Adsorption behavior and mechanism of glufosinate onto goethite

A review of organophosphonates, their natural and anthropogenic sources, environmental fate and impact on microbial greenhouse gases emissions - Identifying knowledge gaps

Organophosphonates (OPs) are a unique group of natural and synthetic compounds, characterised by the presence of a stable, hard-to-cleave bond between the carbon and phosphorus atoms. OPs exhibit high resistance to abiotic degradation, excellent chelating properties and high biological activity. Despite the huge and increasing scale of OP production and use worldwide, little is known about their transportation and fate in the environment. Available data are dominated by information concerning the most recognised organophosphonate - the herbicide glyphosate - while other OPs have received little attention. In this paper, a comprehensive review of the current state of knowledge about natural and artificial OPs is presented (including glyphosate). Based on the available literature, a number of knowledge gaps have been identified that need to be filled in order to understand the environmental effects of these abundant compounds. Special attention has been given to GHG-related processes, with a particular focus on CH4. This stems from the recent discovery of OP-dependent CH4 production in aqueous environments under aerobic conditions. The process has changed the perception of the biogeochemical cycle of CH4, since it was previously thought that biological methane formation was only possible under anaerobic conditions. However, there is a lack of knowledge on whether OP-associated methane is also formed in soils. Moreover, it remains unclear whether anthropogenic OPs affect the CH4 cycle, a concern of significant importance in the context of the increasing rate of global warming. The literature examined in this review also calls for additional research into the date of OPs in waste and sewage and in their impact on environmental microbiomes.

Multiscale computational simulation of pollutant behavior at water interfaces

The investigation of pollutant behavior at water interfaces is critical to understand pollution in aquatic systems. Computational methods allow us to overcome the limitations of experimental analysis, delivering valuable insights into the chemical mechanisms and structural characteristics of pollutant behavior at interfaces across a range of scales, from microscopic to mesoscopic. Quantum mechanics, all-atom molecular dynamics simulations, coarse-grained molecular dynamics simulations, and dissipative particle dynamics simulations represent diverse molecular interaction calculation methods that can effectively model pollutant behavior at environmental interfaces from atomic to mesoscopic scales. These methods provide a rich variety of information on pollutant interactions with water surfaces. This review synthesizes the advancements in applying typical computational methods to the formation, adsorption, binding, and catalytic conversion of pollutants at water interfaces. By drawing on recent advancements, we critically examine the current challenges and offer our perspective on future directions. This review seeks to advance our understanding of computational techniques for elucidating pollutant behavior at water interfaces, a critical aspect of water research.

Effect of glyphosate, its metabolite AMPA, and the glyphosate formulation Roundup® on brown trout (Salmo trutta f. fario) gut microbiome diversity

Glyphosate is used worldwide as a compound of pesticides and is detectable in many environmental compartments. It enters water bodies primarily through drift from agricultural areas so that aquatic organisms are exposed to this chemical, especially after rain events. Glyphosate is advertised and sold as a highly specific herbicide, which interacts with the EPSP synthase, an enzyme of the shikimate metabolism, resulting in inhibition of the synthesis of vital aromatic amino acids. However, not only plants but also bacteria can possess this enzyme so that influences of glyphosate on the microbiomes of exposed organisms cannot be excluded. Those influences may result in subtle and long-term effects, e.g., disturbance of the symbiotic interactions of bionts with microorganisms of their microbiomes. Mechanisms how the transformation product aminomethylphosphonic acid (AMPA) of glyphosate might interfere in this context have not understood so far. In the present study, molecular biological fingerprinting methods showed concentration-dependent effects of glyphosate and AMPA on fish microbiomes. In addition, age-dependent differences in the composition of the microbiomes regarding abundance and diversity were detected. Furthermore, the effect of exposure to glyphosate and AMPA was investigated for several fish pathogens of gut microbiomes in terms of their gene expression of virulence factors associated with pathogenicity. In vitro transcriptome analysis with the fish pathogen Yersinia ruckeri revealed that it is questionable whether the observed effect on the microbiome is caused by the intended mode of action of glyphosate, such as the inhibition of EPSP synthase activity.

Investigation of the performance of activated carbon cloth to remove glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos from aqueous solutions by adsorption/electrosorption

The present study investigates the removal of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos herbicides from their 5 × 10^-5 M aqueous solutions onto activated carbon cloth by adsorption and electrosorption. Analysis of these highly polar herbicides was achieved by UV-visible absorbance measurements, after derivatization with 9-fluorenylmethyloxycarbonyl chloride. The limit of quantification values of glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were 1.06 × 10^-6 mol L^-1, 1.38 × 10^-6 mol L^-1, 1.32 × 10^-6 mol L^-1 and 1.08 × 10^-6 mol L^-1, respectively. Glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos were removed from their aqueous solutions with higher efficiencies by means of electrosorption (78.2%, 94.9%, 82.3% and 97%, respectively) than of open-circuit adsorption (42.5%, 22%, 6.9% and 81.8%, respectively). Experimental kinetic data were fitted to pseudo-first order and pseudo-second order kinetic models. It was determined that pseudo-second order kinetic model represents experimental data better with satisfactory coefficient of determination, r² (> 0.985) and normalized percent deviation, P (< 5.15) values. Adsorption isotherm data were treated according to Freundlich and Langmuir isotherm models. Based on the r² (> 0.98) and P (< 5.9) values, it was found that experimental data well fitted to Freundlich isotherm model. Adsorption capacities of activated carbon cloth for glyphosate, glufosinate, aminomethylphosphonic acid and bialaphos, expressed in terms of Freundlich constant, were calculated as 20.31, 118.73, 239.33 and 30.68 mmol g^-1, respectively. The results show that the studied ACC can be used in home/business water treatment systems as an adsorbent due to its high adsorption capacity.

A ratio fluorescence sensor based on rhodamine B embedded metal-organic framework for glyphosate detection in agri-food products

Glyphosate, a broad-spectrum and high-efficiency herbicide, could accumulate in the human body through the consumption of agri-food products. Herein, a ratio fluorescence sensor based on rhodamine B-embedded amino-functionalized iron-based metal-organic framework (MOF, NH2-MIL-88(Fe)@RhB) bonded with Cu2+ was developed for rapid detection of glyphosate. The synthesized NH2-MIL-88(Fe) was a biconical prism and had a cavity for the embedding of RhB as a reference compound. In the presence of Cu2+, Lewis interactions with NH2-MIL-88(Fe)@RhB cause the fluorescence signal to be turned off. When glyphosate was added, the signal was turned on due to chelation with Cu2+ and hydrogen bonding interactions with NH2-MIL-88(Fe)@RhB. Under optimal conditions, the developed sensor exhibited a linear range of 0.60-45 μmol L-1 with a response time of less than 1 min. The sensor was applied in the analysis of agri-food products (tea, soybean, wheat, cucumber), with recoveries between 97.93% and 109.06%, indicating its promising application in agri-food safety.

Copper Glufosinate-Based Metal-Organic Framework as a Novel Multifunctional Agrochemical

Pesticides are agrochemical compounds used to kill pests (insects, rodents, fungi, or unwanted plants), which are key to meet the world food demand. Regrettably, some important issues associated with their widespread/extensive use (contamination, bioaccumulation, and development of pest resistances) demand a reduction in the amount of pesticide applied in crop protection. Among the novel technologies used to combat the deterioration of our environment, metal-organic frameworks (MOFs) have emerged as innovative and promising materials in agroindustry since they possess several features (high porosity, functionalizable cavities, ecofriendly composition, etc.) that make them excellent candidates for the controlled release of pesticides. Moving toward a sustainable development, in this work, we originally describe the use of pesticides as building blocks for the MOF construction, leading to a new type of agricultural applied MOFs (or AgroMOFs). Particularly, we have prepared a novel 2D-MOF (namely, GR-MOF-7) based on the herbicide glufosinate and the widely used antibacterial and fungicide Cu²⁺. GR-MOF-7 crystallizes attaining a monoclinic P2₁/c space group, and the asymmetric unit is composed of one independent Cu²⁺ ion and one molecule of the Glu^2- ligand. Considering the significant antibacterial activity of Cu-based compounds in agriculture, the potential combined bactericidal and herbicidal effect of GR-MOF-7 was investigated. GR-MOF-7 shows an important antibacterial activity against Staphylococcus aureus and Escherichia coli (involved in agricultural animal infections), improving the results obtained with its individual or even physical mixed precursors [glufosinate and Cu(NO₃)₂]. It is also an effective pesticide against germination and plant growth of the weed Raphanus sativus, an invasive species in berries and vines crops, demonstrating that the construction of MOFs based on herbicide and antibacterial/antifungal units is a promising strategy to achieve multifunctional agrochemicals. To the best of our knowledge, this first report on the synthesis of an MOF based on agrochemicals (what we have named AgroMOF) opens new ways on the safe and efficient MOF application in agriculture.

Effects of Phosphonate Herbicides on the Secretions of Plant-Beneficial Compounds by Two Plant Growth-Promoting Soil Bacteria: A Metabolomics Investigation

Plant growth-promoting rhizobacteria (PGPR) that colonize plant roots produce a variety of plant-beneficial compounds, including plant-growth regulators, metal-scavenging compounds, and antibiotics against plant pathogens. Adverse effects of phosphonate herbicides, the most extensively used herbicides, on the growth and metabolism of PGPR species have been widely reported. However, the potential consequence of these effects on the biosynthesis and secretion of PGPR-derived beneficial compounds still remains to be investigated. Here, using high-resolution mass spectrometry and a metabolomics approach, we investigated both the intracellular metabolome and the extracellular secretions of biomass-normalized metabolite levels in two PGPR species (Pseudomonas protegens Pf-5, a Gram-negative bacterium; Priestia megaterium QM B1551, a Gram-positive bacterium) exposed to three common phosphonate herbicides (glyphosate, glufosinate, and fosamine; 0.1-1 mM) in either iron (Fe)-replete or Fe-deficient nutrient media. We quantified secreted auxin-type plant hormone compounds (phenylacetic acid and indole-3-acetic acid), iron-scavenging compounds or siderophores (pyoverdine and schizokinen), and antibiotics (2,4-diacetylphloroglucinol and pyoluteorin) produced by these PGPR species. The Fe-replete cells exposed to the phosphonate herbicides yielded up to a 25-fold increase in the production of both auxin and antibiotic compounds, indicating that herbicide exposure under Fe-replete conditions triggered metabolite secretions. However, the herbicide-exposed Fe-deficient cells exhibited a near 2-fold depletion in the secretion of these auxin and antibiotic compounds as well as a 77% decrease in siderophore production. Intracellular metabolomics analysis of the Fe-deficient cells further revealed metabolic perturbations in biosynthetic pathways consistent with the impaired production of the plant-beneficial compounds. Our findings implied that compromised cellular metabolism during nutrient deficiency may exacerbate the adverse effects of phosphonate herbicides on PGPR species.

Ecotoxicology of glyphosate and recent advances in its mitigation by adsorption

Glyphosate (N-[phosphonomethyl]glycine) is one of the most popular herbicides now used in agricultural practice. The aim of this paper was to discuss the research progress and innovations in recent years on the mitigation of glyphosate (GLY) from aqueous media by adsorption. The ecotoxicology of GLY was discussed in the domain of its chronic and sub-chronic toxicity, genotoxicity, reproductive toxicity, and carcinogenicity, and potential risks of food contamination were discussed. It was observed that polymers and resins are the best class of adsorbents for GLY adsorption from aqueous media. GLY adsorption was best fit to either Freundlich or Langmuir isotherm depending on the nature of the adsorbent. The pseudo-second-order kinetics was also the best fit for modelling the kinetics of GLY adsorption. A review of the thermodynamics revealed that GLY adsorption was usually spontaneous and exothermic. Research trends and knowledge gaps are in the area of chemical mobility in environmental systems (especially in the presence of other chemical species), the use of heavy metal-laden adsorbent and molecular modelling. Furthermore, it was observed that the ecotoxicology of GLY still has some contentious areas where there is no conclusive stance.

Enhanced Hydrolysis of p-Nitrophenyl Phosphate by Iron (Hydr)oxide Nanoparticles: Roles of Exposed Facets

Iron (hydr)oxide nanoparticles are one of the most abundant classes of naturally occurring nanoparticles and are widely used engineered nanomaterials. In the environment these nanoparticles may significantly affect contaminant fate. Using two goethite materials with different contents of exposed {021} facet and two hematite materials with predominantly exposed {001} and {100} facets, respectively, we show that exposed facets, one of the most intrinsic properties of nanocrystals, significantly affect the efficiency of iron (hydr)oxide nanoparticles in catalyzing acid-promoted hydrolysis of 4-nitrophenyl phosphate (pNPP, selected as a model organophosphorus pollutant). Attenuated total reflectance Fourier-transform infrared spectroscopy analysis and density functional theory calculations indicate that the pNPP hydrolysis reaction on the iron (hydr)oxide surface involves the inner-sphere complexation between the phosphonate moiety of pNPP and the surface ferric iron (Fe(III)), through ligand exchange with primarily the singly coordinated surface hydroxyl groups of iron (hydr)oxides. Both the abundance and affinity of these adsorption sites are facet-dependent. Exposed facets also determine the reaction kinetics of surface-bound pNPP mainly by regulating the Lewis acidity of the surface Fe(III) atoms. These findings underline the important roles of facets in determining the reactivity of naturally occurring metal-based nanoparticles toward environmental contaminants and may shed light on the development of nanomaterial-based remediation strategies.

Molecular Recognition at Mineral Interfaces: Implications for the Beneficiation of Rare Earth Ores

Ce-bastnäsite is the single largest mineral source for light rare-earth elements. In view of the growing industrial importance of rare-earth minerals, it is critical to develop more efficient methods for separating the valuable rare-earth-containing minerals from the surrounding gangue. In this work, we employ a combination of periodic density functional theory (DFT) and molecular mechanics (MM) calculations together with the de novo molecular design program HostDesigner to identify bis-phosphinate ligands that preferentially bind to the (100) Ce-bastnäsite surface rather than the (104) calcite surface. DFT calculations for a simple phosphinate ligand were employed to qualitatively understand key behaviors involved in ligand-metal, ligand-solvent, and solvent-metal interactions. These insights were then used to guide the search for flexible, rigid, and semirigid hydrocarbon linkers to identify candidate bis-phosphinate ligands with the potential to bind preferentially to Ce-bastnäsite. Among the five most promising bis-phosphinate ligands suggested by theoretical studies, three ligands were synthesized and their adsorption characteristics to bastnäsite (100) interfaces were characterized using vibrational sum-frequency (vSFG) spectroscopy, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, and isothermal titration calorimetry (ITC). The efficacy of the selective interfacial molecular binding was demonstrated by identifying a bis-phosphinate ligand capable of providing an overall higher surface coverage of alkyl groups relative to a monophosphinate ligand. The results highlight the interplay between adsorption binding strength and maximum surface coverage in determining ligand efficiency to render the mineral surface hydrophobic. DFT calculations further indicate that all tested ligands have higher affinity for Ce-bastnäsite than for calcite. This is consistent with the ITC data showing stronger adsorption enthalpy to bastnäsite than to calcite, making these ligands promising candidates for selective flotation of Ce-bastnäsite.

Identification and characterization of an amidase from Leclercia adecarboxylata for efficient biosynthesis of L-phosphinothricin

L-phosphinothricin (L-PPT) is an important broad-spectrum herbicide with expanding utilization because it is environmentally benign. A strain Leclercia adecarboxylata ZJB-17008 with capability of catalyzing rac-4-(hydroxy(methyl)phosphoryl)-2-(2-phenylacetamido) butanoic acid (rac-S) to L-PPT was screened and identified, from which an amidase (La-Ami) was cloned and secretory expressed in Bacillus subtilis WB 800 for the bioproduction of L-PPT. The recombinant La-Ami exhibited an excellent enantioselectivity (99.9% ee) and remarkable thermostability with a half-life of 19.8 h at 50 °C. Furthermore, La-Ami displaying a high space-time yield of 787.2 g L^-1 d^-1 at 50 °C and pH 8.5 under the rac-S concentration of 500 mM (150 g L^-1). The finally refined L-PPT was obtained with a purity of 99% and a total yield reached 90%. These results implying that this secretory expressed amidase La-Ami is possible to be applied in the large-scale bioproduction of L-PPT.

Sorption, transport and biodegradation - An insight into bioavailability of persistent organic pollutants in soil

Contamination of soils with persistent organic pollutants (POPs), such as organochlorine pesticide, polybrominated diphenyl ethers, halohydrocarbon, polycyclic aromatic hydrocarbons (PAHs) is of increasing concern. Microbial degradation is potential mechanism for the removal of POPs, but it is often restricted by low bioavailability of POPs. Thus, it is important to enhance bioavailability of POPs in soil bioremediation. A series of reviews on bioavailability of POPs has been published in the past few years. However, bioavailability of POPs in relation to soil organic matter, minerals and soil microbes has been little studied. To fully understand POPs bioavailability in soil, research on interactions of POPs with soil components and microbial responses in bioavailability limitation conditions are needed. This review focuses on bioavailability mechanisms of POPs in terms of sorption, transport and microbial adaptation, which is particularly novel. In consideration of the significance of bioavailability, further studies should investigate the influence of various bioremediation strategies on POPs bioavailability.

Stimulatory effect and adsorption behavior of rhamnolipids on lignocelluloses degradation system

Di-rhamnolipid and mixed rhamnolipid were added to rice straw degrading system to investigate their mechanism of stimulatory effect. By batch adsorption experiments, it was shown that the equilibrium adsorption time of rhamnolipids on rice straw single system was the shortest (50min). The adsorption capacity of Trichoderma reesei single system was the strongest, whose Q_e,exp for di-rhamnolipid and mixed rhamnolipid was 10.57×10^-2mg·g^-1 and 8.13×10^-2mg·g^-1, respectively. The adsorption of rhamnolipids on consortia system was not the simple adduct of the two single systems. The adsorption of rhamnolipids on the three different systems might belong to chemisorptions. SEM and FTIR analyses were used to observe the morphology and to analyze the chemical functions in lignocellulosic biomass degradation with rhamnolipid. It was shown that after addition of rhamnolipids, the basic tissue in rice straw was severely destroyed and hydrogen bond was formed between biosurfactant and bacteria in lignocellulose degrading system.

The influence of salt matrices on the reversed-phase liquid chromatography behavior and electrospray ionization tandem mass spectrometry detection of glyphosate, glufosinate, aminomethylphosphonic acid and 2-aminoethylphosphonic acid in water

The analysis of highly polar and amphoteric compounds in seawater is a continuing challenge in analytical chemistry due to the possible formation of complexes with the metal cations present in salt-based matrices. Here we provide information for the development of analytical methods for glyphosate, glufosinate, AMPA, and 2-AEP in salt water, based on studies of the effects of salt matrices on reversed-phase liquid chromatography-heated electrospray ionization-tandem mass spectrometry (RP-LC-HESI-MS/MS) after derivatization of the target compounds with FMOC-Cl. The results showed that glyphosate was the only analyte with a strong tendency to form glyphosate-metal complexes (GMC), which clearly influenced the analysis. The retention times (RTs) of GMC and free glyphosate differed by approximately 7.00min, reflecting their distinct RP-LC behaviors. Divalent cations, but not monovalent (Na+, K+) or trivalent (Al3+, Fe3+) cations, contributed to this effect and their influence was concentration-dependent. In addition, Cu2+, Co2+, Zn2+, and Mn2+ prevented glyphosate detection whereas Ca2+, Mg2+, and Sr2+ altered the retention time. At certain tested concentrations of Ca2+ and Sr2+ glyphosate yielded two peaks, which violated the fundamental rule of LC, that under the same analytical conditions a single substance yields only one LC-peak with a specific RT. Salt-matrix-induced ion suppression was observed for all analytes, especially under high salt concentrations. For glyphosate and AMPA, the use of isotopically labeled internal standards well-corrected the salt-matrix effects, with better results achieved for glufosinate and 2-AEP with the AMPA internal standard than with the glyphosate internal standard. Thus, our study demonstrated that Ca2+, Mg2+, and Sr2+ can be used together with FMOC-Cl to form GMC-FMOC which is suitable for RP-LC-HESI-MS/MS analysis.