Tenax extraction for exploring rate-limiting factors in methyl-β-cyclodextrin enhanced anaerobic biodegradation of PAHs under denitrifying conditions in a red paddy soil.
The effectiveness of anaerobic bioremediation systems for PAH-contaminated soil may be constrained by low contaminants bioaccessibility due to limited aqueous solubility and lack of suitable electron acceptors. Information on what is the rate-limiting factor in bioremediation process is of vital importance in the decision in what measures can be taken to assist the biodegradation efficacy. In the present study, four different microcosms were set to study the effect of methyl-β-cyclodextrin (MCD) and nitrate addition (N) on PAHs biodegradation under anaerobic conditions in a red paddy soil. Meanwhile, sequential Tenax extraction combined with a first-three-compartment model was employed to evaluate the rate-limiting factors in MCD enhanced anaerobic biodegradation of PAHs. Microcosms with both 1% (w/w) MCD and 20mM N addition produced maximum biodegradation of total PAHs of up to 61.7%. It appears rate-limiting factors vary with microcosms: low activity of degrading microorganisms is the vital rate-limiting factor for control and MCD addition treatments (CK and M treatments); and lack of bioaccessible PAHs is the main rate-limiting factor for nitrate addition treatments (N and MN treatments). These results have practical implications for site risk assessment and cleanup strategies.
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China; Key Laboratory of Soil Environmental and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: sunmingming@njau.edu.cn.
Mingming
M
Sun
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Mao
M
Ye
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China. Electronic address: fenghu@njau.edu.cn.
Feng
F
Hu
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
Huixin
H
Li
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Ying
Y
Teng
Yantai Institute of Costal Zone Research, Chinese Academy of Sciences, Yantai 264003, PR China.
Yongming
Y
Luo
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Xin
X
Jiang
Department of Chemistry, Maseno University, Private Bag, Maseno 40105, Kenya.
Fredrick Orori
FO
Kengara
D000693:Anaerobiosis; D001673:Biodegradation, Environmental; D009566:Nitrates; D011084:Polycyclic Aromatic Hydrocarbons / Q000032:analysis / Q000378:metabolism*; D011108:Polymers / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis / Q000378:metabolism*; D047392:beta-Cyclodextrins
D009566:Nitrates; D011084:Polycyclic Aromatic Hydrocarbons; D011108:Polymers; D012989:Soil Pollutants; D047392:beta-Cyclodextrins; C108732:methyl-beta-cyclodextrin; C010514:tenax
Anaerobic biodegradation; Methyl-β-cyclodextrin; Nitrate; Polycyclic aromatic hydrocarbons; Rate-limiting factors; Tenax TA