Fate and behaviour of metformin and its transformation product guanylurea in soil-water systems
type: CreativeWork
description: Due to the widespread occurrence of diabetes, metformin (MET) has become one of the most prescribed medicines in the world. The human body excretes MET through urine and faeces as an unchanged compound and MET eventually ends up in wastewater treatment plants, where the compound is transformed into its bacterial dead-end product, guanylurea (GUA). Monitoring of surface, drinking and groundwaters, sediments and sludge has shown the persistence of these compounds in the environment. Recently, researchers have documented that MET at 40 μg/L, which has been detected in wastewater effluent, also caused endocrine disrupting effects in fish. Due to its high usage, persistence in the environmental media and chronic ecotoxicity, MET has been identified as an emerging contaminant, but there is a dearth of information about its fate in the environment. Globally, land-application of wastewater effluents and sludge has become a popular disposal method, thus, understanding the fate of MET and GUA in the soil environment is crucial to assessing their risk to the wider ecosystems. Forced degradation studies of MET and GUA indicated that combined hydrolysis and photolysis contributed to <30% degradation at neutral pH. Hydrolysis of MET was <16% for all pH range studied while hydrolysis of GUA resulted to 60% and 50% degradation in acidic (pH4) and basic (pH 9) solutions, respectively. Photolytic degradation was <5% for both compounds at all pH conditions. Batch sorption experiments revealed low to moderate sorption of MET and GUA in soils with their distribution coefficients ranging between 10.6 and 53.5 L/kg. The contrasting sorption behaviour of MET and GUA towards changes in pH and ionic strength suggests involvement of different sorption mechanisms for the two compounds. Electrostatic interactions and cation-exchange were the most significant mechanisms for MET and GUA sorption, respectively, at environmentally relevant pH range between 5.7 and 8.5. Biosolid-amended soils have a…
abstract: Due to the widespread occurrence of diabetes, metformin (MET) has become one of the most prescribed medicines in the world. The human body excretes MET through urine and faeces as an unchanged compound and MET eventually ends up in wastewater treatment plants, where the compound is transformed into its bacterial dead-end product, guanylurea (GUA). Monitoring of surface, drinking and groundwaters, sediments and sludge has shown the persistence of these compounds in the environment. Recently, researchers have documented that MET at 40 μg/L, which has been detected in wastewater effluent, also caused endocrine disrupting effects in fish. Due to its high usage, persistence in the environmental media and chronic ecotoxicity, MET has been identified as an emerging contaminant, but there is a dearth of information about its fate in the environment. Globally, land-application of wastewater effluents and sludge has become a popular disposal method, thus, understanding the fate of MET and GUA in the soil environment is crucial to assessing their risk to the wider ecosystems. Forced degradation studies of MET and GUA indicated that combined hydrolysis and photolysis contributed to <30% degradation at neutral pH. Hydrolysis of MET was <16% for all pH range studied while hydrolysis of GUA resulted to 60% and 50% degradation in acidic (pH4) and basic (pH 9) solutions, respectively. Photolytic degradation was <5% for both compounds at all pH conditions. Batch sorption experiments revealed low to moderate sorption of MET and GUA in soils with their distribution coefficients ranging between 10.6 and 53.5 L/kg. The contrasting sorption behaviour of MET and GUA towards changes in pH and ionic strength suggests involvement of different sorption mechanisms for the two compounds. Electrostatic interactions and cation-exchange were the most significant mechanisms for MET and GUA sorption, respectively, at environmentally relevant pH range between 5.7 and 8.5. Biosolid-amended soils have a…
author: Briones, Rowena
license: https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm
date published: 2019
date modified: 2026-07-24T01:05:49Z
provider: University of Auckland
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: ResearchSpace@Auckland

PropertyValue
property ID: Handle
value: https://hdl.handle.net/2292/46342