Effect of NAPL mixture and alteration on 222Rn partitioning coefficients: Implications for NAPL subsurface contamination quantification

Assessing Light Non-Aqueous Phase Liquids in the Subsurface Using the Soil Gas Rn Deficit Technique: A Literature Overview of Field Studies

“…In their laboratory experiments to determine k N/w , Hunkeler et al [52] used a diesel mixture and reported a value of 40 ± 2.3. Schubert et al [53] proposed instead a value of 60 ± 1.3, which was similar to the value of 60.7 ± 6.1 found by Le Meur et al [110] for fresh diesel. Briganti et al [54] obtained intermediate values (47.7) using LNAPL sampled from a diesel-contaminated site for their experiments.…”

“…The results showed partition coefficient values ranging from 25.1 ± 2.5 to 74.8 ± 7.5, considering phenomena such as evaporation and UV degradation. Le Meur et al [110] found a minor variability in the coefficient value, due to the alteration of the LNAPL sample by these phenomena, also considering gasoline for their experiments. The k N/w for fresh gasoline resulted, in fact, in 37.4 ± 5.6, while with the alteration effects, they were in the range of 30.8 ± 4.6 and 37.4 ± 5.6.…”

“…Comparable results were obtained by Schubert et al [53], who suggested a value of 38.9 ± 0.9 for a typical gasoline fuel mixture. Based on the information above, it is believed that a range of values for k N/w between 30 and 60 is appropriate for both diesel and gasoline, as suggested by Le Meur et al [110]. The values of the Rn partition coefficient between LNAPL and water reported in the literature for some pure compounds and some LNAPL mixtures are summarized in Table 5.…”

“…Höhener and Surbeck [21] used a similar value of the partition coefficient k N/w , of about 51.5, resulting from a value of 11.7 for the partition coefficient between diesel and air (k N/g ), and considering a value of 4.4 [111] for the dimensionless Henry's constant. Furthermore, Le Meur et al [110] studied the effect of different physical processes that could potentially lead to a change in diesel composition over time by evaluating differences in partition coefficients in altered diesel sample. The results showed partition coefficient values ranging from 25.1 ± 2.5 to 74.8 ± 7.5, considering phenomena such as evaporation and UV degradation.…”

Synthetic and Natural Surfactants for Potential Application in Mobilization of Organic Contaminants: Characterization and Batch Study

“…After a spill, NAPLs migrate downward through the vadose zone and remain trapped in the pore space at residual saturation by capillary forces, in the form of separate phase droplets or ganglia [7]. Light NAPLs float at the water table, while DNAPLs can penetrate the water table and migrate downward into the low permeability layer [8,9]. Over time, NAPLs trapped in the interstitial space may slowly dissolve in groundwater, resulting in long-term persistent sources of aquifer contamination [4].…”