Effect of temperature, pH and total organic carbon variations on microbial turnover of 13C3                         15N-glyphosate in agricultural soil

Angelica M. Muskus; Martin Krauss; Anja Miltner; Ute Hamer; Karolina M. Nowak

doi:10.1016/j.scitotenv.2018.12.195

Effect of temperature, pH and total organic carbon variations on microbial turnover of ¹³C₃ ¹⁵N-glyphosate in agricultural soil

Angelica M. Muskus, Martin Krauss, Anja Miltner, Ute Hamer, Karolina M. Nowak

Research output: Contribution to journal › Article › peer-review

19 Scopus citations

Abstract

Glyphosate is the best-selling and the most-used broad-spectrum herbicide worldwide. Microbial conversion of glyphosate to CO₂ and biogenic non-extractable residues (bioNER) leads to its complete degradation. The degradation of glyphosate may vary in different soils and it depends on environmental conditions and soil properties. To date, the influence of temperature, soil pH and total organic carbon (TOC) on microbial conversion of glyphosate to bioNER has not been investigated yet. The pH or TOC of an agricultural original soil (pH 6.6, TOC 2.1%) was modified using sulfuric acid or farmyard manure (FYM), respectively. Each treatment: original (I), 3% TOC (II), 4% TOC (III), pH 6.0 (IV) and pH 5.5 (V) was amended with ¹³C₃ ¹⁵N-glyphosate and incubated at 10 °C, 20 °C and 30 °C for 39 days. The temperature was the main factor controlling the mineralization and the extractable ¹³C₃ ¹⁵N-glyphosate, whereas higher TOC content and lower pH resulted in enhanced formation of ¹³C-bioNER. After 39 days the cumulative mineralization of ¹³C-glyphosate was in the range of 12–22% (10 °C), 37–47% (20 °C) and 43–54% (30 °C). Extractable residues of ¹³C-glyphosate were in the range of 10–21% (10 °C) and 4–10% (20 °C and 30 °C); whereas those of ¹⁵N-glyphosate were as follows 20–32% (10 °C) and 12–25% (20 °C and 30 °C). The ¹³C-NER comprised about 53–69% of ¹³C-mass balance in soils incubated at 10 °C, but 40–50% in soils incubated at 20 °C and 30 °C. The ¹⁵N-NER were higher than the ¹³C-NER and varied between 62% and 74% at 10 °C, between 53% and 81% at 20 °C and 30 °C. A major formation of ¹³C-bioNER (72–88% of ¹³C-NER) at 20 °C and 30 °C was noted in soil amended with FYM. An increased formation of ¹⁵N-bioNER (14–17% of ¹⁵N-NER) was also observed in FYM-amended soil. The xenobiotic ¹⁵N-NER had a major share within the ¹⁵N-NER and thus need to be considered when assessing the environmental risk of glyphosate-NER.

Original language	English
Pages (from-to)	697-707
Number of pages	11
Journal	Science of the Total Environment
Volume	658
DOIs	https://doi.org/10.1016/j.scitotenv.2018.12.195
State	Published - 25 Mar 2019

Bibliographical note

Funding Information:
This research was supported by the Helmholtz Centre for Environmental Research - UFZ and the German Research Foundation (DFG, No 980/1-3). A KAAD (Katholischer Akademischer-Dienst) scholarship is acknowledged for funding the fellowship of A. Muskus. We thank Ursula Günther, Steffen Kümmel and Matthias Gehre (UFZ, Dept. Isotope Biogeochemistry) for their valuable assistance with compound-specific isotope analysis. The authors are also grateful to Dr. Cindy Weidauer and Dr. Hubert Schupke (UFZ, Dept. Effect-Directed Analysis) for helping with the analysis of glyphosate and AMPA in the soil extracts. Ines Merbach (UFZ, Dept. of Community Ecology, Experimental Station Bad Lauchstädt) is acknowledged for the help in providing the reference soil for the experiments.

Publisher Copyright:
© 2018

Keywords

Amino acids
AMPA
Biogenic non-extractable residues
Mineralization
NER

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10.1016/j.scitotenv.2018.12.195

Cite this

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title = "Effect of temperature, pH and total organic carbon variations on microbial turnover of 13C3 15N-glyphosate in agricultural soil",

abstract = "Glyphosate is the best-selling and the most-used broad-spectrum herbicide worldwide. Microbial conversion of glyphosate to CO2 and biogenic non-extractable residues (bioNER) leads to its complete degradation. The degradation of glyphosate may vary in different soils and it depends on environmental conditions and soil properties. To date, the influence of temperature, soil pH and total organic carbon (TOC) on microbial conversion of glyphosate to bioNER has not been investigated yet. The pH or TOC of an agricultural original soil (pH 6.6, TOC 2.1%) was modified using sulfuric acid or farmyard manure (FYM), respectively. Each treatment: original (I), 3% TOC (II), 4% TOC (III), pH 6.0 (IV) and pH 5.5 (V) was amended with 13C3 15N-glyphosate and incubated at 10 °C, 20 °C and 30 °C for 39 days. The temperature was the main factor controlling the mineralization and the extractable 13C3 15N-glyphosate, whereas higher TOC content and lower pH resulted in enhanced formation of 13C-bioNER. After 39 days the cumulative mineralization of 13C-glyphosate was in the range of 12–22% (10 °C), 37–47% (20 °C) and 43–54% (30 °C). Extractable residues of 13C-glyphosate were in the range of 10–21% (10 °C) and 4–10% (20 °C and 30 °C); whereas those of 15N-glyphosate were as follows 20–32% (10 °C) and 12–25% (20 °C and 30 °C). The 13C-NER comprised about 53–69% of 13C-mass balance in soils incubated at 10 °C, but 40–50% in soils incubated at 20 °C and 30 °C. The 15N-NER were higher than the 13C-NER and varied between 62% and 74% at 10 °C, between 53% and 81% at 20 °C and 30 °C. A major formation of 13C-bioNER (72–88% of 13C-NER) at 20 °C and 30 °C was noted in soil amended with FYM. An increased formation of 15N-bioNER (14–17% of 15N-NER) was also observed in FYM-amended soil. The xenobiotic 15N-NER had a major share within the 15N-NER and thus need to be considered when assessing the environmental risk of glyphosate-NER.",

keywords = "Amino acids, AMPA, Biogenic non-extractable residues, Mineralization, NER",

author = "Muskus, {Angelica M.} and Martin Krauss and Anja Miltner and Ute Hamer and Nowak, {Karolina M.}",

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T1 - Effect of temperature, pH and total organic carbon variations on microbial turnover of 13C3 15N-glyphosate in agricultural soil

AU - Muskus, Angelica M.

AU - Krauss, Martin

AU - Miltner, Anja

AU - Hamer, Ute

AU - Nowak, Karolina M.

PY - 2019/3/25

Y1 - 2019/3/25

N2 - Glyphosate is the best-selling and the most-used broad-spectrum herbicide worldwide. Microbial conversion of glyphosate to CO2 and biogenic non-extractable residues (bioNER) leads to its complete degradation. The degradation of glyphosate may vary in different soils and it depends on environmental conditions and soil properties. To date, the influence of temperature, soil pH and total organic carbon (TOC) on microbial conversion of glyphosate to bioNER has not been investigated yet. The pH or TOC of an agricultural original soil (pH 6.6, TOC 2.1%) was modified using sulfuric acid or farmyard manure (FYM), respectively. Each treatment: original (I), 3% TOC (II), 4% TOC (III), pH 6.0 (IV) and pH 5.5 (V) was amended with 13C3 15N-glyphosate and incubated at 10 °C, 20 °C and 30 °C for 39 days. The temperature was the main factor controlling the mineralization and the extractable 13C3 15N-glyphosate, whereas higher TOC content and lower pH resulted in enhanced formation of 13C-bioNER. After 39 days the cumulative mineralization of 13C-glyphosate was in the range of 12–22% (10 °C), 37–47% (20 °C) and 43–54% (30 °C). Extractable residues of 13C-glyphosate were in the range of 10–21% (10 °C) and 4–10% (20 °C and 30 °C); whereas those of 15N-glyphosate were as follows 20–32% (10 °C) and 12–25% (20 °C and 30 °C). The 13C-NER comprised about 53–69% of 13C-mass balance in soils incubated at 10 °C, but 40–50% in soils incubated at 20 °C and 30 °C. The 15N-NER were higher than the 13C-NER and varied between 62% and 74% at 10 °C, between 53% and 81% at 20 °C and 30 °C. A major formation of 13C-bioNER (72–88% of 13C-NER) at 20 °C and 30 °C was noted in soil amended with FYM. An increased formation of 15N-bioNER (14–17% of 15N-NER) was also observed in FYM-amended soil. The xenobiotic 15N-NER had a major share within the 15N-NER and thus need to be considered when assessing the environmental risk of glyphosate-NER.

AB - Glyphosate is the best-selling and the most-used broad-spectrum herbicide worldwide. Microbial conversion of glyphosate to CO2 and biogenic non-extractable residues (bioNER) leads to its complete degradation. The degradation of glyphosate may vary in different soils and it depends on environmental conditions and soil properties. To date, the influence of temperature, soil pH and total organic carbon (TOC) on microbial conversion of glyphosate to bioNER has not been investigated yet. The pH or TOC of an agricultural original soil (pH 6.6, TOC 2.1%) was modified using sulfuric acid or farmyard manure (FYM), respectively. Each treatment: original (I), 3% TOC (II), 4% TOC (III), pH 6.0 (IV) and pH 5.5 (V) was amended with 13C3 15N-glyphosate and incubated at 10 °C, 20 °C and 30 °C for 39 days. The temperature was the main factor controlling the mineralization and the extractable 13C3 15N-glyphosate, whereas higher TOC content and lower pH resulted in enhanced formation of 13C-bioNER. After 39 days the cumulative mineralization of 13C-glyphosate was in the range of 12–22% (10 °C), 37–47% (20 °C) and 43–54% (30 °C). Extractable residues of 13C-glyphosate were in the range of 10–21% (10 °C) and 4–10% (20 °C and 30 °C); whereas those of 15N-glyphosate were as follows 20–32% (10 °C) and 12–25% (20 °C and 30 °C). The 13C-NER comprised about 53–69% of 13C-mass balance in soils incubated at 10 °C, but 40–50% in soils incubated at 20 °C and 30 °C. The 15N-NER were higher than the 13C-NER and varied between 62% and 74% at 10 °C, between 53% and 81% at 20 °C and 30 °C. A major formation of 13C-bioNER (72–88% of 13C-NER) at 20 °C and 30 °C was noted in soil amended with FYM. An increased formation of 15N-bioNER (14–17% of 15N-NER) was also observed in FYM-amended soil. The xenobiotic 15N-NER had a major share within the 15N-NER and thus need to be considered when assessing the environmental risk of glyphosate-NER.

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