Correlation between biological and physical availabilities of phenanthrene in soils and soil humin in aging experiments

Abstract

The bioavailability of an organic compound in a soil or sediment commonly declines with the soil‐chemical contact time (aging). A series of parallel desorption and bioavailability experiments was carried out on phenanthrene previously aged up to ∼100 d in Mount Pleasant silt loam (Mt. Pleasant, NY, USA) or Pahokee peat soil to determine as a function of the aging period the degree of correlation between the reduction in bioavailability and the rate and extent of desorption and the influence of soil organic matter composition on availability. The mineralization of phenanthrene by two bacteria and the uptake of phenanthrene by earthworms showed expected declines with aging. Likewise, the rate of phenanthrene desorption in the absence of organisms decreased with aging. The decline in initial rate of mineralization or desorption was nearly an order of magnitude after 50 to 60 d of aging. Plots of normalized rates of mineralization or desorption practically coincided. Similarly, plots of normalized fraction mineralized or fraction desorbed during an arbitrary period gave comparable slopes. The partial removal of organic matter from the peat by extraction with dilute NaOH to leave the humin fraction reduced the biodegradation of phenanthrene aged for 38 and 63 d as compared to the nonextracted peat, but the effect disappeared at longer incubation times. The rate of desorption from samples of peat previously extracted with NaOH or Na4P2O7 declined with aging and, for a given aging period, was significantly slower than from nonextracted peat. This work shows that the reduction in bioavailability of phenanthrene over time in soil is directly correlated with reduction of its physical availability due to desorption limitations. In addition, this study shows that removal of extractable humic substances leads to a decline in the rate of desorption and in the bioavailability of the substrate.

Effects of ozonation on soil organic matter of contaminated soil containing residual oil

“…Sorption and distribution of HOCs in SOM fractions have received great attention, and many results have been presented for natural soils. Different SOM fractions showed different sorption/desorption properties, which affected the fate of HOCs in soils (Luo et al 2008;Pan et al 2006;White et al 1999). Studies have revealed that the sorption nonlinearity and hysteresis increased in the order of humic acid/ fulvic acid (HA/FA)<soil<HM (Pan et al 2006;Xing and Pignatello 1997).…”

Evaluation of toxicity risk of polycyclic aromatic hydrocarbons (PAHs) in crops rhizosphere of contaminated field with sequential extraction

“…The amount of methanol/water extractable pyrene in soils with either low or high concentration of pyrene was low as well, but the proportion of PAHs extracted by butanol was much higher during 24-week aging time (Macleod and Semple 2003). It has been suggested that methanol/water removed nonpolar parent compounds and polar metabolites (Kelsey et al 1997) and butanol removed the weakly associated fraction of HOCs in soil (White et al 1999). In the present study, the similar amount of PAHs was also extracted by methanol/water.…”

Using a Bayesian approach to improve and calibrate a dynamic model of polycyclic aromatic hydrocarbons degradation in an industrial contaminated soil

“…This phenomenon also referred to "aging" actually encompasses multiple processes including the diffusion and sorption of PAHs into the soil organic and inorganic fractions. It highlights the fact that (bio)availability decreases with increasing contact time (Hatzinger and Alexander, 1995;White et al, 1999).…”

“…PAHs dissipation in soil is mostly driven by two processes: adsorption and biodegradation (White et al, 1999;Wilcke, 2000). When PAHs enter the soil, they rapidly sorb on minerals and organic matters in soil aggregates.…”