Chemical-specific emission rates for simple aromatic and polycyclic aromatic hydrocarbon compounds (PAHs) from bitumens during hot mix asphalt (HMA) production and placement activities were evaluated using a headspace gas chromatography method. Temperature-dependent headspace concentrations of the EPA listed aromatic and polycyclic aromatic compounds were measured in the laboratory using headspace gas chromatographs equipped with a variety of detectors. The methodology has previously been calibrated and verified by a program of simultaneous laboratory and field tests, and is accurate in identifying field inhalation exposure potential to individual compounds in asphalt fumes.The results indicated that chemical-specific emission rates of aromatic and PAHs are strongly linked to both the performance grade of the asphalt binder and the binder temperature. Individual chemical compounds were quantified for 22 paving grade bitumen sources from throughout the United States. Chemical-specific emission rates from each binder were measured at a series of temperatures spanning the range, typically used for application of HMA, and at temperatures well in excess of those used for HMA applications in the United States. Emissions of all detected compounds increased with elevating temperature. The amount and composition of PAHs were markedly influenced by changes in temperature. At binder temperatures at or below 190 • C, only very small amounts of mostly 2-and 3-ringed PAHs were emitted. Concentrations of individual two-ringed PAHs ranged from 0.5 to 11 μg/m 3 at 150 • C and ranged from 2.0 to 100 μg/m 3 at 190 • C. Concentrations of 3-ringed PAHs were below method detection level of 0.1 μg/m 3 and ranged from 0.1 to 120 μg/m 3 at 190 • C. Larger ring number PAHs were below detection at 150 • C and less than 10 μg/m 3 for 4-ringed PAHs at 190 • C. As binder temperature increased above the typical limit for HMA production and application, several PAHs with greater ring numbers (4-, 5-, and 6-ringed PAHs) and more potent toxicity equivalency factors (carcinogenic potential) were detected.

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A gas chromatograph (GC) methodology was developed that considers film thickness, aggregate surface area, and mix temperatures, since these variables are expected to influence the production of potentially odorous volatile organic compounds (VOCs). Fifteen grams of 3 mm diameter glass beads (used to simulate a single fine size aggregate) is placed in a standard GC vial, and then coated with 0.5 g of asphalt to produce a film thickness of about 11 µm. This is representative of a typical dense graded hot mix asphalt (HMA) film thickness. The sealed vials are stored in the headspace sampler oven at the desired test temperature for 1 h. During this time, the maximum agitation option on the automated headspace sampler is used to simulate the exposure of the aggregate surface to air when the mix is either mixed in the rotary drum dryer, loaded into the haul trucks, or transferred from the trucks into the paver. This methodology was used to identify and quantify more than 80 VOC compounds found in the vial headspace at 170°C (338°F); this temperature is at the high end of typical temperatures for the majority of HMA production operations. Individual compounds were grouped based on common characteristics: alkanes, heterocyclics, phthalates, aromatics, polyaromatic hydrocarbons (PAH), sulfur-containing, chlorinated, and organic acids. Of these groups, the aromatic, sulfur-containing, heterocyclics, and organic acid compounds have the highest potential for generating odors sometimes associated with HMA production operations. Five pairs of asphalt binders (one with and one without odor complaints) were evaluated using this methodology. In all cases, the asphalt with the reported complaints had either more compounds that exceeded odor thresholds or higher concentrations, or both.

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The taxonomy and physiology of microorganisms isolated from contaminated ground‐water recovery wells prone to biofouling are characterized for an industrial site in Rochester, New York. Principal aquifer contaminants include acetone, cyclohexane, dichloroethane, dichloromethane, 1,4–dioxane, isopropanol, methanol, and toluene. These contaminants represent a significant fraction (up to 95%) of the total organic carbon in the ground water. Ground‐water samples from 12 recovery wells were used to isolate, quantify, and identify aerobic and anaerobic bacterial populations. Samples from selected wells were also characterized geochemically to assess redox conditions and availability of essential and trace nutrients. Dominant bacteria, listed in order of descending numbers, including sulfate‐reducers (Desulfovibrio desulfuricans), anaerobic heterotrophs (Actinomyces, Bacteriodes, Bacillus, Agrobacterium), aerobic heterotrophs (Pseudomonas, Flavobacterium, Nocardia, Citrobacter), iron‐oxidizers (Gallionellaferruginea, Crenothrixpolyspora), iron‐reducers (Shewanella), and sulfur‐oxidizers (Thiobacillusferrooxi‐dans). Fungi were also recovered in low numbers. Both aerobic and anaerobic heterotrophs were able to utilize all principal contaminants as sole carbon and energy sources except 1,4–dioxane. The prevalence of heterotrophic bacteria and their ability to use the available anthropogenic carbon suggests that aerobic and anaerobic heterotrophs contribute to the biofouling of wells at this site, in addition to the often cited fouling due to iron‐oxidizing bacteria and sulfate‐reducing bacteria.