With a host of educational institutions, Xianlin Science City in Nanjing, Jiangsu province, is a true center for learning. It can also teach a few lessons in environmental rejuvenation.

Men net fish at a reclaimed lake in Huaibei, Anhui province, in May. The wetland park was once a dug-out area of Yangzhuang Coal Mine. Chen Banggan / for China Daily

Authorities in Jiangsu have spent 140 million yuan ($22 million) in a decade converting former mines into green spaces, and as a result have seen a boom in development.

"Planting trees at these sites has turned deserted areas into beautiful scenery," said Liu Zhenping, geological environment director for the Jiangsu Land and Resources Department.

It has also brought potential economic benefits, he said, adding that more than 60 hectares of land have been reclaimed, worth an estimated 2 billion yuan.

More than 230,000 people work and live in Xianlin Science City, which covers 47 square kilometers and is home to 12 colleges, including Nanjing University, and four middle and primary schools.

Officials are now aiming to repeat the success nationwide.

The target is to reforest the majority of mines near key ecologically fragile areas and residential areas by 2015, according to Tao Qingfa, deputy director of the geological environment department at the Ministry of Land and Resources.

Speaking at a national conference on Aug 3, he said that between June and December authorities will record all former mines that need to be planted with trees, draw up an environmental recovery plan and report to the ministry.

The re-greening of disused mines is urgent because the mining industry has brought severe environmental problems, such as land subsidence, soil pollution and a lowering of the groundwater level, said Zhang Jinde, senior engineer of the China Geological Environmental Monitoring Institute.

By the end of 2010, mines had damaged nearly 4 million hectares of land, left more than 4,500 areas threatened by land subsidence and caused direct economic losses of about 34 billion yuan, according to the Ministry of Land and Resources.

Every year, on average, mines in China are estimated to discharge nearly 5 billion tons of polluted water.

"If we want to recover the damage caused by mining activities, trillions of yuan are needed with dozens of years to go at least," said Zhang, adding that at least the country is starting on its way.

In Jiangsu, the common method of environmental recovery is to lay fertile earth over the mined land and then plant trees to restore the area, Liu explained.

But tree planting is just the first step, said Zhang.

"Environmental recovery to avoid potential geological disasters and environmental pollution is the final goal.

"For nonferrous metal mines, how to solve soil pollution and repair the damaged groundwater system are still under research," he added.

The country is on its way toward restoring the environment around mines with a specialized environmental recovery fund for mines established in 2001. Nearly 60 billion yuan has been allocated as of 2011, reclaiming about 496,000 hectares of land, the ministry said.

Since 2005, the Ministry of Land and Resources launched the national mine park's construction program and 61 deserted mines across the country received approval for building parks.

wangqian@chinadaily.com.cn