Influence of soil biochar aging on sorption of the herbicides MCPA, nicosulfuron, terbuthylazine, indaziflam, and fluoroethyldiaminotriazine

6 páginas.-- 3 figuras.-- 3 tablas.-- 22 referencias© 2014 American Chemical Society. Sorption of four herbicides and a metabolite of indaziflam on a fresh macadamia nut biochar and biochars aged one or two years in soil was characterized. On fresh biochar, the sorption was terbuthylazine (Kd = 595) > indaziflam (Kd = 162) > MCPA (Kd = 7.5) > fluoroethyldiaminotriazine (Kd = 0.26) and nicosulfuron (Kd = 0). Biochar surface area increased with aging attributed to the loss of a surface film. This was also manifested in a decline in water extractable organic carbon with aging. Correspondingly, an increase in the aromaticity was observed. The higher surface area and porosity in aged biochar increased sorption of indaziflam (KdBC-2yr = 237) and fluoroethyldiaminotriazine (KdBC-1yr = 1.2 and KdBC-2yr = 3.0), but interestingly decreased sorption of terbuthylazine (KdBC-1yr = 312 and KdBC-2yr = 221) and MCPA (KdBC-1yr = 2 and KdBC-2yr = 2). These results will facilitate development of biochars for specific remediation purposes.We acknowledge the postdoctoral fellowship MINECO/FECYT for C.T. and the funding project AGL2013-48446-C3-1-R. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program.Peer Reviewe