No place to hide
Move over Erin Brockovich. 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.
Ruffell’s latest research shows that geophysical techniques can be used to characterise the waste.
GPR surveys suggested the presence of a highly conductive waste such as farmyard slurry in a peat bog in Northern Ireland, simply because the suspect pocket in the bog reflected no microwaves.
“Soft, diggable, scented peat bogs make an attractive place to bury waste, but geophysical surveys can see right through them,” Ruffell says. His method requires investigators to walk over the ground above the suspect site, but landowners can refuse to grant them access.
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.
Her research has also shown that it is possible to detect waste from space using satellite images.
As illegally buried waste sites tend to be located near industrial sites, landfills and roads, she drew up a map of potential illegal waste sites in a region of north-east Italy. Her team narrowed down the search by scrutinising IKONOS satellite images for patches of disturbed vegetation.
Of 34 sites identified from space as potential illegal dumps, chemical analyses have shown contamination at 17. Police investigations to track down those responsible have begun.
Via New Scientist