Biodegradation in soil of hydrophobic pollutants in nonaqueous‐phase liquids (NAPLs)

A study was conducted to determine the mineralization in soil and subsoil of hydrophobic organic compounds present in several nonaqueous‐phase liquids (NAPLs). When present in soil in some NAPLs, di(2‐ethylhexyl) phthalate (DEHP) was not appreciably mineralized, phenanthrene was slowly transformed after an acclimation phase, and hexadecane and naphthalene were biodegraded rapidly. The extent of suppression of biodegradation of test compounds varied with different solvents as NAPLs. The rate of mineralization in subsoil of phenanthrene dissolved in some NAPLs was very slow, but additions of N and P enhanced the degradation. The addition of N and P to soil did not increase the mineralization of DEHP dissolved in NAPLs. The existence of a NAPL in polluted environments may thus markedly affect the susceptibility of organic compounds to biodegradation.