Arsenic concentrations and speciation in wild birds from an abandoned realgar mine in China

Tissue Distribution and Toxicological Risk Assessment of Mercury and Other Elements in Northern Populations of Wolverine (Gulo gulo)

Wolverines are facultative scavengers that feed near the top of terrestrial food chains. We characterized concentrations of mercury and other trace elements in tissues of wolverine from a broad geographic area, representing much of their contemporary distribution in northwestern North America. We obtained tissues from 504 wolverines, from which mercury was measured on muscle (n = 448), kidney (n = 222), liver (n = 148), hair (n = 130), and brain (n = 52). In addition, methylmercury, seven trace elements (arsenic, cadmium, chromium, cobalt, lead, nickel, selenium), and arsenic compounds were measured on a subset of samples. Concentrations of mercury and other trace elements varied between tissues and were generally highest in kidney compared to brain, liver and muscle. Mercury was predominately as methylmercury in brain and muscle, but largely as inorganic mercury in liver and kidney. Mercury concentrations of hair were moderately correlated with those of internal tissues (Pearson r = 0.51-0.75, p ≤ 0.004), making hair a good non-lethal indicator of broad spatial or temporal differences in mercury exposure to wolverine. Arsenobetaine was the dominant arsenic compound identified in tissues, and arsenite, arsenocholine and dimethylarsinic acid were also detected. A preliminary risk assessment suggested the cadmium, lead, mercury, and selenium concentrations in our sample of wolverines were not likely to pose a risk of overt toxicological effects. This study generated a comprehensive dataset on mercury and other trace elements in wolverine, which will support future contaminants study of this northern terrestrial carnivore.

Simultaneous stabilization of particulate and bioavailable arsenic in soils from the realgar mining area by polyacrylamide, nano-SiO2, and ferrihydrite composite materials

Arsenic (As) contamination in realgar mining areas poses a severe environmental and health risk, highlighting the critical need for effective strategies to manage As migration, particularly in its particulate and bioavailable states. Soil erosion and water leaching serve as significant pathways for spreading As, emphasizing the imperative to curtail its mobility. In the present study, we proposed an effective strategy that combines the utilization of polyacrylamide (PAM), nano-SiO2 (NS), and ferrihydrite (Fh) to elevate the stability of As in soils from a realgar mining area. The results show that this composite material demonstrates the capability to concurrently regulate soil erosion and mitigate the leaching of bioavailable As. The combination of the three materials in the proportion of 0.5 % PAM +0.1 % NS + 1.0 % Fh can reduce the soil particulate and bioavailable As content by 99.11 % and 93.98 %, respectively. The unconfined compressive strength of the soil can be increased by about 30 % under this condition. The SEM analyses show that the addition of PAM and NS can significantly enhance the aggregation of soil particles and then reduce the soil erosion rate. These findings highlight the significant potential of the proposed approach in mitigating As contamination in soil within mining environments. The approach offers a sustainable and comprehensive solution to address the transport of heavy metal contaminants in both particulate and bioavailable states in mining areas.

Review: Abandoned mines as a resource or liability for wildlife

Abandoned Mine Lands (AMLs) are areas where previous mineral extraction or processing has occurred. Hundreds of thousands of AMLs exist within the United States. Contaminated runoff from AMLs can negatively affect the physiology and ecology of surrounding terrestrial and aquatic habitats and species and can be detrimental to human health. As a response, several U.S. federal and state agencies have launched programs to assess health risks associated with AMLs. In some cases, however, AMLs may be beneficial to specific wildlife taxa. There is a relative paucity of studies investigating the physiological and ecological impacts of AMLs on wildlife. We conducted a systematic review examining published scientific articles that assessed the negative and positive impacts of AMLs across invertebrate and vertebrate taxa. We also offer suggestions on evaluating AMLs to develop effective mitigation strategies that reduce their negative tole on human and wildlife communities. Peer-reviewed publications were screened across WebofScience, PubMed and Google Scholar databases. Abandoned mine lands were generally detrimental to wildlife, with adverse effects ranging from bioaccumulation of heavy metals to decreased ecological fitness. Conversely, AMLs were an overall benefit to imperiled bat populations and could serve as tools for conservation. Studies were unevenly distributed across different wildlife taxa groups, echoing the necessity for additional taxonomically diverse research. We suggest that standardized wildlife survey methods be used to assess how different species utilize AMLs. Federal and state agencies can use these surveys to establish effective remediation plans for individual AML sites and minimize the risks to both wildlife and humans.

In silico comparative structural and functional analysis of arsenite methyltransferase from bacteria, fungi, fishes, birds, and mammals

BACKGROUND

Arsenic, a ubiquitous toxic metalloid, is a threat to the survival of all living organisms. Bioaccumulation of arsenic interferes with the normal physiological pathway. To overcome arsenic toxicity, organisms have developed arsenite methyltransferase enzyme, which methylates inorganic arsenite to organic arsenic MMA (III) in the presence of S-adenosylmethionine (SAM). Bacteria-derived arsM might be horizontally transported to different domains of life as arsM or as3mt (animal ortholog). A systematic study on the functional diversity of arsenite methyltransferase from various sources will be used in arsenic bioremediation.

RESULTS

Several arsenite methyltransferase protein sequences of bacteria, fungi, fishes, birds, and mammals were retrieved from the UniProt database. In silico physicochemical studies confirmed the acidic, hydrophilic, and thermostable nature of these enzymes. Interkingdom relationships were revealed by performing phylogenetic analysis. Homology modeling was performed by SWISS-MODEL, and that was validated through SAVES-v.6.0. QMEAN values ranged from - 0.93 to - 1.30, ERRAT score (83-96), PROCHECK (88-92%), and other parameters suggested models are statistically significant. MOTIF and PrankWeb discovered several functional motifs and active pockets within the proteins respectively. The STRING database showed protein-protein interaction networks.

CONCLUSION

All of our in silico studies confirmed the fact that arsenite methyltransferase is a cytosolic stable enzyme with conserved sequences over a wide range of organisms. Thus, because of its stable and ubiquitous nature, arsenite methyltransferase could be employed in arsenic bioremediation.

Enhancement of phytoextraction efficiency coupling Pteris vittata with low-dose biochar in arsenic-contaminated soil

Phytoremediation of arsenic (As) by Pteris vittata (P. vittata) is a cost-effective and environmentally friendly method for restoring As-contaminated sites. However, the phytoextraction efficiency is low in some cases, such as clay soil, thus biochar was applied to enhance the efficiency of As extraction. The paper investigated the effect of biochar on soil characteristic, As mobility, and As uptake in P. vittata with a 90-day greenhouse experiment. Biochar derived from rice straw was added at rates of 0.5, 1.5, and 4% (w/w). The results showed that, under biochar amendment, soil pH raised from 5.24 to 6.03 and 4.91 to 5.85, soil dissolved organic carbon (DOC) increased 11.1-46.1% and 2.8-11.2%, respectively, in rhizosphere and bulk soils. Biochar also increased soil catalase (CAT) activity significantly, especially for the rhizosphere soil. Besides, biochar increased the labile As in the soils and transfer coefficient from roots to aboveground, thereby enhancing As accumulation by P. vittata tissues. The accumulation of As in fronds of P. vittata was up to 350 mg kg-1 in 1.5% biochar, which was more than twice the control and far beyond other biochar treatments. The results indicate that biochar addition is favorable to improve phytoremediation of P. vittata in As-contaminated soil and 1.5% (w/w) biochar may be a reasonable application ratio, thus providing an effective solution to enhance the efficiency of As phytoextraction.

Multiple trace elements exposure of Grey-cheeked Fulvettas Alcippe morrisonia, a nuclear member in bird mixed-species flocks, and implications for bioindicator

Birds are vulnerable to metal pollution, which can serve as indicators of environmental safety monitoring. In this study, we evaluated three non-essential (Pb, Cd, and As) and two essential (Cu and Zn) trace elements of living (only feathers) and deceased (feathers and tissues) Grey-cheeked Fulvetta (Alcippe morrisonia) at a highly polluted mine tailings and a reference site. Five metal concentrations in the feathers of living Grey-cheeked Fulvettas were higher at the mine site. Among these, the levels of Cd and Pb in most feathers exceeded the threshold, resulting in an ecotoxicological concern. The correlation analysis suggested that feathers from Grey-cheeked Fulvettas might be useful bioindicators for local metal contamination assessment. The toxicological effects of trace metals on Grey-cheeked Fulvetta might affect its leadership ability. Therefore, understanding the effects of metal pollution on Grey-cheeked Fulvetta would show important practical implications for the conservation of bird communities.

Research progress on speciation analysis of arsenic in traditional Chinese medicine

Traditional Chinese medicine contains arsenic (As), which in the natural environment accumulates in plants during the growth of Chinese medicinal materials; there are mineral medicines containing As in Chinese patent medicine such as As4S4, As2S3, etc. Due to the toxicity of As-containing compounds and its role in inflammation and treatment of cancers such as leukemia, it is necessary to analyze the chemical form of As. A comprehensive investigation of the compound forms of heavy metals rather than the simple total amount of elements will lay the foundation for the scientific and objective evaluation of the safety of heavy metals. This article summarizes the speciation of As in bulk Chinese medicinal materials and Chinese patent medicines in recent years, and reviews the main research methods of As speciation analysis. The separation and detection combined analysis method focuses on the high-performance liquid chromatography-plasma mass spectrometry and high-performance liquid chromatography-hydride generation-atomic fluorescence spectroscopy, etc. Taking the advanced synchrotron radiation source as the research platform, the use of X-ray near edge absorption fine structure spectrum and micro-area X-ray fluorescence analysis as a microscopic analysis technique supports direct analysis of the As speciation in situ. It is the most promising morphological analysis method.

Study on the speciation of arsenic in the genuine medicinal material honeysuckle

Arsenic (As) accumulated in genuine medicinal materials will not only deteriorate the original medicinal properties of the medicinal materials but also harm the eater’s body. In this study, inductively coupled plasma mass spectrometry (ICP-MS) technology was used to investigate the total As content of honeysuckle in four regions, namely Fengqiu, Henan, Xinmi, Shandong, and Julu, Hebei, as well as the speciation and content of As in the roots, stems, and leaves of honeysuckle. This research shows that the total As content of honeysuckle in the four regions was 0.25–0.3 mg/kg. At 1.5 mol/L H3PO4, 200 W, we performed ultrasonic extraction for 30 min at 60°C and adopted high performance liquid chromatography-inductively coupled plasma mass spectrometry (HPLC-ICP-MS) to analyze the As speciation of honeysuckle plants. The soil As speciation mainly exists in the form of As(v). In the medicinal part of honeysuckle, the amount of different As speciation is ranked in the descending order as As(v) > As(iii) > dimethyl As acid > monomethyl As acid > AsC. As(v) is the main speciation, accounting for 64.5% of the total, followed by the most toxic As(iii), which is 18.8%. As(v) absorbed by the root system of honeysuckle from the soil tends to transform to As(iii) when transported upwards, and the transformation process mainly occurs in the roots.

Semiautomatic method for the ultra-trace arsenic speciation in environmental and biological samples via magnetic solid phase extraction prior to HPLC-ICP-MS determination

A novel magnetic functionalized material based on graphene oxide and magnetic nanoparticles (MGO) was used to develop a magnetic solid phase extraction method (MSPE) to enrich both, inorganic and organic arsenic species in environmental waters and biological samples. An automatic flow injection (FI) system was used to preconcentrate the arsenic species simultaneously, while the ultra-trace separation and determination of arsenobetaine (AsBet), cacodylate, As^III and As^V species were achieved by high performance liquid chromatography combined with inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The sample was introduced in the FI system where the MSPE was performed, then 1 mL of eluent was collected in a chromatographic vial, which was introduced in the autosampler of HPLC-ICP-MS. Therefore, preconcentration and separation/determination processes were automatic and conducted separately. To the best of our knowledge, this is the first method combining an automatic MSPE with HPLC-ICP-MS for arsenic speciation, using a magnetic nanomaterial based on MGO for automatic MSPE. Under the optimized conditions, the LODs for the arsenic species were 3.8 ng L^-1 AsBet, 0.5 ng L^-1 cacodylate, 1.1 ng L^-1 As^III and 0.2 ng L^-1 As^V with RSDs <5%. The developed method was validated by analyzing Certified Reference Materials for total As concentration (fortified lake water TMDA 64.3 and seawater CASS-6 NRC) and also by recovery analysis of the arsenic species in urine, well-water and seawater samples collected in Málaga. The developed method has shown promise for routine monitoring of arsenic species in environmental waters and biological fluids.

New Method for Simultaneous Arsenic and Selenium Speciation Analysis in Seafood and Onion Samples

This paper presents a new method for the simultaneous speciation analysis of arsenic (As(III)-arsenite, As(V)-arsenate, DMA-dimethylarsinic acid, MMA-methylarsonic acid, and AsB-arsenobetaine) and selenium (Se(IV)-selenite, Se(VI)-selenate, Se-Methionine, and Se-Cystine), which was applied to a variety of seafood and onion samples. The determination of the forms of arsenic and selenium was undertaken using the High-Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS) analytical technique. The separation of both organic and inorganic forms of arsenic and selenium was performed using two analytical columns: an anion exchange column, Dionex IonPac AS22, containing an alkanol quaternary ammonium ion, and a double bed cation-anion exchange guard column, Dionex Ion Pac CG5A, containing, as a first layer, fully sulfonated latex for cation exchange and a fully aminated layer for anion exchange as the second layer. The ammonium nitrate, at pH = 9.0, was used as a mobile phase. The method presented here allowed us to separate the As and Se species within 10 min with a suitable resolution. The applicability was presented with different sample matrix types: seafood and onion.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Application of stable isotopes to the bioaccumulation and trophic transfer of arsenic in aquatic organisms around a closed realgar mine

The bioaccumulation and trophic transfer of As along food webs in freshwater ecosystems remain largely unknown. In this study, multiple environmental and biological samples were collected from a closed realgar mining area in South China. The As concentrations in the surface water, sediments and soils in the mining area were 0.62-3293 μg/L, 9.53-4543 mg/kg and 7.32-5008 mg/kg, respectively, and gradually decreased with distance from the central mining sites, indicating that historic As mining activities had an eminent impact on As contamination around the mine. The As concentrations in aquatic organisms ranged from 0.60 mg/kg to 45.75 mg/kg and varied markedly among sites and species, reflecting the influence of various physiologic and environmental factors. Arsenic species identified by liquid chromatography inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) were mainly organic, comprising 8% to 66% of the total As. Both the proportions and concentrations of inorganic As were positively correlated with total As. This correlation could be attributed to the higher assimilation and accumulation of inorganic As or the lower biotransformation ability of inorganic As with the increasing total As in the studied organisms. Values of δ¹³C and δ¹⁵N in aquatic organisms ranged from -30.59‰ to -15.07‰ and from 4.31‰ to 12.98‰, respectively, indicating multiple trophic levels and variety in the diet sources of these organisms. The δ¹⁵N increased distinctly in the order of planktivorous<herbivorous<omnivorous<carnivorous, which is generally consistent with the increasing trophic levels in the freshwater ecosystem. No significant correlation was observed between As concentrations and δ¹⁵N in the freshwater organisms, suggesting no biomagnification of As in the food web.

Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan

In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. In comparison of species, SOD and tGSH activities were higher in bank myna and cattle egret, while CAT activity and TBARS concentrations were higher in pond heron and cattle egret, respectively. We deduced that tissues with higher accumulation of metal(loid)s such as liver and kidney were under a great risk to oxidative damage. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. Globally, metal- and As-induced oxidative stress is least emphasized in multiple tissues of birds that is needed to be addressed with focus on case-control studies using dose-response approach. Graphical abstract .

A Systematic Review on Arsenic Bio-Availability in Human and Animals: Special Focus on the Rice-Human System

The present systematic review synthesizes the diverse documentation of research on the occurrence of arsenic in soil-water systems and the human and animal bio-availability scenarios related to food chain contamination by arsenic. Humans and animals may drink arsenic-contaminated groundwater in addition to consuming foods that have been grown in arsenic-contaminated groundwater and soils. Rice grain is a potential arsenic carrier and the staple food in many parts of the world, particularly in Southeast Asian countries. Data have been summarized from 183 articles describing different aspects of arsenic flow in the food chain, that is, the soil-water-rice-human system and the water-crops-animals system and the bio-availability of arsenic to humans and animals. The phyto-availability of arsenic depends on the physicochemical and biological conditions of soil and water. In humans, the bio-accessibility of inorganic arsenic is 63-99%. Arsenic is more bio-available from rice than from other foods: different food materials differ in bio-accessible potential. Additionally, the review identifies trends in research on arsenic contamination and food chain flow considering arsenic species, toxicity assessment, and bio-accessibility studies. This systematic review provides a comprehensive assessment of the documented evidence to be used to guide future research on arsenic availability for the rice plant and subsequent availability to humans from cooked rice that can determine arsenic toxicity. The review also highlights how the focus of research on arsenic as a pollutant has changed in the past decades.

Arsenic uptake, transformation, and release by three freshwater algae under conditions with and without growth stress

This study was carried out using indoor controlled experiments to study the arsenic (As) uptake, biotransformation, and release behaviors of freshwater algae under growth stress. Three freshwater algae, Microcystis aeruginosa, Anabaena flosaquae, and Chlorella sp., were chosen. Two types of inhibitors, e.g., Cu²⁺ and isothiazolinone, were employed to inhibit the growth of the algae. The algae were cultivated to a logarithmic stage in growth media containing 0.1 mg/L P; then, 0.8 mg/L As in the form of arsenate (iAs^V) was added, while both inhibitors were simultaneously added at dosages of 0.1 and 0.3 mg/L, with no addition of inhibitors in the control. After 2 days of exposure, the average growth rate (μ_2d) was measured to represent the growth rates of the algae cells; the extra- and intracellular As concentrations in various forms, i.e., arsenate, arsenite (iAs^III), monomethyl arsenic (MMA), and dimethyl arsenic (DMA), were also measured. Without inhibitors, the average growth rate followed the order of M. aeruginosa, Chlorella sp., and A. flosaquae, with the growth rate of M. aeruginosa significantly higher than that of the other two algae. However, when Cu²⁺ was added as an external inhibitor, the order of the average growth rate for the three algae became partially reversed, suggesting differentiation of the algae in response to the inhibitor. This differentiation can be seen by the reduction in the average growth rate of M. aeruginosa, which was as high as 1730% at the 0.3-mg/L Cu²⁺ dosage when compared with the control, while for the other two algae, much fewer changes were seen. The great reduction in M. aeruginosa growth rate was accompanied by increases in extracellular iAs^V and iAs^III and intracellular iAs^V concentrations in the algae, indicating that As transformation is related to the growth of this algae. Much fewer or neglectable changes in growth were observed that were consistent with the few changes in the extra- and intracellular As speciation for the other two algae with Cu²⁺ inhibition and all the three algae with isothiazolinone inhibition, corroborating the above hypothesis again. All the algae tested in this study demonstrated great abilities for As transformation and release, as seen by the much higher rates of 86.11-99.98% and 81.11-99.89% for transformation and release when compared to the control, respectively. When inhibitors were added, the transformation and release values of only A. flosaquae decreased remarkably down to 72.37-86.79% and 64.67-85.24%, respectively, while no changes were seen for these values in the other two algae, indicating that growth stress did not affect the As transformation and release of the other algae. The biological productivity of As by the three algae followed the order of M. aeruginosa, Chlorella sp., and A. flosaquae, which was generally consistent with the As transformation and release in conditions with and without inhibitors, suggesting that the As behavior in the algae that was related to growth stress largely differed among algae species.