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Natural and accelerated detoxification of RDX and atrazine in contaminated soil and water
Abstract
Xenobiotic contamination of soil and water is a serious problem and poses a potential threat to human health and the environment. Natural transformation of two triazines, RDX and atrazine, was characterized in soil and augmented through addition of zero-valent iron (Fe$\sp0).$ RDX sorption in Sharpsburg surface soil was adequately described by a linear isotherm $\rm(K\sb{d}=0.97$ L kg$\sp{-1}).$ An increase in sorption from 34% at 30 min to only 37% at 168 d indicated time-independent sorption. During the 168-d equilibration, readily available RDX (extractable with 3 mM CaCl$\sb2)$ decreased from 75 to 52%, while potentially available RDX (acetonitrile-extractable) increased from 24 to 32%. Only 8% of the added $\sp{14}$C was unextractable at 168 d and no bound residue formed when solid-phase RDX was present. Limited RDX sorption and transformation indicated the importance of remediating RDX-contaminated water and soil. Treating an aqueous solution of 32 mg RDX L$\sp{-1}$ with 1% Fe$\sp0$ (w/v) resulted in complete RDX destruction within 72 h. Treating contaminated soil (30 mg RDX kg$\sp{-1})$ with 2% Fe$\sp0$ (w/w) increased RDX mineralization from 16 to 60% within 112 d. RDX destruction increased from 75 to 99% within 24 h when the Eh of an RDX-contaminated soil slurry was maintained at $-$150 mV and neutral pH. Agitating 20 $\mu$g atrazine L$\sp{-1}$ with 10% Fe$\sp0$ (w/v) removed 93% of the atrazine from solution within 48 h. About 5% of the atrazine sorbed to the iron was readily available and 33% was potentially available. The remaining 62% consisted of atrazine transformation products or unextractable residues. Treating Sharpsburg surface soil (1 mg atrazine kg$\sp{-1})$ with Fe$\sp0$ (2% w/w) increased atrazine mineralization from 4 to 11% after 120 d. Results indicate that Fe$\sp0$ enhances RDX and atrazine transformation and should be a viable treatment for field-scale remediation of contaminated water and soil.
Subject Area
Soil sciences|Environmental science|Agronomy
Recommended Citation
Singh, Jasbir, "Natural and accelerated detoxification of RDX and atrazine in contaminated soil and water" (1997). ETD collection for University of Nebraska-Lincoln. AAI9815908.
https://digitalcommons.unl.edu/dissertations/AAI9815908