Abstract:
Horton Plains is one of the most important natural resources in Sri Lanka which has
been threatened by a large-scale forest dieback. A previous study revealed that
isolated soil Cd as one of the key causes behind forest dieback in Horton Plains. The
extraordinary capabilities of biochar in detoxifying both organic and inorganic
contaminants have been well recognized and it is vital to develop an effectual and
cost effective method using biochar would be an applicable remedial measure.
Biochar has the ability to immobilize heavy metals from contaminated soil due to
its’ chemical composition. The pH and the CEC of the forest soil used for the study
were 5.4 and 210 c mols kg -1
respectively. The soil was rich with organic matter and
the content of soil organic matter (SOM) has reached up to 13.4%. Bio char which
was prepared under controlled conditions using the wood collected from Horton
Plains was used as the soil treatment and along with the control the study consisted
of two treatments of five replicates. Ten soil samples which contained 25 g were
acquired from bulked soil and five of them were treated from 5 g of biochar available
in Horton plains and every single soil sample was spiked with 20 ml of 500 ppm Cd
solution. Treatments were added to the soil samples and the available Cd was
extracted using standard methods in literature, and the Cd concentrations were
analyzed using the Atomic Absorption Spectrophotometer (AAS). Immobilization
of Cd in the soil samples treated with biochar naturally available in Horton plains
was significant (P < 0.03) and the rate of the reduction of the available Cd in the soil
was drastic. However, the control has also shown its capacity to immobilize soil Cd
because of the existence of extraordinary level of SOM and active natural sorbents
presence in SOM such as humic and fulvic acids.