Illegal toxic waste spotted from space

Today's environmental detectives can use radar, helicopters and even satellite images to help them spot illegal toxic waste dumps and help catch those responsible.

Ironically, the tightening of restrictions on waste disposal and the enforcement of new recycling laws have made illegal dumping more likely, turning it into big business for the criminals involved.

The trouble is digging up suspect dumps to investigate their contents can release toxins into local water supplies. But with new remote-sensing techniques, such as ground-penetrating radar (GPR), you can find toxic trash without disturbing the soil. Instead, you bounce microwaves off buried materials and the strength of returning signals provides clues to what they are.

Alastair Ruffell, a forensic geologist at Queen's University, Belfast in the UK, has used GPR in 17 cases for the environment agencies of Scotland, the Republic of Ireland and Northern Ireland. Most are ongoing, however three have resulted in the culprits being jailed and fined.

Sonia Silvestri of the Italian construction firm consortium, Consorzio Venezia Nuova in Venice, has used the transient electromagnetic method to get around such difficulties. TEM is a form of GPR in which electric and magnetic fields are induced in the ground by an electric current pulsing through a coil. It can be carried out from a helicopter hovering 10 metres above the ground. Silvestri recently used the method to identify pollution leaking from a large landfill into groundwater to the north of Padua in north-east Italy. She will present her TEM results at the Twelfth International Waste Management and Landfill Symposium in Sardinia next week.


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