Magnetite is a magnetic, Fe(II)-Fe(III)-mineral formed through abiogenic and biogenic pathways. It constitutes an attractive material for remediation due to its reactivity, large surface-area-to-volume ratio when present as nanoparticles, and magnetic recoverability. Magnetite can be repeatedly microbially oxidized or reduced, but it is unclear how this influences the reactivity of magnetite towards toxic metal or metalloid contaminants. In this study, magnetite (both abiogenic and biogenic) was exposed to microbial Fe(II) oxidation and Fe(III) reduction, before reacted with hexavalent chromium (Cr(VI)) or pentavalent arsenic (As(V)). Results showed microbial reduction of both magnetite types improved the removal rate of Cr(VI) from solution, though surprisingly microbial Fe(II)-oxidation also showed enhanced reactivity towards Cr(VI) compared to un-treated magnetite. Synchrotron based analysis confirmed the formation of Cr(III) at the surface of the magnetite. Reactivity with As was less dramatic and showed un-treated material was able to remove As(V) from solution faster than microbially Fe(III)-reduced and Fe(II)-oxidized magnetite. The presence of humic substances was also shown to lead to a decreased reactivity of biogenic and abiogenic magnetite towards As(V) and Cr(VI). Our results imply that Fe-metabolizing bacteria influence the immobilization of contaminants and should be considered when evaluating remediation schemes, especially where Fe-metabolizing bacteria are active.

A new method for the speciation analysis of inorganic germanium (Ge(OH)(4)), monomethylgermanium (MMGe) and dimethylgermanium (DMGe) in complex acidic aqueous leachates by liquid chromatography coupled to inductively coupled plasma mass spectrometry (LC-ICP-MS) was developed. The species are separated using anion exchange chromatography with tartrate added as complexing agent. When tartrate was added to the sample and the eluent chromatography was not affected by sulfate concentrations up to 100 mM. The He collision mode (MS/MS mode) removes polyatomic plasma- and matrix-based interferences, thus providing the selectivity in Ge speciation required for the complex samples. With LOQs of 62 ng L-1 (DMGe), 67 ng L-1 (MMGe) and 164 ng L-1 (Ge(OH)(4)) the method was sufficiently sensitive for the intended application. The developed method was applied to biological and chemical leachates of sulfidic flue dust from copper shale smelting (Theisen sludge). Only small amounts of methylated Ge species were determined next to inorganic Ge in these leachates. (C) 2019 Elsevier B.V. All rights reserved.

ABSTRACT Side chain-containing steroids are ubiquitous constituents of biological membranes that are persistent to biodegradation. Aerobic, steroid-degrading bacteria employ oxygenases for isoprenoid side chain and tetracyclic steran ring cleavage. In contrast, a Mo-containing steroid C-25 dehydrogenase (S25DH) of the dimethyl sulfoxide (DMSO) reductase family catalyzes the oxygen-independent hydroxylation of tertiary C-25 in the anaerobic, cholesterol-degrading bacterium Sterolibacterium denitrificans. Its genome contains eight paralogous genes encoding active site α-subunits of putative S25DH-like proteins. The difficult enrichment of labile, oxygen-sensitive S25DH from the wild-type bacteria and the inability of its active heterologous production have largely hampered the study of S25DH-like gene products. Here we established a heterologous expression platform for the three structural genes of S25DH subunits together with an essential chaperone in the denitrifying betaproteobacterium Thauera aromatica K172. Using this system, S25DH1 and three isoenzymes (S25DH2, S25DH3, and S25DH4) were overproduced in a soluble, active form allowing a straightforward purification of nontagged αβγ complexes. All S25DHs contained molybdenum, four [4Fe-4S] clusters, one [3Fe-4S] cluster, and heme B and catalyzed the specific, water-dependent C-25 hydroxylations of various 4-en-3-one forms of phytosterols and zoosterols. Crude extracts from T. aromatica expressing genes encoding S25DH1 catalyzed the hydroxylation of vitamin D3 (VD3) to the clinically relevant 25-OH-VD3 with >95% yield at a rate 6.5-fold higher than that of wild-type bacterial extracts; the specific activity of recombinant S25DH1 was twofold higher than that of wild-type enzyme. These results demonstrate the potential application of the established expression platform for 25-OH-VD3 synthesis and pave the way for the characterization of previously genetically inaccessible S25DH-like Mo enzymes of the DMSO reductase family. IMPORTANCE Steroids are ubiquitous bioactive compounds, some of which are considered an emerging class of micropollutants. Their degradation by microorganisms is the major process of steroid elimination from the environment. While oxygenase-dependent steroid degradation in aerobes has been studied for more than 40 years, initial insights into the anoxic steroid degradation have only recently been obtained. Molybdenum-dependent steroid C25 dehydrogenases (S25DHs) have been proposed to catalyze oxygen-independent side chain hydroxylations of globally abundant zoo-, phyto-, and mycosterols; however, so far, their lability has allowed only the initial characterization of a single S25DH. Here we report on a heterologous gene expression platform that allowed for easy isolation and characterization of four highly active S25DH isoenzymes. The results obtained demonstrate the key role of S25DHs during anoxic degradation of various steroids. Moreover, the platform is valuable for the efficient enzymatic hydroxylation of vitamin D3 to its clinically relevant C-25-OH form.

The investigation aims at a hydrometallurgical processing approach for an environmentally hazardous material called "Theisenschlamm", which is a flue dust of former copper shale processing in Germany. Besides eliminating the negative environmental impact, processing of this material would also be a contribution to a circular economy, since it contains about 16 wt.-% zinc, 14 wt.-% lead, minor amounts of copper and tin, as well as valuable elements of strategic economic importance, such as rhenium, molybdenum and germanium. The mainly sulfidic matrix of the Theisenschlamm was characterised using scanning electron microscopy in combination with QEMSCAN software. Leaching of Theisenschlamm in acidic and alkaline media, as well as the effect of oxidising agents, was studied in order to extract zinc, copper, rhenium, germanium and molybdenum. In both sulphuric acid and sodium hydroxide solutions, the addition of oxidising agents (hydrogen peroxide and ozone) improved metal extraction efficiencies significantly. The leaching system sulphuric acid/hydrogen peroxide was investigated in more detail, with focus on the optimisation of rhenium extraction and its effect on the extraction efficiencies of the other target elements. Response surface methodology was applied with respect to H2SO4 concentration (0.1-1.2 mol/L), H2O2 concentration (0.1-2.8 mol/L) and solid:liquid ratio (40-150 g/L). This study shows that oxidative leaching enables the extraction of zinc, copper, rhenium, germanium and molybdenum from this sulfidic material. In terms of rhenium extraction, a low acid concentration is favourable; however, lowering the acid concentration results in a reduced yield of other target elements (e.g. molybdenum).

The recovery of strategic elements from secondary mineral sources and low-grade ores is of increasing relevance due to a changing global market as well as for reasons of sustainability. The present article shows the potential of biohydrometallurgy as an effective technology for mobilization of metals from secondary sources. Furthermore, the application of membrane separation as a successful technique to recover metals from bioleaching solutions is presented. These issues are discussed within the scope of recent research projects.

The recovery of strategic elements from secondary mineral resources and low grade ores is of increasing relevance, due to a changing global market as well as for reasons of sustainability. The present article shows the potential of biohydrometallurgy as an efficient technology for mobilization of metals from secondary mineral resources. Furthermore, the application of membrane separation as a successful technique for the recovery of metals from bioleaching solutions is presented. These issues are discussed within the scope of recent research projects.

Strategic elements are essential for industrialized countries and both, demand and prices are constantly increasing. The exploitation of so far unutilized polymetallic mining waste could ensure a reliable supply. Mining residues, like the investigated German flue dust deposit from copper ore smelting, represent a promising approach for metal extraction. By bioleaching, the sulfide bonded metals can be dissolved from the mineral phase. Downstream processes are required to separate the target elements from the obtained multicomponent leaching solution. One promising technology is nanofiltration (NF). Three polymeric NF membranes (NF99HF, UTC-60, NP010) were screened to investigate the separation performance of Co, Cu, Ge, Mo, Re, and Zn in a dead-end set-up, in particular the pH-dependent retention. The study shows that pH and thus, the formed ionic species have a major influence on retention and separation performance. Mainly based on size exclusion, a selective separation of Re seems feasible with the NF99HF and UTC-60 at pH 7. Under acidic conditions, a separation during concentrating cannot be realized in dead-end by NF because shearing forces and the build-up concentration as well as the electric field gradient forces the permeation of the solutes. However, if the recovery and ionic strength of the solution is set low, the selectivity can be increased even at pH 2. (C) 2017 Elsevier B.V. All rights reserved.

A novel sequential extraction method for evaluation of the mobilization behavior of rare earth elements in soils and mine tailings materials is presented. The sequence consists of the following four steps: 0.05 mol L(-1) calcium nitrate (easily soluble and ion exchange fraction), 0.1 mol L(-1) citric acid (fraction mobilized by complexation and carbonate bound), 0.05 mol L(-1) hydroxylamine hydrochloride (pH = 2) (reducible fraction), 1.4 mol L(-1) nitric acid (acid soluble fraction). The procedure was optimized with a certified soil material and a mine tailings material and was applied to eight samples of a soil profile. The different results obtained by using either the developed method or the widespread used BCR-Method for comparison are discussed. There were clear advantages using the newly created sequential extraction procedure in getting more detailed information about the bioavailable fraction and a fraction addressing REE phosphates.

Increasing production of rare earth elements (REE) might lead to future contamination of the environment. REE have been shown to accumulate in high concentrations in roots of plants. Plant experiments with Zea mays exposed to a nutrient solution containing gadolinium (Gd) or yttrium (Y) with 10 mg L-1 Gd or Y were carried out to investigate this accumulation behaviour. Total concentrations of 3.17 g kg(-1) and 8.43 g kg(-1) of Gd and Y were measured in treated plant roots. Using a novel combination of laser ablation mass spectrometry and time-of-flight secondary ion mass spectrometry, imaging of location and concentration of Gd and Y was carried out in root thin sections of treated roots. Single spots of elevated REE concentration were found at the epidermis, while inside the cortex, weak signals of Gd+ and Y+ were aligning with the root cell structures. The composition of Gd-containing secondary ions proves an REE-oxide phase accumulated at the epidermis, limiting REE availability for further uptake. (C) 2016 Elsevier Ltd. All rights reserved.

Environmental contextThe environmental behaviour and toxicological effects of antimony depend strongly on the specific form of the element, and thus methods have been developed for measuring the various forms of antimony. These methods, applicable to quite clean samples, often fail when applied to more complex environmental samples. We discuss some of the pitfalls in determining environmental antimony forms and the resulting risk of getting the bigger picture wrong regarding antimony pollution. AbstractThe major findings of ~20 years of research on the analysis of antimony species in environmental samples are summarised in this paper. The complex chemistry of antimonite (SbIII) as well as of antimonate (SbV) plays a major role in chromatographic speciation of these species. For simple matrices, like surface or ground-water samples, antimony redox speciation has become a routine analysis and is robust and highly reproducible, if certain aspects are taken into consideration. These aspects are the formation of a stable complex of SbIII and complex formation kinetics. Then the antimony redox species can be separated on an anion-exchange column and detected with a suitable element detector (inductively coupled plasma–mass spectrometry (ICP-MS) or hydride generation–atomic fluorescence spectrometry (HG-AFS)) for trace analysis. The influence of complexing agents in the sample matrix, or in the eluent, on the formation of SbIII and SbV complexes and possible corruption of chromatography is discussed. This ability of antimony to form rather stable complexes also increases the risk of artefact formation during extraction of solid samples.

Antimony has a fascinating, but also difficult, environmental chemistry, with many fundamental questions yet unanswered. In the Foreword to the first Research Front on antimony published in Environmental Chemistry in 2009, William Maher, the guest editor, qualified antimony in the environment as ‘the new global puzzle’ and listed some issues that, besides developing better analytical procedures, urgently needed to be examined: chemical speciation, environmental cycling, mechanisms by which plants and animals accumulate and exclude antimony, and potential environmental risks. These subjects remain topical seven years later. The present Research Front gathers a series of papers on antimony, ranging from environmental issues to human health, with the aim of reflecting the current situation and fostering significant future work. Not surprisingly, many of these papers tackle the questions posed by William Maher. The need for reliable data, and hence for reliable analytical methods, remains the Achilles heel in antimony research, with adequate certified reference materials still missing for many matrices and many open questions regarding chemical speciation. Daus and Hansen clarify the situation as far as chromatographic-based methods for the determination of Sb/Sb redox speciation is concerned; their review article opens the Research Front. Antimony biomethylation remains a controversial issue with reported results being suspiciously dependent on the techniques (with the most widely applied hydride generation very prone to artefacts) and standards used. In this regard, the new analytical method for determining the content of trimethylated antimony in plant tissues developed by Mestrot and co-workers represents a significant step forward that will help to develop studies on soil-plant transfer of this alkyl derivative of antimony. Antimony mobility in the various environmental compartments remains a hot topic, as discussed in three articles in the present Research Front. Majzlan and co-workers address existing contradictory observations in the literature regarding the mobility of antimony in water and soils by taking into account the kinetics of formation of the mineral tripuhyite, which is considered to be the last sink of antimony in nature. Other discrepancies such as the greater mobility of antimony observed in shooting range soils when compared with that observed in laboratory experiments and the absence of Sb in such soils are addressed in a study by Ilgen and Trainor, wherein the effects of chemical controls on the oxidation of Sb to Sb are examined. Interestingly, Pb, present in high amounts in such soils, owing to its use in bullets, catalyses this oxidation process. The effect of a third factor, i.e. microorganisms, on the mobility of antimony is studied in unpolluted wetland soils by Rouwane et al. These authors have found that, in contrast with arsenic, soil microbial activity may not fully control the release of antimony, with natural organic matter probably being a key controlling factor. On the biological side, current knowledge on how antimony enters cells and how cells react in the presence of this element is presented in the review article by Tamás. Finally, the response of human epidermal keratinocytes to Sb (added as potassium antimony tartrate) and As (added as sodium arsenite) points to a potential action of antimony as a human skin carcinogen worthy of further study. The Research Front closes with the presentation of a new approach, using antimony as an example, for building up knowledge from data. The Building up Knowledge Initiative (BUKI) aims to avoid repetition of unproven beliefs and studies on similar subjects that jeopardise real scientific progress. Antimony presents an excellent test case for the BUKI. We are very pleased to present this collection of papers at the forefront of antimony environmental research and hope that the studies will provide precious, pertinent food for thought for further antimony research.We thank the authors and referees for their substantial contributions to this Research Front.

Aims: The aim of this study was to investigate the potential of bioleaching for the treatment of an environmentally hazardous waste, a blast-furnace flue dust designated Theisen sludge.Methods and Results: Bioleaching of Theisen sludge was investigated at acidic conditions with Acidithiobacillus ferrooxidans in pure and mixed-species culture with Acidiphilium. In shaking-flask experiments, bioleaching parameters (pH, redox potential, zinc extraction from ZnS, ferrous-and ferric-iron concentration) were controlled regularly. The analysis of the dissolved metals showed that 70% zinc and 45% copper were extracted. Investigations regarding the arsenic and antimony species were performed. When iron ions were lacking, animonate (Sb(V)) and total arsenic concentration were highest in solution. The bioleaching approach was scaled up in stirred-tank bioreactors resulting in higher leaching efficiency of valuable trace elements. Concentrations of dissolved antimony were approx. 23 times, and of cobalt, germanium, and rhenium three times higher in comparison to shaking-flask experiments, when considering the difference in solid load of Theisen sludge.Conclusions: The extraction of base and trace metals from Theisen sludge, despite of its high content of heavy metals and organic compounds, was feasible with iron-oxidizing acidophilic bacteria. In stirred-tank bioreactors, the mixed-species culture performed better.Significance and Impact of the Study: To the best of our knowledge, this study is the first providing an appropriate biological technology for the treatment of Theisen sludge to win valuable elements.

The oxidation of phenylarsine oxide (PhAsO) and cacodylic acid (CA) by UV-A assisted heterogeneous photocatalysis using ZnO and TiO2 was studied. The influence of pH and catalyst load was assessed using multifactorial design. Both studied variables showed a significant effect on organoarsenical degradation. PhAsO was completely removed in 5 min at pH 6.3 using TiO2 as catalyst under optimum conditions. In contrast, the same removal extent was achieved at a wider pH range (pH 4 to 10), when ZnO was used. A 100% degradation was reached for CA at 60 min irradiation using ZnO and pH 9.3. In comparison, only 60 % CA degradation was achieved using TiO2 at pH 6.5. Regarding the by-product formation during photocatalysis, the main degradation products found for PhAsO were phenylarsonic acid (PhAs), phenol and inorganic arsenate. With CA, only methanol and inorganic arsenate were found as main reaction products.

Since decades, the demand of strategic elements is increasing. On the one hand, the industrialization of emerging countries is advancing due to the desire of a higher standard of living. On the other hand, the technical progress of the industrial countries leads to an enhanced provisioning of raw materials, such as strategic elements. Therefore, the supply is becoming increasingly difficult and supply bottlenecks might occur. Hence, the potential of secondary mining has to be exploited to uncover yet untapped resources. In the present study, the potential of a Theisenschlamm mono-landfill, a residue of German copper smelting with various strategic elements (e.g. Co, Ge, Mo, Re, Sb) included, shall be illustrated. By means of a hybrid process, consisting out of bioleaching and downstream processing, the target elements shall be mobilized and processed. As part of the element-specific procedures, the presented study investigates the applicability of nanofiltration to separate mono-and divalent metal ions in aqueous solution. Three thin-film polymeric nanofiltration membranes were investigated to determine the pH-dependent separation performance of Ge, Mo, and Re. Membrane screening experiments were conducted in dead-end set-up (15 bar, 25 degrees C) with the single and combined elements and aimed at identifying a suitable membrane for the proposed cross-flow set-up. The results demonstrate that rhenium could be separated from the multicomponent solution by the utilized RO90 membrane, which accounts for a market potential of approx. 19 Mio. $.

Chemie Ingenieur TechnikVolume 88, Issue 9 p. 1344-1344 Vortrag Vom Abfallprodukt zum strategischen Metall – Ein hybrider Prozess zur Wertstoffrückgewinnung aus Laugungslösungen K. Meschke, Corresponding Author K. Meschke Katja.Meschke@tun.tu-freiberg.de Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandTechnische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorK. Bohlke, K. Bohlke Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorDr. B. Daus, Dr. B. Daus Helmholtz-Zentrum für Umweltforschung GmbH UFZ, Department Analytik, Permoserstraße 15, 04318 Leipzig, DeutschlandSearch for more papers by this authorDr. R. Haseneder, Dr. R. Haseneder Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorProf. Dr. J.-U. Repke, Prof. Dr. J.-U. Repke Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, Deutschland Technische Universität Berlin, Prozess- und Verfahrenstechnik, Fachgebiet Dynamik und Betrieb technischer Anlagen, Straße des 17. Juni 135, 10623 Berlin, DeutschlandSearch for more papers by this author K. Meschke, Corresponding Author K. Meschke Katja.Meschke@tun.tu-freiberg.de Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandTechnische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorK. Bohlke, K. Bohlke Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorDr. B. Daus, Dr. B. Daus Helmholtz-Zentrum für Umweltforschung GmbH UFZ, Department Analytik, Permoserstraße 15, 04318 Leipzig, DeutschlandSearch for more papers by this authorDr. R. Haseneder, Dr. R. Haseneder Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, DeutschlandSearch for more papers by this authorProf. Dr. J.-U. Repke, Prof. Dr. J.-U. Repke Technische Universität Bergakademie Freiberg, Institut für Thermische Verfahrenstechnik, Umwelt- und Naturstoffverfahrenstechnik, Leipziger Straße 28, 09599 Freiberg, Deutschland Technische Universität Berlin, Prozess- und Verfahrenstechnik, Fachgebiet Dynamik und Betrieb technischer Anlagen, Straße des 17. Juni 135, 10623 Berlin, DeutschlandSearch for more papers by this author First published: 29 August 2016 https://doi.org/10.1002/cite.201650226AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume88, Issue9Special Issue: ProcessNet-Jahrestagung und 32. DECHEMA-Jahrestagung der Biotechnologen 2016September, 2016Pages 1344-1344 RelatedInformation

The dissolution of arsenic-bearing iron(III) (oxyhydr)oxides during combined microbial iron(III) and arsenate(V) reduction is thought to be the main mechanism responsible for arsenic mobilization in reducing environments. Besides its mobilization during bioreduction, arsenic is often resequestered by newly forming secondary iron(II)-bearing mineral phases. In phosphate-bearing environments, iron(II) inputs generally lead to vivianite precipitation. In fact, in a previous study we observed that during bioreduction of arsenate(V)-bearing biogenic iron(III) (oxyhydr)oxides in phosphate-containing growth media, arsenate(V) was immobilized by the newly forming secondary iron(II) and iron(II)/iron(III)mineral phases, including vivianite. In the present study, changes in arsenic redox state and binding environment in these experiments were analyzed. We found that arsenate(V) partly replaced phosphate in vivianite, thus forming a vivianite-symplesite solid solution identified as Fe3(PO4)1.7(AsO4)0.3·8H2O. Our data suggests that in order to predict the fate of arsenic during the bioreduction of abiogenic and biogenic iron(III) (oxyhydr)oxides in arsenic-contaminated environments, the formation of symplesite-vivianite minerals needs to be considered. Indeed, such mineral phases could contribute to a delayed and slow release of arsenic in phosphate-bearing surface and groundwater environments.

Arsenic contamination of groundwater and soils threatens the health of tens of millions of people worldwide. Understanding the way in which arsenic is taken up by crops such as rice, which serve as a significant source of arsenic in the human diet, is therefore important. Membrane transport proteins that catalyse arsenic uptake by roots, and translocation through the xylem to shoots, have been characterized in a number of plants, including rice. The transporters responsible for loading arsenic from the xylem into the phloem and on into the seeds, however, are yet to be identified. Here, we show that transporters responsible for inositol uptake in the phloem in Arabidopsis also transport arsenic. Transformation of Saccharomyces cerevisiae with AtINT2 or AtINT4 led to increased arsenic accumulation and increased sensitivity to arsenite. Expression of AtINT2 in Xenopus laevis oocytes also induced arsenite import. Disruption of AtINT2 or AtINT4 in Arabidopsis thaliana led to a reduction in phloem, silique and seed arsenic concentrations in plants fed with arsenite through the roots, relative to wild-type plants. These plants also exhibited a large drop in silique and seed arsenic concentrations when fed with arsenite through the leaves. We conclude that in Arabidopsis, inositol transporters are responsible for arsenite loading into the phloem, the key source of arsenic in seeds.

Arsenic (As) plays an important role in rice production as vast soils used for rice cultivation contain As. To understand how rice plants deal with inorganic As (III) and As (V) and organic As in their tissue, it is important to obtain specific information on how much and what species of As are present in which tissue of the rice plant. The protocol presented here allows to analyse the As contents and As speciation in roots, shoots, and husks of rice plants, and thus permits direct comparison of the As contents of these rice plant tissues.