Slow pyrolyzed biochars from crop residues for soil metal(loid) immobilization and microbial community abundance in contaminated agricultural soils

Avanthi Deshani Igalavithana, Jinje Park, Changkook Ryu, Young Han Lee, Yohey Hashimoto, Longbin Huang, Eilhann E. Kwon, Yong Sik Ok, Sang Soo Lee

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

This study evaluated the feasibility of using biochars produced from three types of crop residues for immobilizing Pb and As and their effects on the abundance of microbial community in contaminated lowland paddy (P-soil) and upland (U-soil) agricultural soils. Biochars were produced from umbrella tree [Maesopsis eminii] wood bark [WB], cocopeat [CP], and palm kernel shell [PKS] at 500 �C by slow pyrolysis at a heating rate of 10 �C min−1. Soils were incubated with 5% (w w−1) biochars at 25 �C and 70% water holding capacity for 45 d. The biochar effects on metal immobilization were evaluated by sequential extraction of the treated soil, and the microbial community was determined by microbial fatty acid profiles and dehydrogenase activity. The addition of WB caused the largest decrease in Pb in the exchangeable fraction (P-soil: 77.7%, U-soil: 91.5%), followed by CP (P-soil: 67.1%, U-soil: 81.1%) and PKS (P-soil: 9.1%, U-soil: 20.0%) compared to that by the control. In contrast, the additions of WB and CP increased the exchangeable As in U-soil by 84.6% and 14.8%, respectively. Alkalinity and high phosphorous content of biochars might be attributed to the Pb immobilization and As mobilization, respectively. The silicon content in biochars is also an influencing factor in increasing the As mobility. However, no considerable effects of biochars on the microbial community abundance and dehydrogenase activity were found in both soils.

Original languageEnglish
Pages (from-to)157-166
Number of pages10
JournalChemosphere
Volume177
DOIs
Publication statusPublished - 2017 Jan 1
Externally publishedYes

Keywords

  • Black carbon
  • PLFA
  • Slow pyrolysis
  • Soil enzymes
  • Toxic metals

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemistry(all)

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