Processes controlling diurnal variations of PCDD/Fs in the New Jersey coastal atmosphere

• Published in: Atmospheric environment (1994) 2003-03, Vol.37 (7), p.959-969
• Main Authors: Lohmann, Rainer, Brunciak, Paul A, Dachs, Jordi, Gigliotti, Cari L, Nelson, Eric, Ry, Daryl Van, Glenn, Thomas, Eisenreich, Steven J, Jones, Joanne L, Jones, Kevin C
• Format: Article
• Language: English
• Subjects: Air–water exchange; Applied sciences; Atmospheric pollution; Boundary layer height; Diurnal; Exact sciences and technology; Marine; OH-radical reactions; PCDD/Fs; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/S1352-2310(02)00971-8

Consecutive 12 hour day–night air samples (∼500 m 3 each) were taken over 7 days at three land-based sites and an over-water site in coastal New Jersey (NJ) in July 1998, in a campaign designed to shed light on factors controlling ambient PCDD/F concentrations. The sampling sites were chosen to reflect contrasting environments: urban/industrial from the center of the New York (NY)–NJ metropolitan area (Liberty Science Center, LSC); coastal Atlantic (Sandy Hook, SH); suburban NJ (New Brunswick, NB); over-water in Raritan Bay (RB). Despite proximity to the major NY/NJ conurbation, ambient PCDD/F concentrations in the region were low compared to literature data for other urban locations. Mean ∑Cl 4–8DD/Fs and ∑TEQ (in fg/m 3) were: 1400 and 16 at NB; 1000 and 9.5 over RB; 880 and 8.5 at LSC; and 830 and 6.6 at SH. Di- and tri-chlorinated dibenzo- p-dioxins and -furans (PCDD/Fs) were also measured and dominated the ∑Cl 2–8DD/F concentrations. Air–water exchange calculations demonstrated the relative importance of Cl 2–3DD volatilizing from the Lower Hudson River Estuary for ambient concentrations (∼25% of advection), but was of minor importance for the other PCDD/Fs. The study provides evidence that advective transport, local inputs and atmospheric processes combine in a complex manner to control ambient PCDD/F concentrations. These processes generally dominate any local diurnal influence of OH-radical-mediated depletion, which we had hypothesized would be detectable by measuring higher night- and day-time concentrations. Rather, it is implied that changes in the mixed boundary layer height resulted in higher night- than daytime concentrations at the urban and coastal sites. A strong diurnal signal, dominated by the lower chlorinated dioxins and furans, was detected at the rural site (NB) during a period of lower wind speeds.