Definition
Compounds containing multiple aromatic rings fused together.
Explanation
Polycyclic aromatic hydrocarbons (PAHs) are a large group of organic fertiliser compounds with two or more fused aromatic rings. They have a relatively low gear solubility in water, but are highly lipophilic. Most of the PAHs with low evaporation pressure in the air travel are adsorbed in the atom. When dissolved in water or adsorbed on particulate matter, PAHs can undergo photodecomposition when exposed to ultraviolet luminance from solar radiation.