Pb Interactions Research Articles

Effective removal of Pb(II) ions using Fe3O4/MgO adsorbent: A comprehensive study  

The effective removal of heavy metal ions, particularly Pb(II), from contaminated water sources remains a pressing environmental concern. This study explores the potential of Fe3O4/MgO nanocomposites as an efficient adsorbent for selective Pb(II) removal. The Fe3O4/MgO nanocomposite was synthesized using a controlled sol-gel method and characterized using various techniques. X-ray diffraction (XRD) analysis confirmed the presence of cubic MgO and cubic Fe3O4. Pb(II) adsorption induced a crystallographic transformation, forming hexagonal Mg(OH)2 crystals, indicating interaction with the adsorbent. Scanning Electron Microscope (SEM) analysis revealed pyramid-like and irregular crystal morphologies. Pyramid-like structures provided a larger surface area and active sites for effective Pb(II) interaction, while irregular crystal particles, representing magnetic Fe3O4, contributed to stability and dispersibility. Vibrating sample magnetometer (VSM) results confirmed superparamagnetic behaviour with a saturation magnetization of 32.02 emu g-1, indicating potential for magnetic separation and recovery in various wastewater treatment applications. Adsorption experiments utilized optimized conditions: an initial concentration of 600 mg L-1, adsorbent dosage of 0.25 g L-1, pH of 7, and 120 minutes of reaction time. The Fe3O4/MgO nanocomposite exhibited exceptional performance with a remarkable 99.98% removal efficiency and a high adsorption capacity of 2399.44 mg g-1. These impressive results underscore the outstanding adsorption potential of the nanocomposite. Adsorption kinetics followed the pseudo-second-order model (R2 = 0.99), confirming suitability for Pb(II) removal. The Freundlich model indicated a heterogeneous surface with different adsorption sites. Overall, the Fe3O4/MgO nanocomposite exhibits potential as a cost-effective, environmentally friendly adsorbent for removing Pb(II) ions, providing a promising solution for water purification and environmental remediation.

Exposure to Multiple Metal(loid)s and Hypertension in Chinese Older Adults.

Evidence about effects of metal(loid)s on hypertension among adults is insufficient. The aim of our study was to evaluate the individual and joint associations between seven selected metal(loid)s and hypertension, including lead (Pb), manganese (Mn), nickel (Ni), arsenic (As), cadmium (Cd), chromium (Cr), and vanadium (V)) in Chinese older adults. This study included 1009 older adults, and the blood concentrations of seven metal(loid)s were evaluated by inductively coupled plasma mass spectrometry (ICP-MS). The following conditions were considered as hypertension: (1) either systolic blood pressure ≥ 140mm Hg or diastolic blood pressure ≥ 90mm Hg, (2) a self-reported history of hypertension, or (3) currently taking antihypertensive medications. Logistic regression was utilized to investigate the association between individual metal(loid) and hypertension, while Bayesian kernel machine regression (BKMR) was employed to investigate the association of the metal(loid) mixture with hypertension. Adjusted single-metal(loid) model showed a significant positive association between Pb and hypertension (OR = 1.24, 95%CI = 1.03-1.50). This significant association still existed in multi-metal(loid) model (OR = 1.22, 95%CI = 1.01-1.47). BKMR further indicated a positive linear association of Pb with hypertension. The metal(loid) mixture was positively associated with hypertension in older adults, although not significant. Within the mixture, Pb had the highest posterior inclusion probabilities value (PIP = 0.9192). There were multiplicative interactions of Pb and Mn on hypertension. In addition, Pb and Mn had additive effects on the association of other blood metal(loid)s with hypertension. The associations of multiple metal(loid)s with hypertension are dependent on diabetes, areas, age, and BMI. The metal(loid) mixture exposure may contribute to hypertension in Chinese older adults, mainly driven by Pb and interactions of Pb and Mn. Reducing exposure to these metal(loid)s may prevent hypertension among older adults, which is especially true for those living with diabetes.

Heavy metals altered the xenobiotic metabolism of rats by targeting the GST enzyme: An in vitro and in silico study

Among all the heavy metals, Pb, Cd, and As are the most harmful pollutants in the environment. They reach into the organisms via various levels of food chains i.e. air and water. Glutathione-s-transferase (GST, E.C. 2.5.1.18), a key enzyme of xenobiotics metabolism, plays an important role in the removal of several toxicants. The present study aimed to evaluate any inhibitory action of these heavy metals on the GST enzyme isolated from the hepatic tissues of rats. A 10 % (w/v) homogenate of rat liver was prepared in cold and centrifuged at 4 °C at 9000xg for 30 min. The supernatant was collected and kept frozen at −20 °C or used fresh for carrying out different experiments. The activity of GST was monitored spectrophotometrically at 340 nm using 220 μg of soluble protein with varying equal substrate concentrations (0.125–2 mM) in phosphate buffer (50 mM, pH 6.5). To assess the impact of heavy metals on the enzyme activity, different concentrations of Cd (0–0.6 mM) and Pb (0–2 mM) were added to the reaction mixture followed by monitoring the residual activity. The optimum temperature and pH of rat liver GST were found to be 37 °C and 6.5, respectively. The Km value for GST was 0.69 mM and the Vmax was found to be 78.67 U/mg. The Cd and Pb significantly altered the kinetic behaviour of the enzyme. The Vmax and Kcat/Km parameters of GST were recorded to be decreased after interaction with Cd and Pb individually and showed a mixed type of inhibition pattern suggesting that these inhibitors may have a greater binding affinity either for the free enzyme or the substrate-enzyme complex. These metals showed a time-dependent enzyme inhibition profile. Cd was found to be the most potent inhibitor when compared to other treated metals; the order of inhibitory effect of metal ions was Cd>Pb>As. The in silico ion docking analysis for determining the probable interactions of Cd and Pb with fragmented GST validated that Cd exhibited higher inhibition potential for the enzyme as compared to Pb. The results of the present study indicated that exposure of both the Cd and Pb may cause significant inhibition of hepatic GST; the former with higher inhibitory potential than the later. However, As proved to be least effective against the enzyme under the aforesaid experimental conditions.

Interaction of Pb(II) with microplastic-sediment complexes: Critical effect of surfactant

In this study, the impact of surfactants on the adsorption behavior of Pb(II) onto microplastics-sediment (MPs-S) complexes was investigated. Firstly, virgin polyamide (VPA) and polyethylene (VPE) were placed in Xiangjiang River sediment for six months to conduct in-situ aging. The results indicated that the biofilm-developed polyamide (BPA) and polyethylene (BPE) formed new oxygen-containing functional groups and different biofilm species. Furthermore, the adsorption capacity of Pb(II) in sediment (S) and MPs-S complexes was in the following order: S > BPA-S > VPE-S > VPA-S > BPE-S. The addition of sodium dodecyl benzenesulfonate (SDBS) promoted the adsorption of Pb(II), and the adsorption amount of Pb(II) increased with the higher concentration of SDBS, while adding cetyltrimethylammonium bromide (CTAB) showed the opposite result. The adsorption process of MPs-S complexes to Pb(II) was dominated by chemical adsorption, and the interaction between MPs-S complexes and Pb(II) was multilayer adsorption involving physical and chemical adsorption when the surfactants were added. Besides, the pH exerts a significant effect on Pb(II) adsorption in different MPs-S complexes, and the highest adsorption amount occurred at pH 6. Noteworthy, CTAB promoted the adsorption ability of Pb(II) when the exogenous FA was added. The binding characteristic of sediment endogenous DOM components and Pb(II) was influenced by the addition of MPs and surfactants. Finally, it confirmed that adsorption mechanisms mainly involve electrostatic and hydrophobic interaction. This study provides a new perspective to explore the environmental behaviors of Pb(II) by MPs and sediments with the addition of surfactants, which was conducive to evaluating the ecological risks of MPs and heavy metals in aquatic environments.

Inclusive study of peanut shells derived activated carbon as an adsorbent for removal of lead and methylene blue from water

Green and efficient agro-waste-based activated carbon has been prepared utilizing peanut shells for adsorptive elimination of an industrial dye, methylene blue, and lead from polluted water. The carbonaceous biomass obtained from peanut shells was chemically activated using either NaOH, ZnCl2, or steam and characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and N2 adsorption and desorption studies. The adsorption process was optimal for methylene blue at alkaline pH, while pH 4.5 was optimal for Pb (II) adsorption. The adsorption takes place through pseudo-second-order kinetic, and the rate-governing step of the adsorption procedure are intraparticle diffusion and film diffusion. Furthermore, the thermodynamics of the adsorption process has been studied, and the obtained Gibbs free energy (ΔG°) values are negative (− 35.90 to − 43.59 kJ mol−1) indicating the spontaneous adsorption of the investigated pollutants on the prepared activated carbon. As per the correlation coefficient, the obtained results were best fit by the Langmuir isotherm with maximum adsorption capacity of 303.03 mg g−1 for methylene blue and 130.89 mg g−1 for Pb (II). The activated carbon successfully removed methylene blue and Pb (II) with %removal exceeding 95%. The mechanisms of interaction of Pb (II) with the activated carbon is a combination of electrostatic interaction and ion exchange, while methylene blue interacts with the activated carbon via π–π interaction, hydrogen bonds, and electrostatic interaction. Thus, the prepared activated carbon has been employed to decontaminate wastewater and groundwater samples. The developed agro-waste-based activated carbon is a promising, cost-efficient, green, and accessible tool for water remediation.

APOE ε4 allele modifies the associations of toxic metals and their mixture with cognitive impairment among older adults

BackgroundThe evidence of interactive effect of the toxic metal (TM) mixture and apolipoprotein E (APOE) ε4 gene on cognitive impairment in older adults is scarce. We aimed to explore whether the associations of single TMs and their mixture with cognitive impairment depend on APOE ε4 in Chinese community-dwelling older people. MethodsA total of 1148 older adults from a subset of the baseline survey of a cohort study were included. Blood arsenic (As), cadmium (Cd), lead (Pb), strontium (Sr), and vanadium (V) were detected by inductively coupled plasma mass spectrometry. APOE gene (rs429358, rs7412) polymorphisms were analyzed by the Polymerase Chain Reaction instrument. Mixed effects logistic regression was applied to estimate the relationships of single TMs and APOE genotype with cognitive impairment. Weighted quantile sum (WQS) and Bayesian kernel machine regression (BKMR) models were performed to examine joint impacts of the TM mixture, as well as the interaction of the TM mixture with APOE ε4 genotype on cognitive impairment. ResultsPb displayed a significant linear association with an increased odds of cognitive impairment after adjustment for covariates (Ptrend = 0.045). While APOE genotype did not show a significant correlation with cognitive impairment. WQS showed that the TM mixture was associated with an increased risk of cognitive impairment by 31.0% (OR=1.31, 95% CI: 0.92, 1.87) while no significance was found. BKMR exhibited a significant linear association between the TM mixture and cognitive impairment. Moreover, both WQS and BKMR indicated that Pb contributed the most to cognitive impairment within the mixture. Significant interactions of Pb or the TM mixture and APOE genotype on cognitive impairment were observed, contributing to 38.1% and 38.2% of total effects, respectively. ConclusionsAPOE ε4 allele amplifies the associations of single Pb or the TM mixture with cognitive impairment. These findings may help to develop precision prevention.

Adsorption of Pb(II) and Ag(I) using iron/manganese oxides modification biochar

The iron/manganese oxides modification biochar (Mn/Fe-biochar) is prepared by pyrolysis of RS impregnated with KMnO4 and Fe(NO3)3 for Pb(II) and Ag(I) removal from wastewater. Pb(II) and Ag(I) adsorption process on Mn/Fe-biochar are exactly analyzed using the Pseudo-second order and Hill model. Pb(II) and Ag(I) adsorption capacity of Mn/Fe-biochar are 88.49 and 134.80 mg/g based on Hill model, respectively. Adsorption thermodynamics analysis indicates the feasible and spontaneous Pb(II) and Ag(I) adsorption on Mn/Fe-biochar. Adsorption mechanism analysis indicates that π-π interaction and surface functional groups contribute to Pb(II) and Ag(I) removal. Density functional theory calculation indicates that binding energies of Pb(II) and Ag(I) interactions with -Mn-O group are the largest than that of the -OH, -COOH, -Fe-O groups, indicating that -Mn-O group plays an important role in Pb(II) and Ag(I) adsorption process. Reusability analysis indicates that Mn/Fe-biochar still has high Pb(II) and Ag(I) adsorption capacity after three cycles. The preliminary economic analysis indicates that the production cost of the Mn/Fe-biochar is estimated as the $4.94/1 kg.

Regio- and Stereo-Selective Isomerization of Borylated 1,3-Dienes Enabled by Selective Energy Transfer Catalysis.

Configurationally-defined dienes are pervasive across the bioactive natural product spectrum, where they typically manifest themselves as sorbic acid-based fragments. These C5 motifs reflect the biosynthesis algorithms that facilitate their construction. To complement established biosynthetic paradigms, a chemical platform to facilitate the construction of stereochemically defined, functionalizable dienes by light-enabled isomerization has been devised. Enabled by selective energy transfer catalysis, a variety of substituted β-boryl sorbic acid derivatives can be isomerized in a regio- and stereo-selective manner (up to 97 : 3). Directionality is guided by a stabilizing nO→pB interaction in the product: this constitutes a formal anti-hydroboration of the starting alkyne. This operationally simple reaction employs low catalyst loadings (1 mol %) and is complete in 1 h. X-ray analysis supports the hypothesis that the nO→pB interaction leads to chromophore bifurcation: this provides a structural foundation for selective energy transfer.

Regio‐ and Stereo‐Selective Isomerization of Borylated 1,3‐Dienes Enabled by Selective Energy Transfer Catalysis

AbstractConfigurationally‐defined dienes are pervasive across the bioactive natural product spectrum, where they typically manifest themselves as sorbic acid‐based fragments. These C5 motifs reflect the biosynthesis algorithms that facilitate their construction. To complement established biosynthetic paradigms, a chemical platform to facilitate the construction of stereochemically defined, functionalizable dienes by light‐enabled isomerization has been devised. Enabled by selective energy transfer catalysis, a variety of substituted β‐boryl sorbic acid derivatives can be isomerized in a regio‐ and stereo‐selective manner (up to 97 : 3). Directionality is guided by a stabilizing nO→pB interaction in the product: this constitutes a formal anti‐hydroboration of the starting alkyne. This operationally simple reaction employs low catalyst loadings (1 mol %) and is complete in 1 h. X‐ray analysis supports the hypothesis that the nO→pB interaction leads to chromophore bifurcation: this provides a structural foundation for selective energy transfer.

Hardness of surface hydroxyls and its pivotal role in the flotation of cassiterite from quartz via lead ions activation

Current research has trouble explaining the selective flotation mechanism realized by metal ions, which hinders the advancement of effective flotation techniques. In this work, the selective activation flotation of cassiterite from quartz with Pb2+ is taken as an example to illustrate the pivotal roles of surface hydroxyls in selective flotation. Accordingly, flotation, adsorption amount, and X-ray photoelectron spectroscopy (XPS) measurements and systematic first-principles calculations have been used to investigate the roles of hydroxyl groups on the selective adsorption of Pb2+. The obtained flotation, adsorption amount, and XPS test results consistently show that the Pb2+ can more strongly interplay with cassiterite than quartz resulting in selective flotation of cassiterite from quartz. The electron localization functional results illustrate that the electron localization of oxygen of Si-O bonds is stronger than the Sn-O bond resulting in the weaker electron migration ability (high hardness) of oxygen atoms of quartz than oxygen atoms of cassiterite. This makes the cassiterite surface hydroxyl groups less hard than quartz. Further crystal orbital Hamilton population and partial density of states show that the Pb2+ interacts with the oxygen atoms on cassiterite forming chemical bonds before and after the adsorption of benzohydroxamic acid (BHA). On the other hand, the interaction of Pb2+ with quartz is physical in the presence of BHA. The strong adsorption of Pb2+ on cassiterite makes it easier for BHA adsorption which accounts for the selective flotation of cassiterite from quartz. This work sheds new light on establishing a consistent and dependable theory that the hardness of surface hydroxyls is the original factor affecting the selective adsorption of metal ions on oxide mineral surfaces.

Adsorption behavior of lead, cadmium, and arsenic on manganese-modified biochar: competition and promotion.

Biochar adsorption of heavy metals has been a research hotspot, yet there has been limited reports on the effect of heavy metal interactions on adsorption efficiency in complex systems. In this study, the adsorbent was prepared by pyrolysis of rice straw loaded with manganese (BC-Mn). The interactions of Pb, Cd and As adsorption on BC-Mn were systematically studied. The results of the adsorption isotherms for the binary metal system revealed a competitive adsorption between Pb and Cd, resulting in decreased Pb (from 214.38mg/g to 148.20mg/g) and Cd (from 165.73mg/g to 92.11mg/g). A notable promotion occurred between As and Cd, showing an increase from 234.93mg/g to 305.00mg/g for As and 165.73mg/g to 313.94mg/g for Cd. In the ternary metal system, Pb inhibition did not counteract the promotion of Cd and As. Furthermore, the Langmuir isotherm effectively described BC-Mn's adsorption process in monometallic, binary, and ternary metal systems (R2 > 0.9294). Zeta and FTIR analyses revealed simultaneous competition between Pb and Cd for adsorption on BC-Mn's -OH sites. XPS analysis revealed that As adsorption by BC-Mn facilitated the conversion of MnO2 and MnO to MnOOH, resulting in increased hydroxyl radical production on BC-Mn's surface. Simultaneously, Cd combined with the adsorbed As to form ternary Cd-As-Mn complexes, which expedited the removal of Cd. These results help to provide theoretical support as well as technical support for the treatment of Pb-Cd-As contaminated wastewater.

Biochar and vermicompost modulated Pb toxicity in summer savory (Satureja Hortensis L.) plants through inducing physiological and biochemical changes

The primary environmental factor affecting the biochemical attributes of plants is soil pollution by heavy metals. The detrimental effects of heavy metals on plants can be lessened by soil amendments. The goal of the current research was to determine the potential of biochar (BC) and vermicompost (VC) as soil amendments in reducing Pb toxicity in summer savory (Satureja HortensisL.) though physiological and biochemical modifications. Therefore, the pot experiment was conducted with Pb toxicity (control (non-Pb), 300, and 600 mg kg soil-1) and soil amendments (control, 2% BC, 10% VC, and 1% BC+5% VC) based on a completely randomized design. The results showed that Pb toxicity at 600 mg kg soil-1 led to significant decreases in shoot weight (41%), root weight (25%), leaf relative water content (20%), and chlorophyll content (39%) compared to the control. However, it resulted in increases in malondialdehyde (61%) and electrolyte leakage (49%) when BC and VC were not applied. The results showed that Pb toxicity at 600 mg kg soil-1 led to decreases in shoot weight (41%), root weight (25%), leaf relative water content (20%), and chlorophyll content (39%), but increases in malondialdehyde (61%), and electrolyte leakage (49%) compared to the control in the treatments without BC and VC application. However, BC and VC, particularly their combination were more effective in improving plant growth. The interaction of Pb at 300 mg kg-1 and combined BC and VC resulted in higher total phenolic content, total flavonoid content, essential oil (EO) content, and EO yield with 29, 62, and 39, and 35% raises compared with the control. Agglomerative hierarchical clustering revealed that Pb at 300 and 600 mg kg soil-1 differed from the control, and that combined VC and BC significantly varied from their individual values. Combining BC and VC is more effective than using them separately in alleviating Pb toxicity, as it enhances plant growth and secondary metabolite production. The results have the potential to benefit the improvement of summer savory resistance in Pb-polluted soils.

ALICE luminosity determination for Pb–Pb collisions at √s NN = 5.02 TeV

Luminosity determination within the ALICE experiment is based on the measurement, in van der Meer scans, of the cross sections for visible processes involving one or more detectors (visible cross sections). In 2015 and 2018, the Large Hadron Collider provided Pb–Pb collisions at a centre-of-mass energy per nucleon pair of √s NN = 5.02 TeV. Two visible cross sections, associated with particle detection in the Zero Degree Calorimeter (ZDC) and in the V0 detector, were measured in a van der Meer scan.This article describes the experimental set-up and the analysis procedure, and presents the measurement results. The analysis involves a comprehensive study of beam-related effects and an improved fitting procedure, compared to previous ALICE studies, for the extraction of the visible cross section. The resulting uncertainty of both the ZDC-based and the V0-based luminosity measurement for the full sample is 2.5%. The inelastic cross section for hadronic interactions in Pb–Pb collisions at √s NN = 5.02 TeV, obtained by efficiency correction of the V0-based visible cross section, was measured to be 7.67 ± 0.25 b, in agreement with predictions using the Glauber model.

Development of α-Cyclodextrin-Based Orally Disintegrating Tablets for 4-Phenylbutyrate.

Despite major improvements brought about by the introduction of taste-masked formulations of 4-phenylbutyrate (PB), poor compliance remains a significant drawback to treatment for some pediatric and dysphagic patients with urea cycle disorders (UCDs). This study reports on the development of a cyclodextrin (CD)-based orally disintegrating tablet (ODT) formulation for PB as an alternative to existing formulations. This is based on previous reports of the PB taste-masking potential of CDs and the suitability of ODTs for improving compliance in pediatric and dysphagic populations. In preliminary studies, the interactions of PB with α and βCD in the solid state were characterized using X-ray diffraction, scanning electron microscopy, dissolution, and accelerated stability studies. Based on these studies, lyophilized PB-CD solid systems were formulated into ODTs after wet granulation. Evaluation of the ODTs showed that they had adequate physical characteristics, including hardness and friability and good storage stability. Notably, the developed αCD-based ODT for PB had a disintegration time of 28 s and achieved a slightly acidic and agreeable pH (≈5.5) in solution, which is suitable for effective PB-CD complexation and taste masking. The developed formulation could be helpful as an alternative to existing PB formulations, especially for pediatric and dysphagic UCD patients.

A hot carrier perovskite solar cell with efficiency exceeding 27% enabled by ultrafast hot hole transfer with phthalocyanine derivatives

Illustration of hot hole transfer through interfacial S–Pb interactions, and a peak efficiency of 27.30% was achieved under 5.9 suns via ultrafast hot hole extraction.

Metal-doped niobate pyrochlores and double-perovskites for glycerol valorization: structural and electronic properties and DFT calculations.

In this study, metal-doped niobates and perovskites were obtained by a solid-state reaction. The solids were evaluated in the esterification of glycerol in the presence of acetic acid to produce valuable esters of glycerol. The structural features of the solids indicated the ZnNb2O6, Pb2.8Nb2O7.8 and CuNb2O6 columbite main phases and La2MnFeO6 double-perovskite. Density functional theory (DFT) studies of Pb2.8Nb2O7.8 clearly confirmed the existence of a robust orthorhombic structure and its electronic properties were correlated with the Nb and Pb interactions. The morphological and elemental analyses also indicated that not all surface elements, as well as morphology, were crucial for catalytic properties. All solids were active and selective toward triacetin formation upon glycerol esterification with acetic acid. The catalytic performance depends mainly on the availability of the surface and its structural stability, as well as defects formation. Recyclability studies indicated that the La2MnFeO6 double-perovskite was an efficient catalyst, achieving glycerol conversion of 68% and triacetin selectivity of 25% up to 4 cycles of use in the reaction. The structural defects near the Mn4+/Mn3+ surface sites resulted in the diffusion of anions and an increased concentration of oxygen vacancies contributed to the stable performance of the solid in glycerol ester production.

Preparation of Pb-Ca Master Alloy by Molten Salt Electrolysis

Lead-acid batteries (LABs) are commonly utilized in various applications such as electric motorcycles, uninterruptible power systems, and stationary energy storage devices. Calcium (Ca) is an essential element being added to Pb grid alloys to increase their mechanical strength. In this paper, molten salt electrolysis is used to prepare Pb-Ca master alloy in molten CaCl2-NaCl at 700 °C. The Ca concentration reaches 2.51 wt%, and the current efficiency reaches 85.0% for the 1 A-scale electrolyzer and 75.8% for the 50 A-scale cell. Compared with the traditional physical mixing ways, Ca is selectively and gradually deposited in the liquid Pb cathode without worrying about the immense heat generated by mixing Ca and Pb. In addition, molten salt serves as a media to avoid the oxidation of Ca. Through thermodynamic calculations and electrochemical measurements, the Pb-Ca formation prefers to happen rather than Pb-Na alloy in molten CaCl2-NaCl because of the stronger interaction of Ca and Pb than Na and Pb. Overall, this paper provides a straightforward strategy to prepare Pb-Ca master alloys, which can be expanded to prepare various liquid semimetal alloys containing reactive metals.

Interaction and Transport Characteristics of Lead and Cadmium in Different Soil-wheat Systems

In this study, four groups of lead(Pb) and cadmium(Cd) combined treatments with different concentration ratios were set up in Hailun black soil, Xianning brown-red soil, and Changwu Heilu soil, and wheat(Zhengmai 9023) was planted for a five-month pot experiment to analyze the Pb-Cd interaction behavior on heavy metal bioaccumulation in wheat under three soil-wheat systems. The low pH brown-red soil had the highest water-soluble Cd and Pb contents with significant Pb-Cd interactions in the soil, whereas the black soil with high organic matter and Heilu soil with high calcium carbonate content exhibited lower Cd and Pb activities. Among the three soils, wheat height and dry weight showed the poorest growth performance in the Heilu soil, but the wheat height increased by 2.68-8.49 cm compared with that in the control under the Pb-Cd combined treatment, whereas Pb-Cd interaction had the least effect on wheat height and dry weight in black soil and inhibited the growth of wheat in the brown-red soil. In the transport process of Cd or Pb in wheat, Pb-Cd interaction showed quite different effects in the three soil-wheat systems. Under the 125 mg·kg-1 and 250 mg·kg-1 Pb treatments, the Pb content in wheat grain planted in brown-red soil significantly increased by 73.2% and 19.1% with the addition of Cd, respectively, and therefore there was a synergistic effect between Pb and Cd. Under the 0.3 mg·kg-1 and 0.6 mg·kg-1 Cd treatments, the Cd content in wheat grains planted in black soil decreased by 51% and 33% with the addition of Pb, respectively; therefore, there was an antagonist effect between Pb and Cd. In the Heilu soil, a synergistic effect of Cd on Pb transport in wheat leaves was only observed under high Pb treatment. Therefore, pH and organic matter content were the key factors that determined the interaction behavior of Pb and Cd. The wheat food security risk of Pb and Cd combined pollution was higher than that of single metal pollution in acidic brown-red soil and lower in high organic matter black soil, whereas the interaction of Pb and Cd had little impact on the wheat food security risk of alkaline Heilu soil.

Effects of combined PS-Pb pollution on the calcification of Paphia undulata: Coexistence of antagonistic and synergistic effects

Similar to respiration, shellfish function as a carbon source because they release carbon dioxide during calcification which uses soluble inorganic carbon in seawater to form biological calcium deposits, such as shells, which is important for shellfish survival. Almost all filter feeding shellfish feed mainly on phytoplankton, which are the most dominant primary producers in marine ecosystems. Microplastics and Pb generally coexist in the habitat of Paphia undulata, and microplastics adsorb Pb. Both of these two matters negatively affect metabolism that affects calcification. Thus, it is speculated that the interaction between microplastics and Pb affects the calcification of P. undulata by affecting its metabolism. This hypothesis is related to the carbon cylce drived by filter feeding shellfish under combined pollution of microplastic and Pb. Nevertheless, related studies are extremely rare. To verify this hypothesis, P. undulata was exposed to PS-Pb combined pollution for 96 h, during which microplastics and Pb were represented by polystyrene (PS) with a particle size of 5.0 µm and Pb (NO3)2, respectively. Ammonia excretion was affected by PS and the interaction of PS and Pb. Not the oxygen consumption but the ratio of O/N was affected by PS, Pb and their interaction. If the concentrations of PS and Pb were 50 and 6 μg/L, respectively; the ratio of O/N of P. undulata was higher than that under the other treatments. The calcification was influenced by Pb and the interaction of PS and Pb, e.g., as the concentrations of PS and Pb were 25 and 6 μg/L, respectively, the calcification rate of P. undulata was the lowest. Moreover, the calcification rate was positively correlated with the ratio of O/N, i.e., there was a correlation between the calcification rate and metabolic substrates. PS and Pb at low concentrations had a synergistic effect on calcification, while they tended to produce antagonism at high concentrations. All these facts mean that the effect of compound pollution on calcification is not a simple addition of the effects of the two pollutants that influence calcification by affecting metabolism, and the effects of the PS-Pb combined pollution on the carbon cycle in offshore areas should be reassessed.

Interaction of Heavy Metal Lead with Gut Microbiota: Implications for Autism Spectrum Disorder.

Autism Spectrum Disorder (ASD), a neurodevelopmental disorder characterized by persistent deficits in social interaction and communication, manifests in early childhood and is followed by restricted and stereotyped behaviors, interests, or activities in adolescence and adulthood (DSM-V). Although genetics and environmental factors have been implicated, the exact causes of ASD have yet to be fully characterized. New evidence suggests that dysbiosis or perturbation in gut microbiota (GM) and exposure to lead (Pb) may play important roles in ASD etiology. Pb is a toxic heavy metal that has been linked to a wide range of negative health outcomes, including anemia, encephalopathy, gastroenteric diseases, and, more importantly, cognitive and behavioral problems inherent to ASD. Pb exposure can disrupt GM, which is essential for maintaining overall health. GM, consisting of trillions of microorganisms, has been shown to play a crucial role in the development of various physiological and psychological functions. GM interacts with the brain in a bidirectional manner referred to as the "Gut-Brain Axis (GBA)". In this review, following a general overview of ASD and GM, the interaction of Pb with GM in the context of ASD is emphasized. The potential exploitation of this interaction for therapeutic purposes is also touched upon.