The distributions of BTEX compounds in the ambient atmosphere of the Nan-Ji-Do abandoned landfill site in Seoul

Abstract

In this study, the concentrations of major aromatic volatile organic compounds (VOCs) which include benzene, toluene, m-xylene, p-xylene, o-xylene, and ethylbenzene were measured at the Nan-Ji-Do (NJD) landfill site during the spring and fall season of 2000. According to our study, the mean (and median) concentration values for these VOC species were computed to be 1.65 (1.12) ppb for benzene, 9.62 (6.63) ppb for toluene, 1.84 (1.08) ppb for m, p-xylene, 0.83 (0.46) ppb for o-xylene, and 1.17 (0.78) ppb for ethylbenzene; large differences in two statistical terms appear to originate from the consistent occurrences of data sets with unusually high concentrations such that they induce eccentricities in the predictable, Gaussian-type patterns of their frequency distribution. The concentration levels of major aromatic species in our study area, when compared with those of other environmental settings, are slightly higher or comparable to those typically found in urbanized areas affected by various anthropogenic source types. The findings of the moderately high concentration levels at NJD may reflect at least partially the effects of efficient mixing at high elevation of 95 m, despite the fact that large quantities of VOCs are emitted from this landfill area. Inspection of our measurement data further indicated that in many occasions these VOCs can be subordinate to different, but distinctive, patterns of periodicity over diurnal or seasonal scale. Results of correlation analysis indicate that toluene is correlated most significantly and abundantly with both VOC and the concurrently determined environmental parameters, while benzene lacks strong correlations even with other aromatic VOCs. In light of the peculiarity in the behavior of benzene, we suggest that the processes affecting BTEX levels in the landfill area may be distinguished from other source processes that can also be important in the urbanized areas.