Research undertaken in the Irati Forest in the western Pyrenees has highlighted how pollutants can settle in ostensibly clean environments, having travelled long distances through the atmosphere.
University of the Basque Country’s IBeA research group examined two species – one of moss, one lichen – to find the extend to which they contained traces of persistent organic compounds (POPs).
Ainara Gredilla, an IBeA researcher said: ‘These organic compounds travel a long way through the atmosphere on the wind and they build up in the environment: they are absorbed and accumulated by living beings.
‘Areas at high altitudes are very sensitive to persistent organic pollutants, so we wanted to find out the extent to which they had accumulated in the lichens and mosses in Irati. In fact, the Irati forest is regarded as a clean environment, since, apart from tourism, there is no human activity other than sustainable livestock and agriculture.’
POPs are a broad category of chemicals that tend not to degrade in the environment. They build up in the food chain, and are known for travelling long distances through the air.
Within the categories of POPs that the team tested for (OCPs, PAHs and PCBs), PAHs were found in concentrations ‘significantly higher’ than the other two.
PAHs are Polycyclic Aromatic Hydrocarbons, a group of chemicals formed during incomplete combustion of organic materials like fossil fuels, often found in smoke and soot.
The team point out that while pollution that is transported over long distances through the atmosphere should not be underestimated, their research also showed that agricultural practices that have been carried out in the area for decades have also affected air quality.
The researchers said: ‘You may think that part of the pollution has come from and continues to come from urban areas, but to a great extent the impact of local agriculture is also significant.
‘Today, there are still controlled burning processes in some areas around the Pyrenees, and we believe that there are still many PAHs coming from there. To reduce the presence of PAHs in the atmosphere of the Irati forest, controlling the combustion processes that take place around the forest is mandatory. On the other hand, traces of pesticides that were used in the past have not been eliminated (OCPs).’
As for PCBs: ‘We suspect they come from electrical insulators used around the Irabia reservoir. It is likely that the PCBs used in the past have remained there and are still detectable today.’
The full research can be read here.