Site‐Specific Sorption Values for Mixtures of Volatile and Semivolatile Organic Compounds in Sandy Soils

Abstract

AbstractThe purpose of this work was to determine site‐specific partition coefficients, Kd values, for the sorption and desorption of a mixture of 11 volatile and semivolatile organic compounds (VOC and SVOC) in subsurface, low organic soils (average site ƒOC = 0.00019) and ground water from the Toms River superfund site in southern New Jersey. Although literature Kd values are available for some of these compounds, many of the previously published values were measured with single compounds instead of a mixture of compounds. Kd values were determined via column desorption studies using soils with preexisting contamination and uncontaminated site ground water via retardation factors and via batch sorption studies with contaminated ground water and uncontaminated soils. Partition coefficients estimated from the batch and column studies were usually not different across VOC/SVOC and were usually not related to solubility characteristics of the target compounds. Kd values derived from the column experiments were usually an order of magnitude smaller than those estimated from the batch studies. Estimates of Kd values through log KOW or water solubility relationships were usually greater than the experimentally derived Kd values, especially for those compounds with log KOW values greater than 3. Predicted Kd values from the partition models were similar to calculated values for the less hydrophobic compounds (Log KOW < 3). In addition, Kd values determined from batch and column studies were usually smaller than literature values. These comparisons suggest that determining site‐specific partition coefficients is necessary for hydrophobic compounds in soils or sediments that have low organic carbon contents.