Chemical pollution

?Though not as impactful as compaction issues, road soils can also face severe issues associated with reduced resource flow (water, nutrients, oxygen, etc.), changes to soil chemistry, and generation of sediment pollution through erosional processes.
?Pollutants such as heavy metals, organic compounds, and nitrogen-oxide compounds from fuel leaks and gaseous emissions contaminate soils, water bodies, and the atmosphere with many deleterious impacts for the ecosystems in which roads exist. Heavy metals accumulate in soil and biota, and both these and other chemical pollutants can enter the local watershed and have impacts downstream. Vehicle-related contaminants are commonly detected near roads and can be dispersed hundreds of meters into ecosystems.
?Chemical contamination decreases exponentially with distance from roads , but can still reach great distances if transported by water.
?Biota sensitive to road contaminants or other effects suffer, potentially hindering restoration efforts. Since seeding with native species is a common restoration method, pollution preventing the growth of plants  introduced during decommissioning activities can impede restoration efforts.