Date of Award

Summer 2021

Document Type

Open Access Dissertation

Department

Environmental Health Sciences

First Advisor

Eric Vejerano

Abstract

Volatile organic compounds (VOCs) dominate the class of pollutants that accumulate in the atmosphere and indoors. Partitioning coefficient is a measure of a compound’s ability to distribute between two phases. Assessing the partitioning of VOCs is essential to determine their transport, fate, behavior, and adverse environmental and health impacts across multiple environmental compartments. Studies on VOC partitioning have been limited because discriminating the small mass fraction of VOCs in aerosol particles is difficult to quantify. The partitioning of VOCs into soil, air, and aerosol particle phases was investigated under dynamic laboratory conditions. A bench-scale system that precisely controlled the relative humidity (RH), temperature, and composition of aerosol particles was developed to investigate the partitioning of surrogate VOCs into inorganic (ammonium sulfate) and organic (succinic acid) aerosol particles. The gas-particle partitioning coefficients (Kp) were experimentally derived at different RH levels and temperatures. The soil-to-air partitioning (KSA) was investigated as a function of the soil water and organic matter contents. Partitioning of non-polar substituted aromatics was sensitive to the organic matter content in water-saturated soil. KSA decreased with high water content only for non-polar substituted aromatic VOCs. KSA of VOCs on soil with high organic matter content correlated strongly with the saturated vapor pressure and octanol-air partitioning constant, but not on clay soil. Kp of VOCs decreased as RH levels increased. The amount of VOC that partitioned onto inorganic aerosol particles was significant only at low RH levels, whereas RH levels exceeding 50% have a negligible effect on partitioning. The enthalpy of desorption for trichloroethylene and 1,2-dichlorobenzene partitioning into both aerosol particles was constant over the temperature range of 278.15K to 308.15K, whereas n-butanol exhibited nonlinear temperature dependence. KSA values were used to calculate the VOC concentrations released from a simulated chemical spill under a worst-case scenario, and Kp values were used to calculate the regional deposition of particles into the respiratory tract. Accumulated VOC concentrations in the atmosphere from the soil were below the threshold limits set by regulatory agencies. The mass of deposited aerosol-particle phase VOCs was below 200 pg during a 24 h inhalation.

Rights

© 2021, Jeonghyeon Ahn

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