Mepa said today that it is continuing to collect samples of black dust from localities in the south of Malta for analysis, but recent studies showed that the dust recovered from Fgura had different properties from fly ash produced by the power stations.
The samples started being collected in August, but not enough dust has been collected so far to make an analysis feasible and secure.
The authority was reacting to complaints about the presence of the dust, thought to be soot, in various localities. The Opposition this morning called on the government to assume its political responsibilities for the problem, which has existed for years.
Enemalta said the dust could originate from various sources, not necessarily its power stations (see separate stories)
Mepa said a number of samplers were installed in August in agreement with the Fgura council but, to date, due to the intensity of the problem having decreased and following a spate of bad weather very little black dust was collected.
The authority said it wanted to collected the samples using a standard methodology, since the samples given to it by residents were heavily contaminated with dust (from construction), organic matter, matter of insect origin and other detritus.
This is the latest attempt by the authority to discover the source of the dust.
In an ‘initial analysis report on coarse dust in Fgura’ published by the authority last year following a number of complaints from residents in the area in 2007, initial analysis concluded that the black dust, was composed mostly of larger sized particles with diameters larger than 10 micrometres. Larger dust particles were capable of settling down a short time after being emitted, and a short distance away from the source.
Environment director Martin Seychell said that ‘The Stacey Report’, commissioned in 1999 by the Ministry for the Environment, had shed some light on the problem but failed to compare the particles in Fgura to the fly ash emitted by the power station.
The report assumed that once the Fgura “fall out” samples were “similar in appearance to fly ash commonly emitted by power stations” and since trace amounts of vanadium and nickel were detected in these samples, the Marsa Power Station was indicated as the possible source.
In 2007, the authority decided to carry out its own investigation and used The Stacey report as a starting point. It decided on a fresh set of analyses given that the electrostatic precipitators - to reduce dust, were installed in three out of six boilers in early 2000 and that the power stations in Malta shifted to one percent S heavy fuel oil in April 2004 (in order to enable Malta to meet the obligations of the acquis).
Mepa also wanted to try to attempt a comparison between the “fall out” and “fly ash” samples.
Mepa had decided to collect samples from residentsand “fly ash” from a boiler at the Marsa Power Station, grit samples from ship maintenance activities at the Malta Shipyards and a soot sample from the engine of a heavy goods vehicle.
Laboratory tests concluded that while “fly-ash” samples taken from the Marsa Power Station featured levels of vanadium and nickel, commonly found in such plants, no trace of nickel or vanadium was detected in “fall out” samples handed over by the Fgura residents.
Mepa had no hard scientific evidence in favour of the hypothesis that the Marsa Power station was the likely source.
The authority said that recently it also sent samples of “fly ash” to a laboratory abroad for a conventional analysis using wet chemistry. This analysis showed that the average content of nickel, vanadium and magnesium in the “fly ash” from the Marsa Power Station was 8,500 mg/kg of nickel, 33,200 mg/kg of vanadium and 57,000 mg/kg of magnesium.
In parallel a sample of the “fall out” dust obtained from a private residence on the outskirts of Tarxien, which was relatively uncontaminated was also analysed by SEM/EDX at the Heritage Malta Laboratories in Bighi. However, no nickel, vanadium and magnesium were detected in this sample. The average size range of these “fall out” particles was considerably larger than the flyash sample, circa 120µm.
Besides collecting the new samples from around the locality in Fgura, the authority is mapping the complaints from Fgura to investigate the possibility of there being a localised source of pollution. MEPA is committed to ensure that the source of this ‘nuisance’ dust is identified and mitigated.