title: The prediction of PAHs bioavailability in soils using chemical methods: state of the art and future challenges.
abstract: The evaluation of the available fraction of hydrophobic organic contaminants (HOCs) is extremely important for assessing their risk to the environment and human health. This available fraction, which can be solubilized and/or easily extracted, is believed to be the most accessible for bioaccumulation, biosorption and/or transformation by organisms. Based on this, two main types of chemical methods have been developed, closely related to the concepts of bioaccessibility and freely available concentrations: non-exhaustive extractions and biomimetic methods. Since bioavailability is species and compound specific, this work focused only in one of the most widespread group of HOCs in soils: polycyclic aromatic hydrocarbons (PAHs). This study aims at producing a state of the art knowledge base on bioavailability and chemical availability of PAHs in soils, clarifying which chemical methods can provide a better prediction of an organism exposure, and which are the most promising ones. Therefore, a review of the processes involved on PAHs availability to microorganisms, earthworms and plants was performed and the outputs given by the different chemical methods were evaluated. The suitability of chemical methods to predict bioavailability of the 16 US EPA PAHs in dissimilar naturally contaminated soils was not yet demonstrated, being especially difficult for high molecular weight compounds. Even though the potential to predict microbial mineralization using non-exhaustive extractions is promising, it will be very difficult to achieve for earthworms and plants, due to the complexity of accumulation mechanisms which are not taken into account by chemical methods. Yet, the existing models could be improved by determining compound, species and site specific parameters. Moreover, chemical availability can be very useful to understand the bioavailability processes and the behavior of PAHs in soils. The inclusion of chemical methods on risk assessment has been suggested and it is promising, despite some methods overpredict risks.
authors.affiliation: University of Aveiro, Department of Chemistry & CESAM, Campus de Santiago, 3810-193 Aveiro, Portugal. Electronic address: acachada@ua.pt.
authors.forename: A
authors.initials: A
authors.lastname: Cachada
authors.affiliation: Department of Biology, Faculty of Sciences, University of Oporto, Rua do Campo Alegre, 4169-007 Porto, Portugal; Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Rua dos Bragas 289, P 4050-123 Porto, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Pereira
authors.affiliation: University of Aveiro, Department of Geosciences, GeoBioTec-GeoBioSciences, Geotechnologies and Geoengineering Research Center, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: E Ferreira
authors.initials: EF
authors.lastname: da Silva
authors.affiliation: University of Aveiro, Department of Chemistry & CESAM, Campus de Santiago, 3810-193 Aveiro, Portugal.
authors.forename: A C
authors.initials: AC
authors.lastname: Duarte
mesh_terms: D000818:Animals; D004784:Environmental Monitoring / Q000379:methods*; D009835:Oligochaeta; D010944:Plants; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D011084:Polycyclic Aromatic Hydrocarbons; D012987:Soil; D012989:Soil Pollutants
keywords: ACE; ANT; BC; BCF; BSAF; BaA; BaP; BghiP; Bioavailability; BuOH; C(PS); C(free); C(org); C(soil); CRY; Chemical availability; EqPT; EtOH; FLA; Frap; HMW; HOCs; K(BC); K(OC); K(OW); K(disk); LMW; Lip; MGP; MeOH; NP; OC; PAHs; PHE; POM-SPE; PYR; PrOH; SFE; SOM; SWE; Soils; TECAMs; acenaphthene; anthracene; benzo(a)anthracene; benzo(a)pyrene; benzo(ghi)perylene; bioconcentration factor; biota-to-soil accumulation factor; black carbon; black carbon normalized partition coefficient; chrysene; concentration in soil; concentrations in an organism; dissolved concentration in pore water; equilibrium concentration in the sampler; equilibrium partition theory; ethanol; fluoranthene; high molecular weight; hydrophobic organic contaminants; lipids; low molecular weight; manufactured gas plant; methanol; n-butanol; naphthalene; octanol–water partition coefficient; organic carbon; organic carbon–water partition coefficient; partition coefficient between disks and soils; phenanthrene; polyoxymethylene solid phase extraction; propanol; pyrene; rapid desorbing fraction; soil organic matter; subcritical water extraction; supercritical fluid extraction; triolein embedded cellulose acetate membranes