Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

A batch-equilibration technique was employed to study the impact of two organophosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu2+) sorptiondesorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu2+ sorption, increased Cu2+ desorption and prolonged the equilibrium time of Cu2+ sorption-desorption. But GPS appeared to exert a stronger influence on Cu2+ sorption-desorption due to its stronger complexion with Cu2+. When MDP was added, Cu2+ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu2+ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu2+ desorption in the presence of GPS.Without pesticides and with the existence of MDP, Cu2+ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu2+ desorption kinetics in the presence of GPS although its sorption could be also described by these two equations.     

Effects of methamidophos and glyphosate on copper sorption-desorption behavior in soils

A batch-equilibration technique was employed to study the impact of two organo-phosphorus pesticides methamidophos (MDP) and glyphosate (GPS) on copper (Cu2+) sorption-desorption for phaeozem and burozem collected from Northeastern China. The addition of the two pesticides decreased Cu2+ sorption, increased Cu2+ desorption and prolonged the equilibrium time of Cu2+ sorption-desorption. But GPS appeared to exert a stronger influence on Cu2+ sorption-desorption due to its stronger complexion with Cu2+. When MDP was added, Cu2+ sorption-desorption was linearly correlated with MDP treatment concentrations. But in the presence of GPS, Cu2+ sorption first underwent a rapid decrease period, and then slowly tended towards a steady period. The reverse pattern could be found for Cu2+ desorption in the presence of GPS. Without pesticides and with the existence of MDP, Cu2+ sorption-desorption kinetics was well conformed to two-constant equation and Elovich equation. But that was not the case for Cu2+ desorption kin     

Enhanced sorption of Cu2+ and Ni2+ by acid-pretreated Chlorella vulgaris from single and binary metal solutions

The influence of HCl pretreatment (0.1 mM) on sorption ofCu²⁺ and Ni²⁺ by Chlorella vulgariswas tested using single and binary metal solutions. The optimal initial pH forsorption was 3.5 for Cu²⁺ and 5.5 for Ni²⁺. Second orderrate kinetics described well sorption by untreated and acid-pretreated cells.The kinetic constant q_e (metal sorption at equilibrium) for sorptionof test metals from single and binary metal solutions was increased afterpretreatment of the biomass with HCl. The Langmuir adsorption isotherm wasdeveloped for describing the various results for metal sorption. In single metalsolution, acid pretreatment enhanced q_max for Cu²⁺ andNi²⁺ sorption by approximately 70% and 65%, respectively.Cu²⁺ and Ni²⁺ mutually interfered with sorption of theother metal in the binary system. The combined presence of Cu²⁺ andNi²⁺ led to their decreased sorption by untreated biomass by 19% and88%, respectively. However, acid-pretreated biomass decreased Cu²⁺and Ni²⁺ sorption by 15 and 22%, respectively, when both the metalswere present in the solution. The results suggest a reduced mutual interferencein sorption of Cu²⁺ and Ni²⁺ from the binary metal systemdue to the acid pretreatment. Acid-pretreated cells sorbed twice the amount ofCu²⁺ and ten times that of Ni²⁺ than the untreated biomassfrom the binary metal system. Acid pretreatment more effectively enhanced thesorption of Ni²⁺ form the binary metal solution. The total metalsorption by untreated and acid-pretreated biomass depended on theCu²⁺ : Ni²⁺ ratio in the binary metal system. Acidpretreatment of C. vulgaris could be an effective andinexpensive strategy for enhancing Cu²⁺ and Ni²⁺ sorptionfrom single and binary metal solutions.     

Sorption of Copper and Zinc to the Plasma Membrane of Wheat Root

Sorption of Cu²⁺ and Zn²⁺ to the plasma membrane (PM) of wheat root (Triticum aestivum Lcv. Scout 66) vesicles was measured at different pH values and in the presence of organic acids and other metals. The results were analyzed using a Gouy-Chapman-Stem model for competitive sorption (binding and electrostatic attraction) to a negative binding site. The binding constants for the two investigated cations as evaluated from the sorption experiments were 5 M^–1 for Zn²⁺ and 400 M^–1 for Cu²⁺. Thus, the sorption affinity of Cu²⁺ to the PM is considerably larger than that of Ca²⁺, Mg²⁺ or Zn²⁺. The greater binding affinity of Cu²⁺ was confirmed by experiments in which competition with La³⁺ for sorption sites was followed. The amount of sorbed Cu²⁺ decreased with increasing K⁺, Ca²⁺, or La³⁺ concentrations, suggesting that all these cations competed with Cu²⁺ for sorption at the PM binding sites, albeit with considerable differences among these cations in effectiveness as competitors with Cu²⁺. The sorption of Cu²⁺ and Zn²⁺ to the PM decreased in the presence of citric acid or malic acid. Citric acid (as well as pH) affected the sorption of Cu²⁺ or Zn²⁺ to PM more strongly then did malic acid.     

沉水植物菹草在低温条件下对重金属Cu、Pb、Zn的吸附和富集

在10℃的较低温度条件下,研究了冬春季节生长旺盛的沉水植物菹草(Potamogeton crispus L.)对重金属离子Cu²⁺,Pb²⁺,Zn²⁺的生物吸附特征及解吸情况,对不同初始浓度重金属水体中的重金属离子去除率情况,以及在此过程中菹草各器官(叶、茎、根茎、根)对重金属离子的富集情况。结果表明,菹草对Cu²⁺,Zn²⁺的吸附在20 min内达到平衡,对Pb²⁺的吸附在50 min内达到平衡,吸附动力学结果符合伪二级动力学方程,决定系数分别达1,1,0.997 8。Freundlich等温线可较好地拟合菹草吸附Cu²⁺,Pb²⁺,Zn²⁺的过程,Cu²⁺,Pb²⁺,Zn²⁺的吸附容量分别达到66.900 6,26.543 0,30.371 8 mg·L^-1。以去离子水作洗脱剂,解吸液中3种重金属离子浓度均低于仪器检出限(0.01 mg·L^-1),解吸程度微弱。投放菹草后,随着初始处理浓度的升高,水体Cu²⁺的去除率先降低后升高,Pb²⁺的去除率的变化趋势与Cu²⁺类似。Zn²⁺去除率则随水体Zn²⁺初始浓度的升高而逐渐升高。菹草各器官对水体3种重金属离子的富集能力不同,排序为Cu²⁺＞Zn²⁺＞Pb²⁺。不同器官对同一种重金属离子的富集量差异显著,叶是富集重金属离子的主要器官。水体重金属离子的初始浓度会影响菹草各器官富集重金属离子的能力,一般随水体重金属初始浓度升高,菹草各器官的重金属离子富集量虽有不同程度的增加但富集系数持续减小。     

不同污染负荷土壤中镉和铅的吸附－解吸行为

采用一次平衡法,对3种不同污染负荷土壤Cd2 和Pb2 的吸附-解吸行为进行了比较.结果表明,低污染负荷土壤对Cd2 和Pb2 的吸附能力高于高污染负荷土壤.3种土壤对Cd2 的吸附等温线与Freundlich方程有较好的拟合性,Pb2 的等温吸附过程可用Langmuir方程与Freundlich方程来描述.双常数方程是描述这3种不同污染负荷土壤中Cd2 和Pb2 吸附动力学行为的最优模型,其次为Elovich方程,最差模型是一级动力学方程.Pb2 的解吸滞后现象较Cd2 明显.高污染负荷土壤的吸附态Cd2 、Pb2 解吸率高于低污染负荷土壤,Cd2 、Pb2 解吸量与其初始吸附量之间的关系符合二次幂方程.3种土壤Cd2 、Pb2 的解吸速率随重金属初始浓度的增加而增加,随解吸时间的延长而降低.     

Synthesis and characterization of novel guar gum hydrogels and their use as Cu sorbents

To prepare novel hydrogels for use in water technologies, guar gum was subjected to acid hydrolysis. The depolymerized guar gum obtained there from and the native guar gum were oxidized to their respective polycarboxylic forms using NO_x as oxidant. All these polymers were crosslinked with N,N-methylenebisacrylamide, and were used as Cu²⁺ sorbents. The candidate hydrogel exhibiting the highest uptake was used further to investigate the effect of external stimuli on sorption. The sorption on hydrogels was fast as the highest sorption was observed after 2 h at 40 °C and 20 ppm of Cu²⁺ ions. The hydrogel prepared from the oxidized guar gum afforded the maximum sorption capacity of 125.893 mg g⁻¹. Langmuir and Freundlich isotherms, and pseudo second order kinetics matches the experimental data. The evidence of sorption was obtained by characterizing Cu²⁺-loaded hydrogels by FTIR spectroscopy.     

Hysteretic Behavior of Imidacloprid Sorption-Desorption in Soils of Croatian Coastal Regions

Sorption and desorption are important processes that influence the transport, transformation, and bioavailability of imidacloprid in the soils. Equilibrium batch experiments were carried out using six coastal Croatian soils. The equilibrium sorption and desorption experimental data showed the best fit to the Freundlich equation. Sorption parameters predicted with the Freundlich model, K_F ^sor and 1/n ranged from 2.92 to 5.74 (mg/kg)/(mg/L)^1/n, and 0.888 to 0.919, respectively. The sorption of imidacloprid was found to be sensitive to organic carbon (OC) content. The highest sorption was observed in Krk soil (OC 4.74%) and the lowest in Zadar soil (OC 1.06%). Fitted desorption parameter values, K_F ^des , were consistently higher than those associated with sorption. The opposite trend was observed for the exponential parameter 1/n. Results also suggested that imidacloprid sorption-desorption by soil is concentration-dependent, i.e. at lower imidacloprid concentrations a greater sorption percentage and lower desorption percentage occurred. Desorption studies revealed that there was a hysteresis effect in all the tested soils. Hysteresis coefficient values (H) varied from 0.656 to 0.859. The study results emphasize that the controlled application of imidacloprid is obligatory, especially in soils with a low organic carbon content, in order to minimize a risk of environmental and groundwater pollution.     

Differential copper binding to alpha-synuclein and its disease-associated mutants affect the aggregation and amyloid formation

BackgroundCopper is an essential trace element required for the proper functioning of various enzymes present in the central nervous system. An imbalance in the copper homeostasis results in the pathology of various neurodegenerative disorders including Parkinson’s Disease. Hence, residue specific interaction of Cu²⁺ to α-Syn along with the familial mutants H50Q and G51D needs to be studied in detail.MethodsWe investigated the residue specific mapping of Cu²⁺ binding sites and binding strength using solution-state NMR and ITC respectively. The aggregation kinetics, secondary structural changes, and morphology of the formed fibrils in the presence and absence of Cu²⁺ were studied using fluorescence, CD, and AFM respectively.ResultsCopper binding to α-Syn takes place at three different sites with a higher affinity for the region 48-53. While one of the sites got abolished in the case of H50Q, the mutant G51D showed a binding pattern similar to WT. The aggregation kinetics of these proteins in the presence of Cu²⁺ showed an enhanced rate of fibril formation with a pronounced effect for G51D.ConclusionCu²⁺ binding results in the destabilization of long-range tertiary interactions in α-Syn leading to the exposure of highly amyloidogenic NAC region which results in the increased rate of fibril formation. Although the residues 48-53 have a stronger affinity for Cu²⁺ in case of WT and G51D, the binding is not responsible for enhancing the rate of fibril formation in case of H50Q.General SignificanceThese findings will help in the better understanding of Cu²⁺ catalyzed aggregation of synucleins.     

Slow vapor‐phase desorption of toluene from several ion‐exchanged montmorillonites

The sorption and desorption of volatile compounds from soils and clays exhibit a wide range of kinetics. While much of the sorptive interaction is very rapid, a certain fraction of volatile compounds that enter soil and clays are only slowly desorbed. It is generally believed that the formation of this recalcitrant or slowly desorbing fraction of volatile organic compounds (VOCs) in soils is due to the diffusion of compounds to poorly accessible sorption sites. However, the exact nature of these sites is in doubt. In montmorillonite, there are two likely possibilities for formation of the recalcitrant fraction: sites between the clay lamella and sites within clay particle aggregates. Because montmorillonite may be an important fraction of many soils, we have explored the formation of slowly desorbing toluene on a montmorillonite clay that was ion exchanged with five different ions (K⁺, Na⁺, Ca²⁺, Mg²⁺, and Fe³⁺) to form mineralogically similar clays with varying interlamellar spacing. The recalcitrant fraction was quantified for varying sorption and desorption times. The type of ion exchanged into the clay appears to have an important influence on the formation of a recalcitrant fraction.     

Validation of TOF-SIMS and FE-SEM/EDS Techniques Combined with Sorption and Desorption Experiments to Check Competitive and Individual Pb2+ and Cd2+ Association with Components of B Soil Horizons

Sorption and desorption experiments were performed by the batch method on the B horizons of five natural soils: Umbric Cambisol, Endoleptic Luvisol, Mollic Umbrisol, Dystric Umbrisol, and Dystric Fluvisol. Individual and competitive sorption and desorption capacity and hysteresis were determined. The results showed that Pb²⁺ was sorbed and retained in a greater quantity than Cd²⁺ and that the hysteresis of the first was greater than that of the second. The most influential characteristics of the sorption and retention of Pb²⁺ were pH, ECEC, Fe and Mn oxides and clay contents. For Cd²⁺ they were mainly pH and, to a lesser extent, Mn oxides and clay content. The combined use of TOF-SIMS, FE-SEM/EDS and sorption and desorption analyses was suitable for achieving a better understanding of the interaction between soil components and the two heavy metals. They show the preferential association of Pb²⁺ with vermiculite, chlorite, Fe and Mn oxides, and of Cd²⁺ with the same components, although to a much lesser extent and intensity. This was due to the latter’s higher mobility as it competed unfavourably with the Pb²⁺ sorption sites. TOF-SIMS and FE-SEM/EDS techniques confirmed the results of the sorption experiments, and also provided valuable information on whether the soil components (individually or in association) retain Cd²⁺ and / or Pb²⁺; this could help to propose effective measures for the remediation of contaminated soils.     

Influence of hydrogen cations on kinetics and equilibria of heavy-metal sorption by algae—sorption of copper cations by the alga Palmaria palmata (Linnaeus) Weber & Mohr (Rhodophyta)

The influence of hydrogen cations on kinetics and equilibria of sorption of copper cations by the marine alga Palmaria palmata (Linnaeus) Weber & Mohr was studied under static conditions. The competitive effect of the H⁺ cations is described, which influenced the uncertainty of evaluation of the alga sorption capacity. Under static conditions, the variation of the Cu²⁺/H⁺ concentration ratio during sorption was found nonmonotonic. The Langmuir isotherm model was used to determine the sorption capacity of the alga, namely 12.4 mg g^?1 of dry algae mass. A similar value was determined from the kinetic parameters of the ionic exchange which is considered a pseudo-second-order chemical reaction. The consistent results indicated that the mathematical models used correctly described the equilibria and kinetics of the ionic exchange between algae and solutions.     

Biosorption of metal ions byAzotobacter vinelandii

Azotobacter vinelandii was better than eitherDerxia gummosa orRhizobium trifolii for sorption of UO ₂ ²⁺ . Its maximum binding capacity was 0.25 mmol UO ₂ ²⁺ /g dry biomass with an affinity constant of 333 l/mmol at pH 4.1 according to the Langmuir model. In a semisynthetic medium,A. vinelandii showed the highest sorption capacity in the early stationary phase. The binding of UO ₂ ²⁺ , Cu²⁺, Ca²⁺ and Zn²⁺ was affected by the pH of the solution. With HCl as eluent, virtually all the sorbed UO ₂ ²⁺ was released. The presence of Cu²⁺, Cd²⁺, Ca²⁺, and Zn²⁺ inhibited the UO ₂ ²⁺ biosorption whereas Mg²⁺ and K⁺ had no effect.     

Copper susceptibility in Acinetobacter junii BB1A is related to the production of extracellular polymeric substances

Acinetobacter junii BB1A cells, grown in different media, were differentially inhibited in the presence of the copper. The minimum inhibitory concentration of Cu²⁺ was influenced by the nutrient status of the media. The production of extracellular polymeric substances (EPS) was stimulated by the copper present in the growth medium. The nature of the EPS was anionic showing non-Newtonian pseudoplastic behaviour. The thermal behaviour of the EPS was studied by differential scanning calorimetry. The EPS was amorphous in nature with a crystalline index of 0.16. Scanning electron micrographs revealed its porous structure. Cells grown in the presence of quorum sensing inhibitor (QSI: 4-Nitropyridine-N-oxide) did not produce EPS and were found to be more sensitive to Cu²⁺ than cells which produced EPS in the absence of QSI. EPS production in different media in the presence and absence of Cu²⁺ was determined. The production of EPS was the highest in brain heart Infusion medium and the lowest in AB minimal medium. The sorption of Cu²⁺ by EPS extracted from cells grown in non-copper-complexing AB medium was demonstrated by energy dispersive X-ray spectroscopy. A pertinent functional aspect of EPS in providing protection to A. junii in copper stress condition has been revealed.     

Removal of copper using marine brown alga, Undaria Pinnatifida modified with oxime

Summary As oxime is selective for Cu²⁺, oxime groups were introduced to the cell wall of alga by glutaraldehyde. Such modified biomass showed high affinity for Cu²⁺, which resulted in the increase of copper sorption capacity about 4.5 times higher than that of natural alga. For pH range from 2.5 to 3.0, only Cu²⁺ were removed by alga biomass modified with oxime, while other heavy metal ions such as Ca²⁺,Cd²⁺,Pb²⁺ were not adsorbed. By changing pH, selective recovery of Cu²⁺ was achieved.     

Adsorption of Ni2+ and Cu2+ using Bio-Mineral: Adsorption Isotherms and Mechanisms

Heavy metal pollution has become one of the most serious environmental pollution problems. This study aimed to determine the adsorption and desorption characteristics of Ni²⁺ and Cu²⁺ by bio-mineral which was induced by Bacillus subtilis, and to explore the effect of pH on adsorption characteristics. The results showed that the Langmuir model gave a better fit to the experimental data than the Freundlich model, which demonstrated the adsorption was of a single-molecule layer form. The maximum adsorption capacities of the bio-mineral for Ni²⁺ and Cu²⁺ were determined as 67.114 mg/g and 69.930 mg/g, respectively. The desorption rates of Ni²⁺ and Cu²⁺ were very low, especially for Ni²⁺ which was almost 0. Besides, the bio-mineral maintained high adsorption capability for metals ions within a wide pH range (pH ≥ 3). It did not show any new phases after adsorption of Ni²⁺ and Cu²⁺ tested by FTIR, indicating that the bio-mineral and heavy metal ions might mainly physically be adsorbed. The bio-mineral has a larger internal and external specific surface area, pore volume and colloidal properties which are beneficial for the adsorption of metals ions, but shows limits in desorption. This study provides a theoretical basis for the utilization of bio-mineral and opens a new perspective for the remediation of heavy metals pollution.     

Biosorption of copper by fungal melanin

Summary Melanin obtained from Aureobasidium pullulans and Cladosporium resinae was an efficient biosorbent for copper. Copper uptake could be expressed using various adsorption isotherms; melanin from A. pullulans obeyed Freundlich and Langmuir isotherms whereas C. resinae melanin followed the BET isotherm indicating a more complex type of adsorption than in A. pullulans. In general, uptake capacities of melanin were greater than for intact biomass and the higher uptake by pigmented rather than albino biomass could be correlated with the presence of melanin. Cu²⁺ was less readily desorbed from melanin by dilute mineral acids than from intact biomass and again, the relative ease of Cu²⁺ desorption from pre-loaded pigmented or albino biomass was correlated with the presence or absence of melanin. Mg²⁺ and Zn²⁺ appeared to be the most effective cations for desorption with Na⁺ and K⁺ the least effective. The addition of melanin to a coppercontaining culture of the albino strain of A. pullulans resulted in some reduction of toxicity.     

Sorption of Glyphosate on Soil Components: The Roles of Metal Oxides and Organic Materials

Predicting the behavior, fate, and transport potential of a herbicide in any soil involves understanding the sorption characteristics. The sorption characteristics of glyphosate (GPS) on soil and their main components were investigated, indicating that the mineral phase is more important than the organic carbon in adsorption of GPS. Sorption isotherms were determined from each component using the batch equilibrium method at various concentrations (5, 10, 15, 20, 25, and 30 mg L^?1) and sorption affinity of GPS was approximated by the Freundlich equation. The sorption strength K _f [mg kg^?1 (L mg^?1)^?n] across the various components ranged from 2.1–134.9 while the organic carbon-normalized Freundlich sorption capacity values, K _foc, ranged from 1.28–3.53 mg kg^?1-OC/(mg L^?1)ⁿ. Infrared Fourier transform spectroscopy (FTIR) of the components showed significant structural differences. The results suggest that the presence of the oxides and hydroxides iron, in particular in soil solutions, enhanced GPS adsorption. They also suggest that reduction in OC% due to various treatments may enhance the remobilization of GPS into the aqueous phase (i.e., groundwater), though at different rates. Comparatively, contribution of surface area to the adsorption of GPS on the various components proved more significant than contents of organic carbon.     

Nickel in plants: I. Uptake kinetics using intact soybean seedlings

The absorption of Ni²⁺ by 21-day-old soybean plants (Glycine max cv. Williams) was investigated with respect to its concentration dependence, transport kinetics, and interactions with various nutrient cations. Nickel absorption, measured as a function of concentration (0.02 to 100 μm), demonstrated the presence of multiple absorption isotherms. Each of the three isotherms conforms to Michaelis-Menten kinetics; kinetic constants are reported for uptake by the intact plant and for transfer from root to shoot tissues. The absorption of Ni²⁺ by the intact plant and its transfer from root to shoot were inhibited by the presence of Cu²⁺, Zn²⁺, Fe²⁺, and Co²⁺. Competition kinetic studies showed Cu²⁺ and Zn²⁺ to inhibit Ni²⁺ absorption competitively, suggesting that Ni²⁺, Cu²⁺, and Zn²⁺ are absorbed using the same carrier site. Calculated K_m and K_i constants for Ni²⁺ in the presence and absence of Cu²⁺ were 6.1 and 9.2 μm, respectively, whereas K_m and K_i constants were calculated to be 6.7 and 24.4 μm, respectively, for Ni²⁺ in the presence and absence of Zn²⁺. The mechanism of inhibition of Ni²⁺ in the presence of Fe²⁺ and Co²⁺ was not resolved by classical kinetic relationships.     

Multi-metal biosorption and bioaccumulation by Exiguobacterium sp. ZM-2

The present work deals with the biosorption performance of dried and non-growing biomasses of Exiguobacterium sp. ZM-2, isolated from soil contaminated with tannery effluents, for the removal of Cd²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ from aqueous solution. The metal concentrations studied were 25 mg/l, 50 mg/l, 100 mg/l, 150 mg/l and 200 mg/l. The effect of solution pH and contact time was also studied. The biosorption capacity was significantly altered by pH of the solution. The removal of metal ions was conspicuously rapid; most of the total sorption occurred within 30 min. The sorption data have been analyzed and fitted to the Langmuir and Freundlich isotherm models. The highest Q_max value was found for the biosorption of Cd²⁺ at 43.5 mg/g in the presence of the non-growing biomass. Recovery of metals (Cd²⁺, Zn²⁺, Cu²⁺ and Ni²⁺) was found to be better when dried biomass was used in comparison to non-growing biomass. Metal removal through bioaccumulation was determined by growing the bacterial strain in nutrient broth amended with different concentrations of metal ions. This multi-metal resistant isolate could be employed for the removal of heavy metals from spent industrial effluents before discharging them into the environment.