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Luanne Hendricks - Thesis.pdf (1.73 MB)

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Soil Bioavailability of Aminomethylphosphonic Acid: A Metabolite of Glyphosate

Hendricks, Luanne R
http://orcid.org/0000-0002-9185-1825
http://rave.ohiolink.edu/etdc/view?acc_num=osu1592583268434087

Abstract Details

2020, Master of Science, Ohio State University, Environment and Natural Resources.
Aminomethylphosphonic acid (AMPA) is a microbial degradation product of the herbicide glyphosate, and industrial phosphonates. In addition to possible negative effects on human health, AMPA may inhibit soil microbial growth and alter the soil microbial community composition. Strong soil adsorption causes AMPA to persist in the environment, slowing degradation, and making AMPA a possible long-term environmental contaminant. Review of the research literature in Chapter 1 revealed knowledge gaps concerning the effects of AMPA on soil microorganisms in different soil types and in isolation from glyphosate. Although there have been many studies on the behavior and effects of glyphosate in different soil types, there is scarce data that isolates the effects of AMPA. Therefore, the research objectives were to (1) study the effects of AMPA on soil microorganisms, (2) investigate how soil type affects AMPA bioavailability, (3) determine if chemical extractability can be used to predict AMPA bioavailability, and (4) investigate AMPA in isolation from glyphosate. Based on the literature, the hypotheses were that (1) a higher concentration of AMPA would be found to have a greater effect on soil microorganisms, and (2) bioavailability would be less in soils with high clay, high iron and aluminum oxides, and low pH. Chapter 2 describes a 139-day incubation study on three diverse soils with no exposure to glyphosate. These soils included a sandy soil, and two high clay soils with different mineralogy. Three field relevant concentrations of AMPA, including the control, were applied directly to soil, and the effects of AMPA on soil microbial respiration and phospholipid fatty acids were analyzed. Chapter 3 describes an investigation of AMPA bioavailability using chemical extraction, and correlations of extractable AMPA with microbial responses. Total soil carbon and pH appeared to be the most important soil factors affecting response to AMPA. Based on PLFA results, AMPA was the least bioavailable in the sandy soil, which was counter to the hypothesis. Results showed hormetic effects in metabolic quotient and PLFA abundance responses to AMPA concentration, with the lower concentration showing greater response than the higher concentration. The significance of this finding is that effects of a chemical at a low concentration cannot always be predicted based on test results using a higher concentration, which is frequently done in toxicological studies. There was no clear evidence that AMPA at field relevant concentrations negatively impacted soil health. AMPA extractability was highest in sandy soil, and lowest in high clay, high iron and aluminum oxide soil, consistent with the hypothesis. Extractability results showed an interaction effect between soil and AMPA concentration. The higher AMPA concentration was proportionately more extractable in the sandy soil than the lower concentration. Correlations between extractable AMPA and PLFA were weak and mostly negative, consistent with the expected increase in stress markers towards the end of the incubation. Results did not provide evidence that AMPA extractability using monopotassium phosphate reflected AMPA bioavailability.
Richard Dick, PhD (Advisor)
Jeffory Hattey, PhD (Committee Member)
Roman Lanno, PhD (Committee Member)
137 p.
Environmental Health; Environmental Science; Microbiology; Soil Sciences
Aminomethylphosphonic acid; AMPA; glyphosate; soil bioavailability; soil adsorption; chemical extraction; microbial respiration; phospholipid fatty acid analysis; PLFA

Recommended Citations

Citations

  • Hendricks, L. R. (2020). Soil Bioavailability of Aminomethylphosphonic Acid: A Metabolite of Glyphosate [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1592583268434087

    APA Style (7th edition)

  • Hendricks, Luanne. Soil Bioavailability of Aminomethylphosphonic Acid: A Metabolite of Glyphosate. 2020. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1592583268434087.

    MLA Style (8th edition)

  • Hendricks, Luanne. "Soil Bioavailability of Aminomethylphosphonic Acid: A Metabolite of Glyphosate." Master's thesis, Ohio State University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=osu1592583268434087

    Chicago Manual of Style (17th edition)

osu1592583268434087
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