Modelling PAHs Transfer from Polluted Soil to Herbaceous Species in Phytoremediation Attempts

Abstract

To address the soil–plant transfer modelling of 13 US-EPA Polycyclic Aromatic Hydrocarbons (PAHs), a mechanistic model—MM_19—has been developed based on the fugacity concept. For that, the Mackay_97 model has been improved in terms of reconsidering the losses related to the transport and transformation mechanisms taking place in the compartments—roots and aboveground shoots—of the three short-life species (Eleusine indica, Cynodon dactylon and Alternanthera sessilis). Model input parameters consist of both experimental and literature data, including the initial soil and air PAHs content, flowrates, PAHs physico-chemical properties, retention times and transport half-lives of PAHs inside plant species. Using in situ weather data and Penman’s law, xylem flows were estimated as the evapotranspiration for each plant. Model calibration was performed using a Generalized Reduced Gradient (GRG) nonlinear optimization solver method. Sensitivity analysis showed that the phloem flow was the most sensitive among all tested parameters. According to the Nash–Sutcliffe efficiency (NSE), the MM_19 model is more efficient than the Mackay_97 model for all three plant species. Finally, the impact of PAHs physico-chemical parameters on their sol-plant transfer was discussed in terms of slight, intermediate and high molecules weight. The NSE values showed that the MM_19 model is more efficient than the Mackay_97 model. Indeed, comparisons between experimental and simulated results in the MM_19 model showed similarities for each compartment of the plant species. Thus, the MM_19 model can be used to predict the soil–plant transfer of organic pollutants.

Concentrations and source identification of priority polycyclic aromatic hydrocarbons in sediment cores from south and northeast Thailand

“…It is also interesting to note that numerous factors can dramatically alter the percentage contributions of ΣPAHs(3,4) and ΣPAHs(5,6). The influence of PAH molecular weights on the soil-plant transfer of PAHs was investigated using three short-life herbaceous species, namely Eleusine indica , Cynodon dactylon , and Alternanthera sessilis ( Matsodoum Nguemté et al., 2020 ). Model and experimental results showed that PAH concentrations can vary significantly between different compartments of plants.…”

“…For instance, Fluo and Pyr (i.e. LMW PAHs) tend to bioaccumulate in stem and leave compartments while HMW PAHs tend to occur in plant lipids and comparatively higher organic matter areas ( Balasubramaniyam, 2015 ; Matsodoum Nguemté et al., 2020 ). Because both lakes are surrounded by highly biodiverse herbaceous tropical plants, the impact of plant ab sorption on the alteration of percentage contributions of PAHs is undeniable.…”