The level of sulphur dioxide in the air in the Cottonera area has decreased substantially since 2004 due to reduced emissions from the Marsa power station, studies have shown.
On the other hand, levels of nitrogen oxides, benzene and other compounds are relatively high due to intensive traffic in the area.
Emissions resulting from shipyard activities, including particulate matter, were significant at times.
In a presentation on water and air quality in Cottonera, Professor Victor Axiak, head of the University’s Biology Department, unveiled a collection of studies conducted by the research group within his department over the past 20 years.
The presentation formed part the Skopri l-Università fit-Tlett Ibliet (Discover University in the Three Cities) initiative.
The main contributor to the decrease is most probably the changeover from one per cent to 0.7 per cent sulphur heavy fuel oil, which reduced the Marsa power station’s emissions. The changeover took place in August 2010.
The news comes as the Marsa power station is being temporarily fired up again to make up for a shortfall of energy caused by damages to the new plant extension at Delimara. The Government has said the damage should take an estimated six months.
Prof. Axiak explained the historic development and growth of the Three Cities were directly related to the maritime developments of Grand Harbour and the Drydocks.
He said the Three Cities were born out of such activities and therefore had an effect on the quality of air and sea surrounding them.
Moreover, the Cottonera region had one of the highest population densities in Malta. While the average population density for Malta is 1,200 people for every square kilometre, in Senglea it is 15,000 people over the same area.
Prof. Axiak said such a high population density, as well as the heavy traffic in the area, pose additional risks to the environmental quality.
Studies over the years have identified the Marsa Power Station, the Drydocks, maritime activities within Grand Harbour, several locations dealing with oil and fuel storage and bunkering, heavy traffic, and a number of potential sewage overflows lining the coastline as the main risks to the environment.
Turning to the quality of water around the Three Cities, Prof. Axiak said the shores of Senglea, Vittoriosa and Cospicua are unfit for bathing, with relatively high levels of sewage pollution.
All waters within Grand Harbour were officially designated as unsuitable for bathing, and are not included in the national monitoring programme for bathing waters.
In the Cottonera area, this recurrent sewage pollution is probably due to overflows from a number of sources along the coastline.
These marine emissions are also responsible for the poor water quality with respect to water transparency, excessive nutrients and chlorophyll levels, which makes water green and sometimes smelly.
Other marine pollutants directly related to maritime activities within Grand Harbour and the shipyards include oil and fuel residues, and heavy metals, he said.
Brief reference was also made to pollution by tributyltin (TBT) which was used as anti-fouling agent in marine paints.
Prof. Axiak said this pollutant was found to cause what is known as “imposex” whereby female snails used to grow a penis.
In the late 1990s and early 2000s, all such snails collected from the Grand Harbour, including along Cottonera coastline, were affected by imposex.