title: Effect of biochars and microorganisms on cadmium accumulation in rice grains grown in Cd-contaminated soil.
abstract: Cadmium (Cd) contaminated in rice grains is a serious problem because most Asians consume rice on a daily basis. Rice grown in Cd-contaminated soil normally did not have high concentration of Cd. However, soil samples used in this study had high concentrations of Cd. The purpose of this study was to clearly see the effects of biochar and microorganism addition in rice growing in Cd-contaminated soil. The initial Cd concentration in Cd-contaminated soil used in this study was about 650 mg kg(-1). Cadmium concentration in rice plants grown in Cd-contaminated soil with the addition of 1% (w/w) different biochars such as sawdust fly ash (SDFA), bagasse fly ash (BGFA), and rice husk ash (RHA) was investigated. The results showed that SDFA was the best biochar in terms of reducing cadmium accumulation in rice grains when compared to BGFA and RHA under the same conditions. In addition, rice plants grown in Cd-contaminated soil with the addition of various nonpathogenic microorganisms, such as Pseudomonas aeruginosa, Bacillus subtilis, and Beauveria bassiana were also studied. The results showed that the addition of 2% (v/v) microorganisms can reduce Cd accumulation in grains. It was found that grains obtained from Cd-contaminated soil with the addition of P. aeruginosa had the lowest cadmium concentration compared to the ones from soil amended with other strains. This was due to the fact that P. aeruginosa adsorbed more Cd itself into its cells than other strains. The rice plants grown in Cd-contaminated soil with the addition of biochars and microorganisms were also compared. The results showed that adding 2% (v/v) microorganisms seemed to reduce Cd accumulation in rice grains better than adding 1% (w/w) biochars. In addition, the amounts of calcium and magnesium in rice grains and the dry weight of plant in Cd-contaminated soil amended with P. aeruginosa were the highest in comparison to other microorganisms, biochars, and the soil without any amendments (Cd-soil control). It might be possible that microorganisms can cause leaching of Ca, Mg, etc. from contaminated soil and compete with Cd to be uptaken by plants. This would cause the increase in plant dry weight and higher mineral nutrients accumulation in grains. Both biochars and microorganisms are suitable for reducing the amount of Cd in rice grains. The application should depend on farmers, biochars available in nearby areas, etc. Therefore, microorganisms and biochars can be used to solve the problem of cadmium contamination in rice grains.
authors.affiliation: Department of Urban and Industrial Environment, Science and Technology Faculty, Suan Dusit Rajabhat University, Bangkok, 10300, Thailand.
authors.forename: Parinda
authors.initials: P
authors.lastname: Suksabye
authors.affiliation: School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand.
authors.forename: Apinya
authors.initials: A
authors.lastname: Pimthong
authors.affiliation: School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand.
authors.forename: Prapai
authors.initials: P
authors.lastname: Dhurakit
authors.affiliation: Pilot Plant and Development and Training Institute, King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand.
authors.forename: Phenjun
authors.initials: P
authors.lastname: Mekvichitsaeng
authors.affiliation: School of Bioresources and Technology, King Mongkut's University of Technology Thonburi, Bangkok, 10150, Thailand. paitip.thi@kmutt.ac.th.
authors.forename: Paitip
authors.initials: P
authors.lastname: Thiravetyan
mesh_terms: D002104:Cadmium / Q000378:metabolism*; D002606:Charcoal; D060729:Coal Ash; D004787:Environmental Pollution; D012275:Oryza / Q000254:growth & development / Q000378:metabolism*; D012987:Soil; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*
chemical_list: D060729:Coal Ash; D012987:Soil; D012989:Soil Pollutants; C540010:biochar; D002104:Cadmium; D002606:Charcoal
keywords: B. bassiana; B. subtilis; Biochars; Cadmium; Microorganisms; P. aeruginosa; Rice grains