%0 Journal Article
%T Biodegradation of Aged Residues of Atrazine and Alachlor in a Mix-Load Site Soil by Fungal Enzymes
%A Anastasia E. M. Chirnside
%A William F. Ritter
%A Mark Radosevich
%J Applied and Environmental Soil Science
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/658569
%X Soils from bulk pesticide mixing and loading (mix-load) sites are often contaminated with a complex mixture of pesticides, herbicides, and other organic compounds used in pesticide formulations that limits the success of remediation efforts. Therefore, there is a need to find remediation strategies that can successfully clean up these mix-load site soils. This paper examined the degradation of atrazine (2-chloro-4-ethylamino-6-isopropylamino-S-triazine; AT) and alachlor (2-chloro- , -diethyl-N-[methoxymethyl]-acetanilide) in contaminated mix-load site soil utilizing an extracellular fungal enzyme solution derived from the white rot fungus, Phanerochaete chrysosporium, grown in a packed bed bioreactor. Thirty-two percent of AT and 54% of AL were transformed in the biometers. The pseudo first-order rate constant for AT and AL biodegradation was 0.0882£¿d£¿1 and 0.2504£¿d£¿1, respectively. The half-life ( ) for AT and AL was 8.0 and 3.0 days, respectively. Compared to AT, the initial disappearance of AL proceeded at a faster rate and resulted in a greater amount of AL transformed. Based on the net evolved from the biometers, about 4% of the AT and AL initially present in the soil was completely mineralized. 1. Introduction Bulk pesticide mixing and loading (mix-load) sites are major contributors of pesticide contamination of ground and surface waters [1]. Many of these sites contain extremely high concentrations of pesticides, fertilizers, and other organic compounds used in pesticide formulations, which may limit bioremediation efforts due to the toxicity effects of the high pesticide concentrations to the indigenous microbes [2, 3], the complexity of the mixture of compounds present [4], and the natural heterogeneity of the soil and water environment [5]. Remediation treatment strategies must evaluate and overcome the difficulties associated with mix-load sites. Bioaugmentation has become a cost-effective alternative for cleanup of contaminated soil and groundwater. Although bacterial degradation schemes are utilized more often, there is great potential for the use of fungal degradative systems. Certain fungi, particularly the white rot fungi (WRF), are often more successful degrading pesticides than other microorganisms because of their ability to tolerate and/or detoxify pesticides found in complex mixtures and at high concentrations, such as those soils from mix-load sites [4]. The WRF, Phanerochaete chrysosporium, has been shown to degrade a variety of pesticides in the laboratory. However, field applications have not had as much success due to the
%U http://www.hindawi.com/journals/aess/2011/658569/