses of biodiversity throughout the region. With only 10-30 per cent of natural habitats left in many countries, any further decrease could have much more serious consequences for biodiversity than the initial stage, when 50 per cent of the original habitat was lost (ESCAP, 1995a).
Marine and Coastal Environments
Most people in the region live along the coasts, with one quarter of the world's 75 largest cities being near or on the region's coastlines (ESCAP, 1995a). Growth rates of coastal populations are generally higher than the national average due to migration to coastal urban areas and industrial centres. Most of these large cities and industrial areas are located in highly productive low-lying estuarine areas.
The marine resources of the region are economically important to most countries, with 47 per cent of world fisheries production being found in this region. Of this, marine and fresh-water fisheries account for 76 per cent and 24 per cent of production, respectively (FAO/RAPA, 1994). The region is also the centre of global mariculture (87 per cent of total world production) (FAO/RAPA, 1994), with major consequences for coastal habitats and water quality.
For insular and archipelagic states, marine resources are the key source of external earnings for development and marine-based tourism is playing an increasingly important role. Several countries rely almost exclusively on fisheries products for dietary protein. Trends show that the marine fish catch is rising steadily in almost all subregions. The average annual fish catch is comparatively higher in South-East Asia.
Coastal and marine pollution in this region is mainly due to direct discharge from rivers, surface runoff and drainage from port areas, domestic and industrial effluents, and various contaminants from ships. River waters are generally heavily contaminated by municipal sewage, industrial effluent, and sediments. Asian rivers account for nearly 50 per cent of the total sediment load (13.5 billion tons) transported by the world's rivers each year (UNEP, 1992).
As much as 70 per cent of the waste effluent discharged into the Pacific Ocean has no prior treatment (Fuavo, 1990). More than 40 per cent of marine pollution in the region is derived from land-based activities through riverine discharge, with maritime transport contributing a further 12 per cent (Weber, 1993). The Government of Korea estimates that at least 80 per cent of pollutants in the Yellow and South seas of the Korean Peninsula come from inland activities (domestic and industrial) through the four largest Korean rivers (Government of Korea, 1994).
The major sources of heavy metal contamination are industrial effluent and dumping of land-based solid waste into the sea. In India, for example, exceptionally high concentrations of lead, cadmium, and mercury have been observed in Thane creeks on the Bombay Coast, and sediment along the creeks and offshore stations was reported to contain significant concentrations of lead (India, 1993). In Pakistan, heavy metal contaminations have been detected in water and sediment from the coastal area within the mouth of the Indus River (Tariq et al., 1993). Moreover, there is increasing evidence of these toxic substances getting into the food chain.
The sources of marine pollution from sea-based activities include marine transportation and offshore mineral exploration and production activities. Accidental oil spills have been frequently reported along these routes.
In the Straits of Malacca alone, 490 shipping accidents were reported in 1988-92, resulting in a considerable amount of oil spillage (Straits Times, 1993). It has been reported that beach tar along the west coast of India is a severe problem, with total deposits of up to 1,000 tons per year (GESAMP, 1991). In the port of Chittagong in Bangladesh, an estimated 6,000 tons of crude oil is spilled annually, while crude oil residue and wastewater effluent from land-based refineries amount to about 50,000 tons per year (Khan, 1993). Approximately 5 million tons of oil enter the Arabian Sea each year, while the Bay of Bengal receives some 400,000 tons from similar sources (ESCAP, 1995a). Similarly, oil pollution from shipping and offshore oil rigs is a concern in East Asian seas.
Increased use of agro-chemicals in this region is also a matter to be considered. Fertilizer consumption rose 74 per cent in 1982-92, from 33.3 million to 57.8 million tons (ESCAP, 1995a). Use of pesticides, which contribute to enhanced agricultural productivity, appears to be increasing, especially in developing countries. An estimated 1,800 tons of pesticides enter the Bay of Bengal annually (Holmgren, 1994), and increased use of pesticides in some areas has resulted in contamination of shell-and finfish.
Loss of coastal habitats includes substantial loss of mangrove forests in South-East Asia, particularly for the construction of shrimp ponds and for paddy rice cultivation, with negative impacts on commercial fisheries that rely on species using the mangroves as nursery areas. Thailand and the Philippines are clear examples: some 208,218 hectares and 200,000 hectares of mangroves, respectively, were cleared between 1961 and 1993 (GESAMP, 1993). Identical problems because of shrimp culture have occurred in Bangladesh, India, and Sri Lanka. One example of this destructive sequence of events is the Chakaria Sundarbans in eastern Bangladesh, which have been almost completely cleared for aquaculture (ESCAP, 1995a).
Similarly, coastal construction (particularly for tourist facilities), inland mining, and poor land use practices have increased sediment loads in coastal waters in countries such as Fiji, Indonesia, Malaysia, and Thailand, with adverse impacts on sensitive coral reef systems. At present, the status of coral reefs has been significantly improved in Thailand, thanks to the efforts of non-governmental organizations and local people (OEPP, 1996).
Occurrences of "red tides," a special plankton bloom, has been an environmental problem of major concern in the coastal areas of the region. In addition to severely depleting oxygen levels, leading to the mass death of aquatic organisms, the red tides also cause a paralytic shellfish poisoning, with serious risks to human health. For example, an outbreak of red tides in the Philippines in 1990 proved costly for the fisheries and shellfish industries (ESCAP, 1995a). The frequency of the appearance of red tides in Tolo Harbour, Hong Kong, ranged from 2 in 1977 to 9 in 1994. China is also experiencing an increasing threat of red tides in its coastal waters; there were a total of 19 incidents of red tide in 1993 (ESCAP, 1995a).
A major cause for concern throughout the region is overfishing and the use of destructive fishing techniques, particularly in the highly diverse coral reef systems. Most stocks throughout the region are currently being fully harvested, while a number are being exploited at unsustainable levels. Increasingly frequent and severe toxic algal blooms and the eutrophication of bays and semi-enclosed water bodies are growing problems throughout the region. Coastal erosion resulting from increased land subsidence from ground-water extraction, sediment starvation as a consequence of inland dam and irrigation barrage construction, and offshore mining of sand are notable problems in some localities. The high volume of maritime traffic and rising numbers of international tourist arrivals pose additional threats to marine and coastal environments.
Though the consequences of marine environmental pollution are becoming increasingly evident, the level of pollution in most coastal waters is still reasonably manageable. Countries of the Asia and Pacific region have joined various international and regional agreements to resolve the problem. Over the past five years, the situation in the coastal zone has improved in a few localities. This has been helped along by extensive use of remote sensing on a pilot project basis to obtain data on suspended sediments in a water column, topography, bathymetry, sea state, water colour, chlorophyll-a, sea-surface temperature, fisheries, oil slicks, and submerged and emergent vegetation, including mangroves and seagrass.
Urban and Industrial Environments
In 1995, the Asia and Pacific region was home to 3.3 billion people, with an average annual population growth rate of 1.7 per cent and an average density (in 1990) of 95 people per square kilometre, equivalent to that of Europe (UN, 1993). Countries range in population size from a few thousand in some of the smaller Pacific island nations to China (1.2 billion), India (900 million), and Indonesia (200 million).
The urban populations in the developing countries grew between 3 and 6.5 per cent a year in the mid-1990s. About 35 per cent of the region's population is urban, compared with 43 per cent for the world as a whole. The region contains 13 of the 25 largest cities of the world. By 2015, some 903 million people in Asia are expected to live in cities with a population of more than 1 million (WRI/UNEP/ UNDP/WB, 1996).
The environmental stress generated by urbanization in the region has been categorized as relating to poverty and arising from economic growth and affluence. The rise of cities has been accompanied by a proliferation of slums and squatter settlements without access to basic infrastructure, clean water, and sanitation, with associated health risks. (See Table 2.5.) Further, the lack of basic infrastructure results in local environmental degradation. It is expected that a large share of the world's urban poor will continue to live in South Asia (WRI/UNEP/ UNDP/WB, 1996).
Environmental concerns resulting from the economic growth and affluence of urban areas include congestion; increasing air and water pollution; loss of productive agricultural land; loss of coastal habitats to conversion and land reclamation; overextraction of ground-water resources, resulting in land subsidence; and deforestation as a consequence of increased demand for construction timber.
The problems of urbanization are not confined to continental or large archipelagic states but also occur in small island states such as Maldives, Tuvalu, and Tonga, where in-migration to the capital islands has resulted in severe land and, in some instances, fresh-water shortages, and in hot spots of coastal pollution.
About 700 million tons of solid waste and 1,900 million tons of industrial waste are generated each year in Asia and the Pacific (ESCAP, 1995a). Among the various subregions, East Asia generates the largest share of municipal solid waste. Broad calculations indicate that its share may increase to 60 per cent by the year 2000 because of the large population base and high economic growth rate (ESCAP, 1995a).
The key issues regarding solid waste management are the environmental health implications due to inadequate coverage of waste collection; improper storage prior to collection; and poor standards of disposal (ESCAP, 1995a). It is estimated that 30-50 per cent of municipal solid waste is uncollected (ESCAP, 1995a).
The disposal of domestic and industrial waste is given relatively low priority in many countries, with only around 70 per cent of the waste in urban municipal areas being collected and only some 5 per cent of this being treated (ESCAP, 1995b). Solid waste disposal is a particular problem in the small island states due to their limited land area; disposal areas have been used for land reclamation in some of these countries, resulting in contamination and pollution of surrounding coastal areas.
Extensive and reliable data on the generation of hazardous wastes in the region are not available. Rough estimates indicate that about 100 million tons are produced annually, with as much as 90 per cent generated in China and India (ESCAP, 1995a). About 60-65 per cent of these wastes end up in landfills; 5-10 per cent are dumped in the oceans; and only about 25 per cent are either incinerated or undergo physico-chemical treatment (ESCAP, 1995a). However, there is growing awareness in the region, especially in Japan, China, and India, about the detoxification of wastes and about immobilization by fabrication into bricks and other usable products (ESCAP, 1995a). Another issue of concern is wastes being brought into the region for disposal.
Wastewater disposal poses another problem. In many places, untreated domestic and industrial wastes are discharged directly into canals and rivers. Some Governments are in the process of taking measures to increase the treatment of wastewater. In 1992, about 68.6 per cent of industrial wastewater and 18.5 per cent of municipal wastewater generated in China was treated (WRI/UNEP/UNDP, 1994). The Government of Thailand has agreed in principle to establish a Central Waste Water Management Authority to consolidate policies and institutions to deal with this matter. The Government is also envisaging a role for private investments in setting up treatment plants (Government of Thailand, 1994). In Singapore, 36 industries were prosecuted in 1993 for discharging acidic effluents into the sewers (ASEAN, 1995). Singapore has significantly improved its facilities for handling wastes and is ensuring a stringent enforcement of standards.
With growing economic activities and consumerism, the quantity of solid wastes generated is growing rapidly. Furthermore, large quantities of industrial and hazardous wastes accompanying the expansion of industries that use chemicals in the region has exacerbated the waste management problem.
