The plants, along with microbes, may have a practical as well as a symbolic role to play in the transformation of derelict urban sites. They are likely to prove a cheap, efficient and safe means of ridding contaminated land of its pollutants.
The drawback, according to scientists and industrialists, is that the Government is not investing enough cash in the research, or imposing enough regulation on landowners, to ensure that Britain is at the leading edge of the developing industry. British research is instead being used in the United States for what could prove for them a useful export trade.
There is a pressing need to bring derelict land into productive use, but until now it has needed heavy investment to clear degraded top soil - producing dust, which is itself hazardous - and replace it with soil from the countryside. The contaminated earth is then dumped on a landfill site, scarring more rural areas. Failure to redevelop abandoned urban sites creates extra pressure to build on greenbelt land.
This process was a factor in persuading the Royal Commission on Environmental Pollution, which reported in February, to argue that more must be done to end the contamination of land. The commission wants land to be better protected from pollution, recognising that the long-term damage to micro- organisms is not understood. Land, the commission says, is in need of comparable protection to water and air, and areas already contaminated should be recovered for beneficial use.
Scientists from around the world are this week looking at one means by which contaminated land could be cleaned. A workshop organised by the quango Horticulture Research International will show how land polluted by pesticides and herbicides can be cleaned in days by the use of bacteria.
While experiments have so far been successful in laboratory conditions, they have not yet been replicated where the microbes have to compete with other bacteria and external factors. But it is believed that eventually the technique will become common practice, with applications in old wood yards and some factories. The process also has exciting potential for cleaning water supplies and clearing up oil spills in seas and rivers.
But derelict sites are more often polluted by metals than by chemicals. Scientists believe they have an equally appropriate, and equally cheap, solution, using accumulator plants. The plants absorb the metals from the soil, allowing the metals to be harvested from the plants, allowing either safer disposal or re-use.
Professor Steve McGrath, senior principal scientist at the Integrated Approach to Crops Research at Rothamsted, Hertfordshire, is leading research into accumulator plants. "We are still at the research stage," he says. "We are seeking funding. It is not a final product. We are dealing with wild plants that have never been grown in a mono-culture. We are still looking for the money for the basic research to improve efficiency."
Rothamsted's researchers would like the work to progress faster, and believe it is hampered by a shortage of financial support. Their frustrations have been exacerbated by watching Americans use their research, to the point at which the US has become leader in the development of the technique.
A tougher regulatory system introduced when the Environment Act comes into force later this year, requiring landowners to take action to clean up contaminated land, should also boost research, says Professor McGrath. But the Environmental Industries Commission, which represents the wastes industry, says that even this is not enough. The EIC is particularly critical that the Landfill Tax, which will levy a charge on disposed wastes, will not apply on contaminated land being cleared, thereby missing an opportunity to give a major boost to research into remediation.
"Regulation has to be looked at in a positive light," says Adrian Wilkes, director of the EIC. "It drives mainstream industry to be more efficient - that has to be good for competitiveness. And it creates demand for our members' products, and that creates a home base for exports.
"The environment technology market is worth at least $250bn worldwide, which makes it larger than pharmaceuticals, and 94 per cent of that is in the rest of the world. But you can't get out there unless you export. That is true especially in land contamination and air pollution. With water pollution, that is not quite so true because of the laws brought in by the European Commission."
Mr Wilkes says that the Government has blocked moves by the EIC for a stricter regulatory regime on land contamination, arguing that there is no competent remediation industry in Britain. "The problem with that argument is that the industry will only develop once the regulations are there," says Mr Wilkes.Reuse content