Determination of the temperature dependence of water solubilities of polycyclic aromatic hydrocarbons by a generator column-on-line solid-phase extraction-liquid chromatographic method

An improved dynamic coupled column liquid chromatographic (DCCLC) technique for determining water solubility data of hydrophobic compounds is presented. The technique is based on pumping water through a thermostated generator column in order to generate emulsion-free, saturated aqueous solutions of the compound under study. Through a switching valve system the solute in the aqueous solution is extracted and concentrated by an on-line solid-phase extraction process and subsequently eluted and analyzed by high performance liquid chromatography (fluorescence detection coupled to photodiode array detection). The improvements carried out to the original DCCLC technique have given rise to savings in time for the experimental work and increased sensitivity during the detection and quantification stage. Applicability of the method for studying highly hydrophobic substances is demonstrated by determining water solubility of anthracene and pyrene in the temperature range of 8.9-49.9 and 8.5-32.2 degrees C, respectively. The measured water solubilities are in good agreement with the best available literature data. The method has also been applied to the determination of water solubility of m-terphenyl, 9, 10-dihydrophenanthrene and guaiazulene, in the temperature range of 4.8-49.9, 4.8-25.0, and 4.5-29.9 degrees C, respectively. The uncertainty in the Sw values determined in this work ranged from 0.7% to 4.6%. The experimental water solubility data, as a function of temperature, are fitted to the equation In Sw = A + B/T; where Sw and T are given in mole fraction and Kelvin, respectively.     

Solubilization, solution equilibria, and biodegradation of PAH's under thermophilic conditions

Biodegradation rates of PAHs are typically low at mesophilic conditions and it is believed that the kinetics of degradation is controlled by PAH solubility and mass transfer rates. Solubility tests were performed on phenanthrene, fluorene and fluoranthene at 20 degrees C, 40 degrees C and 60 degrees C and, as expected, a significant increase in the equilibrium solubility concentration and of the rate of dissolution of these polycyclic aromatic hydrocarbons (PAHs) was observed with increasing temperature. A first-order model was used to describe the PAH dissolution kinetics and the thermodynamic property changes associated with the dissolution process (enthalpy, entropy and Gibb's free energy of solution) were evaluated. Further, other relevant thermodynamic properties for these PAHs, including the activity coefficients at infinite dilution, Henry's law constants and octanol-water partition coefficients, were calculated in the temperature range 20-60 degrees C. In parallel with the dissolution studies, three thermophilic Geobacilli were isolated from compost that grew on phenanthrene at 60 degrees C and degraded the PAH more rapidly than other reported mesophiles. Our results show that while solubilization rates of PAHs are significantly enhanced at elevated temperatures, the biodegradation of PAHs under thermophilic conditions is likely mass transfer limited due to enhanced degradation rates.     

Reductive hydrogenation of polycyclic aromatic hydrocarbons catalyzed by metalloporphyrins

The hydrogenation of polycyclic aromatic hydrocarbons (PAHs) (naphthalene, anthracene, and phenanthrene) catalyzed by metalloporphyrins based on cobalt, nickel or iron was studied in aqueous solutions at room temperature and ambient pressure. Nickel porphyrin (P1) activated by nanosized zero-valent iron (nano-ZVI) and cobalt porphyrins (P2) and (P4) activated by titanium(III) citrate as the electron donor were demonstrated to be promising catalysts for the reductive hydrogenation of PAHs. In particular, partially saturated di-, tetra-, and octahydrogenated products were obtained for anthracene or phenanthrene using a nickel porphyrin activated by nano-ZVI, while naphthalene was transformed to tetralin. Systems containing cobalt porphyrins activated by titanium(III) citrate exhibited a high selectivity and activity toward hydrogenation of anthracene, producing 9,10-dihydroanthracene. However, no formation of hydrogenated hydrocarbons was observed from naphthalene or phenanthrene using cobalt porphyrins.     

Desorption kinetics studies on PAH-contaminated soil under varying temperatures

The purpose of this study was to investigate the effect of temperature on the release of polycyclic aromatic hydrocarbons (PAHs) from aged contaminated soil. The release of fluorene, phenanthrene, anthracene, fluoranthene and pyrene at 7, 15, 18 and 23 degrees C was studied using a column leaching method with a hydraulic retention time of 0.5 h. As the temperature declined from 23 to 7 degrees C the concentrations decreased by a factor of 11-12 for all the studied compounds except for anthracene, which only decreased by a factor 7. Rate constants at maximum release rate at the four studied temperatures were assessed. From temperature dependence studies, apparent activation energies of desorption, E*(des), were calculated. E*(des)-values appeared to be in the range of 105-137 kJ mol(-1) for the studied PAHs and increased with the LeBas molar volume of the compounds. The increase of E*(des) with increased molecular size indicates stronger sorption with increased hydrophobicity of the compounds.     

Physicochemical properties of selected polybrominated diphenyl ethers and extension of the UNIFAC model to brominated aromatic compounds

The aqueous solubilities (S(w)) at various temperatures from 283 K to 308 K and 1-octanol/water partition coefficients (K(ow)) for four polybrominated diphenyl ethers (PBDEs: 4,4'-dibromodiphenyl ether (BDE-15), 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), 2,2',4,4',5-pentabromodiphenyl ether (BDE-99), and 2,2',4,4',5,5'-hexabromodiphenyl ether (BDE-153)) were measured by the generator column method. The S(w) and K(ow) data revealed the effect of bromine substitution and basic structure on S(w) and K(ow). To estimate the infinite dilution activity coefficients (gamma(i)(w,infinity)) of the PBDEs in water from the S(w) data, enthalpies of fusion and melting points for those compounds were measured with a differential scanning calorimeter. Henry's Law constants (H(w)) of the PBDEs were derived from the determined gamma(i)(w,infinity) and literature vapor pressure data. Some physicochemical characteristics of PBDEs were also suggested by comparing the present property data with that of polychlorinated dibenzo-p-dioxins, brominated phenols and brominated benzenes in past studies. Furthermore, in order to represent different phase equilibria including solubility and partition equilibrium for other brominated aromatic compounds using the UNIFAC model, a pair of UNIFAC group interaction parameters between the bromine and water group were determined from the S(w) and K(ow) data of PBDEs and brominated benzenes. The ability of the determined parameters to represent both properties of brominated aromatics was evaluated.     

Bioconcentration of polycyclic aromatic hydrocarbons by the freshwater oligochaete Lumbriculus variegatus

Tissue residues of the PAHs, anthracene, fluorene, fluoranthene and pyrene were determined in Lumbriculus variegatus at four time intervals during both a 96-h exposure period to monitor uptake, and a 96-h clean water period to assess depuration. Mean BCFs were 2390, 1210, 452 and 1920 for fluoranthene, anthracene, fluorene and pyrene, respectively. BCFs were positively correlated with the octanol/water partition coefficient values of the four PAHs. Depuration occurred most rapidly for fluorene, followed by anthracene and fluoranthene. No apparent depuration of pyrene was observed during the 96-h depuration period. Because of rapid depuration of some PAHs, it appears that the 24 h clean water gut clearance period recommended in conjunction with sediment bioaccumulation tests with L. variegatus has potential to result in an under-estimation of bioaccumulation of some chemicals.     

Effects of surfactant and temperature on biotransformation kinetics of anthracene and pyrene

The biotransformation and mineralization of a mixture of two polycyclic aromatic hydrocarbons (PAHs), anthracene and pyrene, which are known contaminants of soil and groundwater, by an enrichment culture in the presence or absence of 100 mg l(-1) Tergitol NP-10, a non-ionic surfactant, and at temperatures of 10 degrees C and 25 degrees C were investigated. The overall biotransformation of 2 mg l(-1) total PAHs with free cell suspensions in batch culture was greater than 97.2% at both examined temperatures. At 25 degrees C, the overall mineralization of anthracene was 48.8% and that of pyrene was 66.1%. However, the decrease of temperature to 10 degrees C had a negative effect on the mineralization of PAHs and reduced it to 18.5% and 61.5% for anthracene and pyrene, respectively. Using a higher PAHs concentration of 20 mg l(-1) at 25 degrees C, the overall biotransformation of anthracene was 80.7% and that of pyrene was 100%, where only 17.3% anthracene and 7.6% pyrene were mineralized to carbon dioxide and water. The addition of surfactant at 25 degrees C increased the overall mineralization of anthracene and pyrene to 33.0% and 27.6%, respectively. However, the addition of surfactant at 10 degrees C had a negative impact on the overall biotransformation of anthracene and pyrene, reducing them to 20.6% and 14.0%, respectively. These results have significant implications in the bioremediation of PAHs-contaminated sites.     

Atmospheric polycyclic aromatic hydrocarbons observed over the North Pacific Ocean and the Arctic area: Spatial distribution and source identification

During the 2003 Chinese Arctic Research Expedition from the Bohai Sea to the high Arctic (37–80°N) aboard the icebreaker Xuelong (Snow Dragon), air samples were collected using a modified high-volume sampler that pulls air through a quartz filter and a polyurethane foam plug (PUF). These filters and PUFs were analyzed for particulate phase and gas phase polycyclic aromatic hydrocarbons (PAHs), respectively, in the North Pacific Ocean and adjacent Arctic region. The ∑PAHs (where ∑=15 compounds) ranged from undetectable level to 4380 pg m⁻³ in the particulate phase and 928–92 600 pg m⁻³ in the gas phase, respectively. A decreasing latitudinal trend was observed for gas-phase PAHs, probably resulting from temperature effects, dilution and decomposition processes; particulate-phase PAHs, however, showed poor latitudinal trends, because the effects of temperature, dilution and photochemistry played different roles in different regions from middle-latitude source areas to the high latitudes. The ratios of PAH isomer pairs, either conservative or sensitive to degradation during long-range transport, were employed to interpret sources and chemical aging of PAHs in ocean air. In this present study the fluoranthene/pyrene and indeno[123-cd]pyrene/benzo[ghi]pyrene isomer pairs, whose ratios are conservative to photo-degradation, implies that biomass or coal burning might be the major sources of PAHs observed over the North Pacific Ocean and the Arctic region in the summer. The isomer ratios of 1,7/(1,7+2,6)-DMP (dimethylphenanthrene) and anthracene/phenanthrene, which are sensitive to aging of air masses, not only imply chemical evolving of PAHs over the North Pacific Ocean were different from those over the Arctic, but reveal that PAHs over the Arctic were mainly related to coal burning, and biomass burning might have a larger contribution to the PAHs over the North pacific ocean.     

An oxygenated metabolite of benzo[a]pyrene increases hepatic β-oxidation of fatty acids in chick embryos

Polycyclic aromatic hydrocarbons (PAHs) are well-known carcinogens to humans and ecotoxicological effects have been shown in several studies. However, PAHs can also be oxidized into more water soluble-oxygenated metabolites (Oxy-PAHs). The first purpose of the present project was to (1) assess the effects of a mixture containing three parent PAHs: anthracene, benz[a]anthracene, and benzo[a]pyrene versus a mixture of their oxygenated metabolites, namely: anthracene-9,10-dione, benz[a]anthracene-7,12-dione, and 9,10-dihydrobenzo[a]pyrene-7-(8H)-one on the hepatic fatty acid β-oxidation in chicken embryos (Gallus gallus domesticus) exposed in ovo. The second and also main purpose of the project was to (2) assess the effects of the parent PAHs versus their oxy-PAHs analogues when injected individually, followed by (3) additional testing of the individual oxy-PAHs. The hepatic β-oxidation was measured using a tritium release assay with [9,10-³H]-palmitic acid (16:0) as substrate. The result from the first part (1) showed reduced hepatic β-oxidation after exposure in ovo to a mixture of three PAHs, however, increased after exposure to the mixture of three oxy-PAHs compared to control. The result from the second part (2) and also the follow-up experiment (3) showed that 9,10-dihydrobenzo[a]pyrene-7-(8H)-one was the causative oxy-PAH. The implication of this finding on the risk assessment of PAH metabolite exposure in avian wildlife remains to be determined. To the best of our knowledge, no similar studies have been reported.     

采油废水中多环芳烃的生态风险评价

先利用C-18固相萃取小柱富集大港油田港东联合处理站污水处理站的采油废水中16种多环芳烃(PAHs,即萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽、苯并[a]芘、茚并[1,2,3-cd]芘、二苯并[a,h]蒽和苯并[g,h,i]苝),再用气相色谱/质谱(GC/MS)分析测定其浓度,以评价PAHs的去除率和生态风险。结果表明:(1)采油废水经处理后,COD、石油类去除率分别达到82.27%、91.06%;外排水COD、石油类达到《污水综合排放标准》(GB 8978—1996)一级标准要求,优于中国采油废水处理的一般水平。(2)采油废水主要以2、3环的PAHs为主,约占总量的93%以上。(3)苯并[a]芘超过《地表水环境质量标准》(GB 3838—2002)中限值。(4)处理前的采油废水中蒽、菲和苯并[a]芘具有一定的生态风险;处理后的外排水中萘、蒽、菲、荧蒽、苯并[a]芘的暴露浓度(PEC)/预测无效应浓度(PNEC)均小于1,目前尚未对环境造成威胁。但是8种PAHs(苊烯和苯并类PAHs除外)总和表现出较大的毒性,需要引起重视。     

Temperature dependence of Henry's law constants of metolachlor and diazinon

A dynamic system based on the water/air equilibrium at the interface within the length of a microporous tube has been used to determine experimentally the Henry's law constants (HLC) of two pesticides: metolachlor and diazinon. The measurements were conducted over the temperature range 283-301 K. At 293 K, HLCs values are (42.6+/-2.8) x 10(3) (in units of M atm(-1)) for metolachlor and (3.0+/-0.3)x10(3) for diazinon. The obtained data were used to derive the following Arrhenius expressions: HLC=(3.0+/-0.4) x 10(-11) exp((10,200+/-1,000)/T) for metolachlor and (7.2+/-0.5) x 10(-15) exp((11,900+/-700)/T) for diazinon. At a cumulus cloud temperature of 283 K, the fractions of metolachlor and diazinon in the atmospheric aqueous phase are about 57% and 11% respectively. In order to evaluate the impact of a cloud on the atmospheric chemistry of both studied pesticides, we compare also their atmospheric lifetimes under clear sky (tau(gas)), and cloudy conditions (tau(multiphase)). The calculated multiphase lifetimes (in units of hours) are significantly lower than those in gas phase at a cumulus temperature of 283 K (in parentheses): metolachlor, 0.4 (2.9); diazinon, 1.9 (5.0).     

Synergistic solubilization of polycyclic aromatic hydrocarbons by mixed anionic-nonionic surfactants

Water solubility enhancements of naphthalene (Naph), acenaphthylene (Acen), anthracene (An), phenanthrene (Phen) and pyrene (Py) by micellar solutions of single and mixed anionic-nonionic surfactants were measured and compared. Effects of typical inorganic ions, such as NH(4)(+), Na(+) and Mg(2+) coexisted with the organic pollutants (in soils) on water solubilities of polycyclic aromatic hydrocarbons (PAHs) in the presence of single and mixed surfactants were also investigated. Solubilities of PAHs in water are greatly enhanced in a linear fashion by each of Triton X-100 (TX100), Triton X-305 (TX305), Brij 35, and sodium dodecyl sulfate (SDS). Solubility enhancement efficiencies of surfactants above the critical micelle concentration (CMC) follow the order of TX100>Brij 35>TX305>SDS. PAHs are solubilized synergistically in mixed anionic-nonionic surfactant solutions, especially at low surfactant concentrations. The synergistic power of the mixed surfactants is SDS-TX305>SDS-Brij 35>SDS-TX100. Synergistic effect of a given mixed-surfactant solution on different PAHs also appears to be linearly related to the solute logK(ow). The noted synergism for the mixed surfactants is attributed to the formation of mixed micelles, the lower CMC of the mixed-surfactant solutions, and the increase of the solute's molar solubilization ratio or micellar partition coefficients (K(mc)) because of the lower polarity of the mixed micelles. Suitable quantity of inorganic cations can enhance the solubilization capacities of anionic-nonionic mixed surfactants, the effect being Mg(2+)>NH(4)(+)>Na(+). The water solubility of pyrene was slightly increased by anthracene and significantly increased by 1,2,3-TCB in the presence of SDS-Brij 35. Mixed surfactants may improve the performance of surfactant-enhanced remediation of soils and sediments by decreasing the applied surfactant level and thus the remediation cost.     

Henry's law constants of phenol and mononitrophenols in water and aqueous sulfuric acid

Phenols are widely present in the atmosphere and nitration probably in the aerosol phase leads to nitrophenols. Nitration by nitric acid in sulfuric acid can be rapid, but little is known of the process under atmospheric conditions. The Henry's law constants K(H)(dagger) of phenol and 2-, 3- and 4-nitrophenol were all measured by a bubble stripping method as: 2820mol kg(-1) atm(-1) (at 298K), 147mol kg(-1) atm(-1) (at 298K), 1.6x10(4)mol kg(-1)atm(-1) (at 308K) and 2.1x10(4)mol kg(-1) atm(-1) (at 308K), respectively. The Henry's law constant of phenol in sulfuric acid systems is lower by more than a factor of two at 1020mol kg(-1) atm(-1) (at 298K) in 40wt% sulfuric acid, which is in line with salting-out of oxygen-containing aromatic compounds in water-sulfuric acid systems. The Henry's law constants of 2- and 4-nitrophenol behave differently and are almost independent of sulfuric acid concentration. The variation of K(H)(dagger) with temperature (T) described in terms of -dln(K(H)(dagger))/d(1/T) does not to vary with sulfuric acid concentration, suggesting enthalpy of dissolution for phenol is independent of sulfuric acid. The series of Henry's law constants measured here can describe the equilibrium situation for phenols in careful determinations of phase partitioning in the atmosphere.     

Characterizing the interactions between polycyclic aromatic hydrocarbons and fulvic acids in water

Polycyclic aromatic hydrocarbons (PAHs) are persistent, bioaccumulative, and toxic chemicals and are listed as priority pollutants by the US EPA. Although they are sparsely soluble in water, their solubility can be increased by binding to dissolved organic matter in natural waters, which will further increase their environmental risk as toxic pollutants. In this study, the interaction between PAHs, exemplified by fluorene and anthracene, and fulvic acid (FA) was studied using fluorescence quenching titration method with fluorescence emission spectra, respectively. The association of FA with the mixture of fluorene and anthracene was also evaluated by excitation–emission matrix (EEM) fluorescence spectrometry combined with parallel factor (PARAFAC) analysis. Results demonstrate that EEM fluorescence spectrometry with PARAFAC analysis was sensitive and reliable to determine the binding properties of PAHs with FA in a mixed aqueous solution. The conditional stability constants and binding capacities show that both PAHs bind to FA tightly.     

Fate and transport of monoterpenes through soils. Part I. Prediction of temperature dependent soil fate model input-parameters

Monoterpenes are C10H(n)O(n') compounds of natural origin and are potentially environmentally safe substitutes for traditional pesticides. Still, an assessment of their environmental behaviour is required. As a first step in a theoretical study focussing on monoterpenes applied as pesticides to terrestrial environments, soil fate model input-parameters were determined for 20 monoterpenes with widely different structural characteristics. Input-parameters are the water solubility (S(W)), vapour pressure (P), n-octanol-water partition coefficient (K(OW)), atmospheric air and bulk water diffusion coefficients (D(A)air and D(W)water), first order biodegradation rate constants (k), and their temperature dependence. Values for these parameters were estimated or taken from previous experimental work. The quality of the estimations was discussed by focussing on their statistics and by comparison with available experimental data. From these properties, the air-water partition coefficient (K(AW), Henry's Law constant), the interface-water partition coefficient (K(IW)) and the organic matter-water partition coefficient (K(OM)) could be estimated with varying levels of accuracy. In general, little experimental data turned out to be available on biodegradation rate constants and on the temperature dependence of physico-chemical parameters.     

Sequential UV-biological degradation of polycyclic aromatic hydrocarbons in two-phases partitioning bioreactors

A method based on UV-irradiation in organic solvent followed by transfer of the remaining pollutants into silicone oil for subsequent biodegradation in a biphasic system inoculated with a phenanthrene degrading Pseudomonas sp. was tested for the treatment of various mixtures of PAHs. Acetone was first selected as the most suitable solvent compared to methanol, acetonitrile and silicone oil for the removal of pyrene and phenanthrene. The sequential treatment was then applied to the treatment of a mixture of fluorene, phenanthrene, anthracene, fluoranthrene, pyrene, benzo(a)anthracene and benzo(a)pyrene in acetone. These compounds were photodegraded in the following order of initial removal rates (mg l(-1) d(-1)): benzo(a)pyrene (7.8) > anthracene (5.0) > benzo(a)anthracene (2.5) > fluoranthrene (1.8) > pyrene (1.5) > phenanthrene (1.2) > fluorene (0.2). UV-treatment allowed complete removal of, anthracene, benzo(a)anthracene and benzo(a)pyrene and removals of 63% of pyrene and 37% of fluorene after 434 h or irradiation. The subsequent biological treatment removed the remaining phenanthrene and fluorene by 100% and 90%, respectively, after 790 h of cultivation. Although less efficient due to the presence of interfering compounds, the UV-biological treatment of a soil extract allowed a 63% removal of the seven PAHs named above. Microbial growth did not occur when the pollutants were directly supplied to the microorganism showing that biphasic systems reduced the toxicity effects cause by mixtures of PAHs at high concentrations. This study demonstrates the potential of selective UV treatment of high molecular weight PAHs followed by biological treatment of the low molecular weight species in biphasic systems.     

Contamination of polycyclic aromatic hydrocarbons (PAHs) in microlayer and subsurface waters along Alexandria coast,Egypt

The residues of seven polycyclic aromatic hydrocarbons (PAHs) pollutants in microlayer and subsurface seawater samples collected from Alexandria coast, Egypt, were analyzed by gas chromatography–electron-impact mass spectrometry-selected ion monitoring mode (GC–MS-SIM). The pollutants studied were, fluorene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene and benzo[a]pyrene. Total PAH levels in microlayer ranged from 103 to 523 ng/l, while it ranged in subsurface samples from 13 to 120 ng/l. The Western Harbor location recorded the highest level of PAHs pollutant over all the other location for both subsurface and microlayer waters. The two major PAHs in microlayer water at the Western Harbor were fluorene and phenanthrene, making up 27% and 20% of the total PAHs, while the two major PAHs in subsurface water at the Eastern Harbor were phenanthrene and fluoranthene recording up 21% each of the total PAHs. The total PAH levels were generally in the nano-gram per liter for microlayer and subsurface seawater samples. The dominant PAHs in both subsurface and microlayer samples were fluoranthene, pyrene and benzo[a]pyrene. The microlayer enrichment factor at Alexandria’s Mediterranean coast was ranged from 29 for fluorene to 3 for phenanthrene and benzo[a]pyrene which showed PAHs concentration in the microlayer with an average of five times more than the total PAH in the subsurface samples.     

A critical compilation of Henry's law constant temperature dependence relations for organic compounds in dilute aqueous solutions

A comprehensive compilation of published studies reporting directly measured experimental determinations of Henry's law constant (HLC) temperature dependence relationships for organic compounds in dilute, non-saline aqueous solutions under ambient conditions was conducted. From this effort, 55 such studies (covering 204 organic compounds) were identified, critically reviewed, summarized and discussed. Of the 204 compounds, 57 were studied in more than one investigation. For the 57 'multi-studied' compounds, relatively good agreement (averaging within 20-30%) was found between the results from different investigations. Given such results, a 'consensus' relationship (i.e., an average temperature dependence relation) was generated for each of the multi-studied compounds. Overall, considering relations established for 197 of the 204 compounds investigated (the results for the other 7 compounds being excluded due to poor correlation coefficients), the average slope of the temperature dependence line was found to correspond to an increase in HLC values by a factor of 1.88 (i.e., an 88% increase) per 10 degrees C rise in temperature (thermodynamically equivalent to an average enthalpy of volatilization of 47 kJ/mole). The associated range found for the temperature dependence slope corresponds to an increase in HLC values by a factor ranging from 1.12 to 3.55 (i.e., a 12-255% increase) per 10 degrees C rise (equivalent enthalpy of volatilization range: 8-93 kJ/mole). The wide range of slope values found indicates that serious errors may result if one applies the commonly cited 'rule of thumb' that HLC values double per 10 degrees C rise in temperature to a specific compound. In light of this finding, when faced with a lack of data, a prudent course for practitioners to take appears to be conducting a laboratory study to determine the exact temperature dependence for the compound(s) of interest.     

Aqueous solubility, Henry's law constants and air/water partition coefficients of n-octane and two halogenated octanes

New data on the aqueous solubility of n-octane, 1-chlorooctane and 1-bromooctane are reported between 1 degree C and 45 degrees C. Henry's law constants, K(H), and air/water partition coefficients, K(AW), were calculated by associating the measured solubility values to vapor pressures taken from literature. The mole fraction aqueous solubility varies between (1.13-1.60)x10(-7) for n-octane with a minimum at approximately 23 degrees C, (3.99-5.07)x10(-7) for 1-chlorooctane increasing monotonically with temperature and (1.60-3.44)x10(-7) for 1-bromooctane with a minimum near 18 degrees C. The calculated air-water partition coefficients increase with temperature and are two orders of magnitude lower for the halogenated derivatives compared to octane. The precision of the results, taken as the average absolute deviations of the aqueous solubility, the Henry's law constants, or the air/water partition coefficients, from appropriate smoothing equations as a function of temperature is of 3% for n-octane and of 2% and 4% for 1-chlorooctane and 1-bromooctane, respectively. A new apparatus based on the dynamic saturation column method was used for the solubility measurements. Test measurements with n-octane indicated the capability of measuring solubilities between 10(-6) and 10(-10) in mole fraction, with an estimated accuracy better than +/-10%. A thorough thermodynamic analysis of converting measured data to air/water partition coefficients is presented.