Temperature-Dependent Sorption of Naphthalene, Phenanthrene, and Pyrene to Low Organic Carbon Aquifer Sediments

Abstract

Sorption experiments were conducted with naphthalene, phenanthrene, and pyrene on low organic carbon sediments at 4 and 26 °C using batch and column techniques. Experimental controls ensured the absence of biologic and photolytic activity and colloidfree solution supernatants. Equilibrium distribution coefficients (K d ) increased 1.1-1.6 times with a decrease in temperature of 22 °C. Fraction instantaneous sorption (F) values did not change significantly with a decrease in temperature of 22 °C. Desorption rate constants (k 2 ) decreased 1.2-2.6 times with a decrease in temperature of 22 °C. Times to equilibrium were at least 40 h. The magnitude of observed K d and k 2 values and the effect of temperature on K d (e.g., low enthalpy of sorption) are consistent with sorbate partitioning between the aqueous phase and small amounts of organic matter (f oc ) 0.02%) on the sediments. The temperature dependence of K d and k 2 may be small as compared to the effects of heterogeneities in field-scale aquifer systems. Thus, thermal gradients may not be of major importance in most saturated subsurface regimes when predicting solute transport. However, aquifer remediation pump-and-treat times could be decreased because increased temperature decreases both retardation and tailing.

Retention behavior of hydrophobic organic chemicals as a function of temperature in soil leaching column chromatography

“…The use of temperature as a system variable Chemosphere 49 (2002) [569][570][571][572][573][574] www.elsevier.com/locate/chemosphere could give fundamental information about the twophase transport properties. Thermodynamic enthalpy is important to understand the process, and has been applied to the sorption process in the batch equilibrium method (Chiou et al, 1979(Chiou et al, , 1983Wauchope et al, 1983;Woodburn et al, 1989;Goss, 1992), but little work has been done concerning the effect of temperature on the transport process in soil columns (Piatt et al, 1996). The theoretical temperature dependence of the retention factor (k 0 ) of a solute is given by the vanÕt Hoff equation (Gilpin and Squires, 1981;Woodburn et al, 1989):…”

Effect of temperature on the distribution of polycyclic aromatic hydrocarbons in soil and sediment

“…Only few studies have been performed in order to evaluate the effect of temperature on the desorption of "fresh" added PAHs into the soil/sediment. Piatt et al (1996) have observed that the desorption of PAHs from the low organic carbon sediments is favoured as the temperature increases. On the other hand, the temperature effect on the desorption of PAHs significantly increased when considering naturally contaminated soil (Enell et al 2005).…”

“…Sorption is also the primary physico-chemical process affecting the transport, biodegradability, and bioavailability of many hydrophobic organic chemicals, including PAHs, in soils and sediments (Piatt et al 1996;Ortega-Calvo et al 1997;Reemtsma & Mehrtens 1997). The extent of the PAH sorption-desorption in soils and sediments depends strongly on the hydrophobicity of the solute and the total organic carbon content of the soil/sediment (Karickhoff et al 1979;Chiou et al 1998;Reeves et al 232 2004; .…”

“…sorption is an exothermic process in nature (Piatt et al 1996;Chiou 2002). However, positive temperature dependencies for sorption of organic chemicals have also been reported (Moreale & van Bladel 1979;Brücher & Bergström 1997).…”

“…These values compare well with the results of He et al (1995) who reported 25% decrease in the adsorption of fluoranthene on soil with temperature increased from 5°C to 15°C. According to Piatt et al (1996), the decreased sorption of PAHs at higher temperatures was due to increased PAH solubilities in water at higher temperatures. Other investigators also concluded that the aqueous activity coefficient is a major factor controlling the extent of sorption of hydrophobic organic pollutants in soils/sediments with temperature (Karickhoff 1984;Chiou 2002).…”