Ilhan Olmez

Emissions of trace elements from motor vehicles: Potential marker elements and source composition profile

Abstract The phasing-out of leaded gasoline has rapidly reduced the value of Pb, the traditional marker element for emissions from gasoline-powered vehicles for receptor-model studies. Also, the emission characteristics have changed considerably due to factors such as modern catalytic converters and changes in motor oil additives. These changes have made current motor-vehicle source composition profiles questionable. In this study we attempted to identify marker elements and to develop a new source composition profile for motor vehicle emissions. To accomplish this, we collected numerous samples directly from motor ovehicles and in locations that are heavily influenced by these emissions. All the samples were analysed for trace element concentrations by Instrumental Neutron Activation Analysis (INAA). Rare earth elements (REEs) are used in catalytic supports and have been suggested as possible marker elements for motor vehicle emissions. Our results show that considerable amounts of Zn, Br, and Sb are emitted by motor vehicles: their combined emissions are much larger than the sum of the REEs. Also Sb, Zn, and Br have smaller coarse/fine particle ratios (C/F ratios) than do the REEs. It is suggested that Sb, Br, and Zn are potential marker elements. Furthermore, based on our analysis, a partial elemental composition library for motor vehicle emissions is updated and a brief discussion of the origins of elemental constituents from motor vehicle exhausts is given.

Concentration and Composition of Atmospheric Aerosols from the 1995 SEAVS Experiment and a Review of the Closure between Chemical and Gravimetric Measurements

ABSTRACT We summarize the results from the various measurements and the inter-sampler comparisons from Southeastern Aerosol and Visibility Study (SEAVS), a study with one of its objectives to test for closure among chemical, gravimetric and optical measurements of atmospheric aerosol particles. Sulfate and organics are the dominant components of the SEAVS fine particles (nominally, particles with aerodynamic diameter <2.5 u,m) but between 28 and 42% (range over various samplers) of the gravimetrically measured total fine particle concentration is unidentified by the chemical measurements. Estimates of water associated with inorganic components and measurement imprecision do not totally explain the observed difference between gravimetric and chemical measurements. We examine the theoretical and empirical basis for assumptions commonly made in the published literature to extrapolate total fine particle concentration on the basis of chemical measurements of ions, carbon and elements.

A composite receptor method applied to philadelphia aerosol

Particles were collected in dichotomous samplers at three sites in the Philadelphia area during summer, 1982, and analyzed by x-ray fluorescence, instrumental neutron activation, pyrolysis, and ion chromatography. An intermethod comparison showed that fine-fraction results agreed within measurement error for S, Ca, Mn, Fe, Zn and Sb. A composite of chemical mass balance, multiple linear regression, and stratification by wind direction was used to apportion mass into ten categories. Primary emissions from residual-oil combustion, catalytic crackers, an antimony roaster, and municipal incinerators contributed less than 10% of PM-10. The portions of average PM-10 attributed to crustal matter and vehicle exhaust were 17 + or - 2 and 6 + or - 2, respectively. That attributed to sulfate plus related water and ions was 50 to 55%. Wind-stratified data indicated that 80 + or - 20% of the sulfate was from a regional background. Multiple linear regression of S vs tracers Se and either V or Ni indicated that 72 + or - 8 and 16 + or - 5% could be attributed to coal- and residual oil-fired power plants, respectively.

Composition of fine particle regional sulfate component in Shenandoah Valley

Fine fractions of atmospheric particulate samples collected over 3 weeks in July/Aug 1980 in Shenandoah Valley, VA, and previously analyzed by X-ray fluorescence analysis to provide data for many additional elements. Modified factor analysis of the combined data yielded a regional sulfate component containing S, NH/sub 4//sup +/, V, Mn, Zn, Se, As, In, Sb, And Pb. If the component originates mainly from coal combustion, there is modification of the elemental composition pattern during transport from distant mental composition pattern during transport from distant power plants to the receptors, even in the <2.5-..mu..m fraction. The regional sulfate component should be used in receptor-model treatments of areas strongly affected by sulfate from distant sources, as it may account for substantial fractions of several airborne elements, especially Se and Mn. Particulate S/Se mass ratios from this and other work are usually in the vicinity of 3300 in areas not immediately affected by fresh SO/sub 2/ sources, but drop significantly near such sources.

Distribution of trace elements in selected pulverized coals as a function of particle size and density

Abstract Trace elements in coal have diverse modes of occurrence that will greatly influence their behavior in many coal utilization processes. Mode of occurrence is important in determining the partitioning during coal cleaning by conventional processes, the susceptibility to oxidation upon exposure to air, as well as the changes in physical properties upon heating. In this study, three complementary methods were used to determine the concentrations and chemical states of trace elements in pulverized samples of four US coals: Pittsburgh, Illinois No. 6, Elkhorn and Hazard, and Wyodak coals. Neutron Activation Analysis (NAA) was used to measure the absolute concentration of elements in the parent coals and in the size- and density-fractionated samples. Chemical leaching and X-ray absorption fine structure (XAFS) spectroscopy were used to provide information on the form of occurrence of an element in the parent coals. The composition differences between size-segregated coal samples of different density mainly reflect the large density difference between minerals, especially pyrite, and the organic portion of the coal. The heavy density fractions are therefore enriched in pyrite and the elements associated with pyrite, as also shown by the leaching and XAFS methods. Nearly all the As is associated with pyrite in the three bituminous coals studied. The sub-bituminous coal has a very low content of pyrite and arsenic; in this coal arsenic appears to be primarily organically associated. Selenium is mainly associated with pyrite in the bituminous coal samples. In two bituminous coal samples, zinc is mostly in the form of ZnS or associated with pyrite, whereas it appears to be associated with other minerals in the other two coals. Zinc is also the only trace element studied that is significantly more concentrated in the smaller (45 to 63 μm) coal particles.

Atmospheric trace element concentrations over the eastern Mediterranean Sea: Factors affecting temporal variability

Concentrations of elements and ions were measured in aerosol samples collected between March 1992 and December 1993 at a rural station on the Mediterranean coast of Turkey. Concentrations of pollution-derived elements are lower than corresponding concentrations reported for the western Mediterranean region, due to the longer distances traveled by the particles to reach the eastern Mediterranean region. Concentrations of elements vary on timescales ranging from days to seasons. Short-term variations in the concentrations of pollution-derived elements are explained by transport from source regions. Short-term variations in the concentrations of sea-salt and crustal elements, on the other hand, are due to the episodic nature of wind-induced particle generation mechanisms. Transport failed to explain long-term variations due to lack of seasonal changes in air mass transport patterns. The seasonal variations in the concentrations of anthropogenic elements are determined by the wet deposition of particles, which is more extensive in the wet season, and distances between source regions and the sampling site. The long-term variations in the concentrations of crustal and sea-salt elements are explained by seasonal changes in their source strengths. Distant rains on the path of the air masses which transport anthropogenic particles to the eastern Mediterranean are more influential on the observed seasonal behavior of pollution-derived elements than local rain events.

A new approach to understanding multiple-source groundwater contamination: Factor analysis and chemical mass balances

Abstract Groundwater contamination studies are becoming more important particularly concerning their ability to identify specific sources of the contamination. In most cases, groundwater contamination studies are based upon general physical and/or chemical characterization of subsurface waters and provide information only as to whether a specific sample from a particular aquifer is being contaminated or not. A technique utilizing instrumental neutron activation analysis together with principal componene factor analysis and chemical mass balances has been shown to be a useful tool in helping to differentiate among several possible sources for groundwater contamination. In addition, this technique has been utilized to apportion relative contributions from each source of contamination.

Atmospheric mercury in the vapor phase, and in fine and coarse particulate matter at Perch River, New York

Daily samples of size segregated atmospheric particulate matter (da < 2.5 μm, and 2.5 μm < da < 10 μm), and vapor-phase mercury have been collected at five locations in upstate New York over a period of two years. Atmospheric concentrations were determined for mercury and, in the particulate matter, for up to 38 other elements by Instrumental Neutron Activation Analysis (INAA). At the Perch River sampling site, the average vapor-phase mercury concentration was 2.4 ng m−3 with a seasonal pattern of higher winter and lower summer concentrations observed over both years of sampling. The average fine and coarse particulate concentrations were 0.058 and 0.025 ng m−3, respectively. Concentrations for the particulate concentrations followed a log-normal frequency distribution with the most frequently occurring value for fine particulates being 0.012 ng m−3 and for coarse particulates 0.009 ng m−3. Episodic high concentrations of both fine and coarse particulate mercury indicate the impact of specific s ources. No correlation was found among the three different types of samples on either an overall or daily basis. By applying factor analysis (FA) to the data and using known marker species for specific types of emissions, the sources of the particulate mercury were identified and their contributions estimated. Fine particulate mercury concentrations were primarily associated with regional sources in the midwestern U.S.A., with copper smelting, and with the combined influence of aluminum and precious metals processing. Coarse particulate mercury concentrations were principally related to local aluminum processing facilities. The source identification results of the FA were confirmed by examining back-projected, mixed-layer wind trajectories. From February 1993 through the end of the particulate sampling in September 1993 fine particulate mercury concentrations declined significantly possibly due to the installation of particulate controls at one or more of the copper smelters.

Chemical composition of particles in the black sea atmosphere

Abstract Shipborne samples collected from the Black Sea atmosphere were analysed by instrumental neutron activation analysis, atomic absorption spectrometry and ion chromatography for approximately 40 elements and ions. Concentrations of most of the elements are found to be a factor of two higher in the western part of the Black Sea than corresponding concentrations in the eastern part. Main source regions for anthropogenic elements were in Europe. The WNW, WSW and SSW sectors together account for 70% of observed concentrations of elements. Principal component analysis showed a crustal, a marine and three anthropogenic factors. Two of the anthropogenic factors were the result of long-range transport of particles and the third indicated a local iron and steel industry. Atmospheric fluxes of elements to the Black Sea were calculated using observed concentrations, scavenging ratios and precipitation data and results were compared with riverine fluxes of elements. For crustal elements, riverine fluxes were found to be dominant, but for pollution-derived elements, atmospheric fluxes were comparable to riverine fluxes to the Black Sea.

Particle bioturbation in Massachusetts Bay: preliminary results using a new deliberate tracer technique

To better understand temporal and particle size-dependent bioturbation processes, we conducted a study of sediment mixing in Massachusetts Bay using a newly developed deliberate tracer technique. Sediments from a 32-m, fine-grained site were collected and the 38-62 («silt») and 63-125 («sand») μm fractions isolated. These particle-size fractions were labeled with two different noble metals (Au: silt & Ag: sand) using a thermal diffusion technique. Mixtures of the tracers were spread onto the seafloor in April and July 1992 by divers and were tube-cored (3 replicates) ∼ 80 d later in each case. Vertical profiles of the tracers were measured at μg/g (Ag) and ng/g (Au) levels by instrumental neutron activation analysis