Journey to be 'soil doctors'

A global leader in technology for collecting arsenic from soil, Chen's team discovered Chinese brake fern, Pteris vittata L., which had a strong capacity to extract arsenic from soil in 1999.

Besides the brake fern, the researchers found and cultivated a dozen more such pollution-extracting plants, called by scientists "hyper-accumulators". They had also developed technologies to recycle and further processed the plants into useful industrial materials by biomass incineration.

"It's proven that the hyper-accumulators are the best possible choice for soil recovery as the technology is of lower cost and has lower risk of secondary pollution," Chen said.

China has the largest proven reserves of arsenic with about 70 percent world share, while 61.6 percent of the Chinese reserve was concentrated in Guangxi, Yunnan and Hunan areas, statistics from the Center for Environmental Remediation showed.

"Mine exploration usually leads to soil pollution," the 46-year-old scientist said.

In the early years of his research in the early 1990s, Chen focused on the impact of arsenic pollution and rules of its transfer.

"It was like you knew what disease the patients had but had no drug to cure them," he said. "So from 1995 on, we decided to find ways to repair the contaminated soil."

At that time, soil remediation was still an emerging division for academic research in China.

Less than ten researchers in the country were studying renovation of heavy metal-polluted soil, Chen said. "In contrast, more than 100 institutes and universities are working on the subject now."

"Now soil remediation almost becomes a fashionable word," he said.

Chen's team has been engaging in risk assessment and clean-up of soil in recent years, or "physical examination" and "hospitalized treatment" as Chen described the tasks.

"We can't renovate each piece of land that was polluted because it’s quite costly," he said. "That's why we have to assess the severity and distribution of polluted fields and give treatment accordingly," he said.

"We usually don't recommend patients with a cold to go to hospital," he said.

Chen, however, admitted it was a pity there was no "clear picture" of soil pollution situation in the country, though some experts estimated one fifth, or about 20 million hectares, of China's arable land had been polluted.

Zhang Shanling, soil office head of the Department of Nature and Ecology Conservation under the Ministry of Environmental Protection, said a national soil pollution survey has came to its final stage of data collection, and the result was expected to be worked out by the end of this year.

The government launched China's first soil pollution survey in 2006 backed by a budget of 1 billion yuan.

The program aimed to assess soil quality across the country by analyzing the amount of heavy metals, pesticide residue and organic pollutants in the soil.

Chen Tongbin said his team was now engaging in promoting the use of soil remediation technology through plants to wider regions across the country.

"We hope we can set up more bases in different parts of the country to see to more patients," he said.

"China is a country with a vast territory and varied climates. Though the core technology and engineering application are there, we have to test them in different areas and make adaptations accordingly," he said.

(Xinhua News Agency May 26, 2009)