PAH plant uptake prediction: Evaluation of combined availability tools and modeling approach
Résumé
Transfer to plant is one of the main human exposure pathways of polycyclic aromatic
hydrocarbons (PAH) from contaminated soils. However existing models implemented
in risk assessment tools mostly rely on i) total contaminant concentration and ii) plant
uptake models based on hydroponics experiments established with pesticides (Briggs
et al., 1982, 1983). Total concentrations of soil contaminants are useful to indicate
pollution, however they do not necessarily indicate risk. Methods describing actual
bioavailability of soil contaminant are supposed to give more accurate and realistic
risk assessments. However these methods still need to be validated and some
guidelines for their selection, implementation and interpretation need to be
established. As part of the IBRACS project (“Integrating Bioavailability in Risk
Assessment of Contaminated Soils: opportunities and feasibilities”,
http://projects.swedgeo.se/ibracs/), a SNOWMAN research project, we evaluated how
two availability tools, Tenax extraction and POM pore water estimate, could predict
PAH plant uptake using the Briggs models. Maize was cultivated for five weeks on
fourteen contaminated industrial soils from Belgium, France and Sweden. Total PAH
concentrations were determined in roots and shoots and compared to those estimated
from Tenax extraction, POM and total concentrations. As a result, both availability
measurement methods gave similar estimation of PAH pore water concentrations.
However those concentrations lead to underestimate actual root and shoot uptakes
calculated using classical uptake models. In this case, total soil concentration
correlated better to actual uptake and gave more accurate predictions. Those results
would suggest an alternative uptake pathway involving direct contact between roots
and soil particles.
Domaines
Sciences du Vivant [q-bio]
Origine : Accord explicite pour ce dépôt
Origine : Accord explicite pour ce dépôt