论文部分内容阅读
A toxic-cadmium spill in January left 3.7 million residents in Liuzhou City in south China’s Guangxi Zhuang Autonomous Region struggling to find a secure supply of drinking water.
Contamination was first detected in the Longjiang River on January 15 when hundreds of dead fish were discovered in the river’s upper reaches. The river is a major tributary of the Liujiang River that runs through Liuzhou.
The Environmental Protection Bureau of Hechi, a city upstream on the Longjiang River, tested local water and discovered cadmium levels higher than those permitted by national safety standards. In the worsthit areas, water samples indicated that cadmium levels were 80 times higher than permitted levels.
Experts with a task force charged with tackling the pollution estimated that about 20 tons of cadmium had been discharged into the Longjiang River, polluting a 300-km stretch of water.
Cadmium is a highly toxic heavy metal used in batteries, electroplating and some industrial paints. Overexposure can lead to fatal liver and kidney damage.
“The metal will have a long-lasting environmental impact on local fish and soil when it sinks into the riverbed,” said Li Li, a researcher with the Chinese Research Academy of Environmental Sciences.
The incident has led to an overhaul of factories and facilities that use heavy metals along the Longjiang River. Investigators have identified Guangxi Jinhe Mining Co. Ltd. and the Hongquan Lithopone Materials Plant as the primary suspects behind the illegal discharge of cadmium. As of February 15, nine people were detained on suspicion they were responsible for the contamination.
Initial investigations show that a lack of pollution treatment facilities, the illegal discharge of toxic sewage and poor supervision by local authorities were the primary causes for the spill.
Ma Jun, Director of the Institute of Public and Environmental Affairs (IPEA), a Beijing-based environmental NGO, said that the pollution was a warning for Hechi, one of the country’s most important mineral producing centers, to tighten regulation of
the industry.
“Lack of proper monitoring in mines poses a threat to local people’s health and damages the environment,” Ma said.
Yet, the cadmium spill is just one of a series of major heavy metal pollution incidents reported in recent years.
Statistics from the Ministry of Environmental Protection (MEP) show that more than 30 serious cases of heavy metal pollution by chemical, photovoltaic, pharmaceutical and IT companies have taken place in 10 provinces across the country since 2009.
“Heavy metals have become one of the country’s main pollutants, seriously threatening public health,” Minister of Environmental Protection Zhou Shengxian said in a report to the Standing Committee of the National People’s Congress, China’s top legislature, on October 25 last year.
A growing threat
Heavy metals refer to a broad group of toxic elements such as cadmium, lead and chromium, most of which are extremely dangerous and can cause a range of ailments, from diseases of the central nervous system, to problems with internal organs, the skin, bones, and teeth. Unlike organic pollutants, heavy metals do not decay and thus pose a long-term threat to people and the environment.
Heavy metal contamination has become a serious problem in China’s industrial regions. Although the government has invested heav- ily in efforts to curb spills and introduce safer handling of toxic substances, major incidents of heavy metal pollution remain regular occurrences.
A spate of lead poisoning cases and reports of cadmium-contaminated rice in recent years have further pushed the issue of heavy metal into the spotlight.
In April 2009, more than 800 children were diagnosed with elevated levels of lead in their blood in Fengxiang, northwest China’s Shaanxi Province. Soon afterward, hundreds of children were found to be suffering from lead poisoning in Wugang, central China’s Hunan Province. In October that year, almost 1,000 children were diagnosed with elevated lead levels in their blood in Jiyuan, central China’s Henan Province.
In July 2009, more than 500 villagers fell sick and two died after being exposed to cadmium that was illegally dumped into the Liuyang River by the Xianghe Chemical Plant in Liuyang, Hunan Province.
In March 2011, more than 160 residents, including 53 children, living near a battery factory in Taizhou, east China’s Zhejiang Province, were diagnosed with excessive lead levels in their blood.
Despite receiving more attention from the media and the general public, heavy metal contamination has not diminished. Instead, it becomes more serious with China’s rivers, seas and farmland absorbing more and more pollutants daily.
Heavy metal pollution stems from hundreds of different sources, but it mostly comes from the purification of metals during the manufacturing process.
According to the MEP, 72 percent of China’s more than 44,600 chemical companies are located on a river bank and 12.2 percent are situated less than 1 km from environmentally sensitive areas, including vital sources of drinking water.
In 2010, a total of 960 of 10,896 companies producing heavy metals were found to be in violation of environmental standards and were ordered to reduce their emissions and enhance safety procedures, the ministry said.
Besides manufacturing, the waste dumped by chemical factories and mines is among the major causes of metal poisoning in the country.
Due to its rapid development, China has seen a steady increase in the amount of industrial waste it produces.
“As of 2012, a total of 19.28 million tons of chromium residue, a hazardous waste material generated during the production of chromium metal and chromium salt, have been released into the country’s environment,” said Zhou.
Ma warned that the residue had gradually penetrated into underground water sources and farmland.
A case in point is an incident in southwest China’s Yunnan Province between April and June last year in which two truckers were accused of dumping more than 5,000 tons of chromium-contaminated waste near a reservoir and on hills around villages in Qujing, causing 77 head of livestock to die and threatening the health of tens of millions of people.
On August 13, 2011, Qujing authorities said in a press release that the illegally dumped chromium slag came from the local Yunnan Luliang Chemical Plant.
Last September, the police arrested five suspects for allegedly dumping the waste.
“Chromium poses great health dangers. Drinking water polluted with it could cause acute poisoning,” said Liu Xiaoduan, a researcher with the Chinese Academy of Geological Sciences.
Land pollution
To protect people and the environment from chromium residue, the State Council, China’s cabinet, ordered in 2005 all local governments around the country to deal with chemical waste within five years. But to date, this task remains incomplete.
In 2006, a severe case of cadmium contamination poisoned 150 residents in Xinma Village in Hunan. Two villagers died as a result of the contamination.
The incident was part of a much wider problem with vast tracts of land on the banks of the Xiangjiang River in Hunan found to be riddled with pollutants. People eating rice and vegetables grown on this land regularly succumbed to illnesses or contracted cancers.
Hunan is known for its huge deposits of nonferrous metals in China. But a lack of regulation and environmental consciousness means that the expanding production of nonferrous metals is turning out to be a major source of toxic pollution in the province.
The Xiangjiang River, which supports 60 percent of the province’s population and 70 percent of its industrial output, has become one of the country’s most polluted rivers.
The poisoning of Xinma villagers and the degradation of their land by pollutants is just one example of a widespread problem affecting swathes of land.
“Pollution has been around for a long time but a lot of incidents have been concealed,”said Chen Tongbin, Director of the Research Center of Environment Restoration at the Chinese Academy of Sciences (CAS).
Chen said that heavy metal pollution is more acute in south China where mining is prevalent. “Heavy metals not only pollute the soil, they also poison rice paddies, especially in Hunan and Jiangxi provinces,” he said.
According to data from the CAS, 715,000 hectares of land in Hunan, or roughly 3.4 percent of the province’s total area, is contaminated by heavy metals.
Another study conducted by the Ministry of Land and Resources in Hunan identified elevated levels of heavy metals in a 250 km by 10 km belt adjacent to the Dongting Lake, China’s second largest freshwater lake. Nearby crops, reeds and shellfish were found to have been contaminated by cancer-causing cadmium.
“Over the entire country, more than 10 million hectares of arable land, accounting for 8.3 percent of the country’s total surface area, have been polluted by heavy metals,” said Minister Zhou, adding that the pollution has wreaked havoc in areas such as the Yangtze River Delta, the Pearl River Delta, and also in Beijing, Tianjin and Hebei Province in north China.
In February 2011, the Nanjing Agricultural University released results of a survey, revealing that about 10 percent of the rice sold in some regions was contaminated with cadmium.
Wang Zuwei, a professor at the College of Urban and Environment Science at Tianjin Normal University, said that cadmium, chromium and arsenic were the major pollutants found in China’s farmland.
In addition to widespread ill health, the pollution leads to a reduction in grain production. According to the Ministry of Land and Resources, heavy metal pollution results in a loss of more than 12 million tons of grain annually, causing direct economic losses of 20 billion yuan ($3.17 billion) every year.
Zou Ji, Vice Dean of the School of Environment and Natural Resources at the Renmin University of China in Beijing, said that because heavy metals in soil do not decay over time and cannot be removed like organic pollutants, scientists have not yet found an economically viable means of converting heavily polluted land into arable land.
“After frequent consumption of poisonous food, heavy metals will accumulate in the human body and cause a series of ailments, which are irreversible,” Zou said.
Despite this, heavy metal-related pollution has not yet been taken seriously in some places. Though the pollution is invisible to the public in its primary stages, Zhou Xinxin, Deputy Director of the Hubei Provincial Bureau of Environmental Protection, said that the worsening situation should be mainly blamed on the inaction of some officials who put economic growth figures ahead of environmental protection.
Media reports in June 2010 said that the government of Leiyang, a city in Hunan, failed to shut down a number of illegal smelting operations that were producing heavy metal pollution, in defiance of repeated orders from provincial authorities.
“China has enacted laws against air and water pollution, but still lacks a policy framework and applicable laws to fight the contamination of the soil,” said Li Fasheng, a researcher with the Chinese Research Academy of Environmental Sciences.
“Land pollution, if not brought under control, will become irreversible in a couple of years, posing serious threats to food safety, human health and social stability,” he warned.
Tighter measures
In April 2011, China issued its first five-year plan for heavy metal pollution prevention and control. It pledges efforts to cut the emission of lead, mercury, chromium, cadmium and arsenic in key regions to 15 percent of the levels recorded in 2007 by 2015.
The plan mainly targets 14 provinces and autonomous regions vulnerable to heavy metal contamination. In these areas, regulatory efforts will focus on 138 communities and 4,452 enterprises, including mines, smelters and battery manufacturers.
Minister Zhou estimated a total of 75 billion yuan ($11.90 billion) would be needed to address pollution over the five-year period.
In order to increase action by local governments against heavy metal pollution, Zhou urged the establishment of an accountability system, stipulating that officials should be accountable for pollution incidents in their regions.
In a separate move, the MEP launched a nationwide campaign to bring listed companies that discharge heavy metal pollutants under tighter scrutiny in June last year. A total of 80 companies listed on Shanghai and Shenzhen stock exchanges were mandated to have their pollution treatment facilities and procedures evaluated.
In August 2011, the MEP took an unprecedented step to release detailed pollution information on more than 1,900 leadacid battery facilities across the country. It was the first time information on an entire industry’s environmental performance was made public.
Reactions to the initiative were overwhelmingly positive. Close scrutiny of the data by the media, environmental NGOs and the public resulted in corrections, which helped the ministry to better supervise the listed facilities. Updated data were released to the public in November.
Ma with the IPEA believes better access to information and government transparency are key to tackling heavy metal pollution and supervising polluters.
“We need to promote government information disclosure and public participation so that local protectionism and wrongdoing can be exposed,” said Ma.
In January, the IPEA published a status report on the handling of information disclosure by 113 cities. The report graded cities on their transparency and found that the cities averaged slightly more than 40 points on a scale of 100. That’s an improvement over the 31-point average three years ago.