Ayse Bozlaker

Dry deposition and soil-air gas exchange of polychlorinated biphenyls (PCBs) in an industrial area.

Ambient air and dry deposition, and soil samples were collected at the Aliaga industrial site in Izmir, Turkey. Atmospheric total (particle+gas) Sigma(41)-PCB concentrations were higher in summer (3370+/-1617 pg m(-3), average+SD) than in winter (1164+/-618 pg m(-3)), probably due to increased volatilization with temperature. Average particulate Sigma(41)-PCBs dry deposition fluxes were 349+/-183 and 469+/-328 ng m(-2) day(-1) in summer and winter, respectively. Overall average particulate deposition velocity was 5.5+/-3.5 cm s(-1). The spatial distribution of Sigma(41)-PCB soil concentrations (n=48) showed that the iron-steel plants, ship dismantling facilities, refinery and petrochemicals complex are the major sources in the area. Calculated air-soil exchange fluxes indicated that the contaminated soil is a secondary source to the atmosphere for lighter PCBs and as a sink for heavier ones. Comparable magnitude of gas exchange and dry particle deposition fluxes indicated that both mechanisms are equally important for PCB movement between air and soil in Aliaga.

Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma–mass spectrometry: Evidence for the release of platinum group and anthropogenic metals from motor vehicles

Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry (DRC-q-ICP-MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130 ng g(-1) respectively in tunnel dusts while they varied between 6 and 8 ng g(-1), 10 and 88 ng g(-1) and 35 and 131 ng g(-1) in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand anthropogenic influences on their biogeochemical cycling.

Quantifying the Contribution of Long-Range Saharan Dust Transport on Particulate Matter Concentrations in Houston, Texas, Using Detailed Elemental Analysis

The trans-Atlantic transport of North African dust by summertime trade winds occasionally increases ambient particulate matter (PM) concentrations in Texas above air quality standards. Exemptions from such exceedences can be sought for episodic events that are beyond regulatory control by providing qualitative supportive information such as satellite images and back-trajectories. Herein we demonstrate that chemical mass balancing can successfully isolate, differentiate, and quantify the relative contributions from local and global mineral dust sources through detailed measurements of a wide suite of elements in ambient PM. We identified a major dust storm originating in Northwest Africa in mid-July 2008 which eventually impacted air quality in Houston during July 25, 26, and 27, 2008. Daily PM2.5 and PM10 samples were collected at two sites in Houston over a 2-week period encompassing the Saharan dust episode to quantify the transported mineral dust concentrations during this peak event. Average PM concentrations more than doubled during the Saharan intrusion compared with non-Saharan. Relative concentrations of several elements often associated with anthropogenic sources were significantly diluted by crustal minerals coincident with the large-scale Saharan dust intrusion. During non-Saharan days, local mineral dust sources including cement manufacturing and soil and road dust contributed in total 26% to PM2.5 mass and 50% to PM10 mass; during the three-day Saharan episode the total dust contribution increased to 64% for PM2.5 and 85% for PM10. Importantly, this approach was also able to determine that local emissions of crustal minerals dominated the period immediately following the Saharan dust episode: simple quantification of bulk crustal materials may have misappropriated this elevated PM to trans-Atlantic transport of Saharan dust.

Indoor/Outdoor Relationships and Anthropogenic Elemental Signatures in Airborne PM2.5 at a High School: Impacts of Petroleum Refining Emissions on Lanthanoid Enrichment

Outdoor emissions of primary fine particles and their contributions to indoor air quality deterioration were examined by collecting PM2.5 inside and outside a mechanically ventilated high school in the ultraindustrialized ship channel region of Houston, TX over a 2-month period. By characterizing 47 elements including lanthanoids (rare earth elements), using inductively coupled plasma-mass spectrometry, we captured indoor signatures of outdoor episodic emissions arising from nonroutine operations of petroleum refinery fluidized-bed catalytic cracking units. Average indoor-to-outdoor (I/O) abundance ratios for the majority of elements were close to unity providing evidence that indoor metal-bearing PM2.5 had predominantly outdoor origins. Only Co had an I/O abundance ratio >1 but its indoor sources could not be explicitly identified. La and 17 other elements (Na, K, V, Ni, Co, Cu, Zn, Ga, As, Se, Mo, Cd, Sn, Sb, Ba, W, and Pb), including air toxics were enriched relative to the local soil both in indoor and outdoor PM2.5 demonstrating their noncrustal origins. Several lines of evidence including receptor modeling, lanthanoid ratios, and La-Ce-Sm ternary diagrams pointed to petroleum refineries as being largely responsible for enhanced La and total lanthanoid concentrations in the majority of paired indoor and outdoor PM2.5.

Characterization of PGEs and Other Elements in Road Dusts and Airborne Particles in Houston, Texas

It is imperative to quantify a wide range of elements in order to rigorously apportion the myriad sources of airborne particulate matter especially in industrialized urban environments. Herein, our recently reported analytical method that is optimized for the measurements of Rh, Pd, and Pt alongside numerous representative, transition, and lanthanoid elements is described. We also implemented the newly developed technique for the detailed elemental analysis of several tunnel dusts, surface road dusts, and airborne particulate matter collected in the greater Houston, Texas area. Rh, Pd and Pt were highly enriched in dusts swept from the road surface of the Washburn Tunnel averaging 152 ± 52, 770 ± 208 and 529 ± 130 ngg−1 respectively. Their concentrations were significantly lower in surface road dusts with Rh, Pd, and Pt ranging only between 5.9–8.4, 33.0–88.2, and 90.8–131 ngg−1. Average Rh, Pd, and Pt concentrations in ambient aerosols were 1.5, 11.1, and 4.5 pgm−3 in PM2.5 and 3.8, 23.1, and 15.1 pgm−3 in PM10, respectively. Rh, Pd, and Pt levels were elevated in the air inside the Washburn Tunnel reaching 12.5, 91.1, and 30.1 pgm−3 in PM2.5 and 36.3, 214, and 61.1 pgm−3 in PM10, respectively. These are amongst the first such detailed measurements in the United States and represent our efforts to rigorously quantify particulate pollution emanating from light-duty vehicles.