TY - JOUR
T1 - Does microbial centimeter-scale heterogeneity impact MCPA degradation in and leaching from a loamy agricultural soil?
AU - Rosenbom, Annette E.
AU - Binning, Philip J.
AU - Aamand, Jens
AU - Dechesne, Arnaud
AU - Smets, Barth F.
AU - Johnsen, Anders R.
N1 - Funding Information:
This study was funded primarily by the Villum Kann Rasmussen Foundation via the Center for Environmental and Agricultural Microbiology (CREAM) and secondarily by the Geological Survey of Denmark and Greenland via the Danish Pesticide Leaching Assessment Programme . We are grateful to Morten Siwertsen and Anders Ekerot from COMSOL Support.
PY - 2014/2/15
Y1 - 2014/2/15
N2 - The potential for pesticide degradation varies greatly at the centimeter-scale in agricultural soil. Three dimensional numerical simulations were conducted to evaluate how such small-scale spatial heterogeneity may affect the leaching of the biodegradable pesticide 2-methyl-4-chlorophenoxyacetic acid (MCPA) in the upper meter of a variably-saturated, loamy soil profile. To incorporate realistic spatial variation in degradation potential, we used data from a site where 420 mineralization curves over 5 depths have been measured. Monod kinetics was fitted to the individual curves to derive initial degrader biomass values, which were incorporated in a reactive transport model to simulate heterogeneous biodegradation. Six scenarios were set up using COMSOL Multiphysics to evaluate the difference between models having different degrader biomass distributions (homogeneous, heterogeneous, or no biomass) and either matrix flow or preferential flow through a soil matrix with a wormhole. MCPA leached, within 250. days, below 1. m only when degrader biomass was absent and preferential flow occurred. Both biodegradation in the plow layer and the microbially active lining of the wormhole contributed to reducing MCPA-leaching below 1. m. The spatial distribution of initial degrader biomass within each soil matrix layer, however, had little effect on the overall MCPA-leaching.
AB - The potential for pesticide degradation varies greatly at the centimeter-scale in agricultural soil. Three dimensional numerical simulations were conducted to evaluate how such small-scale spatial heterogeneity may affect the leaching of the biodegradable pesticide 2-methyl-4-chlorophenoxyacetic acid (MCPA) in the upper meter of a variably-saturated, loamy soil profile. To incorporate realistic spatial variation in degradation potential, we used data from a site where 420 mineralization curves over 5 depths have been measured. Monod kinetics was fitted to the individual curves to derive initial degrader biomass values, which were incorporated in a reactive transport model to simulate heterogeneous biodegradation. Six scenarios were set up using COMSOL Multiphysics to evaluate the difference between models having different degrader biomass distributions (homogeneous, heterogeneous, or no biomass) and either matrix flow or preferential flow through a soil matrix with a wormhole. MCPA leached, within 250. days, below 1. m only when degrader biomass was absent and preferential flow occurred. Both biodegradation in the plow layer and the microbially active lining of the wormhole contributed to reducing MCPA-leaching below 1. m. The spatial distribution of initial degrader biomass within each soil matrix layer, however, had little effect on the overall MCPA-leaching.
KW - COMSOL simulations
KW - MCPA leaching
KW - Monod-kinetics
KW - Preferential transport
KW - Spatial biodegradation
UR - http://www.scopus.com/inward/record.url?scp=84888416926&partnerID=8YFLogxK
U2 - 10.1016/j.scitotenv.2013.11.009
DO - 10.1016/j.scitotenv.2013.11.009
M3 - Article
VL - 472
SP - 90
EP - 98
JO - Science of the Total Environment
JF - Science of the Total Environment
SN - 0048-9697
ER -