Human Activities and Bromoform Emissions: The Underestimated Threat to the Earth's Ozone Layer

 Signed in 1987, the Montreal Protocol successfully reduced the release of harmful chemicals that damage the Earth's vital ozone layer. However, one detrimental substance, bromoform (CHBr3), has not been fully addressed, possibly slowing the ozone layer's recovery or even threatening its future.

A study led by the University of Saskatchewan in Canada discovered that human activities release significantly more bromoform than previously thought. Although naturally produced by phytoplankton and algae, bromoform is also a byproduct of chlorine's water sterilization, which humans can control. In fact, considering human-induced sources, global levels of bromoform can be almost a third higher than previously estimated.

This increase has consequences for the ozone layer, which still requires maximum protection. When bromoform decomposes, it releases bromide, which can significantly impact ozone depletion in the lower stratosphere.

Although the Montreal Protocol does not regulate bromoform due to its short lifetime and large natural sources, the study revealed that human activities contribute significantly to the amount of bromoform reaching the Northern Hemisphere's extratropical stratosphere.

According to the researchers, anthropogenic sources, concentrated primarily along coastlines due to industrial and energy production, could increase emissions in the Northern Hemisphere by up to 70.5 percent.

The study combined existing data on bromoform emissions from ship ballast, power plants, and desalination plants, and used simulation models to estimate CHBr3 levels. The researchers found an "excellent agreement" between the models and actual field measurements.

Although it's challenging to determine the exact amount of bromoform released from natural sources like seaweed and phytoplankton, human-related emissions are more significant than previously realized, and currently, no regulations address bromoform emissions.

The Montreal Protocol has been effective in banning harmful chemicals like CFCs (chlorofluorocarbons), preserving the ozone layer as a crucial barrier against ultraviolet radiation. Based on this study, the agreement may require an update to address bromoform emissions and its contribution to ozone depletion.

The research has been published in Geophysical Research Letters.

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