Trimethylarsine Oxide Research Articles

Seasonal and spatial variations of arsenic and its species in particulate matter in an urban environment of Brno, Czech Republic

The present paper deals with an analysis of total arsenic concentration using ICP-MS/MS and an analysis of concentration of several arsenic species, arsenite (AsIII), arsenate (AsV), monomethylarsonate (MMA), dimethylarsenite (DMA), and trimethylarsine oxide (TMAO), using HPLC-ICP-MS/MS in the PM10 fraction of airborne urban aerosol. The samples were collected during two campaigns, in the autumn of 2022 and in the winter of 2023, at three locations within the central European city of Brno, with the aim to evaluate the seasonal and spatial variations in the PM10 composition. The results confirmed only the seasonal variability in the content of the methylated arsenic species in PM10 influenced by biomethylation processes. To gain better understanding of the possible arsenic origin, a supplementary analysis of the total arsenic concentrations was performed in samples of different size fractions of particulate matter collected using ELPI + . Local emissions, including industrial activities and heating during the winter season, were suggested as the most likely predominant source contributing to the total As content in PM10.Graphical abstract

Occurrence and spatiotemporal distribution of arsenic biotransformation genes in urban dust

Microbially-mediated arsenic biotransformation plays a pivotal role in the biogeochemical cycling of arsenic; however, the presence of arsenic biotransformation genes (ABGs) in urban dust remains unclear. To investigate the occurrence and spatiotemporal distributions of ABGs, a total of one hundred and eighteen urban dust samples were collected from different districts of Xiamen city, China in summer and winter. Although inorganic arsenic species, including arsenate [As(V)] and arsenite [As(III)], were found to be predominant, the methylated arsenicals, particularly trimethylarsine oxide [TMAs(V)O] and dimethylarsenate [DMAs(V)], were detected in urban dust. Abundant ABGs were identified in urban dust via AsChip analysis (a high-throughput qPCR chip for ABGs), of which As(III) S-adenosylmethionine methyltransferase genes (arsM), As(V) reductase genes (arsC), As(III) oxidase genes (aioA), As(III) transporter genes (arsB), and arsenic-sensing regulator genes (arsR) were the most prevalent, collectively constituting more than 90 % of ABGs in urban dust. Microbes involved in arsenic methylation were assigned to bacteria (e.g., Actinomycetes and Alphaproteobacteria), archaea (e.g., Halobacteria), and eukaryotes (e.g., Chlamydomonadaceae) in urban dust via the arsM amplicon sequencing. Temperature, a season-dependent environmental factor, profoundly affected the abundance of ABGs and the composition of microbes involved in arsenic methylation. This study provides new insights into the presence of ARGs within the urban dust.

Chemo‐trapping method for determination of volatile arsenic from paddy soil

AbstractThe objective of this study was to develop a technique for collecting and analyzing volatile arsenic species including arsine (AsH3), methyl arsine (CH3AsH2), dimethyl arsine (CH3)2AsH, and trimethyl arsine (CH3)3As emitted from paddy soil. The four volatile arsenic species were captured on AgNO3‐impregnated sand then eluted and quantified. The AgNO3‐impregnated sand was synthesized by crystallizing AgNO3 on 0.5‐1 mm id. sandy particles at 70 oC. The volatile arsenic species were generated by hydride a mixture containing sodium arsenous (NaAsO2), disodium methyl arsenate ((CH3AsO(ONa)2), sodium cacodylate ((CH3)2AsO(ONa)), and trimethyl arsine oxide ((CH3)3AsO) using NaBH4. The formed volatile arsenic species were purged with an Ar stream then retained on a trap packed with the AgNO3‐impregnated sand followed by elution with 2 mL of 2.5% nitric acid and 0.5 mL of 30% H2O2 at 70oC prior to total analysis by ICPMS and speciation analysis by ion exchange chromatography ‐ ICPMS. The total analysis of arsenic revealed that AgNO3‐impregnated sand can efficiently retain the four volatile arsenic with 91‐102% recovery within a range of 20‐2000 ngAs as total amounts. The detection limit for total arsenic species through the trap was 6.5 ngAs. For a trap packed with 300 mg of AgNO3‐impregnated sand, the capture capacity was greater than 2000 ngAs. The speciation of arsenic eluted from the trap was performed by separation on a Hamilton PRP‐X100 anion‐exchange column with gradient elution using 100 mM (NH4)2CO3 mobile phase followed by ICPMS detection. A pot experiment was conducted to evaluate the efficiency of the purge and trapping method for naturally formed volatile arsenic species emitted from flooded paddy soil. Preliminary results showed that methyl arsenic, trimethyl arsenic and arsine were emitted from the studied paddy soil in which arsine contributes 90% of arsenic emission. This method is showing promise to be applied for the emission of volatile arsenic analysis from paddy soil as well as other solid types of samples.

Species composition and health risk assessment of arsenic in Agaricus blazei Murrill and Tricholoma matsutake from Yunnan Province, China

High concentrations of total arsenic (As) has been found in Agaricus blazei Murrill and Tricholoma matsutake samples. It is important to study the As species in A. blazei and T. matsutake for accurate health risk assessment. Total As was measured by inductively coupled plasma-mass spectrometry (ICP-MS). An analytical method was developed to determine As species in mushroom by using anion exchange and cation exchange chromatography coupled to ICP-MS. Total As contents ranged from 5.25 to 69.5 mg kg1. Arsenobetaine (AsB), inorganic arsenic (iAs), and monomethylarsenic acid (MMA) were the main form of As in A. blazei samples, which accounted for 42.7–88.8 %, 1.59–26.2 %, and 0.74–1.12 % of the extractable As, respectively. AsB, and dimethylarsenic acid (DMA) were the main form of As in T. matsutake samples, which accounted for 88.9–97.9 %, and 1.79–3.80 % of the extractable As, respectively. Arsenocholine (AsC), trimethylarsine oxide (TMAO), and tetramethylarsonium cation (TMA+) were present as well, but only at trace concentrations. The health risk index estimation results indicated that no particular risk of iAs exposure to consumers existed in T. matsutake. The iAs exposure in A. blazei can poses certain health risks.

Arsenic Metabolism, Toxicity and Accumulation in the White Button Mushroom Agaricus bisporus.

Mushrooms have unique properties in arsenic metabolism. In many commercial and wild-grown mushrooms, arsenobetaine (AsB), a non-toxic arsenical, was found as the dominant arsenic species. The AsB biosynthesis remains unknown, so we designed experiments to study conditions for AsB formation in the white button mushroom, Agaricus bisporus. The mushrooms were treated with various arsenic species including arsenite (As(III)), arsenate (As(V)), methylarsenate (MAs(V)), dimethylarsenate (DMAs(V)) and trimethylarsine oxide (TMAsO), and their accumulation and metabolism were determined using inductively coupled mass spectrometer (ICP-MS) and high-pressure liquid chromatography coupled with ICP-MS (HPLC-ICP-MS), respectively. Our results showed that mycelia have a higher accumulation for inorganic arsenicals while fruiting bodies showed higher accumulation for methylated arsenic species. Two major arsenic metabolites were produced in fruiting bodies: DMAs(V) and AsB. Among tested arsenicals, only MAs(V) was methylated to DMAs(V). Surprisingly, AsB was only detected as the major arsenic product when TMAsO was supplied. Additionally, AsB was only detected in the fruiting body, but not mycelium, suggesting that methylated products were transported to the fruiting body for arsenobetaine formation. Overall, our results support that methylation and AsB formation are two connected pathways where trimethylated arsenic is the optimal precursor for AsB formation.

Arsenolipids in raw and cooked seafood products in southwest China: A non-targeted analysis

Arsenolipids are the primary form of arsenic in the fat of marine organisms. Because seafood is a common source of arsenic exposure and some arsenolipids are toxic, studying the abundance and species of arsenolipids in seafood is crucial for health risk assessment. Current arsenolipid research is confined by analytical techniques and limited to raw seafood analysis, despite the fact that most seafood is ingested cooked. Therefore, the aim of this study is to evaluate which seafood contributes to arsenolipid dietary intake and investigate the changes in arsenolipids before and after cooking. In Chongqing, China, popular seafood such as clam, shrimp, oyster, abalone, hairtail, and yellow croaker were collected. The raw and cooked samples prepared from these seafood products were examined using a non-targeted screening approach established for arsenolipids, which coupled high-performance liquid chromatography with data-independent high-resolution quadrupole-time-of-flight electrospray ionization tandem mass spectrometry. Arsenic-containing hydrocarbons (AsHC330, AsHC332, and AsHC360), arsenic-containing fatty acids (AsFA362, AsFA390, AsFA404, AsFA418, and AsFA422), trimethylarsine oxide, and thiolated trimethylarsinic acid were detected. The species of arsenolipids in each type of seafood remained intact after heating in the microwave oven. In cooked samples, the concentrations of AsFA362 and AsFA390 were significantly lower than in raw samples, whereas the concentrations of other arsenolipids were unchanged. Microwave cooking did not result in the thiolation of the detected arsenolipids. The most detected species in raw and cooked samples were AsFA362, AsFA390, and AsFA418. Most arsenolipid species were found in the highest levels in hairtails and yellow croakers. It is the first time that arsenolipids have been found in the oyster, abalone, abalone liver, and yellow croaker. The present study contributes to a better understanding of arsenolipids exposure from seafood, which is useful for assessing the health risks of arsenic.

Carryover effects of silicon‐rich amendments in rice paddies

AbstractRice (Oryza sativa L.) readily accumulates the nutrient silicon (Si) and the toxin arsenic (As), elements that can interact antagonistically both in the plant and in the soil. Thus, many studies have been performed where Si‐rich materials are incorporated into soils to increase plant‐available Si and thereby decrease plant As. However, studies have not examined the dissolution kinetics of Si from Si‐rich materials over multiple seasons and the resulting effects on rice systems. Here, we analyzed the porewater chemistry, CH4 emissions, and rice elemental concentrations from rice paddies in Year 2 that had been amended with Si‐rich materials (silicate fertilizer, rice husk, and charred rice husk) in Year 1. After two crop cycles, plant‐available Si and plant Si concentrations remained elevated in Si‐amended paddies. Silicon‐rich amendments also decreased plant As concentrations, although this effect was only observed in the vegetative tissues. Husk treatment resulted in the lowest porewater redox, highest CH4 emissions, and highest porewater inorganic As. Porewater concentrations and dynamics of inorganic As, dimethylarsinic acid (DMA), and trimethylarsine oxide (TMAO) differed for each amendment, but Si‐rich amendments exhibited elevated inorganic and organic As early in the growing season. These Si‐rich amendments can continue to provide Si and impact rice systems two growing seasons after application.

Distribution and chemical speciation of arsenic in different sized atmospheric particulate matters

The distribution and chemical speciation of arsenic (As) in different sized atmospheric particulate matters (PMs), including total suspended particles (TSP), PM10, and PM2.5, collected from Baoding, China were analyzed. The average total mass concentrations of As in TSP, PM10, and PM2.5 were 31.5, 35.3, and 54.1 µg/g, respectively, with an order of PM2.5 >PM 10 > TSP, revealing that As is prone to accumulate on fine particles. Due to the divergent toxicities of different As species, speciation analysis of As in PMs is further conducted. Most of previous studies mainly focused on inorganic arsenite (iAsIII), inorganic arsenate (iAsV), monomethylarsonate (MMA), and dimethylarsinate (DMA) in PMs, while the identification and sensitive quantification of trimethylarsine oxide (TMAO) were rarely reported. In this study, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs. An anion exchange column was used to separate MMA, DMA and iAsV, while a cation exchange column to separate TMAO and iAsIII. Results showed that iAsV was the dominate component in all the samples, corresponding to a portion of 79.2% ± 9.3% of the total extractable species, while iAsIII, TMAO and DMA made up the remaining 21%. Our study demonstrated that iAsIII accounted for about 14.4% ± 11.4% of the total extracted species, with an average concentration of 1.7 ± 1.6 ng/m3. It is worth noting that TMAO was widely present in the samples (84 out of 97 samples), which supported the assumption that TMAO was ubiquitous in atmospheric particles.

Risks associated with the consumption of inorganic and organic arsenic

It is known that the chronic intake of arsenic (As) leads to the development of multisystem pathologies. In the case of high levels of As consumption, the risks of negative effects of exposure to inorganic and methylated forms persist for decades. The International Agency for Research on Cancer (IARC) has established that all inorganic forms of As are absolute carcinogens (group 1). Methylated forms of As are classified as substances possibly carcinogenic to humans (group 2b). Not metabolized in the human body forms of organic As are not carcinogenic to humans (group 3). The aim - assessment of health risks of various forms of As contained in food, including seafood. Material and methods. The scientific data regarding the risks associated with As contamination of food obtained by using PubMed, Web of Science, Google Scholar databases, legislative and regulatory acts of the Eurasian Economic Union, the Russian Federation, the Codex Alimentarius Commission, the European Union and other coun tries have been analyzed. Results. The analysis of the available data showed that the degree of As toxicity decreased in the following order: glutathione of dimethylarsonic acid (DMAIIIGl) > methylarsic acid (MMAIII) > dimethylarsic acid (DMAIII) > arsenic hydrocarbons (AsHC) > arsenite (AsIII) > arsenate (AsV) > trimethylarsine (TMAIII) > methylarsonic acid (MMAV) > dimethylarsonic acid (DMAV) > DMAIII-sugar glyceride > DMAV-sugar glyceride > thio compounds of DMAV > arsenosugarsIII > arsenosugarsV > tetramethylarsonium chloride (TETPA) > trimethylarsine oxide (TMAO), arsenocholine (AsC) > arsenobetaine (AB). Consequently, the toxicity of some methylated and organic forms of As (for example, DMAIIIGl, AsHC) may be higher than that of its inorganic forms. It is known that As is found in foods mainly in organic forms. When ingested with food, As organic forms are metabolized and, thus, could cause a number of negative effects in the organism. Conclusion. High levels of organic and inorganic forms of As in food, including seafood, could have a negative impact on the health of the population, which makes it necessary to conduct additional assessments of the health risks of various forms of As entering the body. The insufficient amount of data on the toxicity of organic forms of As indicates the impossibility of separate setting of safety maximum levels for organic and inorganic forms of As in foods.

S1065 Arsenic Exposure and Risk of Liver Injury Among U.S. Adults: An Association Modified by Gender

INTRODUCTION: Arsenic has toxic effects on multiple organ systems; however, arsenic toxicity on the liver has not been well explored. Therefore, we examined the association between arsenic exposure and serum ALT, a marker for liver injury and effect modification by gender. METHODS: Individuals >19 years of age from 7 cycles of the National Nutrition and Health Examination Survey (NHANES 2003–16) were included. Associations between serum ALT and creatinine-standardized urinary concentrations of total and 7 arsenic forms were examined. Data were summarized with mean (standard deviation) or frequencies. Urinary arsenic and serum ALT were log-transformed due to right-skewed distributions. We used survey-weighted linear regression without and with adjustments for gender, age, diabetes, hypertension, race, smoking, alcohol use, estimated GFR, and body mass index(BMI). Effect-modification by gender was examined by with an interaction term between gender and arsenic forms. RESULTS: Of the 12,439 participants, 52% were females, 33% hypertensives, 9% were diabetics, 54% were non-smokers, and 68% were whites. The mean age was 48 years. BMI 29 Kg/m2, ALT 26 U/L, and total urinary arsenic 18.4 ug/L. As compared to females, males had significantly higher ALT (30.3 vs 21.9; P < 0.001) and total urinary arsenic levels (19.7 vs 17.3 P = 0.02). In adjusted models, each 10% increase in urinary total arsenic, dimethylarsonic acid, trimethylarsine oxide was associated with 0.1%, 0.4%, and 0.2% increase in serum ALT respectively (all P-values< 0.01); ALT increase with other urinary arsenic forms was not significant. Females had larger increases in ALT than males for 5 arsenic forms; for each 10% increase in arsenous acid, arsenic acid, arsenocholine, monomethylarsonic acid, and dimethylarsenic acid were associated with 0.3%, 0.6%, 0.4%, 0.6%, and 0.4% larger increase in ALT than males (all P < 0.05) (Figure). CONCLUSION: Urinary arsenic levels within an acceptable range (total urinary arsenic< 100ug/L) are associated with a small but significant risk of liver injury as measured by elevation in serum ALT. Females are particularly at a higher risk of liver injury than males. The clinical significance of this liver injury needs examination in longitudinal studies.Figure 1

A Simple and Effective Method for Speciation Analysis of 13 Arsenic Species Using HPLC on a Fluorocarbon Stationary Phase Coupled to ICP-MS.

The separation properties of arsenic species was investigated using HPLC-ICP-MS with several commercially available fluorocarbon stationary phases and no ion-pair reagents in HPLC. One pentafluorophenyl column showed the highest potential for the separation of a larger number of arsenic species when using simple acid-based mobile phases. After modification of the operational parameters in HPLC, the speciation analysis of 13 representative arsenic species: arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, tetramethylarsonium, arsenobetaine, arsenocholine, thio-dimethylarsinic acid, oxo-arsenosugar-glycerol, oxo-arsenosugar-phosphate, oxo-arsenosugar-sulfonate, and oxo-arsenosugar-sulfate, was achieved by HPLC-ICP-MS with the column along with a mobile phase of 0.05% heptafluorobutyric acid-methanol (99:1, volume per volume).

Crystal structure and X-ray absorption spectroscopy of trimethylarsine oxide dihydrate, (CH3)3AsO⋅2H2O

The crystal structure of trimethylarsine oxide dihydrate, (CH3)3AsO⋅2H2O, (TMAO dihydrate) has been solved using parallel tempering with the FOX software package and refined using synchrotron powder diffraction data obtained from beamline 08B1-1 at the Canadian Light Source. Rietveld refinement, performed with the software package GSASII, yielded orthorhombic lattice parameters of a = 13.3937(4) Å, b = 9.53025(30) Å, and c = 11.5951(3) Å (Z = 8, space group Pbca). The Rietveld refined structure was compared with density functional theory calculations performed with VASP and shows reasonable agreement. Arsenic K-edge X-ray absorption spectroscopy analysis also revealed additional information on the electronic structure of the arsenic atom within the TMAO dihydrate structure.

Analysis of Organoarsenic Compounds Concentration in Fish with the Newly Developed LC-MS/MS Method

Most fish contain some kinds of organoarsenic compounds. To assess the health risk for the chronic effects due to intake of these compounds, it is necessary to quantify the concentration of each chemical form, since the toxicity is difference depending on the form. We developed and validated the LC-MS/MS method to determine the concentration of monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), trimethylarsine oxide (TMAO), tetramethylarsonium (TeMA), arsenobetaine (AB), and arsenocholine (AC) in fish. Using this method, we quantified the concentration of each organoarsenic compounds and total arsenic in 50 fish samples from across 10 groups. Total arsenic concentration ranged from 0.53 to 25 mg/kg in all samples, except for in thread-sail filefish where the concentration ranged from 8.3 to 25 mg/kg. With the exception of sardines, in all samples AB was found at the highest level in relation to the total arsenic concentration. In sardines, the concentration of DMA was higher than that of AB, accounting for 16 to 24% of total arsenic. In red sea bream, concentrations of total arsenic, AB, and AC in farm-raised fish were lower than those in wild-caught fish.

Simultaneous determination of oxo- and thio-arsenic species using HPLC-ICP-MS

A method for simultaneous analysis of common oxo-arsenic species and their thio-analogues by coupling ion-pair liquid chromatography to inductively coupled plasma mass spectrometry was developed and validated. The chromatographic separation was performed using a C8 stationary phase and a mobile phase containing 1.2 mmol/L tetramethylammonium hydroxide, 4 mmol/L malonic acid, 6.2 mmol/L sodium butane-1-sulfonate, and 0.05 % (v/v) methanol. Under these conditions, the 11 arsenic species (arsenite, arsenate, dimethylarsinic acid, monomethylarsonic acid, arsenobetaine, arsenocholine, tetramethylarsonium cation, trimethylarsine oxide, dimethyldithioarsinic acid, monomethylmonothioarsinic acid, and trimethyarsine sulfide) were separated. The detection limits for these species ranged from 1.4 to 4.0 ng/g As. The method was applied to the analysis of fish, crustacean, mussel, cephalopod and mushroom samples. Thio-arsenic species DMDTAV were found in mussel Mytilus chilensis and cuttlefish Sepis pharaonis samples in very low contents of 23 and 21 ng/g As, respectively. All seafood samples contained predominantly arsenobetaine (330–8570 ng/g As); other As species were present at various contents from 7 to 325 ng/g As.

Extreme Arsenic and Antimony Uptake and Tolerance in Toad Tadpoles during Development in Highly Contaminated Wetlands.

The effects of extreme concentrations of toxic metalloids, such as arsenic (As) and antimony (Sb), on larval amphibians are not well-understood. We sampled Western Toad tadpoles (Anaxyrus boreas) living in As- and Sb-contaminated wetlands throughout their development. Although the tadpoles completed metamorphosis, they accumulated among the highest concentrations of As and Sb ever reported for a living vertebrate (3866.9 mg/kg; 315.0 mg/kg (dry weight), respectively). Ingestion of contaminated sediment had a more important role in metalloid accumulation than aqueous exposure alone. Metalloids were initially concentrated in the gut; however, by metamorphosis, the majority were found in other tissues. These concentrations subsequently decreased with the onset of metamorphosis, yet remained quite elevated. Sublethal effects, including delayed development and reduced size at metamorphosis, were associated with elevated metalloid exposure. The presence of organic arsenicals in tadpole tissues suggests they have the ability to biomethylate inorganic As compounds. The arsenical trimethyl arsine oxide accounted for the majority of extractable organic As, with lesser amounts of monomethylarsonic acid and dimethylarsinic acid. Our findings demonstrate remarkable tolerance of toad tadpoles to extreme metalloid exposure and implicate physiological processes mediating that tolerance.

Occurrence, Seasonal Variation, and Size Resolved Distribution of Arsenic Species in Atmospheric Particulate Matter in an Urban Area in Southeastern Austria.

Extensive information is available on total arsenic in particulate matter (PM), but little is known about the relative contribution of each individual species. Recent studies often focus on inorganic arsenic as arsenite and arsenate, neglecting the organoarsenicals, i.e., methylarsine, dimethylarsine, and trimethylarsine or the corresponding oxidized forms methylarsonate, dimethylarsinate, and trimethylarsine oxide, although they were already first detected in PM in the mid-1970s. This work presents results from more than 300 daily PM10 and further size-resolved atmospheric PM samples in the size range from 15 nm to 10 μm collected in an urban environment in Austria during the course of a year. An ion-exchange-HPLC (with anion and cation exchange columns) and an ICPMS/MS system were used to study the seasonal variations of total arsenic and all species known to exist in PM. Inorganic arsenic was present in significant amounts in all samples with highest concentrations during winter, but also all organoarsenicals were detected throughout the year. We show that their contribution cannot be ignored, as particles smaller than <1 μm can contain up to 35% of the water+H2O2 extractable arsenic as methylated species, but only dimethylarsinate showed a clear seasonal trend throughout the year.

Arsenic speciation in the bracket fungus Fomitopsis betulina from contaminated and pristine sites.

Uptake, distribution and speciation of arsenic (As) were determined in the bracket fungus Fomitopsis betulina (previously Piptoporus betulinus), commonly known as the birch polypore, collected from a woodland adjacent to a highly contaminated former mine in the Southwest UK and at an uncontaminated site in Quebec, Canada, with no past or present mining activity. The fruiting body was divided into cap, centre and pores representing the top, middle and underside to identify trends in the distribution and transformation of As. Total As, determined by inductively coupled plasma-mass spectrometry (ICP-MS), was approximately tenfold higher in the mushroom from the contaminated compared to the uncontaminated site. Overall, accumulation of As was low relative to values reported for some soil-dwelling species, with maximum levels of 1.6mg/kg at the contaminated site. Arsenic speciation was performed on aqueous extracts via both anion and cation high-performance liquid chromatography-ICP-MS (HPLC-ICP-MS) and on whole dried samples using X-ray absorption near edge structure (XANES) analysis. Seven As species were detected in F. betulina from the contaminated site by HPLC-ICP-MS: arsenite (AsIII), arsenate (AsV), dimethylarsinate (DMAV), methylarsonate (MAV), trimethylarsine oxide (TMAO), tetramethylarsonium ion (Tetra) and trace levels of arsenobetaine (AB). The same As species were observed at the uncontaminated site with the exception of TMAO and Tetra. Arsenic species were localized throughout the fruiting body at the contaminated site, with the cap and pores containing a majority of AsV, only the cap containing TMAO, and the pores containing higher concentrations of DMAV and MAV as well as tetra and a trace of AB. XANES analysis demonstrated that the predominant form of As at the contaminated site was inorganic AsIII coordinated with sulphur or oxygen and AsV coordinated with oxygen. This is the first account of arsenic speciation in F. betulina or any fungi of the family Fomitopsidaceae.

Soil attribute regulates assimilation of roxarsone metabolites by rice (Oryza sativa L.)

Roxarsone (ROX), an organoarsenic feed additive, and its metabolites, can be present in animal manure used to fertilize rice. Rice is prone to absorb arsenic, and is subject to straighthead disorder, which reduces rice yield and is linked with organic arsenic compounds. This study aims to elucidate how soil property affect arsenic accumulation in rice plants fertilized with chicken manure containing ROX metabolites. Manures of chickens fed without or with ROX, designated as control manure and ROX treated manure (ROXCM), respectively, were applied in eight paddy soils of different origins, to investigate the assimilation of arsenic species in rice plants. The results show that inorganic arsenic (arsenate and arsenite), monomethylarsonic acid and dimethylarsinic acid (DMA) were detected in all brown rice and husk, trace tetramethylarsonium and trimethylarsine oxide were occasionally found in these both parts, whereas all these arsenic species were determined in straw, irrespective of manure type. ROXCM application specifically and significantly increased brown rice DMA (P = 0.002), which remarkably enhanced the risk of straighthead disease in rice. Although soil total As impacted grain biomass, soil free-iron oxides and pH dominated arsenic accumulation by rice plants. The significantly increased grain DMA suggests manure bearing ROX metabolites is not suitable to be used in soils with abundant free-iron oxides and/or high pH, if straighthead disorder is to be avoided in rice.

Maritime Deposition of Organic and Inorganic Arsenic.

The speciation of arsenic in wet and dry deposition are ambiguously described in current literature. Presented here is a 2 year study quantifying arsenic species in atmospheric deposition collected daily from an E. Atlantic coastal, semirural site, with comparative urban locations. Inorganic arsenic (Asi) was the principal form of arsenic in wet deposition, with a mean concentration of 0.54 μmol/m3. Trimethylarsine oxide (TMAO) was found to be the dominant form of organic arsenic, determined as above the LoD in 33% of wet deposition samples with a mean concentration of 0.12 μmol/m3. Comparison with codeposited trace elements and prevailing weather trajectories indicated that both anthropogenic and marine sources contribute to atmospheric deposition. Analysis of dry deposition revealed it to be a less significant input to the land-surface for Asi, contributing 32% of that deposited by wet deposition. Dry deposition had a larger proportion of Asi than that found in wet deposition, with TMAO making up only 12% of the sum of species. In comparison, urban sites showed large spatial and temporal variations in organic arsenic deposition, indicating that local sources of methylated species may be likely and that further understanding of biogenic arsine evolution and degradation are required to adequately assess the atmospheric arsenic burden and subsequent contribution to terrestrial ecosystems.

Modifying the Parboiling of Rice to Remove Inorganic Arsenic, While Fortifying with Calcium.

Using village-based rice processing plants in rural Bangladesh, this study considered how parboiling rice could be altered to reduce the content of the carcinogen inorganic arsenic. Parboiling is normally conducted with rough rice (i.e., where the husk is intact) that is soaked overnight at ambient temperatures, and then either steamed or boiled for ∼10 min, followed by drying. Across 13 geographically dispersed facilities it was found that a simple alteration parboiling wholegrain, instead of rough rice, decreased the inorganic arsenic content by 25% ( P = 0.002) in the final polished grain. Also, parboiling wholegrain had little impact on milling quality of the final polished rice. The wholegrain parboiling approach caused statistically significant median enrichment of calcium, by 213%; and a reduction in potassium, by 40%; with all other nutrient elements tested being unaffected. Milled parboiled rough rice had an enriched inorganic arsenic compared to nonparboiled milled rice, but parboiling of wholegrain rice did not enrich inorganic arsenic in the final milled product. Polished rice produced from the parboiling of both rough and wholegrain rice significantly reduced cadmium compared to nonparboiled polished rice, by 25%. This study also identified that trimethylarsine oxide and tretramethylarsonium are widely elevated in the husk and bran of rice and, therefore, gives new insights into the biogeochemical cycling of arsenic in paddy ecosystems.