Temperature dependence of Henry's law constants of thirteen polycyclic aromatic hydrocarbons between 4°C AND 31°C

Abstract

An understanding of the temperature dependence of the Henry's law constant for organic contaminants is critical when modeling the transport and fate of these contaminants in the environment. The Henry's law constants for 13 polycyclic aromatic hydrocarbons (PAHs) were experimentally determined between 4 and 31°C using a gas‐stripping apparatus. The Henry's law constants ranged between 0.02 ± 0.01 Pa m3/mol for chrysene at 4°C and 73.3 ± 20 Pa m3/mol for 2‐methylnaphthalene at 31°C. The temperature dependence of each PAH was modeled using the van't Hoff equation to calculate the enthalpy and entropy of phase change. For nine of the PAHs, the present study reports the first experimental measured temperature dependence of their Henry's law constant. The enthalpies of phase change ranged between 35.4 ± 1.9 kJ/mol for 1‐methylphenanthrene and 100 ± 8 kJ/mol for chrysene. These data can be used to extrapolate Henry's law values within the experimental temperature ranges. For all PAHs except benzo[a]fluorene, the temperature dependence can be predicted within a relative standard error <10%.

Diffusive exchange of PAHs across the air–water interface of the Kaohsiung Harbor lagoon, Taiwan

“…A previous study suggested that colloidal hydrophobic organics could contribute about 12% of total water column hydrophobic organic mass to the truly dissolved concentration (Totten et al, 2001;Yan et al, 2008). The Henry's law constants (HLC) employed in this study were derived from the temperature-corrected values reported by Bamford et al (1999bBamford et al ( , 1999cBamford et al ( , 2002b. Salinity level is also important in studies on saline environments including coastal waters, estuaries, and harbors.…”

“…The use of Tateya's DH w value leads to overestimate fluxes at low temperature and underestimate at high temperature compared with Tenhulscher's data. One decade ago, Bamford et al (1999b;1999c;2002b) measured H values and enthalpy (DH W ) for many PCB and PAH compounds and based on their experimental results it is possible to estimate H values for the remaining compounds. It is a significant improvement over previously published values because the database was developed relied on experimental datasets (Totten et al, 2003;Tsai et al, 2002).…”

Determination of Henry’s Law Constant of Formaldehyde as a Function of Temperature: Application to Air–Water Exchange in Tahtali Lake in Izmir, Turkey

“…The water depth was selected based on previous studies indicating that the equilibrium between gas and aqueousphases is achieved at less than 50 cm of water depth (Sahsuvar, Helm, Jantunen, & Bidleman, 2003;Harrison, Cape, & Heal, 2002;Jantunen & Bidleman, 2000;Bamford, Poster, & Baker, 1999;Bamford, Poster, & Baker, 2000;Betterton & Hoffman, 1988).…”

Regional modelling of polycyclic aromatic hydrocarbons: WRF-Chem-PAH model development and East Asia case studies

“…Our model approach and parameterisation build on a Langmuir-Hinshelwood reaction mechanism involving the decomposition of ozone and formation of longlived reactive oxygen intermediates (Shiraiwa et al, 2011;Berkemeier et al, 2016). Table S2 in the Supplement lists the parameterisations of the reaction rates.…”

“…Since direct K SA measurements are not available for PAHs, soot-air partitioning coefficients (K SA L kg −1 ) are estimated as the ratios of soot-water (K SW ; Jonker and Koelmans, 2002) and the air-water (K AW ) partitioning coefficients (dimensionless, temperature dependent; Bamford et al, 1999). Values of K SW vary substantially (up to a factor of 47 for the PAHs considered here) among relevant soot.…”