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Femi-Oloye OP, Oloye FF, Jones PD, Giesy JP. Sorption behaviour and toxicity of an herbicide safener "cyprosulfamide". THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 859:160077. [PMID: 36372173 DOI: 10.1016/j.scitotenv.2022.160077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/01/2022] [Accepted: 11/05/2022] [Indexed: 06/16/2023]
Abstract
Cyprosulfamide is a herbicide safener that works against the injurious effects of herbicides such as isoxaflutole, dicamba, nicosulfuron, tembotrione, thiencarbazone-methyl. However, its sorption behaviour in soils and toxicity to aquatic organisms are yet to be thoroughly examined. This study determined the octanol-water partition coefficient, sorption properties, acute and chronic toxic effects, and potency of cyprosulfamide to the cladoceran water flea (Daphnia magna). The influence of soil properties such as organic carbon content, cation exchange capacity, pH, and field capacity on adsorption and desorption properties were also examined. The Log Kow (0.55) of cyprosulfamide was less than that of some other safeners, such as benoxacor or furilazole, found in aquatic environments. The sorption of cyprosulfamide to the soil was driven by pH, so sorption decreased with an increase in pH. Other characteristics, such as cation exchange capacity (CEC), organic carbon content, and field capacity, do not directly correlate with the distribution coefficient. Cyprosulfamide generally has a low affinity for soil and is thus mobile and prone to transport to surrounding surface waters. No lethality was observed at the highest concentration (120 mg/L) tested for acute toxicity to D. magna; hence the LC50 will be >120 mg/L. During chronic exposures, cyprosulfamide caused adverse effects at a concentration of 120 mg/L on the number of neonates and brood size. The death rate for the chronic study was a function of concentration and increased with days of exposure. Cyprosulfamide is unlikely to cause lethality to D. magna at relevant environmental concentrations.
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Affiliation(s)
- O P Femi-Oloye
- Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
| | - F F Oloye
- Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
| | - P D Jones
- Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; School of Environment and Sustainability, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada.
| | - J P Giesy
- Toxicology Centre, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5B3, Canada; Department of Integrative Biology, Center for Integrative Toxicology, Michigan State University, 1129 Farm Lane Road, East Lansing, MI, USA; Department of Environmental Sciences, Baylor University, Waco, TX 76706, USA.
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Salata R, Melo VF, Batista LFA, Abate G, Azevedo AC. Atrazine adsorption and desorption on functionalized montmorillonite: aluminum-pillared and lithium saturated. JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART. B, PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES 2022; 57:980-988. [PMID: 36537054 DOI: 10.1080/03601234.2022.2157175] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Atrazine is an herbicide used worldwide, and it is considered a severe environmental contaminant. The present study aims to evaluate the atrazine adsorption in aqueous media in montmorillonite samples which were either in natural state or functionalized through saturation with lithium and pillarization with aluminum by different methods. Montmorillonite saturated with lithium adsorbed significantly more atrazine than the natural montmorillonite sample. Among the samples obtained through the three aluminum-pillarization methods, the mass percentage of adsorbed atrazine was very similar. However, the best combination was the aluminum-pillarization (due to the maintenance of the open interlayer region) and saturation with lithium (due to the significant reduction of the cation exchange capacity of the mineral), because both processes facilitate the interaction of atrazine with the montmorillonite. Another advantage was that the adsorption of atrazine in the pillared and lithium saturated samples had small desorption, which is desirable in the environmental perspective. It is recommended to build filters with aluminum-hydroxy pillared, lithium saturated montmorillonite as an alternative method to rapidly remove atrazine from aqueous media. In addition to the shorter production time, this process resulted in montmorillonite with high occupancy rate and stability of the aluminum-hydroxy pillars.
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Affiliation(s)
- Regiane Salata
- Soil Science and Engineering Department, Federal University of Paraná, Curitiba, Brazil
| | - Vander Freitas Melo
- Soil Science and Engineering Department, Federal University of Paraná, Curitiba, Brazil
| | | | - Gilberto Abate
- Department of Chemistry of Federal, University of Paraná State, Centro Politécnico, Curitiba, Brazil
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Schwendimann L, Sivaprakasam I, Buvaneshwari S, Gurumurthy GP, Mishra S, Ruiz L, Sekhar M, Fleiss B, Riotte J, Mani S, Gressens P. Agricultural groundwater with high nitrates and dissolved salts given to pregnant mice alters brain development in the offspring. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 224:112635. [PMID: 34418854 DOI: 10.1016/j.ecoenv.2021.112635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 08/08/2021] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Groundwater is the main source of drinking water for a significant portion of the human population. In many agricultural areas, diffuse pollution such as high levels of total dissolved salts including nitrate, puts the quality of this resource at risk. However, the effect of exposure to these water contaminants on brain development is currently poorly understood. Here we characterised water from a borewell located in an intensely cultivated area (agricultural) or water from a borewell located in a nearby pristine forest. The agricultural borewell water was rich in nitrates with high total dissolved salts. We then studied the consequence of drinking the agricultural water on mouse brain development. For this, the agricultural borewell water or forest water was given to mice for 6 weeks before and during pregnancy and lactation. The brains of the offspring born to these dams were analysed at postnatal day (P)5 and P21 and compared using immunohistochemistry for changes in glial cells, neurons, myelin, and cell death across many brain regions. Brains from offspring born to dams who had been given agricultural water (versus forest control water) were significantly smaller, and at P21 had a significant degeneration of neurons and increased numbers of microglia in the motor cortex, had fewer white matter astrocytes and an increase in cell death, particularly in the dentate gyrus. This study shows that brain development is sensitive to water composition. It points to the importance of assessing neurodevelopmental delays when considering the effect of water contaminated with agricultural run offs on human health. MAIN FINDING: Pregnant and lactating mice were given borewell water from intensely cultivated land. Offspring brains reveal degeneration of neurons and a loss of astrocytes, increase in microglial cells and cell death, pointing to neurodevelopmental problems.
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Affiliation(s)
| | | | | | - Gundiga P Gurumurthy
- Birbal Sahni Institute of Palaeosciences (BSIP), Lucknow 226007, Uttar Pradesh, India
| | - Saumya Mishra
- CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Laurent Ruiz
- Indo-French Cell for Water Sciences, Indian Institute of Science, Bengaluru 560012, India; GET, Université de Toulouse, CNRS, IRD, UPS, CNES, 31400 Toulouse, France; INRAE, Institut Agro, UMR SAS, Rennes, France
| | - Muddu Sekhar
- Indian Institute of Science, Bengaluru 560012, India; Indo-French Cell for Water Sciences, Indian Institute of Science, Bengaluru 560012, India
| | - Bobbi Fleiss
- Université de Paris, Inserm UMR 1141 NeuroDiderot, F-75019 Paris, France; RMIT University, STEM College, Melbourne, Australia
| | - Jean Riotte
- Indo-French Cell for Water Sciences, Indian Institute of Science, Bengaluru 560012, India; GET, Université de Toulouse, CNRS, IRD, UPS, CNES, 31400 Toulouse, France.
| | - Shyamala Mani
- Indian Institute of Science, Bengaluru 560012, India
| | - Pierre Gressens
- Université de Paris, Inserm UMR 1141 NeuroDiderot, F-75019 Paris, France.
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Stability of Atrazine–Smectite Intercalates: Density Functional Theory and Experimental Study. MINERALS 2021. [DOI: 10.3390/min11060554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Atrazine (A) is one of the most applied herbicides and has a negative impact on the environment and health. Density functional theory (DFT) and experimental methods were used in the study of the immobilization of atrazine in two smectites, montmorillonite (Mt) and beidellite (Bd), as well as in their organically modified structures. Four systems were examined: A-Mt and A-Bd, as well as the structures modified by tetramethylphosphonium cation (TMP), A-TMP-Mt and A-TMP-Bd. The calculations revealed a flat arrangement of the atrazine in the interlayer space of both smectites with higher stability of beidellite structures. The presence of the TMP cation increased the fixation of atrazine in both organically modified smectites. The calculated vibrational spectra allowed a detailed analysis of the overlapping bands observed in the experimental FTIR spectra and their correct assignment. Further, selected FTIR bands unambiguously assigned to atrazine and both smectites served for the estimation of the adsorbed amount of atrazine. It was shown that the adsorption capacity of both TMP-modified smectites did not increase in comparison to the adsorption capacity of unmodified smectite samples.
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Oloye FF, Femi-Oloye OP, Challis JK, Jones PD, Giesy JP. Dissipation, Fate, and Toxicity of Crop Protection Chemical Safeners in Aquatic Environments. REVIEWS OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 258:27-53. [PMID: 34529146 DOI: 10.1007/398_2021_70] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Safeners are a group of chemicals applied with herbicides to protect crop plants from potential adverse effects of agricultural products used to kill weeds in monocotyledonous crops. Various routes of dissipation of safeners from their point of applications were evaluated. Despite the large numbers of safeners (over 18) commercially available and the relatively large quantities (~2 × 106 kg/year) used, there is little information on their mobility and fate in the environment and occurrence in various environmental matrices. The only class of safeners for which a significant amount of information is available is dichloroacetamide safeners, which have been observed in some rivers in the USA at concentrations ranging from 42 to 190 ng/L. Given this gap in the literature, there is a clear need to determine the occurrence, fate, and bioavailability of other classes of safeners. Furthermore, since safeners are typically used in commercial formulations, it is useful to study them in relation to their corresponding herbicides. Common routes of dissipation for herbicides and applied safeners are surface run off (erosion), hydrolysis, photolysis, sorption, leaching, volatilization, and microbial degradation. Toxic potencies of safeners vary among organisms and safener compounds, ranging from as low as the LC50 for fish (Oncorhynchus mykiss) for isoxadifen-ethyl, which was 0.34 mg/L, to as high as the LC50 for Daphnia magna from dichlormid, which was 161 mg/L. Solubilities and octanol-water partition coefficients seem to be the principal driving force in understanding safener mobilities. This paper provides an up-to-date literature review regarding the occurrence, behaviour, and toxic potency of herbicide safeners and identifies important knowledge gaps in our understanding of these compounds and the potential risks posed to potentially impacted ecosystems.
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Affiliation(s)
- Femi F Oloye
- Department of Chemical Sciences, Adekunle Ajasin University, Akungba-Akoko, Nigeria.
| | - Oluwabunmi P Femi-Oloye
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada
- Department of Animal and Environmental Biology, Adekunle Ajasin University, Akungba-Akoko, Nigeria
| | | | - Paul D Jones
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada
- School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK, Canada
| | - John P Giesy
- Toxicology Centre, University of Saskatchewan, Saskatoon, SK, Canada
- Department of Biomedical Veterinary Sciences, University of Saskatchewan, Saskatoon, SK, Canada
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Shattar SFA, Zakaria NA, Foo KY. One step acid activation of bentonite derived adsorbent for the effective remediation of the new generation of industrial pesticides. Sci Rep 2020; 10:20151. [PMID: 33214587 PMCID: PMC7677388 DOI: 10.1038/s41598-020-76723-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/28/2020] [Indexed: 11/08/2022] Open
Abstract
Herein, the facile one step acid activation of bentonite derived functionalized adsorbent (AB) for the effective remediation of both ionic and non-ionic secondary pesticides, ametryn and metolachlor has been attempted. The surface characteristics of AB were examined by the nitrogen adsorption-desorption analysis, scanning electron microscopy (SEM), and Fourier Transforms Infrared (FTIR) Spectroscopy. The adsorptive behavior was evaluated with respect to the effect of contact time, initial concentrations and solution pH. The equilibrium data were fitted to the Langmuir, Freundlich and Temkin isotherm models, while the adsorption kinetic was analyzed using the pseudo-first order and pseudo-second order kinetic equations. Thermodynamic parameters including the standard enthalpy change (ΔH°), standard entropy change (ΔS°), and Gibbs free energy change (ΔG°) were established. Thermodynamic analysis illustrated that the adsorption process was feasible and exothermic in nature, while the characterization findings verified the alteration of FTIR bands, and a high specific surface area of 464.92 m2/g, with a series of pores distributed over the surface. Equilibrium data was best confronted to the pseudo-second order kinetic model, while the adsorptive removal of ametryn and metolachlor onto AB was satisfactory described by the Langmuir isotherm model, with the monolayer adsorption capacities for ametryn and metolachlor of 2.032 and 0.208 mmole/g respectively. The findings outlined the potential of the newly develop AB for the on-site treatment of pesticide polluted water.
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Affiliation(s)
- Siti Fairos Ab Shattar
- River Engineering and Urban Drainage Research Centre (REDAC), Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia
| | - Nor Azazi Zakaria
- River Engineering and Urban Drainage Research Centre (REDAC), Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia
| | - Keng Yuen Foo
- River Engineering and Urban Drainage Research Centre (REDAC), Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300, Nibong Tebal, Penang, Malaysia.
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Brown VS, Ritchie AL, Stevens JC, Harris RJ, Madsen MD, Erickson TE. Protecting direct seeded grasses from herbicide application: can new extruded pellet formulations be used in restoring natural plant communities? Restor Ecol 2018. [DOI: 10.1111/rec.12903] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Vanessa S. Brown
- School of Molecular and Life SciencesCurtin University Bentley Western Australia Australia
| | - Alison L. Ritchie
- Kings Park ScienceDepartment of Biodiversity Conservation and Attractions Western Australia Australia
| | - Jason C. Stevens
- Kings Park ScienceDepartment of Biodiversity Conservation and Attractions Western Australia Australia
- School of Biological SciencesThe University of Western Australia Crawley Western Australia Australia
| | - Richard J. Harris
- School of Molecular and Life SciencesCurtin University Bentley Western Australia Australia
| | - Matthew D. Madsen
- Department of Plant and Wildlife SciencesBrigham Young University Provo UT 84602 U.S.A
| | - Todd E. Erickson
- Kings Park ScienceDepartment of Biodiversity Conservation and Attractions Western Australia Australia
- School of Biological SciencesThe University of Western Australia Crawley Western Australia Australia
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Rajabi H, Noroozifar M. Modified Graphite Paste Electrode with Lewatit FO36 Nanoresin/Multi-Walled Carbon Nanotubes for Determination of Quercetin. RUSS J ELECTROCHEM+ 2018. [DOI: 10.1134/s1023193518030084] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
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Lupul I, Yperman J, Carleer R, Gryglewicz G. Adsorption of atrazine on hemp stem-based activated carbons with different surface chemistry. ADSORPTION 2015. [DOI: 10.1007/s10450-015-9689-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Benassi E, Di Foggia M, Bonora S. Accurate computational prediction of the structural and vibrational properties of s-triazine derivatives in vacuo. A DFT approach. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.03.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Arvand M, Motaghed Mazhabi R, Niazi A. Simultaneous determination of guanine, adenine and thymine using a modified carbon paste electrode by TiO2 nanoparticles-magnesium(II) doped natrolite zeolite. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2012.11.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Simultaneous and sensitive determination of a quaternary mixture of AA, DA, UA and Trp using a modified GCE by iron ion-doped natrolite zeolite-multiwall carbon nanotube. Biosens Bioelectron 2011; 28:56-63. [DOI: 10.1016/j.bios.2011.06.042] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2011] [Revised: 06/14/2011] [Accepted: 06/28/2011] [Indexed: 11/13/2022]
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Kovaios ID, Paraskeva CA, Koutsoukos PG. Adsorption of atrazine from aqueous electrolyte solutions on humic acid and silica. J Colloid Interface Sci 2011; 356:277-85. [DOI: 10.1016/j.jcis.2011.01.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 01/03/2011] [Indexed: 10/18/2022]
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Chen GC, Shan XQ, Wang YS, Pei ZG, Shen XE, Wen B, Owens G. Effects of copper, lead, and cadmium on the sorption and desorption of atrazine onto and from carbon nanotubes. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8297-8302. [PMID: 19068809 DOI: 10.1021/es801376w] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
There are currently few studies on the dual effects of metal ions on the sorption of atrazine and conversely of atrazine on metal adsorption on multiwalled carbon nanotubes (MWCNTs). While a number of sorption models were considered to describe the sorption of atrazine on MWCNTs, the Polanyi-Manes model (PMM) fit the sorption isotherms well with the lowest mean weighted square errors. Atrazine was mainly adsorbed onto the surface and micropores of MWCNTs bundles or aggregates. Hydrogen bonding between azo and amino nitrogen of atrazine and functional groups on MWCNTs also occurred. Oxygenated functionalities, mainly carboxylic groups on MWCNTs surface, decreased the sorption of atrazine. Metal cations Cu2+, Pb2+, and Cd2+ diminished the sorption of atrazine depending on the oxygenated functionalities densities. The mechanisms ascribed were due to the formation of surface or inner-sphere complexes of Cu2+, Pb2+, and Cd2+ through carboxylic groups and hydration, which may occupy part of the surface of MWCNTs-O. The large hydration shell of metal cations may intrude or shield the hydrophobic and hydrophilic sites and indirectly compete with atrazine for surface sites, leading to the inhibition of atrazine adsorption around the metal-complexed moieties.
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Affiliation(s)
- Guang-Cai Chen
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Centre for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China
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Jablonowski ND, Modler J, Schaeffer A, Burauel P. Bioaccessibility of environmentally aged 14C-atrazine residues in an agriculturally used soil and its particle-size aggregates. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:5904-5910. [PMID: 18767643 DOI: 10.1021/es800196z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
After 22 years of aging under natural conditions in an outdoor lysimeter the bioaccessibility of 14C-labeled atrazine soil residues to bacteria was tested. Entire soil samples as well as sand-sized, silt-sized, and clay-sized aggregates (>20, 20-2, and <2microm aggregate size, respectively) were investigated under slurried conditions. The mineralization of residual radioactivity in the outdoor lysimeter soil reached up to 4.5% of the total 14C-activity after 16 days, inoculated with Pseudomonas sp. strain ADP. The control samples without inoculated bacteria showed a mineralization maximum of only about 1% after 44 days of incubation. Mineralization increased in the clay-sized aggregates up to 6.2% of the total residual 14C-activity within 23 days. With decreasing soil aggregate sizes, residual 14C-activity increased per unit of weight, but only minor differences of the mineralization in the soil and soil size aggregates using mineral-media for incubation was observed. Using additional Na-citrate in the incubation, the extent of mineralization increased to 6.7% in soil after 23 days following incubation with Pseudomonas sp. strain ADP. These results show that long-term aged 14C-atrazine residues are still partly accessible to the atrazine degrading microorganism Pseudomonas sp. strain ADP.
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Affiliation(s)
- Nicolai D Jablonowski
- Forschungszentrum Jülich GmbH, Institute of Chemistry and Dynamics of the Geosphere, ICG-4--Agrosphere, 52425 Jülich, Germany.
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Kovaios ID, Paraskeva CA, Koutsoukos PG, Payatakes AC. Adsorption of atrazine on soils: Model study. J Colloid Interface Sci 2006; 299:88-94. [PMID: 16556447 DOI: 10.1016/j.jcis.2006.01.057] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Revised: 01/28/2006] [Accepted: 01/30/2006] [Indexed: 11/24/2022]
Abstract
The adsorption of the widely used herbicide atrazine onto three model inorganic soil components (silica gel, gamma-alumina, and calcite (CaCO(3)) was investigated in a series of batch experiments in which the aqueous phase equilibrated with the solid, under different solution conditions. Atrazine did not show discernible adsorption on gamma-alumina (theta=25 degrees C, 3.8<pH<12.1) or calcite (theta=25 degrees C, 7.7<pH<11.7). Significant and completely reversible adsorption from solutions was found for silica gel suspensions. The adsorption isotherms obtained for atrazine uptake on silica gel particles were best fitted with the Freundlich model. An increase of the ionic strength of the electrolytic solution induced an increase of the surface concentration of atrazine on silica gel, indicating significant electrostatic interactions between atrazine and silica gel particles, possibly through interaction with the surface silanol groups of the solid substrate. Increase of the pH value of the electrolyte solution from 6 to 9 considerably decreased the amount of atrazine adsorbed on the silica gel substrate. Decrease of the solution pH from 6 to 3 had only a slight effect on the surface concentration of the adsorbed atrazine. The adsorption of atrazine on silica gel increased when the temperature was decreased from 40 to 25 degrees C, an indication that the adsorption is exothermic. The calculated enthalpy of adsorption ( approximately 10 kJ/mol) indicates that the uptake at the solid-liquid equilibrium pH (6.1) was largely due to physisorption.
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Affiliation(s)
- Ilias D Kovaios
- Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology, Hellas, P.O. Box 1414, GR-26500 Patras, Greece.
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