China Environmental News Digest

Daily updated Environmental news related to China

Wednesday, February 22, 2006

Scientists use plants to clean area of polluted soil

BEIJING, Feb. 21 (Xinhuanet) -- Chinese scientists are improving the technology to "suck up" poisonous elements, mostly heavy metals like arsenic, copper and zinc, from polluted soil to repair contaminated lands.

some parts of China, scientists have grown poison-accumulating plants, widely regarded as a "hyperaccumulators" in academic circles, in poisonous soil to accumulate heavy metals, which are to be recycled and further processed into useful industrial materials, said Chen Tongbin, a senior researcher with the Geographic Science and Resources Institute of the Chinese Academy of Sciences (CAS), in an exclusive interview with Xinhua on Tuesday.

research team has begun to renovate more than 5,000 mu (about 333.3 hectares) of arsenic polluted fields in south China'sHuanjiang County, Hechi City of Guangxi Zhuang Autonomous Region.

said when floods occur in south China's Yunnan and Guangxi,water containing minerals at the upper reaches of rivers always pollute lower watercourses, causing crop losses or even infertility in large area of lower-reach fields.

5,000-mu soil pollution in Guangxi is serious. Soil contamination is the most dangerous because it is hidden, slow and fundamental," said Chen.

is leading the research on soil recovery technology, whichis funded by the state high technology advancement plan and was initiated in March 1986 and is known as the 863 Program.

global leader in technology for collecting arsenic from soil,Chen's team proved that a brake fern widely found in southern China, with the scientific name of Pteris vittata L., has a strongability to draw arsenic from the soil.

density in the mature plant's leaves averages 0.8 percent, a far cry from organic nutrients of nitrogen and phosphorous," said Chen who started a search for the poison-accumulating plant in 1997 throughout the country.

plant could survive a heavily polluted environment with arsenic density of three percent," said Chen, citing that it must be very useful for soil recovery in China's high arsenic concentration areas like Chenzhou in central China's Hunan Province, as well as southwest China's Guizhou Province and north China's Inner Mongolia Autonomous Region, where a large area of arsenic pollution.

the 1980s, global scientists have blazed a new way in cleaning polluted soil with hyperaccumulators. Decontamination by plants and recycling technologies will make heavy industries less environmentally damaging.

is estimated that soil recovery technologies through plants might have a market worth 2 billion US dollars. "It's proven that the hyperaccumulators are the best possible choice for soil recovery," Chen said.

team has zeroed in on 16 such hyperaccumulators which were all found in China, by means of a field survey and greenhouse cultivation. Meanwhile, they have developed several additives which might strengthen their poison collecting abilities, Chen said.

to Chen's research, poisonous arsenic accumulated by the plant can be stored in a safe place within the brake fern's body which exerts little influence on the overall growth of the plant.

team leads the world by using techniques and equipment like simultaneous-radiation and ESEM, an electron microscope, to analyse directly on live plants why hyperaccumulators can sustain huge densities of poisonous elements.

has called for intensified government effort to alert the public to the danger of soil contamination and promote legislationin this regard.

the Law on Prevention of Soil Contamination drafted by China's State Council and aimed at legally binding on practicescausing soil contamination, is about to be submitted to the National People's Congress, China's top legislature, for deliberation


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