Release of phthalate esters from a local landfill in the Tibetan Plateau: Importance of soil particle-size specific association

High loads of phthalate esters (PAEs) in background regions can be directly attributed to the local sources, and their association with soil particles may determine the environment behaviors. However, little is known about the particle-size specific distributions of PAEs in soils from point source to the surroundings. In this study, 12 PAE congeners were measured in clay ( < 2 mu m), silt (2-63 mu m) and sand fractions (63-250 mu m) from surficial soils and soil profiles (0-200 cm) around the Lhasa landfill. The total concentrations of PAEs in bulk soils varied from 0.44 to 22.3 mu g/g, with a dominance of bis(2-ethylhexyl) phthalate (DEHP). The day-sorbed PAEs exhibited a decreasing trend with the increasing distance from landfill. This distribution pattern was well described by the Gaussian air pollution model, suggesting the airborne particles/gaseous transport of day-sorbed PAEs. The Boltzmann equation explained the spatial variation of silt-sorbed PAEs, reflecting the atmospheric dispersion of silt-sorbed PAEs. In comparison, the sand-sorbed PAEs in surrounding soils showed downslope accumulation possibly due to the aeolian transport of sand particles. Half-life of the most abundant PAL congener DEHP was assumed based on the soil inventories from observed concentration and the Level III fugacity model simulations, and the results indicated significant longer half-life of DEHP in deeper soils (similar to 24,000 h) than in surficial soils (5500 h). This study elucidates that the distribution and fate of soil PAEs would depend on their association with particles in the source area, and the relative stability of DEHP in deeper soils would further increase PAE inventory in soil compartment. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the particle-size specific distributions of PAEs in soils around a landfill in Lhasa, revealing adsorption characteristics of PAEs in different soil fractions and a significantly longer half-life of DEHP in deeper soils. The findings suggest that the distribution and fate of soil PAEs are influenced by their association with particles, and the stability of DEHP in deeper soils can increase PAE inventory in soil compartments.