Henry's Law coefficients of chloropicrin and methyl isothiocyanate

Henry's Law coefficients were measured for the first time for chloropicrin and methyl isothiocyanate (MITC) at 25 °C in deionized water, in 0.10 M NaCl, in 0.20 M NaCl, and in pH 4.0 and 8.0 buffered solutions. For chloropicrin, the Henry's Law coefficient was 2.1±0.3 atm M⁻¹, and did not show significant pH dependence or dependence on ionic strength. For MITC, the coefficient was much smaller, 0.06±0.05 atm M⁻¹. The Henry's Law coefficient for MITC did show dependence on ionic strength, increasing to 0.14±0.05 atm M⁻¹ at 0.20 M, but did not appear to depend on pH. MITC has a much stronger tendency to remain in solution than chloropicrin. The transport of chloropicrin from solution to the atmosphere is likely to be significant environmentally, while MITC shows a much lower rate of volatilization. When transferred to the atmosphere, oxidation and photochemical reactions are likely to dominate the transformation of both chloropicrin and MITC, rather than heterogenous reactions.     

Hydrophobic organic compound partitioning from bulk water to the water/air interface

Partitioning of hydrophobic organic compounds to the interface between water and air may significantly affect the distribution and transfer of many xenobiotic chemicals between vapor and aqueous phases. The fluorescent probe, 1-methylperylene, was used to investigate the affinity of hydrophobic compounds for the water–air interface by varying the ratio of interfacial surface area to water volume in a fused-quartz cuvette. We found that the water–air/water interface partitioning coefficient [K_w−awi=1.2 mol cm^-2_awi/(mol ml^-1_w)] for this polycyclic aromatic hydrocarbon (PAH) was quantitatively consistent with partitioning to the same interface but from the airside, recently reported in the literature for less hydrophobic PAHs. Our results demonstrate significant partitioning from bulk water to the water/air interface for a hydrophobicity range relevant to many xenobiotic compounds. Anticipated implications of this process for the environmental chemistry of hydrophobic compounds include retarded gas-phase transport in unsaturated soils, bubble-mediated transport in water, droplet-mediated transport in the atmosphere, and photochemical reactions.     

Partitioning of formaldehyde between air and ice at −35°C to −5°C

The equilibrium partitioning of formaldehyde (HCHO) between air and snow was studied in a series of laboratory experiments conducted at −5°C, −15°C, and −35°C, in order to understand how partitioning of HCHO between air and polar snow varies with temperature, and thus seasonally on the ice sheet. Measured partitioning coefficients were 56, 93, and 245 mol l⁻¹ atm⁻¹ for −5°C, −15°C and −35°C, respectively, showing a similar trend as the values previously estimated from field observations. Estimates of the pseudo-first-order rate coefficient for air–snow exchange for the same three temperatures were 4.1×10⁻⁴, 1.1×10⁻⁴, and 1.1×10⁻⁵ s⁻¹, respectively. This implies a time scale for air–snow equilibration of the order of hours to days for HCHO accumulated at or near the ice–air interface on snow grains. Comparing the current laboratory partitioning coefficients with those estimated from measurements of air and freshly fallen snow in Greenland during summer demonstrates that the snow is supersaturated and should degas HCHO to the surrounding air. During this degassing, polar snow should be a significant source of HCHO to the lower troposphere.     

Treatment of 1,3-Butadiene in an Air Stream by a Biotrickling Filter and a Biofilter

ABSTRACT

This paper presents results obtained from a performance study on the biotreatment of 1,3-butadiene in an air stream using a reactor that consisted of a two-stage, in-series biotrickling filter connected with a three-stage, in-series biofilter. Slags and pig manure-based media were used as packing materials for the biotrickling filter and the biofilter, respectively. Experimental results indicated that, for the biotrickling filter portion, the butadiene elimination capacities were below 5 g/m³/hr for loadings of less than 25 g/m³/hr, and the butadiene removal efficiency was only around 17%. For the biofilter portion, the elimination capacities ranged from 10 to 107 g/m³/hr for loadings of less than 148 g/m³/hr. The average butadiene removal efficiency was 75–84% for superficial gas velocities of 53–142 m/hr and a loading range of 10–120 g/m³/hr. The elimination capacity approached a maximum of 108 g/m³/hr for a loading of 150 g/m³/hr. The elimination rates of butadiene in both the biotrickling filter and biofilter were mass-transfer controlled for influent butadiene concentrations below about 600 ppm for superficial gas velocities of 29–142 m/hr. The elimination capacity was significantly higher in the biofilter than in the biotrickling filter. This discrepancy may be attributed to the higher mass-transfer coefficient and gas-solid interfacial area offered for transferring the gaseous butadiene in the biofilter.     

Feasibility of a simple laboratory approach for determining temperature influence on SPMD–air partition coefficients of selected compounds

Semipermeable membrane devices (SPMDs) are a widely used passive sampling methodology for both waterborne and airborne hydrophobic organic contaminants. The exchange kinetics and partition coefficients of an analyte in a SPMD are mediated by its physicochemical properties and certain environmental conditions. Controlled laboratory experiments are used for determining the SPMD–air (K_sa's) partition coefficients and the exchange kinetics of organic vapors. This study focused on determining a simple approach for measuring equilibrium K_sa's for naphthalene (Naph), o-chlorophenol (o-CPh) and p-dichlorobenzene (p-DCB) over a wide range of temperatures. SPMDs were exposed to test chemical vapors in small, gas-tight chambers at four different temperatures (−16, −4, 22 and 40 °C). The exposure times ranged from 6 h to 28 d depending on test temperature. K_sa's or non-equilibrium concentrations in SPMDs were determined for all compounds, temperatures and exposure periods with the exception of Naph, which could not be quantified in SPMDs until 4 weeks at the −16 °C temperature. To perform this study the assumption of constant and saturated atmospheric concentrations in test chambers was made. It could influence the results, which suggest that flow through experimental system and performance reference compounds should be used for SPMD calibration.     

Survey of polyfluorinated chemicals (PFCs) in the atmosphere over the northeast Atlantic Ocean

High volume air sampling in Bermuda, Sable Island (Nova Scotia) and along a cruise track from the Gulf of Mexico to northeast coast of the USA, was carried out to assess air concentrations, particle-gas partitioning and transport of polyfluorinated chemicals (PFCs) in this region. Samples were collected in the summer of 2007. Targeted compounds included the neutral PFCs: fluorotelomer alcohols (FTOHs), perfluoroalkyl sulfonamides (FOSAs) and perfluoroalkyl sulfonamido ethanols (FOSEs).Among the FTOHs, 8:2 FTOH was dominant in all samples. Sum of the concentration of FTOHs (gas+particle phase) were higher in Bermuda (mean, 34 pg m^?3) compared to Sable Island (mean, 16 pg m^?3). In cruise samples, sum of FTOHs were highly variable (mean, 81 pg m^?3) reflecting contributions from land-based sources in the northeast USA with concentrations reaching as high as 156 pg m^?3.Among the FOSAs and FOSEs, MeFOSE was dominant in all samples. In Bermuda, levels of MeFOSE were exceptionally high (mean, 62 pg m^?3), exceeding the FTOHs. Sable Island samples also exhibited the dominance of MeFOSE but at a lower concentration (mean, 15 pg m^?3). MeFOSE air concentrations (pg m^?3) in cruise samples ranged from 1.6 to 73 and were not linked to land-based sources. In fact high concentrations of MeFOSE observed in Bermuda were associated with air masses that originated over the Atlantic Ocean.The partitioning to particles for 8:2 FTOH, 10:2 FTOH, MeFOSE and EtFOSE ranged from as high as 15 to 42% for cruise samples to 0.9 to 14% in Bermuda. This study provides key information for validating and developing partitioning and transport models for the PFCs.     

Transport of SO2 and aerosol over the Yellow sea

Aircraft measurements of air pollutants were made to investigate the characteristic features of long-range transport of sulfur compounds over the Yellow Sea for the periods of 26–27 April and 7–10 November in 1998, and 9–11 April and 19 June in 1999, together with aerosol measurements at the Taean background station in Korea. The overall mean concentrations of SO₂, O₃ and aerosol number in the boundary layer for the observation period ranged 0.1–7.4 ppb 32.1–64.1 ppb and 1.0–143.6 cm⁻³, respectively. It was found that the air mass over the Yellow Sea had a character of both the polluted continental air and clean background air, and the sulfur transport was mainly confined in the atmospheric boundary layer. The median of SO₂ concentration within the boundary layer was about 0.1–2.2 ppb. However, on 8 November, 1998, the mean concentrations of SO₂ and aerosol number increased up to 7.4 ppb and 109.5 cm⁻³, respectively, in the boundary layer, whereas O₃ concentration decreased remarkably. This enhanced SO₂ concentration occurred in low level westerly air stream from China to Korea. Aerosol analyses at the downstream site of Taean in Korea showed 2–3 times higher sulfate concentration than that of other sampling days, indicating a significant amount of SO₂ conversion to non sea-salt sulfate during the long-range transport.     

Characterization of odor released during handling of swine slurry: Part II. Effect of production type,storage and physicochemical characteristics of the slurry

The quality of rural life can be affected by offensive odors released from animal buildings and storage units. The objectives of this study were to compare the concentrations of odor and odorants above different types of stirred swine slurry to analyze the relationships between concentrations of odor (and odorants) and physicochemical characteristics of the slurry (i.e. pH, temperature, dry matter, volatile solids, and concentration of 22 chemical compounds); and to propose predictive models for the odor concentration (OC) based on these physicochemical characteristics (solely and in combination with concentrations of specific odorants in the air above the slurries). The study comprised data on concentrations of odor and odorants in the air above slurry samples (fresh and/or stored) collected from production units with farrowing sows, finishing swines, or weaning pigs at eight swine operations (N = 48). OC measured in the air above stirred swine slurry samples were not significantly different among production types or storage times. The physicochemical characteristics of the slurries were not useful for predicting OC or concentrations of hydrogen sulfide (or organic sulfides) above the slurry, but were related to concentrations of other emitted gases such as phenols and indoles (r² = 0.65–0.79, p <0.05), ammonia (r² = 0.86, p < 0.05) and carboxylic acids (r² = 0.23–0.59, p <0.05). There was good precision of predictive models of OC based on selected slurry characteristics (i.e. pH, dry matter, nitrogen content, sulfur content or concentrations of individual aromatic compounds and carboxylic acids) together with concentrations of specific odorants in the air (e.g. hydrogen sulfide) (r² between 0.70 and 0.92). This study suggests that predictive models could be useful for evaluating odor nuisance potentials of swine slurry during handling.     

SVOC partitioning between the gas phase and settled dust indoors

Semivolatile organic compounds (SVOCs) are a major class of indoor pollutants. Understanding SVOC partitioning between the gas phase and settled dust is important for characterizing the fate of these species indoors and the pathways by which humans are exposed to them. Such knowledge also helps in crafting measurement programs for epidemiological studies designed to probe potential associations between exposure to these compounds and adverse health effects. In this paper, we analyze published data from nineteen studies that cumulatively report measurements of dustborne and airborne SVOCs in more than a thousand buildings, mostly residences, in seven countries. In aggregate, measured median data are reported in these studies for 66 different SVOCs whose octanol-air partition coefficients (K_oa) span more than five orders of magnitude. We use these data to test a simple equilibrium model for estimating the partitioning of an SVOC between the gas phase and settled dust indoors. The results demonstrate, in central tendency, that a compound’s octanol-air partition coefficient is a strong predictor of its abundance in settled dust relative to its gas phase concentration. Using median measured results for each SVOC in each study, dustborne mass fractions predicted using K_oa and gas-phase concentrations correlate reasonably well with measured dustborne mass fractions (R² = 0.76). Combined with theoretical understanding of SVOC partitioning kinetics, the empirical evidence also suggests that for SVOCs with high K_oa values, the mass fraction in settled dust may not have sufficient time to equilibrate with the gas phase concentration.     

复合生物滤池处理H2S和NH3的挂膜与工艺条件

采用复合生物滤池(生物滴滤池 生物过滤池)处理H2S和NH3组成的混合恶臭气体,填料分别为经表面改性的天然斜发沸石和木屑.实验研究了该工艺的驯化挂膜情况和主要工艺条件,结果表明,天然斜发沸石和木屑改性后,驯化挂膜周期为10～14 d,比文献中颗粒活性炭挂膜缩短14～18 d.复合生物滤池的最佳工艺条件为:高度120 cm,循环液流量4.56 L/h.同时,生物滴滤池处理水溶性好的NH3气体效果较生物过滤池好,而生物过滤池处理水溶性差的H2S气体较生物滴滤池好.因此,复合生物滤池可用于处理不同水溶性的混合恶臭气体.     

Polycyclic aromatic hydrocarbons in Costa Rican air and soil: A tropical/temperate comparison

Surface soil and passive air samples from a network of 23 sampling sites across Costa Rica were analyzed for polycyclic aromatic hydrocarbons (PAHs), allowing for an evaluation of absolute levels, spatial distribution patterns, air/soil concentration (A/S) ratios and relative composition. Annual mean concentrations of four-ring PAHs in air were low (median of approximately 40 pg m⁻³), except in Costa Rica's densely populated central valley (approximately 650 pg m⁻³). PAH concentrations in soil were also low (median of 5 ng g⁻¹ dry weight) and comparable to those reported for other tropical regions. These low soil concentrations result in A/S ratios of four-ring PAHs in Costa Rica that are higher than the equilibrium air–soil partitioning coefficients and also higher than A/S ratios reported for temperate locations. A series of model calculations of increasing complexity were used to seek an explanation for variable A/S ratios of PAHs under tropical and temperate conditions. Temperature-driven changes in air–soil partitioning and differences in PAH degradability under temperate and tropical conditions are insufficient to explain the higher soil concentrations and lower A/S ratios in temperate regions. However, these can be explained by atmospheric deposition of PAHs during historical periods of much higher emissions and air concentrations and by persistence of PAHs in soils on the order of decades. Low PAH concentrations in tropical soils were found to be consistent with constant or increasing emissions, and in particular, do not require that degradation rates in soil are much faster than in temperate areas. In comparison to temperate soils, soils from Costa Rica and other tropical regions have a higher relative abundance of the lighter PAHs. This likely reflects a higher source contribution from biomass burning in the tropics, as well as the preferential loss of lighter PAHs from temperate soils that experienced high PAH deposition in the past.     

Polyfluorinated compounds in ambient air from ship- and land-based measurements in northern Germany

Neutral volatile and semi-volatile polyfluorinated organic compounds (PFC) and ionic perfluorinated compounds were determined in air samples collected at two sites in the vicinity of Hamburg, Germany, and onboard the German research vessel Atair during a cruise in the German Bight, North Sea, in early November 2007. PUF/XAD-2/PUF cartridges and glass fiber filters as sampling media were applied to collect several fluorotelomer alcohols (FTOH), fluorotelomer acrylates (FTA), perfluoroalkyl sulfonamides (FASA), and perfluoroalkyl sulfonamido ethanols (FASE) in the gas- and particle-phase as well as a set of perfluorinated carboxylates (PFCA) and sulfonates (PFSA) in the particle-phase. This study presents the distribution of PFC in ambient air of the German North Sea and in the vicinity of Hamburg for the first time. Average total PFC concentrations in and around Hamburg (180 pg m^?3) were higher than those observed in the German Bight (80 pg m^?3). In the German Bight, minimum–maximum gas-phase concentrations of 17–82 pg m^?3 for ΣFTOH, 2.6–10 pg m^?3 for ΣFTA, 10–15 pg m^?3 for ΣFASA, and 2–4.4 pg m^?3 for ΣFASE were determined. In the vicinity of Hamburg, minimum–maximum gas-phase concentrations of 32–204 pg m^?3 for ΣFTOH, 3–26 pg m^?3 for ΣFTA, 3–18 pg m^?3 for ΣFASA, and 2–15 pg m^?3 for ΣFASE were detected. Concentrations of perfluorinated acids were in the range of 1–11 pg m^?3. FTOH clearly dominated the substance spectrum; 8:2 FTOH occurred in maximum proportions. Air mass back trajectories, cluster, and correlation analyses revealed that the air mass origin and thus medium to long range atmospheric transport was the governing parameter for the amount of PFC in ambient air. Southwesterly located source regions seemed to be responsible for elevated PFC concentrations, local sources appeared to be of minor importance.     

Use of thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS) on identification of odorant emission focus by volatile organic compounds characterisation

Volatile organic compounds (VOCs) from several different municipal solid wastes’ treatment plants in Mallorca (Spain) have been analysed by thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). Ambient (immission) air was collected during February and March 2011 by active sampling onto sorbents Tenax™ TA and Carboxen™ 1000. The study presents the chemical characterisation of 93 volatile organic compounds (VOCs) from an overall set of 84 immission air samples. 70 VOCs were positively identified.The linear fit for all 93 external standard calibration, from 10 mg L⁻¹ to 150 mg L⁻¹ (n = 4), was within the range 0.974 < r² < 0.998. Limits of detection of the method (LOD) for all the standards were within the range 1.1–4,213 pg, as the absolute standard amount spiked into sorbent tubes in 1 μL standard mixture (dissolved in methanol).Overall results stated systematic correlation between waste’s nature and VOCs’ air composition. Organic wastes show main contribution of terpenes, waste water sludge residues’ of reduced sulphured compounds (RSCs) and municipal solid wastes show contribution of a wide sort of VOCs. The use of a chemometric approach for variable’s reduction to 12 principal components enables evaluation of similarities and dissimilarities between facilities. PCA clearly related samples to its corresponding facility on the basis of their VOCs composition and the ambient temperature.     

Speciation of volatile organic compounds from poultry production

Volatile organic compounds (VOCs) emitted from poultry production are leading source of air quality problems. However, little is known about the speciation and levels of VOCs from poultry production. The objective of this study was the speciation of VOCs from a poultry facility using evacuated canisters and sorbent tubes. Samples were taken during active poultry production cycle and between production cycles. Levels of VOCs were highest in areas with birds and the compounds in those areas had a higher percentage of polar compounds (89%) compared to aliphatic hydrocarbons (2.2%). In areas without birds, levels of VOCs were 1/3 those with birds present and compounds had a higher total percentage of aliphatic hydrocarbons (25%). Of the VOCs quantified in this study, no single sampling method was capable of quantifying more than 55% of compounds and in several sections of the building each sampling method quantified less than 50% of the quantifiable VOCs. Key classes of chemicals quantified using evacuated canisters included both alcohols and ketones, while sorbent tube samples included volatile fatty acids and ketones. The top five compounds made up close to 70% of VOCs and included: 1) acetic acid (830.1 μg m^?3); 2) 2,3-butanedione (680.6 μg m^?3); 3) methanol (195.8 μg m^?3); 4) acetone (104.6 μg m^?3); and 5) ethanol (101.9 μg m^?3). Location variations for top five compounds averaged 49.5% in each section of the building and averaged 87% for the entire building.     

Broadband UV spectroscopy system used for monitoring of SO2 and NO emissions from thermal power plants

A gas monitoring system based on broadband absorption spectroscopic techniques in the ultraviolet region is described and tested. The system was employed in real-time continuous concentration measurements of sulfur dioxide (SO₂) and nitric oxide (NO) from a 220-ton h^?1 circulating fluidized bed (CFB) boiler in Shandong province, China. The emission coefficients (per kg of coal and per kWh of electricity) and the total emission of the two pollutant gases were evaluated. The measurement results showed that the emission concentrations of SO₂ and NO from the CFB boiler fluctuated in the range of 750–1300 mg m^?3 and 100–220 mg m^?3, respectively. Compared with the specified emission standards of air pollutants from thermal power plants in China, the values were generally higher for SO₂ and lower for NO. The relatively high emission concentrations of SO₂ were found to mainly depend on the sulfur content of the fuel and the poor desulfurization efficiency. This study indicates that the broadband UV spectroscopy system is suitable for industrial emission monitoring and pollution control.     

The effects of evaporating essential oils on indoor air quality

Essential oils, predominantly comprised of a group of aromatic chemicals, have attracted increasing attention as they are introduced into indoor environments through various forms of consumer products via different venues. Our study aimed to characterize the profiles and concentrations of emitted volatile organic compounds (VOCs) when evaporating essential oils indoors. Three popular essential oils in the market, lavender, eucalyptus, and tea tree, based on a nation-wide questionnaire survey, were tested. Specific aromatic compounds of interest were sampled during evaporating the essential oils, and analyzed by GC-MS. Indoor carbon monoxide (CO), carbon dioxide (CO₂), total volatile organic compounds (TVOCs), and particulate matters (PM₁₀) were measured by real-time, continuous monitors, and duplicate samples for airborne fungi and bacteria were collected in different periods of the evaporation. Indoor CO (average concentration 1.48 vs. 0.47 ppm at test vs. background), CO₂ (543.21 vs. 435.47 ppm), and TVOCs (0.74 vs. 0.48 ppm) levels have increased significantly after evaporating essential oils, but not the PM₁₀ (2.45 vs. 2.42 ppm). The anti-microbial activity on airborne microbes, an effect claimed by the use of many essential oils, could only be found at the first 30–60 min after the evaporation began as the highest levels of volatile components in these essential oils appeared to emit into the air, especially in the case of tea tree oil. High emissions of linalool (0.092–0.787 mg m⁻³), eucalyptol (0.007–0.856 mg m⁻³), d-limonene (0.004–0.153 mg m⁻³), ρ-cymene (0.019–0.141 mg m⁻³), and terpinene-4-ol-1 (0.029–0.978 mg m⁻³), all from the family of terpenes, were observed, and warranted for further examination for their health implications, especially for their potential contribution to the increasing indoor levels of secondary pollutants such as formaldehyde and secondary organic aerosols (SOAs) in the presence of ozone.     

生物滴滤-生物过滤组合工艺处理汽车喷漆废气中试研究

采用中试规模的生物滴滤-生物过滤组合工艺设备处理某汽车厂喷漆车间废气,研究了组合式反应器对废气的净化效果和2处理单元对污染组分的去除能力及微生物特性.该汽车厂喷漆车间废气中的主要组分为甲苯、二甲苯、乙酸乙酯、乙酸丁酯、丁醇、丙酮和甲基丙基甲酮.组合式反应器对废气中的污染物有较好的处理效果,但不同的污染组分在不同处理单元...     

Influence of temperature on formaldehyde emission parameters of dry building materials

The diffusion coefficient, D, partition coefficient, K, and the initial volatile organic compounds (VOCs) in dry building materials, are the three key parameters used to predict the VOC emissions. D and K may be strongly affected by temperature. We have developed a new and simple method, the C-history method, to measure the diffusion coefficient, D and the partition coefficient, K of formaldehyde in dry building materials at temperatures of 18, 30, 40 and 50 °C. The measured variations of the diffusion coefficients and the partition coefficients with temperature for particle board, vinyl floor, medium- and high-density board are presented. A formula relating the partition coefficient and related factors is obtained through analysis. This formula can predict the partition coefficient in principle and provide an insight for fitting experimental data, and it agrees well with the experimental results.     

Further studies of oxidation processes on filter surfaces: Evidence for oxidation products and the influence of time in service

The sensory pollutants emitted by loaded ventilation filters are assumed to include products formed via oxidation of organics associated with captured particles. In this study, experiments were performed that used either particle production or ozone removal as probes to further improve our understanding of such processes. The measured ratio of downstream to upstream submicron particle concentrations increased when ozone was added to air passing through samples from loaded particle filters. Such an observation is consistent with low volatility oxidation products desorbing from the filter and subsequently partitioning between the gas phase and the surface of particles that have passed through the filter, including particles that were previously too small (<20 nm) to be detected by the instrument used in these studies. A related set of experiments conducted with unused filters and filters that had been in service from 2 to 16 weeks found that ozone removal efficiencies changed in a manner that indicated at least two different removal mechanisms—reactions with compounds present on the filter media following manufacturing and reactions with compounds associated with captured particles. The contribution from the former varies with the type and manufacturer of the filter, while that of the latter varies with the duration of service and nature of the captured particles. In complimentary experiments, a filter sample protected from ozone during its 9 weeks of service had higher ozone removal efficiencies than an identical filter not protected from ozone during the same 9 weeks of service filtering the same air. This result indicates that a filter's exposure history subsequently influences the quantity of oxidation products generated when ozone-containing air flows through it.     

The effect of temperature on the gas–particle partitioning of reactive mercury in atmospheric aerosols

Measurements of gas–particle-partitioning coefficients for reactive mercury in dry urban and laboratory aerosol were found to strongly depend on ambient temperature. Samples of atmospheric and laboratory aerosols (defined as both the gas and particle phases) were collected using filter and absorbent methods and analyzed for reactive mercury using thermal desorption combined with cold vapor atomic fluorescence spectroscopy. Synthetic ambient aerosols were generated in the laboratory from ammonium sulfate and adipic acid mixed with mercuric chloride in a purpose-built aerosol reactor. The aerosol reactor was operated in a temperature-controlled laboratory. Linear relationships between the logarithm of inverse gas–particle partitioning and inverse temperature were observed and parameterized for use in the atmospheric modeling of reactive mercury. Reactive mercury was observed to partition from the particle to the gas phase as ambient temperature increased. Good agreement between measurements made using urban and laboratory aerosols was seen after gas–particle-partitioning coefficients were normalized for surface area instead of mass. Thermodynamic analyses of the urban and laboratory gas–particle-partitioning measurements revealed that the strength of interaction between reactive mercury and particle surfaces was suggestive of chemisorption. Gas–particle-partitioning coefficients made with the Tekran ambient mercury analyzer (AMA) also showed a dependence on temperature. However, the Tekran AMA partitioning coefficients did not agree well with partitioning coefficients measured using the filter-based methods. The disagreement is consistent with the 50 °C operational temperature of the Tekran AMA.