Depositional flux of polychlorinated dibenzo- p-dioxins and polychlorinated dibenzofurans in an urban setting

• Published in: Chemosphere (Oxford) Vol. 64; no. 9; pp. 1550 - 1561
• Main Authors: Correa, Oscar, Raun, Loren, Rifai, Hanadi, Suarez, Monica, Holsen, Thomas, Koenig, Larry
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2006; Elsevier
• Subjects: Air - analysis; Air - standards; Air Pollutants - analysis; Applied sciences; Atmospheric pollution; Benzofurans - analysis; Dibenzofurans, Polychlorinated; Dioxins; Dry; Environmental Monitoring; Exact sciences and technology; Furans; Pollutants physicochemistry study: properties, effects, reactions, transport and distribution; Pollution; Polychlorinated Dibenzodioxins - analogs & derivatives; Polychlorinated Dibenzodioxins - analysis; Texas; Urban air pollution; Urbanization; Wet and bulk deposition; United States; North America; Texas; America; USA, Texas, Houston; USA, Connecticut, Clinton; Dioxins; Urban air pollution; Furans; Dry; Wet and bulk deposition; Atmospheric condition; Dioxin derivatives; Atmospheric fallout; Environmental factor; Air quality; Urban area; Wet deposition; Organic chlorine compounds; Dry deposition; Persistent organic pollutant; Flux density; Air pollution; Pollutant effect; Organic compounds
• DOI: 10.1016/j.chemosphere.2005.11.020
• ISSN: 0045-6535

Dry and wet deposition fluxes of the PCDD/F substituted congeners were measured at two different sites (Clinton Drive and Lang Road) in Houston, TX between December 2003 and April 2004. Average total dry deposition fluxes of 351 and 125 pg m −2 d −1 were found at Clinton Drive and Lang Road, respectively. A wet deposition flux of 2.873 pg m −2 d −1 was measured at the Clinton Drive site. The results indicated that the dry deposition process exhibited spatial variability. In addition, the results also demonstrated that precipitation, although intermittent, is the most important mechanism for the removal of dioxins from atmosphere in the area of study. Combining the contributions of the dry and wet deposition processes at Clinton Drive resulted in a total bulk deposition flux of 527 pg m −2 d −1. The total dry and wet deposition fluxes were dominated by OCDD followed by 1,2,3,4,6,7,8-HpCDD at both sites. Overall average dry deposition velocities of 0.35 and 0.15 cm s −1 were calculated at Clinton Drive and Lang Road sites, respectively. While these velocities were similar to velocities observed in other geographical areas, the contribution of OCDD to the total deposition flux in Houston was significantly higher, probably reflecting the unique nature and character of Houston dioxin sources. The results also showed that lower chlorinated congeners, primarily present in the gas phase, are more likely to be removed from the atmosphere by precipitation. Relationships between the detected congeners in the dry deposition samples and other routinely measured air pollutants/meteorological parameters were found. The results showed that in general, the dry deposition of these congeners was consistently negatively correlated with SO 2 and NO x concentrations in the air and positively correlated with relative humidity. However, more research is needed to ascertain those correlations.