Results of the National Alachlor Well Water Survey

Holden, Larry R.; Graham, Jeffrey A.; Whitmore, Roy; Alexander, W. J.; Pratt, Richard W.; Liddle, Susan K.; Piper, Lanny L.

doi:10.1021/es00029a011

Cited by 139 publications

(69 citation statements)

References 3 publications

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“…For example, Draoui et al (2008) found that parameters related to the soil and vadose zone most strongly affect susceptibility, while Nobre et al (2007) determined that susceptibility is most dependent on depth to water. It has been suggested that the complicated weighting and rating procedure is "self-defeating" (Holden et al 1992). Several studies have shown that DRASTIC is not able to predict nitrate contamination (Rupert 2001).…”

Section: Drasticmentioning

confidence: 99%

“…Several studies have shown that DRASTIC is not able to predict nitrate contamination (Rupert 2001). Holden et al (1992) found "little if any association between DRASTIC scores and herbicide occurrence" and even discovered one nearly significant negative trend.…”

Section: Drasticmentioning

confidence: 99%

“…This indicator, however, is not conservative as it is affected by various nitrogen cycling processes in the soil (Addiscott 2005;Kendall 1998); nitrate can undergo denitrification (Bottcher et al 1990;Fukada et al 2004). Other comparison indicators include pesticides (Holden et al 1992) and chloride (Nobre et al 2007). …”

Section: Intrinsic Susceptibility Accuracymentioning

confidence: 99%

“…Explanations for less than ideal correlations include a lack of analysis for dilution and denitrification (Debernardi et al 2008), poor well log descriptions and discontinuous confining layers (Wei 1998), pumping-induced draw of contaminants (Holman et al 2005), attenuation and degradation of contaminants (Holden et al 1992), and the presence of perched water tables (Ronneseth et al 1995). Groundwater quality data have also been used to optimize and revise susceptibility mapping methods.…”

Section: Intrinsic Susceptibility Accuracymentioning

confidence: 99%

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Assessing risk to groundwater quality using an integrated risk framework

2013

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Risk to groundwater quality is defined as a function of susceptibility, hazard and consequence. Aquifer susceptibility combines the intrinsic susceptibility of the physical system with potential preferential pathways. Hazard threats are assessed based on the potential impact and probability of release. The consequence is the financial cost of the loss of the resource. The risk assessment methodology is applied to the Township of vi

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Section: Drasticmentioning

confidence: 99%

Section: Drasticmentioning

confidence: 99%

Section: Intrinsic Susceptibility Accuracymentioning

confidence: 99%

Section: Intrinsic Susceptibility Accuracymentioning

confidence: 99%

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Assessing risk to groundwater quality using an integrated risk framework

2013

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“…Both of these herbicides have been detected in groundwater samples in Oklahoma and in other agricultural areas in the United States. 2,3 Current standards of the Safe Drinking Water Act include a maximum contaminant level (MCL) of 2 µg/L for alachlor. 4 Propachlor currently has only monitoring requirements, but may have a specific MCL established in the future.…”

Section: Introductionmentioning

confidence: 99%

Biotransformation of Herbicides in the Presence of Various Electron Acceptors

Wilber

Wang

1997

Journal of the Air & Waste Management Association

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Among the important factors affecting the biotransformation of xenobiotic chemicals upon their release into the environment are the dominant electron acceptor condition present and the presence of other, more readily degraded carbon sources. Here, glass-bead biofilm columns were used to investigate the effects of the presence of three different inorganic electron acceptor conditions (oxygen respiration, nitrate reduction, and sulfate reduction) on the biotransformation of the acetanilide herbicides alachlor and propachlor, and to determine the effects of two exogenous carbon sources (acetate and glucose) on their biotransformation under each of these conditions.Biotransformation of alachlor and propachlor occurred in the presence of both carbon sources and under each of the three electron acceptor conditions. Both were transformed most rapidly under sulfate-reducing conditions. Analysis by gas chromatography/mass spectrometry (GC/ MS) did not reveal any significant metabolic products. Both herbicides react abiotically with bisulfide, produced within the sulfate-reducing cultures, though most of the transformation was attributed to the microorganisms. The primary, readily degraded carbon source (acetate or glucose) was needed to establish each culture, and its continuous presence was required to sustain herbicide biotransformation in the sulfate-reducing reactors. Loss of either acetate or glucose from the column influent did not significantly affect herbicide biotransformation in the aerobic or nitratereducing reactors, at least for short periods. Temporary loss of the external electron acceptors (O 2 , NO 3 -, or SO 4 2-

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Leaching of Alachlor from Alginate-Encapsulated Controlled-Release Formulations

Johnson

Pepperman

1996

Pestic. Sci.

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Abstract:The mobility of alachlor from alginate-encapsulated controlled-release (CR) formulations was investigated in two contrasting soil profiles. Two CR formulations of alachlor were prepared with the following components (1) basesodium alginate + kaolin + 'Tween' 20@ (1 + 10 + 0.5 by mass) and (2) base + 40 g kg-' linseed oil. These were compared to technical grade alachlor and to a commercial alachlor EC formulation ('Lasso' 4EC). All herbicide treatments were labeled with ['4C]alachlor and were applied to duplicate soil columns that were composed of a surface and a subsoil horizon. Each horizon was packed to a depth of 12.5 cm, giving a total column length of 25 cm. The columns were leached with 21 cm (420 ml) to 30 cm (600 ml) of 0.01 M calcium chloride for a period of 7 to 10 days. Alachlor leaching from the EC formulations was the same as that from the technical material in both soils: 33% in the Evesboro and 10% in the Conover soil. The CR-Oil formulation leached 4 and 2% of the applied ['4C]alachlor, compared to 12 and 3% for the CR-N formulation for the Evesboro and Conover soils, respectively. The CR-Oil formulation also increased the amount of ['4C]alachlor retained in the soil surface horizon (105-114%), compared to CR-N (39-45%), technical material (14-23%) and EC (12-17%).

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Results of the National Alachlor Well Water Survey

Cited by 139 publications

References 3 publications

Assessing risk to groundwater quality using an integrated risk framework

Assessing risk to groundwater quality using an integrated risk framework

Biotransformation of Herbicides in the Presence of Various Electron Acceptors

Leaching of Alachlor from Alginate-Encapsulated Controlled-Release Formulations

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