Dry Deposition of Particulate Polychlorinated Biphenyls and Polycyclic Aromatic Hydrocarbons to Lake Michigan

Abstract

Dry deposition was collected from November 1993 to October 1995 at multiple sites within the Lake Michigan basin to estimate fluxes of particulate polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) as part of the Lake Michigan Mass Balance Study (LMMBS). Samples were also collected during the Atmospheric Exchange over Lakes and Oceans (AEOLOS) project to estimate fluxes to coastal waters adjacent to the Chicago urban area. Fluxes of particulate PCBs and PAHs were higher in Chicago than <15 km offshore and at rural sites. Geometric mean dry deposition fluxes across the Lake Michigan basin ranged from 3.6 to 65 mg/m2-day for particle mass, 0.06 to 0.21 μg/m2-day for Σ-PCBs, and 0.25 to 18 μg/m2-day for Σ-PAHs. Similarities in both the distribution pattern of PCB congeners and PAHs and the magnitude of their fluxes between dry deposition and surficial sediment suggest that dry deposition may dominate loadings to the lake. Conservative estimates of loadings to Lake Michigan through particle dry deposition are estimated to be 1100 kg/yr for PCBs and 5000 kg/yr for PAHs. These loadings are more than 3× greater than loadings by wet deposition and, for PCBs, are similar to inputs by air/water exchange.

Particle-phase dry deposition and air–soil gas exchange of polycyclic aromatic hydrocarbons (PAHs) in Izmir, Turkey

“…The PAH levels at the urban site determined in this study are comparable to those reported by Possanzini et al [30] for downtown Rome and by Halsall et al [31] for urban sites in London and Manchester. Because of their higher volatility, low to medium molecular weight PAHs (3-5 rings) were more abundant in the gas-phase in the present study, similar to the previous studies [24,[32][33][34]. Higher ambient PAH concentrations were measured in the gasphase and 14 PAH concentrations were dominated by lower molecular weight PAHs (Fig.…”

“…The decrease in deposition velocity with increasing molecular weight is supported by other experimental studies which have shown that a greater fraction of the higher molecular weight PAHs are associated with fine particles relative to the lower molecular weight compounds [4,36,37]. A similar decrease in deposition velocity with increasing molecular weight was previously reported for PAHs [4,5,[33][34][35]38]. Table 3 shows the individual PAH concentrations in soils taken from the suburban site.…”

“…Deposition fluxes measured in this study were within the range of values reported previously elsewhere. The particle-phase PAH dry deposition fluxes measured by Franz et al [33] for rural Lake Michigan, and reported by Tasdemir and Esen [34] for Bursa were considerably lower. However, fluxes measured in this study were lower than those reported for urban Chicago [4,33], and for the industrial, urban and rural areas in Taiwan [23].…”

Overall elemental dry deposition velocities measured around Lake Michigan

“…Details about these locations are presented elsewhere Sofuoglu et al, 1998;Franz et al, 1998). The dry deposition samples were collected with Eagle II automatic dry deposition collectors.…”

“…These plates are automatically covered when a moisture sensor detects rain or snow and exposed to the atmosphere during dry periods. The sampler is described in more detail elsewhere (Franz et al, 1998;Sofuoglu, 1996).…”