Dissipation and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to organic matter in soils amended by exogenous rich-carbon material

Abstract

Purpose The aim of the research was to assess the effect of biochar addition on aging, degradation, and sorption processes of polycyclic aromatic hydrocarbons (PAHs) to soil organic matter. The study was carried out as a sorption experiment in strictly controlled water and air conditions, which allowed for the accurate observation and prediction of PAH behavior in soils. Materials and methods Four soils were fortified with a PAH mixture (Fluorene-Flu, Anthracene-Ant, Phenanthrene-Phe, Pyrene-Pyr, Chrysene-Chry) at 20 mg kg −1 of single-compound concentration level. The experiment was carried out in two trials: soils + 5PAHs amended with biochar and soil + 5PAHs without biochar addition with incubation times of 0, 1, 3, 6, and 9 months. After each interval time, the extractable (E-SOM) and stable organic matter (S-SOM) were measured as well as PAHs determined in two forms: total concentration (PAH-tot) and residual concentration (PAH-rest) after E-SOM extraction. The PAH loss and halflife times were estimated according to pseudo first-order kinetics equation. Results and discussion The amounts of PAH-tot in the soils without biochar decreased by an average of 92%, while in soil with biochar, this was 41% after 9 months of aging. The amount of PAHs-rest bounded with S-SOM after 9 months of incubation varied from 0.9 to 3.5% and 0.2 to 1.3% of the initial PAH concentration, respectively, for soils non-induced and induced by biochar. In soils without biochar, Flu, Ant, Phe, and Pyr exhibited similar T 1/2 (43-59 days), but Chry was characterized by a much higher and broader T 1/2 than other hydrocarbons (67-280 days). Biochar addition to the soils significantly influenced the half-life changes for all PAHs. The highest changes were noted for Phe (14-fold increase), and the lowest was for Flu (7-fold increase). Conclusions The addition of exogenous-rich carbon material such as biochar to the soil significantly changes the behavior and sorption potential of PAHs in the soil. Soils enriched with biochar are characterized by a higher persistence of PAHs, longer aging time, and lower affinity for sorption by native organic matter structures. Soils freshly polluted by PAH are mainly sorbed by E-SOM, which significantly increases their accessibility and reduces formation of bound-residues in the soil.

Purification of Aqueous Media by Biochars: Feedstock Type Effect on Silver Nanoparticles Removal

“…Adsorbed nanoparticles may have formed clusters on the solid. Besides silver nanoparticles, biochar was also used in the removal of other contaminants, e.g., heavy metals [ 28 , 32 , 33 ], dyes [ 34 , 35 ], gold nanoparticles [ 10 ], antibiotics [ 36 , 37 ], and PAH [ 38 , 39 ].…”

Effects of Biochar Combined with Nitrogen Fertilizer Reduction on Rapeseed Yield and Soil Aggregate Stability in Upland of Purple Soils

“…This study demonstrated that biochar amendment led to an increase in soil organic carbon in 2-5, 1-2, 0.25-1 and <0.25 mm aggregates for each nitrogen fertilizer treatment, and SOC in 2-5, 1-2, 0.25-1 and <0.25 mm aggregates increased with the increase in biochar application. This was because the organic carbon content of biochar used in this experiment was 537.97 g•kg −1 , being a carbon-rich exogenous organic matter, thus it could increase the soil microbial biomass and promote the formation of soil humus to contribute to the formation of organic macromolecules such as carbohydrates and aromatic hydrocarbons, thereby increasing the content of soil organic carbon and producing more cementing materials, finally resulting in the redistribution of microaggregates in the soil into large aggregates [28]. This was also the reason why the application of 10 t•ha −1 biochar in this study promoted the formation of soil large aggregates and thus improved the stability of soil aggregates.…”

Using Toxic Equivalent Quotients (TEQs) to Evaluate the Risk of Polycyclic Aromatic Hydrocarbons Compounds in Soil at Basrah Governorate, Iraq

“…Soil is a critical environment because different pollutants come from various human activities, such as agriculture, industry, mining and transports which can pollute the soil with many dangerous pollutants, one of them is polycyclic aromatic hydrocarbon compounds (PAHs) (Wang et al, 2018). Polycyclic aromatic hydrocarbons are specific persistent organic pollutants that stay for long periods in the environment (Ukalska-Jaruga et al, 2020).…”