Details

Autor(en) / Beteiligte

• Boostani, Hamid Reza
• Najafi-Ghiri, Mahdi
• Hardie, Ailsa G.
• Khalili, Dariush

Titel

Comparison of Pb stabilization in a contaminated calcareous soil by application of vermicompost and sheep manure and their biochars produced at two temperatures

Ist Teil von

• Applied geochemistry, 2019-03, Vol.102, p.121-128

Ort / Verlag

Elsevier Ltd

Erscheinungsjahr

2019

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Soil contamination with potentially toxic elements (PTEs) is increasing due to human activities including the widespread use of chemical fertilizers, sludge and industrial wastewater in agriculture. In situ stabilization of soil PTEs using organic amendments is a cost effective and efficacious method. A laboratory experiment was conducted to investigate the effect of two organic materials (sheep manure (SM) and vermicompost (VC)) and their biochars (SMB and VCB) produced at two pyrolysis temperatures (300 and 500 °C) at 2 wt. % on Pb immobilization in a contaminated calcareous soil. A sequential extraction procedure, mobility factor and release kinetics were used for evaluating efficiency of the amendments. Addition of the biochars resulted in a significant decrease in exchangeable (10.4–19.6%) and carbonate (3.8–10.5%) forms of soil Pb, while Pb bound to amorphous Fe oxides (4.3–52.9%) was increased. The application of VCB produced at 500 °C resulted in the greatest mobility factor reduction (11%), likely due to its characteristics such as high pH (10.5), high P (0.39%) and ash content (67.7%). Two first-order reactions model best fitted the Pb release data extracted by EDTA, indicating Pb release took place from two sections of the soil with different adsorption and solubility properties. The lowest amount of Pb extracted in Q1 and Q2 phases were observed in VCB (115.2 mg kg−1) and SMB (105.5 mg kg−1) produced at 500 °C treatments, respectively. Generally, the effect of biochars produced at higher temperature (500 °C) on the soil Pb stabilization was greater than those produced at lower temperature (300 °C), while the feedstocks (SM and VC) had no significant effect in stabilizing soil Pb. •Two first-order reactions model best fitted the Pb release data from the treated soil.•Biochars produced at 500 °C increased soil Pb stabilization to greater extent than 300 °C.•Vermicompost biochar (500 °C) reduced Pb mobility factor the most due to higher ash %.•Unpyrolyzed vermicompost and sheep manure had no effect on soil Pb stabilization.