... L. Adam a , Steve D. Comfort a , Tian C. Zhang b & Matthew C. Morley b ... In a l... more ... L. Adam a , Steve D. Comfort a , Tian C. Zhang b & Matthew C. Morley b ... In a laboratory investigation, we observed that permanganate was highly effective in transforming and mineralizing RDX (Adam et al., 20041. Adam, ML, Comfort, SD, Morley, MC and Snow, DD 2004. ...
Atrazine is the most widely used herbicide in the U.S. and has been detected in surface water and... more Atrazine is the most widely used herbicide in the U.S. and has been detected in surface water and groundwater. Technologies are needed for onsite and in situ remediation of water and soil containing atrazine. We investigated the potential of using fine-grained, zero-valent iron (Fe0) to remove atrazine and promote its degradation in contaminated water and soil. Atrazine loss from aqueous solution increased with increasing Fe0concentration (w/v). Agitating 20 μg14C-ring-labeled atrazine L−1with 10% Fe0(w/v) removed 92% of the14C from solution within 48 h. Only about 4% of the14C lost from solution was extractable from the iron with 3 mM CaCl2(readily available pool), 81% was extractable with CH3CN (potentially available pool), and 11% was unextractable residues. A companion experiment indicated that most of the14C extracted from the iron with 3 mM CaCl2after the 48-h Fe0treatment was unaltered atrazine, while the CH3CN extract contained approximately 33% atrazine and 48% was unidenti...
A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin... more A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin to monitor N transformations following liquid manure injections. Liquid manure with and without a nitrification inhibitor [nitrapyrin, 2‐chloro‐6‐(trichloromethyl)pyridine, 13 mg a.i. L−1 liquid manure] was injected into an uncropped area in June 1985. Soil samples were taken using a grid placed over the vertical cross‐section of the injected bands permitting spatial sampling in the vertical plane. Sampling was done 5, 12, 26, 39, 67, 99, and 350 d after manure application by progressive exposure of the band. Soil water content, pH, NH4‐N, (NO2 + NO3)‐N, Cl, and water‐soluble C were determined. The synagraphic computer program, SYMAP, was used to evaluate spatial changes in inorganic N concentrations in the manure injection zone. Nitrapyrin was not effective in inhibiting nitrification at the rate used. Nitrification occurred at the outer fringes of the band within 5 d; maximum concentr...
Past disposal practices at munitions production plants have contaminated terrestrial and aquatic ... more Past disposal practices at munitions production plants have contaminated terrestrial and aquatic ecosystems with 2,4,6‐trinitrotoluene (TNT). We determined TNT transport, degradation, and long‐term sorption characteristics in soil. Transport experiments were conducted with repacked, unsaturated soil columns containing uncontaminated soil or layers of contaminated and uncontaminated soil. Uncontaminated soil columns received multiple pore volumes (22–50) of a TNT‐3H2O pulse, containing 70 or 6.3 mg TNT L−1 at a constant pore water velocity. TNT breakthrough curves (BTCs) never reached initial solute pulse concentrations. Apex concentrations (C/Co) were between 0.6 and 0.8 for an initial pulse of 70 mg TNT L−1 and 0.2 to 0.3 for the 6.3 mg TNT L−1 pulse. Earlier TNT breakthrough was observed at the higher pulse concentration. This mobility difference was predicted from the nonlinear adsorption isotherm determined for TNT sorption. In all experiments, a significant fraction of added TN...
Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) has been identified as one of five pesticides presen... more Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) has been identified as one of five pesticides present in Montana groundwaters. We determined the effects of degradation and time of water application on the transport of dicamba in a Lohmiller clay soil (fine, montmorillonitic, mesic Ustic Torrifluvent). Carbon 14‐labeled dicamba was surface applied (0.35 kg ha−1) to disturbed soil columns (5.0 cm diam; 29 cm length) previously conditioned with 3 mM CaCl2. The columns were allowed to incubate (23.5 °C) in triplicate for 0, 14, 21, 28, and 42 d. Following incubation, the columns were attached to a vacuum chamber containing a fraction collector and leached with 3 mM CaCl2 under unsaturated conditions. Dicamba breakthrough curves were determined for each incubation period. The percentage of dicamba recovered in the column effluent decreased from 85% (of total applied) after no incubation to 9.5% after 42 d of incubation. The decline of dicamba in the effluent coincided with an accumulation o...
... L. Adam a , Steve D. Comfort a , Tian C. Zhang b & Matthew C. Morley b ... In a l... more ... L. Adam a , Steve D. Comfort a , Tian C. Zhang b & Matthew C. Morley b ... In a laboratory investigation, we observed that permanganate was highly effective in transforming and mineralizing RDX (Adam et al., 20041. Adam, ML, Comfort, SD, Morley, MC and Snow, DD 2004. ...
Atrazine is the most widely used herbicide in the U.S. and has been detected in surface water and... more Atrazine is the most widely used herbicide in the U.S. and has been detected in surface water and groundwater. Technologies are needed for onsite and in situ remediation of water and soil containing atrazine. We investigated the potential of using fine-grained, zero-valent iron (Fe0) to remove atrazine and promote its degradation in contaminated water and soil. Atrazine loss from aqueous solution increased with increasing Fe0concentration (w/v). Agitating 20 μg14C-ring-labeled atrazine L−1with 10% Fe0(w/v) removed 92% of the14C from solution within 48 h. Only about 4% of the14C lost from solution was extractable from the iron with 3 mM CaCl2(readily available pool), 81% was extractable with CH3CN (potentially available pool), and 11% was unextractable residues. A companion experiment indicated that most of the14C extracted from the iron with 3 mM CaCl2after the 48-h Fe0treatment was unaltered atrazine, while the CH3CN extract contained approximately 33% atrazine and 48% was unidenti...
A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin... more A field experiment was conducted on a Piano silt loam (Typic Argiudoll) in southcentral Wisconsin to monitor N transformations following liquid manure injections. Liquid manure with and without a nitrification inhibitor [nitrapyrin, 2‐chloro‐6‐(trichloromethyl)pyridine, 13 mg a.i. L−1 liquid manure] was injected into an uncropped area in June 1985. Soil samples were taken using a grid placed over the vertical cross‐section of the injected bands permitting spatial sampling in the vertical plane. Sampling was done 5, 12, 26, 39, 67, 99, and 350 d after manure application by progressive exposure of the band. Soil water content, pH, NH4‐N, (NO2 + NO3)‐N, Cl, and water‐soluble C were determined. The synagraphic computer program, SYMAP, was used to evaluate spatial changes in inorganic N concentrations in the manure injection zone. Nitrapyrin was not effective in inhibiting nitrification at the rate used. Nitrification occurred at the outer fringes of the band within 5 d; maximum concentr...
Past disposal practices at munitions production plants have contaminated terrestrial and aquatic ... more Past disposal practices at munitions production plants have contaminated terrestrial and aquatic ecosystems with 2,4,6‐trinitrotoluene (TNT). We determined TNT transport, degradation, and long‐term sorption characteristics in soil. Transport experiments were conducted with repacked, unsaturated soil columns containing uncontaminated soil or layers of contaminated and uncontaminated soil. Uncontaminated soil columns received multiple pore volumes (22–50) of a TNT‐3H2O pulse, containing 70 or 6.3 mg TNT L−1 at a constant pore water velocity. TNT breakthrough curves (BTCs) never reached initial solute pulse concentrations. Apex concentrations (C/Co) were between 0.6 and 0.8 for an initial pulse of 70 mg TNT L−1 and 0.2 to 0.3 for the 6.3 mg TNT L−1 pulse. Earlier TNT breakthrough was observed at the higher pulse concentration. This mobility difference was predicted from the nonlinear adsorption isotherm determined for TNT sorption. In all experiments, a significant fraction of added TN...
Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) has been identified as one of five pesticides presen... more Dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) has been identified as one of five pesticides present in Montana groundwaters. We determined the effects of degradation and time of water application on the transport of dicamba in a Lohmiller clay soil (fine, montmorillonitic, mesic Ustic Torrifluvent). Carbon 14‐labeled dicamba was surface applied (0.35 kg ha−1) to disturbed soil columns (5.0 cm diam; 29 cm length) previously conditioned with 3 mM CaCl2. The columns were allowed to incubate (23.5 °C) in triplicate for 0, 14, 21, 28, and 42 d. Following incubation, the columns were attached to a vacuum chamber containing a fraction collector and leached with 3 mM CaCl2 under unsaturated conditions. Dicamba breakthrough curves were determined for each incubation period. The percentage of dicamba recovered in the column effluent decreased from 85% (of total applied) after no incubation to 9.5% after 42 d of incubation. The decline of dicamba in the effluent coincided with an accumulation o...
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