The use of biochar (BC) has been suggested for remediation of contaminated soils. In a
recent study published in
Water, Air, & Soil Pollution
we aimed to investigate the role of microorganisms in sorption of PAH
to BC-amended soils. Fungi, especially the wood and litter-degrading
fungi, have shown the ability for humification and to degrade
recalcitrant molecules, and are thus suitable model organisms.
Haplic Arenosol with high organic matter content was chosen to
highlight the importance of soil organic matter (SOM) in PAH sorption,
possibly to form non-extractable residue. Basidiomycetous fungi
Agrocybe praecox and
Phanerochaete velutina
grown on pine bark were inoculated in organic matter (OM)-rich Haplic
Arenosol and OM-poor sandy loam with either BC or chemically activated
BC (ABC) and 14C-labelled pyrene for 60 days.
Fungi did not mineralize pyrene, but increased sorption up to 47–56%
in BC-amended Haplic Arenosol in comparison with controls (13–25%)
without a fungus irrespective of the presence of an adsorbent. In
OM-poor sandy loam, only 9–12% of pyrene was sorbed to amended soil in
the presence of fungus and adsorbent. The results suggest that BC and
fungal amendment increased sorption of pyrene, especially to Haplic
Arenosol more than by either BC or fungi alone.
We found that PAH can effectively be sorbed to carbonaceous soil
amendments and can thus be a promising tool for remediating polluted
sites. The effectiveness of biochar to sorb PAH can further be increased
when activating the biochar thus improving not only its BET surface
area, but also its pore morphology and surface chemistry. The method was
shown to be even further enhanced if biochar addition is combined with
treatment with Basidiomycetous fungi, especially in high SOM soils.
Sorption of pyrene to the BC-SOM complex enhanced by fungi could help
reduce the leaching of pyrene from soil to groundwater, but the results
are yet to be validated under field conditions and the role of soil
microbial population should be further studied.
Read the full article
here.
