Land Ministry to map the extent of soil contamination by heavy metals

As concerns grow over the safety of food supplies, officials plan to undertake a survey of heavy-metal contamination's distribution

PUBLISHED : Friday, 14 June, 2013, 12:00am
UPDATED : Friday, 14 June, 2013, 4:43am

The Ministry of Land and Resources is compiling a nationwide "pollution map" to gauge the level of heavy-metal contamination in soil due to human activities, according to Xinhua.

This undertaking includes collecting soil samples from across the country and testing levels of 78 chemical elements found in both topsoil - less than 25cm deep - and in samples from at least a metre underground, the report said, citing the ministry and its affiliated China Geological Survey.

No timetable for the survey was given, nor did the report say whether the map would be publicly released amid mounting concerns over food safety due to soil contamination. Recent reports said that almost half of the rice in Guangzhou was found to be tainted with cadmium, a heavy metal that can damage kidneys and bones.

Thus far, researchers have found that soil collected in parts of the mid- and lower reaches of the Yangtze River contained high levels of cadmium, mercury, lead and arsenic. The report also said that some cities were found to have "abnormal levels of radiation", without elaborating.

Meanwhile, heavy-metal pollution in soil has been expanding in densely populated eastern China, compared with samples collected in the 1990s, according to Xinhua.

But some analysts have voiced doubts about the new survey. Mainland authorities have kept under wraps the soil-pollution data gathered during a five-year nationwide investigation, dubbing the information a "state secret".

Chen Nengchang , a researcher with the Guangdong Institute of Eco-environmental and Soil Sciences, said he was a confused to see the new report, as the scale of the new survey was too vague to offer a true picture of soil pollution, while findings from the study jointly conducted by the land ministry and Ministry of Environmental Protection have been keep secret.

"Why don't they do some follow-up research to the 2006 survey and release the information to the public," he asked.

Mainlanders are becoming increasingly worried about the safety of crops and vegetables grown in contaminated soil.

A study published last year in the Journal of Immigrant & Refugee Studies , which said that immigrants to New York from mainland China had higher levels of lead, cadmium and mercury in their blood than those from other Asian countries, went viral online yesterday after the official microblog accounts of Xinhua and CCTV posted a link to the study.

The environmental ministry said in 2006 that more than 10 per cent of farmland on the mainland was polluted, and that about 12 million tonnes of grain were contaminated by heavy metals annually. Updated figures have not been released since then.