Degradation of MCPA, 2,4-D, and Other Phenoxyalkanoic Acid Herbicides Using an Isolated Soil Bacterium

Smith, Allan E.; Mortensen, K.; Aubin, Andrew J.

doi:10.1021/jf00038a031

Cited by 27 publications

(24 citation statements)

References 24 publications

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“…Soil temperature, soil pH and nutrient content also influence MCPA breakdown, as these factors regulate the growth and activity of soil microbial communities (Kah & Brown, ; McGhee & Burns, ). The field DT 50 of MCPA is usually between 7 and 60 days (Hornsby et al, ), although a DT 50 of less than 7 days has been recorded in groundwater (Mackay et al, ) and in salt media in the laboratory (A. E. Smith, Mortensen, Aubin, & Molloy, ). As degradation tends to follow an exponential decay, MCPA can persist for more than 3 months in the soil (Mackay et al, ) and almost indefinitely in constantly anaerobic soils (Vink & van der Zee, ).…”

Section: Soil–water Partitioning Mobilization and Fatementioning

confidence: 99%

A review of the pesticide MCPA in the land‐water environment and emerging research needs

et al. 2019

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Due to its high solubility and poor adsorption to the soil matrix, the post‐emergence herbicide 2‐methyl‐4‐chlorophenoxyacetic acid (MCPA) is susceptible to transport into surface and groundwater bodies, where it can result in compromised water quality and breaches of legislative standards. However, there is still poor understanding of catchment scale dynamics and transport, particularly across heterogeneous hydrogeological settings. While it is known that MCPA degrades under aerobic conditions, negligible breakdown can occur in anaerobic environments, potentially creating a legacy in saturated soils. Fast runoff pathways post application are likely transport routes, but the relative contribution from the mobilization of legacy MCPA from anaerobic zones has yet to be quantified, making the delineation of MCPA sources encountered during monitoring programs challenging. While ecotoxicological effects have been examined, little is known about the interaction of MCPA (and its degradation products) with other pesticides, with nutrients or with colloids, and how this combines with environmental conditions to contribute to multiple stressor effects. We examine the state of MCPA knowledge, using case study examples from Ireland, and consider the implications of its widespread detection in waterbodies and drinking water supplies. Research themes required to ensure the sustainable and safe use of MCPA in an evolving agricultural, social and political landscape are identified here. These include the need to identify mitigation measures and/or alternative treatments, to gain insights into the conditions governing mobilization and attenuation, to map pathways of migration and to identify direct, synergistic and antagonistic ecotoxicological effects. This article is categorized under: Water and Life > Stresses and Pressures on Ecosystems Science of Water > Water Quality

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Section: Soil–water Partitioning Mobilization and Fatementioning

confidence: 99%

A review of the pesticide MCPA in the land‐water environment and emerging research needs

et al. 2019

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“…For the same reason, the degradation of phenoxyalkanoic acid herbicides was lower in acidic soils than in soils with pH >6 [56,69,100,112] and higher in soils amended with fertilizers containing nitrogen and phosphorus [109]. Moreover, a very important factor increasing the degradation rate is the previous use of phenoxyalkanoic acid herbicides in the soil [93,106,111,113,114].…”

Section: Factors Affecting the Degradation Processmentioning

confidence: 99%

Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review

Paszko

Muszyński

Materska

et al. 2015

Environmental Toxicology and Chemistry

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The primary aim of the present review on phenoxyalkanoic acid herbicides-2-(2,4-dichlorophenoxy) acetic acid (2,4-D), 2-(4-chloro-2-methylphenoxy) acetic acid (MCPA), (2R)-2-(2,4-dichlorophenoxy) propanoic acid (dichlorprop-P), (2R)-2-(4-chloro-2-methylphenoxy) propanoic acid (mecoprop-P), 4-(2,4-dichlorophenoxy) butanoic acid (2,4-DB), and 4-(4-chloro-2-methylphenoxy) butanoic acid (MCPB)-was to compare the extent of their adsorption in soils and degradation rates to assess their potential for groundwater contamination. The authors found that adsorption decreased in the sequence of 2,4-DB > 2,4-D > MCPA > dichlorprop-P > mecoprop-P. Herbicides are predominantly adsorbed as anions-on organic matter and through a water-bridging mechanism with adsorbed Fe cations-and their neutral forms are adsorbed mainly on organic matter. Adsorption of anions of 2,4-D, MCPA, dichlorprop-P, and mecoprop-P is inversely correlated with their lipophilicity values, and modeling of adsorption of the compounds based on this relationship is possible. The predominant dissipation mechanism of herbicides in soils is bacterial degradation. The contribution of other mechanisms, such as degradation by fungi, photodegradation, or volatilization from soils, is much smaller. The rate of bacterial degradation decreased in the following order: 2,4-D > MCPA > mecoprop-P > dichlorprop-P. It was found that 2,4-D and MCPA have the lowest potential for leaching into groundwater and that mecoprop-P and dichlorprop-P have slightly higher potential. Because of limited data on adsorption and degradation of 2,4-DB and MCPB, estimation of their leaching potential was not possible. Environ Toxicol Chem 2016;35:271-286. # 2015 SETAC

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“…Unfortunately, chlorocresol is also a possible step of the degradative process [23], which would render less attractive purification of the commercial formulation. However, phenoxyacetic herbicides have a low persistence in the soil as they are promptly degraded by soil microorganisms [24] that use herbicide carbon atoms as energy sources; moreover, repeated treatments result in enhanced degradation rates under field conditions as a result of microorganism adaptation. This low persistence gives an environmental advantage without creating agronomic problems as MCPA is applied as a postemergence treatment; therefore, it is not requested any soil residual activity [1].…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the developmental toxicity of the pesticide mcpa and its contaminants phenol and chlorocresol

Bernardini

Spinelli

Presutti

et al. 1996

Enviro Toxic and Chemistry

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Abstract-The embryotoxicity of 4-chloro-2-methylphenoxyacetic acid (MCPA), an extensively used herbicide, has been evaluated and compared to that of phenol and chlorocresol (two common contaminants) with a bioassay that makes use of embryos of the amphibian Xenopus. The MCPA-Na salt used in the bioassay was purified by crystallization and acid-base purification methods, and the concentrations of phenol and chlorocresol were checked by high-performance liquid chromotography. The relationship between the concentration of the tested molecule and the outcomes (i.e., mortality and malformations) was investigated using different models (probit, logit, and complementary log-log). The resulting LC50s for MCPA, chlorocresol, and phenol are 3,607, 13, and 178 mg/L, respectively; the resulting LC10s are 1,526, 6, and 32 mg/L. It is evident that the real MCPA toxicity can be masked by the presence of contaminants much more toxic than the molecule studied. Moreover, our results show that the three chemicals do not present a high teratogenic risk. Growth retardation shows that MCPA, chlorocresol, and phenol are effective at concentrations as low as 2,000, 2.5, and 25 mg/L, respectively.

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Degradation of MCPA, 2,4-D, and Other Phenoxyalkanoic Acid Herbicides Using an Isolated Soil Bacterium

Cited by 27 publications

References 24 publications

A review of the pesticide MCPA in the land‐water environment and emerging research needs

A review of the pesticide MCPA in the land‐water environment and emerging research needs

Adsorption and degradation of phenoxyalkanoic acid herbicides in soils: A review

Evaluation of the developmental toxicity of the pesticide mcpa and its contaminants phenol and chlorocresol

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