Occurrence of volatile and semi-volatile organic compounds in solid waste landfills and their pollution risk to groundwater

The occurrence characteristics of volatile and semi-volatile organic compounds (VOCs/SVOCs) in landfills and the mechanisms driving their migration into groundwater remain unclear. The composition and concentration of VOCs/SVOCs in 14 landfill sites and surrounding groundwater in China were analyzed to explore the distribution characteristics, sources and migration patterns of VOCs/SVOCs in landfills in China. The results showed that, a total of 81 VOCs/SVOCs from nine categories were identified, including monocyclic aromatic hydrocarbons (MAHs), phthalate acid esters and polycyclic aromatic hydrocarbons (PAHs), and which originated mainly from organic solvents and plasticizers. Among the MAHs, ethylbenzene, toluene, m-&p-xylene, and o-xylene (BTEX compounds) were measured at 240.0mg/kg, 147.6mg/kg, 179.9mg/kg, and 75.7mg/kg, respectively. Bis(2-ethylhexyl) phthalate had the highest detection rate (34.4%), and 19 PAHs were detected, with concentrations ranging from 0.1 to 31.4mg/kg. Landfills along the eastern coast exhibited a greater variety of VOCs/SVOCs than inland landfills, and the detection concentrations and rates of VOCs/SVOCs in the middle layer of the landfill were higher. The VOCs were more prone to groundwater migration than the SVOCs, with the order of phenols > anilines > halogenated aromatic and chlorinated aliphatic hydrocarbons > MAHs > PAHs. For the first time, the occurrence characteristics of 81 VOCs/SVOCs in solid waste and their potential influence on groundwater were systematically investigated. This study systematically reveals the pollution risk of VOCs/SVOCs in landfill waste to groundwater and provides a scientific basis for the formulation of pollution control measures. [Display omitted] •BTEX, DEHP, and PAHs were the predominant contaminants in solid waste.•The concentrations of VOCs/SVOCs were highest in the mid-layer of landfills.•Organic solvents and plasticizers were the primary sources of VOCs/SVOCs.•Phenols, anilines and BTEX are more likely to migrate to groundwater.