Arsenic: its chemistry, its occurrence in the earth and its release into industry and the environment

Proteomic analysis of the effects of Dictyophora polysaccharide on arsenic-induced hepatotoxicity in rats

Arsenic (As) is a highly toxic environmental toxicant and a known human carcinogen. Long-term exposure to As can cause liver injury. Dictyophora polysaccharide (DIP) is a biologically active natural compound found in the Dictyophora with excellent antioxidation, anti-inflammation, and immune protection properties. In this study, the Sprague-Dawley (SD) rat model of As toxicity was established using a feeding method, followed by DIP treatment in rats with As-induced liver injury. The molecular mechanisms of As toxicity to the rat liver and the protective effect of DIP were investigated by proteomic studies. The results showed that 172, 328 and 191 differentially expressed proteins (DEPs) were identified between the As-exposed rats versus control rats (As/Ctrl), DIP treated rats versus As-exposed rats (DIP+As/As), and DIP treated rats versus control rats (DIP+As /Ctrl), respectively. Among them, the expression of 90 DEPs in the As/Ctrl groups was reversed by DIP treatment. As exposure caused dysregulation of metabolic pathways, mitochondria, oxidative stress, and apoptosis-related proteins in the rat liver. However, DIP treatment changed or restored the levels of these proteins, which attenuated the damage to the livers of rats caused by As exposure. The results provide new insights into the mechanisms of liver injury induced by As exposure and the treatment of DIP in As poisoning.

Influence of Phosphate on Arsenic Adsorption Behavior of Si-Fe-Mg Mixed Hydrous Oxide

The arsenic adsorption performance of silicon (Si), iron (Fe), and magnesium (Mg) mixed hydrous oxide containing a Si: Fe: Mg metal composition ratio of 0.05:0.9:0.05 (SFM05905) was investigated. SFM05905 was synthesized by the co-precipitation method. Batch experiments on arsenic adsorption were conducted at various temperatures and concentrations. Adsorption isotherms models were represented by a linearized equations and were insensitive to temperature change. The anion selectivity of SFM05905 at single component was high for arsenite (III), arsenate (V), and phosphate (PO4), indicating that PO4 inhibits arsenic adsorption. The adsorption amount of As (III), As (V), and PO4 were compared using a column packed with granular SFM05905, and an aqueous solution was passed by a combination of several anions that are single, binary, and ternary adsorbate systems. As (III) had the highest adsorption amount; however, As (III) and PO4 were affected by each other under the ternary mixing condition. Although the adsorption amount of As (V) was smaller than that of As (III), it was not affected by other adsorbates in the column experiments. Finally, although the adsorption of both arsenic continued, the adsorbed PO4 gradually desorbed.

pH dependent electro-oxidation of arsenite on gold surface: Relative kinetics and sensitivity

A detailed kinetic investigation of As(III) oxidation was performed on gold surface within pH between ∼3.0 and ∼9.0. It was found that the As(III) oxidation on the gold surface follows a purely adsorption-controlled process irrespective of pH. The evaluated adsorption equilibrium constant decreased from 3.21 × 10⁵ to 1.61 × 10⁵ mol L^-1 for acidic to basic medium, which implies the strong affinity of the arsenic species in the acidic medium. Besides, the estimation of Gibbs free energy revealed that an acidic medium promotes arsenic oxidation on gold surface. In mechanistic aspect, the oxidation reaction adopts a stepwise pathway for acidic medium and a concerted pathway for neutral and basic medium. From the substantial kinetic evaluation, it is established that a conducive and compatible environment for the oxidation of arsenic was found in an acidic medium rather than a basic or neutral medium on gold surface. Besides, in sensitivity concern, neutral and highly acidic medium is quite favourable for the arsenite oxidation on gold surface.

Intervention Study of Dictyophora Polysaccharides on Arsenic-Induced Liver Fibrosis in SD Rats

Long-term arsenic (As) exposure can cause liver injury, hepatic cirrhosis, and cancer. Meanwhile, Dictyophora polysaccharides (DIP) have excellent antioxidation, anti-inflammation, and immune protection effects. There are currently few reports on the protection effects of DIP on As-induced hepatotoxicity and its pharmacological value. Therefore, this study was aimed at elucidating the protection of DIP on As-induced hepatotoxicity and exploring its preventive role in antifibrosis. In our study, the SD rat As poisoning model was established by the feeding method to explore the influence of As exposure on liver fibrosis. Then, DIP treatment was applied to the rats with As-induced liver fibrosis, and the changes of serum biochemical indexes and liver tissue pathology were observed. And the expression of fibrosis-related proteins TGF-β1, CTGF, and α-SMA levels was then determined to explore the DIP intervention function. The results demonstrated that through reduced pathological changes of hepatic and increased serum AST, ALT, TP, ALB, and A/G levels, DIP ameliorated liver fibrosis induced by As as reflected. And the administration of DIP decreased the concentration of HA, LN, PCIII, CIV, TBIL, and DBIL. In addition, the synthesis of TGF-β1 inhibited by DIP might regulate the expression of CTGF and decrease the proliferation of fibrinogen and fibroblasts, which reduced the synthesis of fibroblasts to transform into myofibroblasts. And a decrease of myofibroblasts downregulated the expression of α-SMA, which affected the synthesis and precipitation of ECM and alleviated the liver fibrosis caused by exposure to As. In conclusion, based on the pathological changes of liver tissue, serum biochemical indexes, and related protein expression, DIP can improve the As-induced liver fibrosis in rats and has strong medicinal value.

A review on sources, identification and treatment strategies for the removal of toxic Arsenic from water system

Arsenic liberation and accumulation in the groundwater environment are both affected by the presence of primary ions and soluble organic matter. The most important influencing role in the co-occurrence is caused by human activity, which includes logging, agricultural runoff stream, food, tobacco, and fertilizers. Furthermore, it covers a wide range of developed and emerging technologies for removing arsenic impurities from the ecosystem, including adsorption, ion exchangers, bio sorption, coagulation and flocculation, membrane technology and electrochemical methods. This review thoroughly explores various arsenic toxicity to the atmosphere and the removal methods involved with them. To begin, the analysis focuses on the general context of arsenic outbreaks in the area, health risks associated with arsenic, and measuring techniques. The utilization of innovative functional substances such as graphite oxides, metal organic structures, carbon nanotubes, and other emerging types of composite materials, as well as the ease, reduced price, and simple operating method of the adsorbent material, are better potential alternatives for arsenic removal. The aim of this article is to examine the origins of arsenic, as well as identification and treatment methods. It also addressed recent advancements in Arsenic removal using graphite oxides, carbon nanotubes, metal organic structures, magnetic nano composites, and other novel types of usable materials. Under ideal conditions for the above methods, the arsenic removal will achieve nearly 99% in lab scale.

Co-treatment of copper smelting flue dust and arsenic sulfide residue by a pyrometallurgical approach for simultaneous removal and recovery of arsenic

As the typical hazardous arsenic pollutants, copper smelting flue dust (CSFD) and arsenic sulfide residue (ASR) are produced extensively during copper smelting process, which pose significant pressure on environmental protection and green development of the copper industry. This work proposed an economic, efficient, and applicable approach to treat waste with waste, in which the simultaneous removal and recovery of As from CSFD and ASR were realized by a roasting process, with adding sulfuric acid, at a relatively low temperature (300-350 ℃). The thermodynamic analysis and experiments confirmed that the main phases of As₂S₃ and S₀ in the ASR were used as a reductant for reducing As(Ⅴ) in the CSFD, and the introduction of sulfuric acid favorably enhanced the thermodynamic driving force and greatly lowered the reaction temperature. The results indicated that removal and behavior of As were highly dependent on the mass ratio of ASR to CSFD, roasting temperature, and H₂SO₄ dosage. By regulating the parameters, the species As₂S₃, As₂O₅, and arsenate were all converted to volatile As₂O₃, which could be captured and deposited in cold water. In the optimized co-treatment, a satisfied As removal efficiency of 96.12% was achieved, while getting the 97.03% pure As₂O₃.

Root responses to localised soil arsenic enrichment in the fern Pityrogramma calomelanos var. austroamericana grown in rhizoboxes

The terrestrial fern Pityrogramma calomelanos, a cosmopolitan tropical species, is one of the strongest known arsenic (As) hyperaccumulator plants. This study aimed to determine whether P. calomelanos preferentially forages for arsenite (As³⁺) or arsenate (As⁵⁺) in As-contaminated soils, and whether a positive root response to As enhances accumulation in P. calomelanos. Therefore, an experiment using rhizoboxes divided in two halves were constructed with a control soil (C) and As³⁺ or As⁵⁺ dosed soil at either 50 and 100 μg g^-1 As. Micro-X-ray Fluorescence elemental mapping (μXRF) was employed to analyze the distribution of As in roots and fronds, and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) was used to determine As distribution in the reproductive tissues of P. calomelanos. The results showed that Pityrogramma roots do not specifically forage for As-contaminated soil; the area based on pixel counts was similar across all the treatments with no statistical differences. However, frond biomass was slightly higher in the treatments C ǀ As³⁺ and C ǀ As⁵⁺, and the highest accumulation of As in fronds was in the As⁵⁺ ǀ As³⁺ (100 μg g^-1) treatment, with 3418 and 2370 μg g^-1 in old and young fronds respectively. Arsenic cycling across the roots was observed by the μXRF mapping; in C ǀ As⁵⁺ (100) the As was higher and evenly distributed in both sections, whilst in C ǀ As³⁺ (50), the As was higher in the As³⁺ side. The μXRF mapping showed a broader As distribution in older fronds, where As was highest in the rachis and extended into the pinnule through the midrib. Pityrogramma calomelanos does not specifically root forage for As-enriched zones in the soil and grows healthily without signs of toxicity at lower (50 μg g^-1) and higher (100 μg g^-1) concentrations of As³⁺ and As⁵⁺ in the soil.