Microcosm experiments and kinetic modeling of glyphosate biodegradation in soils and sediments

Fiona H. M. Tang*, Thomas C. Jeffries, R. Willem Vervoort, Chris Conoley, Nicholas V. Coleman, Federico Maggi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Glyphosate (GLP) is one of the most widely-used herbicides globally and its toxicity to humans and the environment is controversial. GLP is biodegradable, but little is known about the importance of site exposure history and other environmental variables on the rate and pathway of biodegradation. Here, GLP was added to microcosms of soils and sediments with different exposure histories and these were incubated with amendments of glucose, ammonium, and phosphate. GLP concentrations were measured with a newly-developed HPLC method capable of tolerating high concentrations of ammonium and amino acids. GLP biodegradation occurred after a lag-time proportional to the level of GLP pre-exposure in anthropogenically-impacted samples (soils and sediments), while no degradation occurred in samples from a pristine sediment after 180 days of incubation. Exposure history did not influence the rate of GLP degradation, after the lag-time was elapsed. Addition of C, N, and P triggered GLP degradation in pristine sediment and shortened the lag-time before degradation in other samples. In all microcosms, GLP was metabolised into aminomethylphosphonic acid (AMPA), which was highly persistent, and thus appears to be a more problematic pollutant than GLP. Bacterial communities changed along the gradients of anthropogenic impacts, but in some cases, taxonomically very-similar communities showed dramatically different activities with GLP. Our findings reveal important interactions between agriculturally-relevant nutrients and herbicides.

Original languageEnglish
Pages (from-to)105-115
Number of pages11
JournalScience of the Total Environment
Early online date13 Dec 2018
Publication statusPublished - 25 Mar 2019
Externally publishedYes


  • AMPA
  • Exposure history
  • Herbicide
  • Nutrient
  • Pristine
  • Lag time


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