Influence of Gliricidia sepium Biochar on Attenuate Perchlorate-Induced Heavy Metal Release in Serpentine Soil

Perchlorate (clo4-) is a strong oxidizer,capable of accelerating heavy metal release into regolith/soil. here,we assessed interactions between clo4-and serpentine soil to simulate and understand the fate of ni and mn and their immobilization with the presence of biochar (bc). a soil incubation study (6 months) was performed using serpentine soil in combination with different clo4-concentrations (0.25,0.5,0.75,and 1 wt.%) and three different amendment rates (1,2.5,and 5 wt.%) of gliricidia sepium bc. bioavailable fraction of ni and mn was analyzed using cacl2 extraction method. an increase of clo4-concentrations enhanced bioavailability fraction of ni and mn. however,bc amendments reduced the bioavailability of ni and mn. in comparison,5% bc amendment significantly immobilized the bioavailability of ni (68-92%) and mn (76-93%) compared to other bc amendment rates. electrostatic attractions and surface diffusion could be postulated for ni and mn immobilization by bc. in addition,clo4-may have adsorbed to bc via hydrogen bonding which may reduce the influence of clo4-on ni and mn mobility. overall,it is obvious that bc could be utilized as an effective amendment to immobilize ni and mn in heavy metal and clo4-contaminated soil. © 2017 prasanna kumarathilaka and meththika vithanage.