City clusters in China: air and surface water pollution

China has experienced unprecedented economic growth over the past two decades, accompanied by the development of large-scale industries and services. In the course of this expansion, medium-sized cities and small towns have sprung up around the larger cities, forming city clusters, often with similar or interdependent economies. The development of city clusters in China is somewhat similar to the formation of the megalopolis in the United States, as described by Gottmann (1961). However, there are some differences in terms of the number of cities in an area, their infrastructure, and the services they provide to the region, as compared to the US. City clusters in China tend to be much more concentrated and densely populated, with little room for natural areas; for example, the distance between cities is often less than 10 km in the Pearl River delta. In the city of Guangzhou, spacing between residential buildings is so restricted that they are often referred to as “handshaking” buildings. Also, there is no clear, functional division of infrastructures among the cities, due to a lack of coordination between city planners. Cities within a cluster often compete for available natural resources, investment, and regional funding for infrastructure development and improvement. For example, five separate international airports have been constructed in recent years in the Pearl River delta (including Hong Kong and Macau). Better intercity cooperation could avoid such wasteful redundancy in the future, resulting in a more efficient regional economy (Bao 2005). If, as expected, such rapid development continues over the next several decades, demographic trends suggest that China will experience an even greater rate of urbanization. Population in urban areas has already increased from 20.0% of the total population in 1980 to 36.1% in 2000 (National Bureau of Statistics 2001a), and reached 37.8 % in 2003 (Li and Ji 2003). Despite this rapid pace of urbanization, current levels are still far below the global average (48.3% in 2003; United Nations Population Division 2004). There is still great potential for further urbanization, therefore, particularly as the urbanization process catches up with the pace of industrialization, which is often just as fast in villages (National Bureau of Statistics 1999). The combination of rapid economic growth and urbanization has resulted in substantial environmental problems throughout China, but nowhere more so than in city clusters. A considerable part of China's GDP was achieved at the cost of over-consumption of energy and other natural resources. The Pearl River delta, for example, although accounting for only about 20% of Guangdong province, consumed 67% of the coal and 85% of the oil for the entire region. Due to the close proximity of the cities and the large number of emissions sources, ambient concentrations of SO2 and NO2 in the Pearl River delta region were 2–3 times the level found in other parts of the province (CESPKU and GIES 2004). Pollutants from various cities in the area tend to mix and spread over the entire region (Wang SL et al. 2005). There is an urgent need to incorporate environmental issues into planning China's urban areas, in order to reduce the risks of further environmental degradation. This paper briefly describes the role of city clusters in China's economic development, and describes the regional air and watershed pollution that has developed as a result of the rapid economic growth within these city clusters. We also propose possible solutions to these environmental problems, taking into account the social and economic plans for medium- and long-term development in China. Urbanization in China has occurred most rapidly in the coastal areas, due to the stronger economic base and more developed infrastructure, as well as the greater abundance of natural resources. As a result, several city clusters have arisen in coastal areas and nearby regions (Figure 1). For several reasons, the formation of city clusters often acts as a catalyst for economic growth and enhances the competitiveness of the region as a whole. The central government has therefore developed long-term plans to support rapid coastal urbanization, followed by efforts to increase urbanization, in the central part of the country, thereby aiding economic development (National Bureau of Statistics 2001b). In essence, the three largest city clusters – the Beijing–Tianjin–Bohai Bay, Yangtze River delta, and Pearl River delta regions – have become the forerunners of modernization in China. The distribution of city clusters in eastern China. The closed dots indicate cities, sized according to urban population size; the dashed circles indicate city clusters, sized according to GDP. Details of the Northeast plains, Beijing–Tianjin–Bohai Bay area, Yangtze River delta, and Pearl River delta are given in Table 1; the other city clusters are generally development zones around one large city. Central-China plains, Guanzhong, Wuhan, and Changsha are used as names of city clusters near the cities of Zhengzhou, Xi'an, Wuhan, and Changsha cities, respectively. Redrawn from Zhang (2004). At present, the Yangtze River delta and Pearl River delta areas are the most fully developed, followed by the Beijing–Tianjin–Bohai Bay cluster and the recently initiated Northeast cluster (Table 1). The Pearl River delta city cluster has expanded rapidly since the 1980s, due primarily to former political leader Deng Xiaoping's policy of creating “special economic zones”, designated regions where governmental policy fosters a market economy instead of a planned economy. Similarly, the exponential economic growth of Shanghai in the 1990s led rapidly to accelerated growth among cities in its neighborhood. The Beijing–Tianjin–Bohai Bay area is a unique city cluster that formed spontaneously around the twin megacities of Beijing and Tianjin. The Northeast plains cluster, the former national center for heavy industry from the 1950s and throughout the 1980s, is now facing major challenges in maintaining its economic strength, following the exhaustion of its once abundant natural resources, especially coal, oil, and iron ore. Industrial restructuring and rehabilitation are making the Northeast cluster China's fourth economic pillar (Table 1). While these four regions make up less than 3 % of China's territory, and encompass only about 12% of the country's total population, they account for nearly half of the national GDP (47% in 2001; National Bureau of Statistics 2002). Although the government has also supported increased urbanization of small towns (Bai 2002), it is the large city clusters that are expected to drive economic development for the foreseeable future (Li and Ji 2003). Even so, it is widely predicted that millions of people will migrate from rural areas to adjacent urban areas over the next several decades, leading to the widespread growth of small and medium-sized cities, some of which are likely to become part of future city clusters. For instance, Henan Province, formerly a relatively poor agricultural province but with the largest population of any of China's provinces, has since grown to become the fifth largest provincial economy in China, based on GDP (2004 statistics; Zhang 2005). This economic expansion was due primarily to urban migrations and a subsequent shift in the economic base, from agricultural to industrial. Meanwhile, the Central-China plains city cluster in the same province is also growing very quickly. These developments are seen as a rejuvenation of economic strength in central China. The city clusters have major advantages in terms of regional economic development: the drop in GDP due to environmental pollution resulting from such rapid economic growth has largely been ignored. In 1997, a World Bank report indicated that economic losses caused by environmental pollution in China ranged from 3–8 % of GDP, which attracted the attention of both policy makers and academics (World Bank 1997). Although later estimates provided different numbers, by the end of the 20th century, economic losses due to environmental pollution were probably around 4–5% of GDP, which is comparable to the 5% estimated for the US in the mid-1970s and the 3–5% estimated for the European Union in the mid-1980s (Xu 1998). However, there are no truly reliable estimates of the impact that pollution from city clusters has on GDP, despite the importance of the issue. China has insufficient water resources. The amount of fresh water available per capita is about one-quarter of the global average of 8513 m3 per year (2002 statistics; World Bank 2003). In a survey of more than 600 Chinese cities, two-thirds had inadequate water supplies, while 1 in 6 experienced severe water shortages (Li 2003). Water pollution caused by rapid urbanization and the formation of city clusters has exacerbated the lack of accessible drinking water. While levels of industrial wastewater discharge have largely stabilized, domestic wastewater has increased considerably. While the total amount of released industrial wastewater fluctuated around 22 billion tons from 1995 to 2004, the domestic sewage discharge increased from 13.1 billion tons in 1995 to 22.1 billion tons in 2000, and up to 26.1 billion tons in 2004 (State Environmental Protection Administration SEPA 1995–2004). This was due primarily to the enactment of more stringent controls on industrial sources of wastewater; in 2003, 91% of industrial wastewater was treated, in contrast to only 32% of urban domestic sewage (National Bureau of Statistics 2004). As a consequence, surface water quality has become an issue of great concern in China. A national survey of seven major rivers in China, carried out in 2004, revealed that water quality measurements in 28% of 412 monitored sections were below grade V, the worst grade in the national standard for water quality in China. These results indicate that, for these sections of river at least, the water supply is virtually of no practical or functional use, even for agricultural irrigation. For the Haihe River, which provides the cities of Beijing and Tianjin with the bulk of their drinking water, this figure was as high as 57%, and for the Liaohe River, which supplies water to Northeast China, it was 38% (see Figure 2 for the locations of these rivers). Overall, more than 90% of the river sections that flowed through urban areas showed a water quality of grade V or worse (SEPA 1995–2004). The higher the grade, the worse the water quality; only water with a grade lower than III is drinkable. The same survey suggested that even the water quality of the Yangtze and Pearl Rivers, both of which have relatively abundant water flow, was a cause for concern; approximately 10% of the monitored sections of these two rivers also revealed water quality worse than grade V, and all monitored sections in the urban area of Guangzhou (on the Pearl River) had water quality around grade V or worse. The water quality of the rivers shown in Figure 2 was characterized only by conventional indicators, such as chemical oxygen demand (COD), ammonia, and volatile phenols, among others. The situation is even more worrisome when endocrine disrupting organic substances are taken into consideration as well (An and Hu 2006). Water quality of seven major rivers in China. The length of the bars are normalized to 1; the lengths of the green, yellow, and red bars represent the percentages of each river section with water quality between grades I–III, between grades IV–V, and grade V or worse, respectively. (According to the national surface water quality standards of China GB3838-2002, water of grades I–III is suitable for drinking, grade IV is for industrial and recreational use, and grade V is for agricultural use). Lake Taihu, the third largest freshwater lake in China, provides a typical example of water pollution caused by city clusters. With a total watershed area of about 36 500 km2, Taihu is situated within Jiangsu and Zhejiang provinces. The city of Shanghai, as well as more than 37 other cities and towns, is sited within its watershed. GDP in the area around Lake Taihu increased by a factor of 17 between 1980 and 1998; per capita GDP in the area was three times the national average (State Council of China 1998), while the population density was eight times the national average (Gao et al 2003). The water quality of Lake Taihu has deteriorated greatly during this period (Figure 3), largely as a result of this rapid economic growth. The lake remains the most important source of drinking water for the inhabitants of the Yangtze River delta region, but water quality has dropped by approximately one grade level every decade (Qin et al. 2004), and in 2004 nearly 60% of sampling sites in the lake recorded water quality lower than grade V (SEPA 1995–2004). As a result, the entire watershed area is now facing a shortage of potable water. Residents in the area who enjoyed the clean water of the lake in the past are now compelled to buy bottled water for drinking. Historical trends in water quality in Taihu lake. The water quality grading system is the same as in Figure 2. (Derived from monitoring data provided by National Environmental Monitoring Center) According to Gao et al. (2003), over 80% of COD and 70% of total phosphorus originated from urban and residential areas around the lake, with 42% of COD and 60% of total phosphorus derived from domestic sewage discharge. Research has shown that increased phosphorus concentration is the key factor in the worsening eutrophication of Lake Taihu (Dokulil et al. 2000); domestic sewage is therefore clearly a major source of water pollution in the lake. Future conversion of agricultural areas in the watershed to urban environments will very probably lead to even greater levels of water pollution (Gao et al. 2003). The deteriorating condition of Lake Taihu is typical of the problems associated with the increasingly polluted nature of China's sources of freshwater, and illustrates the urgent need to integrate both water pollution and population controls into the planning for future economic development in the country's watersheds. Air pollution is perhaps China's biggest environmental problem. Results from routine monitoring of 360 cities in 2004 revealed that the air quality of nearly 70% of urban areas did not meet the country's national ambient air quality standards (NAAQS), and that nearly 75% of urban residents were regularly exposed to air considered unsuitable for inhabited areas (SEPA 1995–2004). China has high levels of sulfur dioxide (SO2) and total suspended particulates (TSP), because coal is the source of 60–70% of its primary energy. Meanwhile, the number of motor vehicles has increased substantially since the mid-1980s, primarily in urban areas and city clusters; in Beijing, for example, the number of vehicles increased from 0.5 million in 1990 to 2 million in 2002 (Beijing Municipal Bureau of Statistics 2003). The growing number of cars and trucks has led to much higher levels of atmospheric nitrogen oxides throughout the country, but especially in urban areas. Since 2000, high concentrations of aerial with less than are the most cause of grade an average concentration of such at concentrations In Beijing, the average level of fluctuated around from 2000 to 2004 (Beijing 2005). such as Beijing, Shanghai, and Guangzhou are among the cities of the with the levels of 2002). areas of China are exposed to high levels of pollution (Figure For example, the region from the China to the Yangtze River delta and the Pearl River delta region of is an the of due to atmospheric the of the In the for between 0.5 and for and rural areas, et al. A of of atmospheric in China showed that levels increased by from to and by from 1980 to et al. 2002). of over China in 2002 (Li et al. 2003). In recent the has been the of growing concern (Figure Research that high levels of ambient with less than lead to poor et al. 2003). In the concentration of in Beijing more than seven times the ambient air quality standard by the US Environmental Protection for (Wang et al. 2004). pollution in urban areas a to but particularly to who from the and et al. et al. 2005). severe pollution is in developed of Beijing, taken from the of a on the of on a and on a of and The very high levels are most probably the result of due to chemical in the typical of is formed by the of and volatile organic of concentrations also of the source areas there is considerable of atmospheric are by concentrations et al. 1998). and volatile organic will be into more where concentrations are higher due to increased of concentrations of have been for years in China's urban areas. For example, at the of in Beijing from to 2003 found that concentrations have increased since the and often (Figure A similar in the Yangtze River delta region showed that high concentrations are also often found at sites some distance from or industrial regions (Wang et al. 2005). in the concentrations of ambient in Beijing from to 2003 in a of the about km of The is about km of The the average concentration at grade according to the national ambient air quality standards of China to high levels of both primary and lead to the development of a pollution (Figure The of the air pollution is to the of of in increased atmospheric caused by the formation of will up the conversion of and into and organic and these in a role in further 1997). While it is that these are in locations around the the in China – high concentrations of and their as well as the high concentrations of suspended – result in a level of aerial chemical that is probably unique to the pollution in a Chinese city In recent efforts have been to reduce air pollution in China. such as energy (including primary sulfur emissions through increased of coal and and more stringent standards as well as to have been in urban areas throughout the These to some the rate of increase of emissions (Figure while these be for the of some primary they are insufficient for the of and the resulting chemical that the of the air pollution GDP, number of and of and and discharge of COD in China, on GDP and cars from the National Bureau of Statistics data on emissions of and and COD discharge from The pollution also be to water in of the between and organic and the among water, and of between the and the and the nitrogen water, and pollution that the of the pollution an While abundant from and the US is available to pollution problems as and suspended the and experience to solutions to the unique pollution in China are still The Chinese has as a the of the country's GDP 2000 as the by and it by As a result, each province and from the coastal areas to the parts of China, has its economic development plans A of rapid economic development is therefore expected to spread the city clusters will be as a result, and the natural will be to even greater If, by of China's population in towns and cities, domestic water will be of 2000, while industrial will increase times 2002). As water so will the amount of domestic by a factor of at 2004). not be China's already freshwater will even greater energy is one of the of air pollution in China. the is one of the biggest of energy and but is very in the of these et al. 2004). While China's GDP for only of the total global GDP, were much for instance, China's coal, and for and 20% of 2004). The increase in is cause of air China is a to increase in the number of vehicles between 2002 and is that emissions from motor vehicles will during the same and levels will and and levels will also at high levels 2003). China's already severe air pollution will substantially increase the of throughout the country, as air pollution is estimated to be the primary cause of nearly of all and 2002). According to Environmental and pollution from the of coal approximately per year in China, while some people from in the country's largest urban areas. The estimated that the rate from in polluted areas of China was higher than in areas with air quality 2002). from current levels and the World Bank estimated that by China will need to approximately billion – or about of GDP – to for the that will from the of coal (World Bank 1997). A recent on energy for China that by of in energy and some the of the country's economy only a of current energy 2003). energy will greatly China's energy by and high in terms of emissions per GDP when compared with other will be greatly as is now widely in China that the course of economic development to over the next years avoid the of high energy and widespread and the of that characterized the expansion of the Chinese economy over the The World Bank and the have supported the development of three in China, and this has to and energy but a similar is for the of water and other natural as this and a economy be so that governmental and the all social in the that a economy is also for the of industrial and agricultural to increase current environmental issues and the of into economic planning are for China's future China's economic growth over the past years has to its but at the cost of an exponential increase in pollution over a relatively and 2005). City clusters, where both economic and large are from environmental degradation. China's unique pollution characterized not only by high levels of primary but also by the between and by their spread from source to regional The large-scale watershed pollution and air pollution will to stringent to the are not taken The of both economic losses and due to pollution have a very consideration of future and as China into a of development and economic it at a the the same as in the past two decades, or will environmental energy and the of no be at the of economic The to and Zhang for their and support was provided by the China National Research and the China National