The Impact of Petroleum Mulch on Iran's Sand Dune Soils

You might think of petroleum as just something that fuels our cars. But in the Khuzestan province of Iran, it's also used to fight off the desert. Farmers cover their soil with petroleum to stop wind erosion, a process called mulching. This study found that while this method works, it also comes with a hefty price tag for both humans and the environment. Scientists dug into the sand dune soils at different depths and in areas that have been using petroleum mulch for varying amounts of time. They found that freshly mulched soil (less than 5 years) had the highest levels of polycyclic aromatic hydrocarbons, or PAHs. These are chemicals that can be harmful to both people and wildlife. The good news is that as time passes, the levels of these chemicals drop. But even after 30 to 40 years, the soil still isn't completely clean. The researchers also calculated some risk indices to see how dangerous these chemicals are. They found that the risk is highest in the freshly mulched soil, but even in older samples, there's still some risk. This is especially true for a group of chemicals called alkyl PAHs. While petroleum mulching does help stop the desert from taking over, it's clear that it also hurts the environment. So, it might be time to look for some friendlier ways to keep the sand at bay.