Mineralization of of the herbicide MCPA in urban soils is linked to presence and growth of class III tfdA genes

TY - JOUR

T1 - Mineralization of of the herbicide MCPA in urban soils is linked to presence and growth of class III tfdA genes

AU - Nielsen, Morten S.

AU - Baelum, Jacob

AU - Jensen, Malene B.

AU - Jacobsen, Carsten S.

PY - 2011/5

Y1 - 2011/5

N2 - Mineralization and sorption of C-14-ring labeled herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) were quantified along with the tfdA gene abundance in 7 different soils. The soils tested were five gravel soils from urban locations, one soil from the embankment of a railway track, and finally an agricultural soil as a control. The mineralization experiments were performed with a concentration of MCPA of 5 mg/kg and incubated at 10 degrees C for a period of 60 days.With K-d values ranging from 0.04 to 0.41 l kg(-1) the sorption experiments revealed that binding of MCPA to the six gravel soils was lower compared to the control soil which had a Kd value of 0.91 l kg(-1). The potential for MCPA mineralization varied from less than 5 to over 55% mineralized in 60 days. The most rapid MCPA mineralization was observed in the soil from the Danish railway tracks with 55% mineralized after only 18 days. The mineralization data was fitted to degradation kinetic models, which indicated that growth occurred as a response to MCPA degradation in most of the soils.Soil DNA was extracted and tfdA genes responsible for the first step in MCPA degradation were quantified by real-time PCR (qPCR) at appropriate time points throughout the mineralization experiments. Indicating growth of specific MCPA degraders, the abundance of class III tfdA genes showed an increase during MCPA mineralization in those soils able to mineralize MCPA.These findings emphasize the importance of the presence of microorganisms that are able to readily degrade MCPA, to avoid groundwater leaching following use on urban gravel areas that possess low binding ability of the compound. (C) 2011 Elsevier Ltd. All rights reserved.

AB - Mineralization and sorption of C-14-ring labeled herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) were quantified along with the tfdA gene abundance in 7 different soils. The soils tested were five gravel soils from urban locations, one soil from the embankment of a railway track, and finally an agricultural soil as a control. The mineralization experiments were performed with a concentration of MCPA of 5 mg/kg and incubated at 10 degrees C for a period of 60 days.With K-d values ranging from 0.04 to 0.41 l kg(-1) the sorption experiments revealed that binding of MCPA to the six gravel soils was lower compared to the control soil which had a Kd value of 0.91 l kg(-1). The potential for MCPA mineralization varied from less than 5 to over 55% mineralized in 60 days. The most rapid MCPA mineralization was observed in the soil from the Danish railway tracks with 55% mineralized after only 18 days. The mineralization data was fitted to degradation kinetic models, which indicated that growth occurred as a response to MCPA degradation in most of the soils.Soil DNA was extracted and tfdA genes responsible for the first step in MCPA degradation were quantified by real-time PCR (qPCR) at appropriate time points throughout the mineralization experiments. Indicating growth of specific MCPA degraders, the abundance of class III tfdA genes showed an increase during MCPA mineralization in those soils able to mineralize MCPA.These findings emphasize the importance of the presence of microorganisms that are able to readily degrade MCPA, to avoid groundwater leaching following use on urban gravel areas that possess low binding ability of the compound. (C) 2011 Elsevier Ltd. All rights reserved.

KW - Pesticide

KW - Degradative genes

KW - Sorption

KW - qPCR

KW - Gravel

KW - SORPTION

KW - DEGRADATION

KW - ACID

KW - ATRAZINE

KW - GLYPHOSATE

KW - EXPRESSION

KW - 2,4-D

KW - FIELD

U2 - 10.1016/j.soilbio.2011.01.014

DO - 10.1016/j.soilbio.2011.01.014

M3 - Journal article

SN - 0038-0717

VL - 43

SP - 984

EP - 990

JO - Soil Biology & Biochemistry

JF - Soil Biology & Biochemistry

IS - 5

ER -