When we think about mercury pollution, our minds immediately turn to industrial activities and the use of fossil fuels. It's not just this. A team of MIT researchers has discovered a surprising link between deforestation and increased mercury emissions, opening up new perspectives on the fight against this insidious environmental contaminant.
A significant contribution to global emissions
The study, published in Environmental Science and Technology (I link it here) is eloquent. It reveals that approximately 10% of anthropogenic mercury emissions are due to global deforestation. A particularly alarming fact if we consider that deforestation has not so far been included among the main sources of mercury pollution.
The researchers traced the path of the substance from its emission sources to its places of deposition, mainly through precipitation or absorption by forest ecosystems. The results show that the vegetation, in particular the Amazon rainforest, also plays a crucial role in absorbing mercury from the atmosphere.
The importance of forests as mercury sinks
Plant leaves absorb mercury from the atmosphere similar to how they absorb carbon dioxide. However, unlike carbon dioxide, mercury does not perform an essential biological function for plants. It remains mainly inside the leaves until they fall to the forest floor, where it is absorbed.
This process of sequestration by forests is vital to reducing the amount of toxic methylmercury in the oceans. When mercury reaches bodies of water, it can be transformed into methylmercury by microorganisms and bioaccumulated through the food chain, leading to risky levels of this potent neurotoxin in fish that are then consumed by humans.
The urgency of tackling deforestation
In light of these findings, it becomes clear that the fight against deforestation must be an essential component of global efforts to reduce mercury pollution. The researchers make the easy prediction that if the current rate of deforestation remains unchanged or accelerates, net emissions of this substance will continue to increase.
In particular, the Amazon rainforest contributes approximately 30% of global absorption by emerged lands. Curbing deforestation in the Amazon could therefore have a substantial impact on reducing mercury pollution globally.
Reforestation: part of the anti-mercury solution, but not enough
As with CO2, few illusions: reforesting will not save us. It is not enough. Of course, the authors of the study estimate that reforestation efforts on a global scale could increase annual mercury uptake by about 5%. While this is a significant contribution, the researchers emphasize that reforestation alone cannot replace global pollution control efforts.
We need an integrated approach that includes both the protection of existing forests and the reduction of mercury emissions from industrial sources. Only through coordinated action on multiple fronts will it be possible to effectively address this environmental and health threat.
