Toxic Pollutants Research Articles

Adsorptive and oxidative removal of phenolphthalein by sono-assisted synthesized FeAcC in advanced oxidation-integrated fluidized bed reactor

ABSTRACT Environmental water sources are under increasing threat due to the addition of harmful chemicals not addressed by conventional water treatment processes. To work on this concern, the current study aimed to synthesize sono-assisted Fe-modified activated carbon-chitosan (FeAcC) composite and construct a laboratory-scale ozone-integrated fluidized bed reactor (FBR) to eliminate phenolphthalein (php). Following 120 min of incubation, the adsorbent demonstrated a 27.28 mg g−1 of php adsorption capacity at pH 4 with 0.5 g L−1 of adsorbent dosage. The adsorption efficacy and mechanism were defined using isotherm and kinetic models. The study investigated the impact of different factors including, initial concentration, reuse of FeAcC, recirculation flow rate, and hydraulic retention time (HRT), on the efficiency of php removal. The optimum removal efficiency was observed at approximately 95% after 20 min of operation at 1.5 L min−1 recirculation flow rate (batch FBR) and 70 min of HRT (continuous FBR) under 400 mg h−1 ozonation rate. Experimental parameters were optimized using response surface methodology (RSM) with central composite design (CCD) to improve php removal. The large-scale implementation of the findings in the future can be a step for adding new technology for clean water treatment processes for emerging toxic pollutants.

Fine-tuning of redox-ability, optical, and electrical properties of Bi2MoO6 ceramics via lanthanide doping and rGO integration for photo-degradation of Methylene Blue and Ciprofloxacin

Herein, lanthanide ion (Gd+3) doped Bismuth Molybdate (Bi2MoO6) integrated on the rGO sheets has been prepared as a novel photocatalyst (Gd@Bi2MoO6/rGO) for the photocatalytic treatment of toxic pollutants. Different physiochemical, optical, electrical, thermal, and electrochemical properties of Gd@Bi2MoO6/rGO, along with its counterparts (Bi2MoO6 and Gd@Bi2MoO6), were studied through XRD, SEM/TEM, FT-IR, UV/Vis, I-V, TGA, Mott-Schottky, and EIS measurements. Photocatalytic experiments revealed that Gd@Bi2MoO6/rGO exhibited significantly enhanced photocatalytic activity, achieving 96.2 % photo-degradation of Methylene Blue with 120 min of irradiation, which is 6.5 and 3.1 times higher compared to Bi2MoO6 (40.9 %) and Gd@Bi2MoO6 (64.8 %), respectively. Moreover, Gd@Bi2MoO6/rGO demonstrated a notable photocatalytic efficiency of 81.7 % towards Ciprofloxacin, significant as per the existing literature benchmark. The enhanced photocatalytic activity is ascribed to the in-built Gd+3 redox centers, high electrical conductivity (7.35 × 10−3 S/m), favorable flat band potential (-0.81 V), and low semiconductor impedance (Rct = 51.71 Ω and Rs = 0.90 Ω). Additionally, the electron-capturing ability of lanthanide dopant ions and S-C heterojunction of Gd@Bi2MoO6/rGO facilitates the separation of photo-generated e-/h+ pairs and favors high concentrations of ROS. The results obtained highlight the potential of Gd@Bi2MoO6/rGO for applications in photocatalysis and wastewater treatment.

Chitosan-Based Adsorbents and Catalysts for Removal of Toxic Pollutants from Water and Wastewater

Chitosan-Based Adsorbents and Catalysts for Removal of Toxic Pollutants from Water and Wastewater

Expression and Functional Analysis of the Metallothionein and Metal-Responsive Transcription Factor 1 in Phascolosoma esculenta under Zn Stress.

Metallothioneins (MTs) are non-enzymatic metal-binding proteins widely found in animals, plants, and microorganisms and are regulated by metal-responsive transcription factor 1 (MTF1). MT and MTF1 play crucial roles in detoxification, antioxidation, and anti-apoptosis. Therefore, they are key factors allowing organisms to endure the toxicity of heavy metal pollution. Phascolosoma esculenta is a marine invertebrate that inhabits intertidal zones and has a high tolerance to heavy metal stress. In this study, we cloned and identified MT and MTF1 genes from P. esculenta (designated as PeMT and PeMTF1). PeMT and PeMTF1 were widely expressed in all tissues and highly expressed in the intestine. When exposed to 16.8, 33.6, and 84 mg/L of zinc ions, the expression levels of PeMT and PeMTF1 in the intestine increased first and then decreased, peaking at 12 and 6 h, respectively, indicating that both PeMT and PeMTF1 rapidly responded to Zn stress. The recombinant pGEX-6p-1-MT protein enhanced the Zn tolerance of Escherichia coli and showed a dose-dependent ABTS free radical scavenging ability. After RNA interference (RNAi) with PeMT and 24 h of Zn stress, the oxidative stress indices (MDA content, SOD activity, and GSH content) and the apoptosis indices (Caspase 3, Caspase 8, and Caspase 9 activities) were significantly increased, implying that PeMT plays an important role in Zn detoxification, antioxidation, and anti-apoptosis. Moreover, the expression level of PeMT in the intestine was significantly decreased after RNAi with PeMTF1 and 24 h of Zn stress, which preliminarily proved that PeMTF1 has a regulatory effect on PeMT. Our data suggest that PeMT and PeMTF1 play important roles in the resistance of P. esculenta to Zn stress and are the key factors allowing P. esculenta to endure the toxicity of Zn.

Effect of endocrine-disrupting chemicals on the expression of a calcium ion channel receptor (ryanodine receptor) in the mud crab (Macrophthalmus japonicus)

Endocrine-disrupting chemicals (EDCs) are toxic pollutants generated by artificial activities. Moreover, their hormone-like structure induces disturbances, such as mimicking or blocking metabolic activity. Previous studies on EDCs have focused on the adverse effect of the endocrine system in vertebrates, with limited investigations conducted on ion channels in invertebrates. Thus, in this study, we investigated the potential adverse effects of exposure to bisphenol-A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) at the molecular level on the ryanodine receptor (RyR), a calcium ion channel receptor in Macrophthalmus japonicus. In the phylogenetic analysis, the RyR amino acid sequences in M. japonicus clustered with those in the Crustacean and formed separated branches for RyR in insects and mammals. When exposed to 1 μg L−1 BPA, a significant increase in RyR mRNA expression was observed in the gills on day 1, although a similar level to the control group was observed from day 4 to day 7. However, the RyR expression due to DEHP exposure decreased on days 1 and 4, although it increased on day 7 following exposure to 10 μg L−1. The RyR expression pattern in the hepatopancreas increased for up to 4 days, depending on the BPA concentration. However, there was a tendency for the expression to decrease gradually after the statistical significance increased during the early stage of DEHP exposure (D1). Hence, the transcriptional alterations in the M. japonicus RyR gene observed in the study suggest that exposure toxicities to EDCs, such as BPA and DEHP, have the potential to disrupt calcium ion channel signaling in the gills and hepatopancreas of M. japonicus crabs.

Analysis of Soil In-situ Remediation Technique

Soil in-situ remediation technology is an important environmental protection effort that aims to reduce the content and toxicity of pollutants in soil.In this paper, the commonly used soil in-situ remediation technologies were analyzed, including plant extraction technology, in-situ adsorption technology, and in-situ jet injection technology.In-situ adsorption technology removes or reduces harmful pollutants in the soil by introducing adsorbents to physically or chemically adsorb pollutants.The technology is simple to operate, low cost, and does not require large-scale soil excavation and disposal.However, its effectiveness is affected by factors such as adsorbent selection and dosage, soil properties, etc.

Hydrothermally synthesized Nb -doped TiO2 nanosheets for efficient removal of methylene blue dye on photocatalytic performance

In this work, Niobium-doped (1%, 3%, and 5%) titanium dioxide (Nb-TiO2) nanosheets were successfully formed via the hydrothermal route and further characterized using TEM, XRD, XPS and UV–vis absorption spectroscopy techniques. Phase purity and structural information of the prepared materials were analysed by XRD measurements. The band gap values ranged from 3.27 to 2.98 eV as Nb doping increased, leading to improved photocatalytic activity by creating new energy levels close to the conduction band. The XPS results confirm the amalgamation of Nb5+ ions into TiO2 without affecting the crystallinity, structure or orientation of the occurrence of oxygen vacancies. In 3% Nb-doped TiO2, the degradation efficiency for removing (Methylene blue) MB dye increased by ∼96% for the removal of MB dye within 70 min in comparison to pure and other doped TiO2 catalysts The better photocatalytic activity of 3% Nb-TiO2 is due to the longer time between electron–hole pairs before they recombine into one pair. Hydroxyl radicals (HO•) and superoxide radicals (O2 •−) are the primary reactive entities responsible for the deterioration of MB dye. Therefore, incorporating Nb into TiO2 nanostructures represents an auspicious material for the decomposition of hazardous and toxic pollutants in aquatic environments.

Green Technology Approach Towards the Removal of Heavy Metals, Dyes, and Phenols from Water Using Agro-based Adsorbents: A Review.

The swift pace of socioeconomic development and climatic change have put significant strain on the quality of water resources. While, the bulk availability of agro-based materials arising from nature and agricultural practices has paved the way for researchersin eradicating toxic industrial pollutants such as dyes, heavy-metals, phenolic-compounds, pesticides, etc. by using them as adsorbents. In the area of pollution remediation, inventive technologies have been developing. The adsorption technique stands out among the other wastewater-treatment methods as it is simple, easy, efficient, and cost-effective. The agro-based adsorbents their use in this area contributes to minimizing natural waste. They can be employed in their original raw-form or after undergoing simple processes such as drying, grinding, and carbonization. Moreover, these adsorbents are typically modified physically or chemically to change their surface properties and improve their adsorption efficiency. The low-cost agro adsorbents have shown efficient adsorption capacities towards removing various organic and hazardous water pollutants. With a few exceptions, majority of adsorbents have demonstrated heavy metals, dyes and phenol removal efficiencies exceeding 90%. This review summarizes the available information and strategies for using agro-based adsorbents to eliminate hazardous water pollutants. It is a prospective area for research in the field of environmental pollution.

The Role of Skin-Derived Somatic Cell and Tissue Cryobanks in the Conservation of Aquatic Mammals.

Anthropogenic actions, especially inadequate waste disposal, cause permanent effects on aquatic fauna, resulting in a significant loss in their population. In this scenario, in situ and ex situ conservation strategies have been developed for these species. Among these strategies is the formation of somatic cell and tissue banks derived from skin collection that act complementarily to other biotechnologies. These banks contain all the information for genomic, genetic, and proteomic analyses. They are useful in the assessment of the toxicity of pollutants on the physiology of the species and regenerative and reproductive biotechnologies. The formation of these cryobanks involves different steps, including cryopreservation, with the optimization of all steps occurring in a species-specific manner. There is a diversity of studies on aquatic mammals; however, a low quantity compared to the number of studies on land mammals, with more than 80% of species still unexplored. This is mainly due to the difficulty of execution and asepsis in collecting skin from aquatic mammals and the in vitro culture, which seems to require more particularities for it to be successful. Therefore, this review aims to address the current scenario and the steps involved in the conservation of somatic cells and tissues derived from aquatic mammal skin, as well as results that have been achieved in recent years and the prospects.

Innovative Approaches in Extremophile-Mediated Remediation of Toxic Pollutants: A Comprehensive Review

Innovative Approaches in Extremophile-Mediated Remediation of Toxic Pollutants: A Comprehensive Review

Atomistic understanding of Ti3C2 MXene membrane performance for separation of nitrate ions from aqueous solutions

Water desalination, which is a reliable method for providing drinking water and a suitable solution, as well as the membrane filtration method in wastewater treatment, has increased significantly in recent years. In this research, the separation of nitrite and nitrate ions from aqueous solutions was done using the MXene membrane of the Ti3C2 type using molecular dynamics simulation. In this study, various parameters, such as pore size MXene structure, characteristics of cavities, applied pressure, and flux were investigated. To investigate the removal of toxic pollutants from water, water flux, potential mean force, distribution of water molecules, and density were investigated. The results showed that the amount of penetration through the membrane increased with the increase in pressure. It was observed that by applying pressure to the system, the number of water molecules accumulated in front of the membrane decreases because they quickly pass through the membrane, which indicates the positive effect of increasing pressure on the separation rate of molecules. The permeability of this membrane was several times higher than the existing membranes in the industry. So that Mexene membranes, which consist of at least two layers, can repel ions with 100% success.

Hazardous Hope

This special section seeks to reconsider our troubled times and their histories of irreversible toxic pollution through the lens of hopeful yet critical ways of engaging with this unprecedented condition of life. Thinking with “hazardous hope” as a tool of analysis, the five contributions—combining perspectives from ecocriticism, environmental philosophy, film studies, visual arts, and history—showcase alternative presents and futures of living responsibly with a permanently polluted planet. Writing from the perspective of hazardous hope, the section’s editors argue, includes a plethora of conceptual and methodological repositionings to embrace the ambiguity that comes with living responsibly on a permanently polluted planet. Among them is a shift in focus on the acts and modes of hazardous hope as a relational practice that is focused on reorganizing established processes in radically different ways rather than wishing to achieve a predefined outcome, while at the same time remaining mindful of the polluted status quo. Contributions in this special section are situated across the entire troubled planet, from Chernobyl’s exclusion zone to Brazilian oil fields and from Canada’s tar sands to British asbestos-loaded homes.

السموم البيئية وتأثيراتها على الأعضاء: مراجعة شاملة لتعرض الإنسان وتراكمها

Environmental pollutants lead to problems in ecosystems differently depending on the extent of their toxicity, and thus their arrival to humans leads to health problems at different levels. The danger of any substance introduced into the environment can be determined depending on its quantity (dose). In addition, based on the overdose, it can be considered (whether it is alien or original) is toxic. Poisoning is the harmful effect that occurs as a result of ingestion, inhalation, or contact with a toxic substance. Potential toxic substances include chemical, biological, and physical toxins, fungi, plants, and animal toxins. Environmental pollutants are heavy metals (lead, cadmium, mercury, etc.), pesticides, organic materials, food additives, etc. The severity of the toxic effect depends primarily on the concentration and persistence of the final toxic substance. The final toxic substance is often the original chemical to which the organism is exposed. In other cases, the final toxic substance is a metabolite of the original compound, reactive oxygen species, or nitrogen (ROS, RNS) generated during Transformation into a toxic substance. Exposure to lead can affect proteins that interfere with their enzymatic functions or ability to bind other cellular components, leading to DNA damage and induction of oxidative stress. Asbestos can also damage DNA and affect gene expression. Exposure to acrolein irritates the bronchi, while mercury causes neurological symptoms. This review deals with understanding toxic environmental pollutants that affect humans, the extent of accumulation of toxic substances in organs, and methods of exposure to them.

Investigation of structural and optical properties of TM-doped CuO NPs: Correlation with their photocatalytic efficiency in sunlight-induced pollutant degradation

The presence of non-biodegradable, toxic, and harmful organic pollutants in various environmental mediums poses significant threats to ecosystems and human health. This study investigates the impact of transition metal (TM) doping on the photocatalytic performance of copper oxide nanoparticles (CuO NPs) in degrading methylene blue (MB) dye under sunlight irradiation. CuO NPs are synthesized using the co-precipitation method. X-ray diffraction (XRD) analysis revealed a monoclinic structure with space group C2/c for undoped and TM–doped CuONPs, with crystalline sizes ranging from 13 nm for undoped to 36 nm for Zn-doped CuO. Based on UV–Visible Spectroscopy data, the band gap energies and the nature of electronic band transitions are determined using a new simplified calculation method. Accordingly, direct band gap energy exhibits a slight red-shift as a result of doping with Ni, Mn or Fe, from 1.427 eV for undoped to 1.402 eV for Fe-doped CuO. While Co or Zn doping, induces a trivial blue-shift to 1.468 eV and 1.434 eV respectively. The CuO particles show a heterogenous distribution size and shape. The mean grain size raised from 34.3 nm for undoped to about 100 nm for TM-doped CuONPS, excluding the Co-doped CuO for which the mean grain size reached 154.532 nm with highest standard deviation heterogeneity of 125.737 nm. Furthermore, photocatalytic experiments demonstrated that TM-doping significantly enhanced the degradation rate of MB dye under sunlight irradiation. Co-doped CuO is the most efficient catalyst. This makes TM-doping a promising pathway for the use of CuO NPs in wastewater decontamination applications.

PREPARATION AND CHARACTERIZATION OF ACTIVATED CARBON FROM DATE PALM (Phoenix dactylifera) SEEDS

In this study, agricultural waste (date seeds) were used to produce activated carbon in an oxygenated environment. The produced activated carbon was characterised. The HRSEM showed mesoporous structural morphology, which exhibited a surface area of 54.53 m2/g, pore size of 10.34 nm and pore volume of 0.1256 cc/g. The EDX spectrum revealed the presence of C and O as the major elemental compositions in the activated carbon. The FTIR spectrum indicated the presence of OH-, C=C, C=O and C-H at absorption bands of 3400, 2900, 1650, and 1300 cm-1, respectively. The diffractogram of the activated carbon revealed graphitic carbon 2 peaks of 22o and 43o which are related to (002) and (100) plane, respectively. The conversion of agricultural waste to activated carbon possessing these unique properties could serve as a promising and low-cost adsorbent for the removal of toxic pollutants from industrial wastewater.

Activated carbon from macadamia nutshells for removal of p-Nitrophenol from real wastewater: Thermodynamic evaluation

This Water pollution by organic pollutants have remained a matter of significant apprehension since they tend to accumulate in the body to toxic levels and are often resistant to degradation and consequently endure in the surroundings for an extended duration. Phenolic compounds are among organic pollutants that have gained significant attention in research, due to the various ways these compounds can be used in our everyday activities. Among the most common derivatives of phenols is P-Nitrophenol (PNP), which is one of the most common and toxic pollutants found in wastewater. The nutshells were first charred in a muffle furnace at 600 ͦ C. The resultant ash was then activated and utilized for the adsorption of PNP from the wastewater. In this study, we utilized macadamia nutshell waste, both in its untreated and activated forms, which had been prepared earlier, to investigate the thermodynamic aspects of adsorbing p-Nitrophenol ions from wastewater. The scanning electron microscopy (SEM) images demonstrated the existence of pores within the adsorbent material, which proved to be advantageous for the adsorption process. Furthermore, the Fourier-transform infrared spectroscopy (FTIR) results indicated the presence of functional groups in both the unaltered and modified resins, highlighting their significance as sites for studying the thermodynamics of adsorbing copper p-Nitrophenol ions. The thermodynamic analysis revealed that the standard Gibbs' free energy (ΔG°) values for all metals were negative, indicating that the adsorption process was not only feasible but also favorable. Additionally, the standard enthalpy change (ΔH°), standard entropy (ΔS°), and activation energy (Ea) were all positive and greater than 50 kJ mol-1. This observation confirmed that the adsorption of p-Nitrophenol ions onto both unaltered and modified adsorbents was primarily governed by chemical interactions between the PNP ions and the active sites of the adsorbent material. This conclusion was further supported by the exceedingly low values of sticking probability (S*). This investigation did not only show a good performance of the modified macadamia agricultural waste in adsorbing the PNP ions but also provided another way of reducing the negative effects caused by the nutshells disposed in the environment.

Green low-cost synthesis of zero-valent iron nanoparticles from Palm Petiole Extract for Cr(VI) removal from water.

One of the hottest research topics over the last decades was the valorization or/and recycling of agro-industrial wastes into different valuable liquid or solid products, which is considered a sustainable and low-cost approach. In this study, we developed zero-valent iron nanoparticles from Palm Petiole Extract (P-NZVI) using a green and straightforward approach. The as-synthesized P-NZVI was used to adsorb Cr(VI) in water. The physico-chemical characterizations of P-NZVI, including the particle size, crystalline structure, surface area, morphology, and functional groups, were investigated via several techniques such as UV-vis spectroscopy, SEM, TEM, XRD, FTIR, AFM, DLS, pHZPC measurement, and BET analysis. The adsorption performance of P-NZVI was studied under different operational parameters, including pollutant concentration, pH, temperature, and adsorbent mass. The adsorption rate was found to be 89.3% within 40 min, corresponding to the adsorption capacity of 44.47 mg/g under the following conditions: initial Cr(VI) concentration of 40 mg/L, pH 5, and a P-NZVI dosage of 1 g/L. It was found that the adsorption pattern follows the Langmuir and the pseudo-second-order kinetic models, indicating a combination of monolayer adsorption and chemisorption mechanisms. The thermodynamic study shows that the adsorption process is endothermic and spontaneous. The reusability of P-NZVI was carried out four times, showing a slight decrease from 89.3 to 87%. These findings highlight that P-NZVI's could be an effective green adsorbent for removing Cr(VI) or other types of toxic pollutants from water.

After-effects of a closed copper mine: detailed analysis of environmental impacts in soil and plant samples

In several countries around the world, abandoned mining sites are blighted by pollution from metal and metalloids. Generated by mining processes, toxic pollutants have lasting effects on the ecosystem. The study examined the environmental impact of waste from a copper mine that was operated by the Caucasus Copper Limited Company between 1905 and 1928, revised and commissioned by Etibank in 1936, and ceased operations 75 years ago. Soil and plant samples (needles of Scotch pine, Pinus sylvestris L.) were collected from five specific regions around the mine and the levels of potentially toxic elements (PTEs) were determined, including As, Zn, Pb, Cd, Ni, Mn, Cr, Cu, Al, and Fe. The data obtained were used to calculate the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), ecological risk index (ERI), human health risk index (BCF), and plant enrichment factor (EFPlant). In soil samples, the average EF values of certain elements such as As (453), Cu (59.9), Pb (30.7), Zn (5.26) were detected at high levels. However, average Igeo values indicate high pollution levels for As (8.25), Cd (6.72), Cu (4.94), Pb (4.33) and Zn (2.42), indicating the existence of serious ecological risks in the affected areas. Additionally, the average CF values indicate serious pollution levels from heavy metals such as As (1605), Cd (584), Pb (99.4), Cu (81.9), and Zn (14.6), highlighting the extensive pollution situation resulting from mining activities. Meanwhile, average ERI values indicate that Cd, As, Cu, and Pb pose serious ecological risks in the study areas.These PTEs were found in high concentrations in the waste tail and dump. Furthermore, the analysis determined that there was enrichment for Mn, Cd, Al, Cu, Pb, and Fe elements in plant samples. These PTEs have the potential to spread more widely depending on seasonal conditions and local topography. This situation demonstrates the need to measure metal and metalloids concentrations at certain times, taking into account the potential for environmental pollution of surface runoff water and underground resources in areas with high drainage potential from acid mines, such as at the Kuvarshan mine tailings site.

Synergistic Effect of UiO-66 Directly Grown on Kombucha-Derived Bacterial Cellulose for Dye Removal.

Metal-Organic Frameworks (MOFs) are particularly attractive sorbents with great potential for the removal of toxic dye pollutants from industrial wastewaters. The uniform dispersion of MOF particles on suitable substrates then represents a key condition to improve their processability and provide good accessibility to the active sites. In this work, we investigate the efficiency of a natural bacterial cellulose material derived from Kombucha (KBC) as an active functional support for growing and anchoring MOF particles with UiO-66 structures. An original hierarchical microstructure was obtained for the as-developed Kombucha cellulose/UiO-66 (KBC-UiO) composite material, with small MOF crystals (~100 nm) covering the cellulose fibers. Promising adsorption properties were demonstrated for anionic organic dyes such as fluorescein or bromophenol blue in water at pH 5 and pH 7 (more than 90% and 50% removal efficiency, respectively, after 10 min in static conditions). This performance was attributed to both the high accessibility and uniform dispersion of the MOF nanocrystals on the KBC fibers together with the synergistic effects involving the attractive adsorbing properties of UiO-66 and the surface chemistry of KBC. The results of this study provide a simple and generic approach for the design of bio-sourced adsorbents and filters for pollutants abatement and wastewater treatment.

MERCURY EXPOSURE AND HUMAN REPRODUCTIVE HEALTH (LITERATURE REVIEW)

Mercury (Hg), a highly toxic environmental pollutant, which hazards for human health, including to reproductive system, fertility and pregnancy outcome. Research has shown that Hg could induce impairments in the reproductive function due to cellular deformation of the Leydig cells and the seminiferous tubules, testicular degeneration and degenerative atresia of primordial and primary follicles as well as diminishes the steroidogenesis and synthesis of sex hormones. Some studies investigated miscarriage, spontaneous abortions, stillbirth, and low birth weight due to occupational Hg exposure. This review evaluates the hypothesis that exposure to Hg may. This review evaluates the hypothesis that chronic exposure to mercury can increase the risk of reduced fertility, spontaneous abortion and congenital deficits or abnormalities.