TY - JOUR

T1 - Factors Influencing the Soil–Air Partitioning and the Strength of Soils as a Secondary Source of Polychlorinated Biphenyls to the Atmosphere

AU - Cabrerizo, Ana

AU - Dachs, Jordi

AU - Moeckel, Claudia

AU - Ojeda, MariÌa-JoseÌ

AU - Caballero, Gemma

AU - Barceló, Damià

AU - Jones, Kevin C.

PY - 2011

Y1 - 2011

N2 - Soils are a major reservoir of persistent organic pollutants, and soil–air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil–air partition coefficients (KSA) and soil–air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. KSA values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil–air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R2 ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment.

AB - Soils are a major reservoir of persistent organic pollutants, and soil–air partitioning and exchange are key processes controlling the atmospheric concentrations and regional fate of pollutants. Here, we report and discuss the concentrations of polychlorinated biphenyls (PCBs) in soils, their measured fugacities in soil, the soil–air partition coefficients (KSA) and soil–air fugacity gradients in rural background areas of N-NE Spain and N-NW England. Four sampling campaigns were carried out to assess seasonal and daily variability and differences between sampling sites. KSA values were significantly dependent on soil temperature and soil organic matter quantity, and to a minor extent organic matter type. All the PCB congeners in the soil are close to equilibrium with the atmosphere at rural Ebro sites, but soil fugacities tend to be higher than ambient air fugacities in early and late summer, consistent with the influence of temperature on soil–air partitioning. Therefore, during warm periods, soils increment their strength as secondary sources to the atmosphere. The mixture of PCBs found in the atmosphere is clearly strongly influenced by the mixture of PCBs which escape from soil, with significant correlations between them (R2 ranging between 0.35 and 0.74 and p-level <0.001 for the Ebro sampling sites). Conversely, the close-to-equilibrium to net sink status of rural UK sites, suggest a close coupling of air and soil concentrations, but it is not possible to elucidate the importance of these soils as secondary sources yet, and presumably there are still significant primary sources to the regional/global environment.

U2 - 10.1021/es200400e

DO - 10.1021/es200400e

M3 - Journal article

VL - 45

SP - 4785

EP - 4792

JO - Environmental Science and Technology

JF - Environmental Science and Technology

SN - 1520-5851

IS - 11

ER -