钝化剂在烟草植物修复铅镉污染土壤中的作用简

重金属钝化剂可以改变土壤中重金属的形态,降低其在土壤中的有效浓度、植物毒性及生物有效性,影响污染土壤中植物的生长及其对重金属的吸收。在温室盆栽条件下研究了施加羟基磷灰石（HA）、纳米羟基磷灰石（nHA）、纳米零价铁（nFe⁰）和纳米TiO₂（nTiO₂）对烟草植物修复铅镉污染土壤的作用。结果表明,HA降低土壤中Pb、Cd的有效性、促进烟草生长、增加了烟草叶、茎、根中Cd的吸收量和根系中Pb的吸收量,有利于Pb、Cd的钝化和植物修复。nHA也可以降低土壤中Pb、Cd的有效性,增加了烟草叶中Cd的吸收量,有利于Pb、Cd的钝化和Cd的植物提取。nFe⁰和nTiO₂对于土壤Pb和Cd的钝化作用和植物修复均没有显著影响。综合来看,HA最适合应用于烟草植物修复铅镉污染土壤。     

Plant steroid hormones produced under Ni stress are involved in the regulation of metal uptake and oxidative stress in Brassica juncea L

Brassinosteroids (BRs) are involved in the amelioration of various biotic and abiotic stresses. With an aim to explore the role of BRs under heavy metal stress, plants of Brassica juncea L. were grown in pots. The plants were subjected to various concentrations of Nickel metal (0.0, 0.2, 0.4 and 0.6 mM) and harvested on 60th day in order to observe the expression of these hormones. The isolated BRs from the leaves of Brassica plants characterized by GC-MS include 24-Epibrassinolide (24-EBL), Castasterone, Dolicholide and Typhasterole. The effect of isolated 24-EBL was studied on Ni metal uptake and antioxidative defense system in 60 d old plants of Brassica. It was observed that 24-EBL significantly increased the activities of stress ameliorating enzymes and lowered the metal uptake in plants. This is the first report in B. juncea L. plants showing the expression of BRs under metal treatments and effect of the isolated 24-EBL on metal uptake and in oxidative stress management.     

Acute effects of copper and mercury on the estuarine fish Pomatoschistus microps: Linking biomarkers to behaviour

The main objective of the present study was to investigate possible links between biomarkers and swimming performance in the estuarine fish Pomatoschistus microps acutely exposed to metals (copper and mercury). In independent bioassays, P. microps juveniles were individually exposed for 96 h to sub-lethal concentrations of copper or mercury. At the end of the assays, swimming performance of fish was measured using a device specially developed for epibenthic fish (SPEDE). Furthermore, the following biomarkers were measured: lipid peroxidation (LPO) and the activity of the enzymes acetylcholinesterase (AChE), lactate dehydrogenase (LDH), glutathione S-transferases (GST), 7-ethoxyresorufin-O-deethylase (EROD), superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR) and glutathione peroxidase (GPx). LC₅₀s of copper and mercury (dissolved throughout metal concentrations) at 96 h were 568 μg L⁻¹ and 62 μg L⁻¹, respectively. Significant and concentration-dependent effects of both metals on swimming resistance and covered distance against water flow were found at concentrations equal or higher than 50 μg L⁻¹ for copper and 3 μg L⁻¹ for mercury (dissolved throughout metal concentrations). These results indicate that SPEDE was efficacious to quantify behavioural alterations in the epibenthic fish P. microps at ecologically relevant concentrations. Significant alterations by both metals on biomarkers were found including: inhibition of AChE and EROD activities, induction of LDH, GST and anti-oxidant enzymes, and increased LPO levels, with LOEC values ranging from 25 to 200 μg L⁻¹ for copper and from 3 to 25 μg L⁻¹ for mercury (dissolved throughout metal concentrations). Furthermore, significant and positive correlations were found between some biomarkers (AChE and EROD) and behavioural parameters, while negative correlations were found for others (LPO, anti-oxidant enzymes and LDH) suggesting that disruption of cholinergic function through AChE inhibition, decreased detoxification capability due to EROD inhibition, additional energetic demands to face chemical stress, and oxidative stress and damage may contribute to decrease the swimming performance of fish. Since a reduced swimming capability of fish may reduce their ability to capture preys, avoid predators, and interfere with social and reproductive behaviour, the exposure of P. microps to copper and/or mercury concentrations similar to those tested here may decrease the fitness of wild populations of this species.     

Influence of flooding and metal immobilising soil amendments on availability of metals for willows and earthworms in calcareous dredged sediment-derived soils

Soil amendments previously shown to be effective in reducing metal bioavailability and/or mobility in calcareous metal-polluted soils were tested on a calcareous dredged sediment-derived soil with 26 mg Cd/kg dry soil, 2200 mg Cr/kg dry soil, 220 mg Pb/kg dry soil, and 3000 mg Zn/kg dry soil. The amendments were 5% modified aluminosilicate (AS), 10% w/w lignin, 1% w/w diammonium phosphate (DAP, (NH₄)₂HPO₄), 1% w/w MnO, and 5% w/w CaSO₄. In an additional treatment, the contaminated soil was submerged. Endpoints were metal uptake in Salix cinerea and Lumbricus terrestris, and effect on oxidation-reduction potential (ORP) in submerged soils. Results illustrated that the selected soil amendments were not effective in reducing ecological risk to vegetation or soil inhabiting invertebrates, as metal uptake in willows and earthworms did not significantly decrease following their application. Flooding the polluted soil resulted in metal uptake in S. cinerea comparable with concentrations for an uncontaminated soil.     

Eutrophication of Lake Tasaul,Romania—proposals for rehabilitation

Background, aim, and scope  The reclamation of nonferrous metal-polluted soil by phytoremediation requires an overall and permanent plant cover. To select the most suitable plant species, it is necessary to study metal effects on plants over the time, thereby checking that metals remain stored in root systems and not transferred to aerial parts. In this purpose, the seasonal and annual variations of metal bioaccumulation, transfer, and phytotoxicity in Trifolium repens and Lolium perenne grown in a Cd-, Pb-, and Zn-contaminated soil were also studied. Materials and methods  The experimental site was located near a closed smelter. In spring 2004, two areas were sown with T. repens and L. perenne, respectively. Thereafter, the samplings of plant roots and shoots and surrounding soils were realized in autumn 2004 and spring and autumn 2005. The soil agronomic characteristics, the Cd, Pb, and Zn concentrations in the surrounded soils and plant organs, as well as the oxidative alterations (superoxide dismutase [SOD], malondialdehyde [MDA], and 8-hydroxy-2′-deoxyguanosine [8-OHdG]) in plant organs were carried out. Results  Whatever the sampling period, metal concentrations in soils and plants were higher than background values. Contrary to the soils, the fluctuations of metal concentrations were observed in plant organs over the time. Bioaccumulation and transfer factors confirmed that metals were preferentially accumulated in the roots as follows: Cd>Zn>Pb, and their transfer to shoots was limited. Foliar metal deposition was also observed. The results showed that there were seasonal and annual variations of metal accumulation in the two studied plant species. These variations differed according to the organs and followed nearly the same pattern for the two species. Oxidative alterations were observed in plant organs with regard to SOD antioxidant activities, MDA, and 8-OHdG concentrations. These alterations vary according to the temporal variations of metal concentrations. Discussion  Metal concentrations in surrounded soils and plant organs showed the effective contamination by industrial dust emissions. Metals absorbed by plants were mainly stored in the roots. With regard to this storage, the plants seemed to limit the metal transfer to their aerial parts over the time, thereby indicating their availability for metal phytostabilization. Aerial deposition was another source of plant exposure to nonferrous metals. Despite the occurrence of metal-induced oxidative alterations in plant organs, both plant species seemed to tolerate a high metal concentration in soils. Conclusions  Taken together, these results indicated that T. repens and L. perenne were able to form a plant cover on highly Cd-, Pb-, and Zn-polluted soils, to limit the metal transfer to their aerial parts and were relatively metal-tolerant. All these characteristics made them suitable for phytostabilization on metal-contaminated soils. These findings also highlighted the necessity to take into account seasonal and annual variations for a future phytomanagement. Recommendations and perspectives  In this work, the behavior of plant species grown in metal-polluted soil has been studied during 2 years. Obviously, this time is too short to ensure that metals remain accumulated in the root system and few are transferred in aerial parts over the time. It is why regular monitoring should be achieved during more than a decade after the settlement of the plant cover. This work will be completed by the study of the T. repens and L. perenne effects on mobility of metals in order to evaluate the quantities of pollutants which could be absorbed by the biota and transferred to groundwater. Bioaccessibility tests could be also realized on polluted soils in order to evaluate the phytostabilization impacts on the exposition risks for humans.     

污泥堆肥施用于草坪草栽培:Zn和Cu的分布特征简

为了探索污泥堆肥中重金属在土壤-植物系统中的积累与转移特性,通过温室盆栽实验,分析了污泥堆肥对草坪草高羊茅、黑麦草和白三叶生物量积累的情况,研究了污泥堆肥中Zn和Cu在植物和土壤中的分布特征。结果表明,污泥堆肥施用可以有效促进3种草坪草的积累生物量,在0~6 kg/m²的污泥堆肥施用量范围内,草坪草的生物量积累随着施用量的增加而提高。土壤中Zn和Cu的含量随污泥堆肥施加量的增加而增大,85%以上的Zn和Cu残留在土壤中。污泥堆肥中的Zn和Cu均可以被植物吸收,随着污泥堆肥施用量的增加,草坪草对Zn和Cu的吸收量增大,但当污泥堆肥施用量超过一定阈值时,草坪草吸收Zn和Cu不再增加,甚至减少;对于不同的草坪草,这一阈值有所不同。植物对Zn和Cu的吸收量只占土壤中Zn和Cu减少量的5%左右。根据生物富集系数（BCF）的计算结果推测,污泥堆肥的施用对土壤环境的影响大于对植物体内累积Zn和Cu的影响。     

Protection of palak (Beta vulgaris L. var Allgreen) plants from ozone injury by ethylenediurea (EDU): Roles of biochemical and physiological variations in alleviating the adverse impacts

Ameliorative effects of ethylenediurea (N-[2-(2-oxo-1-imidazolinidyl) ethyl]-N′ phenylurea, abbreviated as EDU) against ozone stress were studied on selected growth, biochemical, physiological and yield characteristics of palak (Beta vulgaris L. var Allgreen) plants grown in field at a suburban site of Varanasi, India. Mean eight hourly ozone concentration varied from 52 to 73 ppb which was found to produce adverse impacts on plant functioning and growth characteristics. The palak plants were treated with 300 ppm EDU at 10 days after germination at 10 days interval up to the plant maturity. Lipid peroxidation in EDU treated plants declined significantly as compared to non-EDU treated ones. Significant increment in F_v/F_m ratio in EDU treated plants as compared to non-EDU treated ones was recorded. EDU treated plants showed significant increment in ascorbic acid contents and reduction in peroxidase activity as compared to non-EDU treated ones. As a result of the protection provided by EDU against ozone induced stress on biochemical and physiological characteristics of palak, the morphological parameters also responded positively. Significant increments were recorded in shoot length, number of leaves plant⁻¹, leaf area and root and shoot biomass of EDU treated plants as compared to non-EDU treated ones. Contents of Na, K, Ca, Mg and Fe were higher in EDU treated plants as compared to non-EDU treated ones. The present investigation proves the usefulness of EDU in partially ameliorating ozone injury in ambient conditions.     

Hydroxyiminodisuccinic acid (HIDS): A novel biodegradable chelating ligand for the increase of iron bioavailability and arsenic phytoextraction

The influence of biodegradable chelating ligands on arsenic and iron uptake by hydroponically grown rice seedlings (Oryza sativa L.) was investigated. Even though the growth solution contained sufficient Fe, the growth of rice seedlings gradually decreased up to 76% with the increase of pH of the solution from 7 to 11. Iron forms insoluble ferric hydroxide complexes at neutral or alkaline pH in oxic condition. Chelating ligands produce soluble ‘Fe–ligand complex’ which assist Fe uptake in plants. The biodegradable chelating ligand hydroxyiminodisuccinic acid (HIDS) was more efficient then those of ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), and iminodisuccinic acid (IDS) in the increase of Fe uptake and growth of rice seedling. A total of 79 ± 20, 87 ± 6, 116 ± 15, and 63 ± 18 mg dry biomass of rice seedlings were produced with the addition of 0.5 mM of EDDS, EDTA, HIDS, and IDS in the nutrient solution, respectively. The Fe concentrations in rice tissues were 117 ± 15, 82 ± 8, 167 ± 25, and 118 ± 22 μmol g⁻¹ dry weights when 0.25 mM of EDDS, EDTA, HIDS, and IDS were added to the nutrient solution, respectively. Most of the Fe accumulated in rice tissues was stored in roots after the addition of chelating ligands in the solution. The results indicate that the HIDS would be a potential alternative to environmentally persistent EDTA for the increase of Fe uptake and plant growth. The HIDS also increased As uptake in rice root though its translocation from root to shoot was not augmented. This study reports HIDS for the first time as a promising chelating ligand for the enhancement of Fe bioavailability and As phytoextraction.     

Mitigation effects of silicon rich amendments on heavy metal accumulation in rice (Oryza sativa L.) planted on multi-metal contaminated acidic soil

The mechanisms of stabilization by silicon-rich amendments of cadmium, zinc, copper and lead in a multi-metal contaminated acidic soil and the mitigation of metal accumulation in rice were investigated in this study. The results from a pot experiment indicated that the application of fly ash (20 and 40 g kg⁻¹) and steel slag (3 and 6 g kg⁻¹) increased soil pH from 4.0 to 5.0-6.4, decreased the phytoavailability of heavy metals by at least 60%, and further suppressed metal uptake by rice. Diffusion gradient in thin-film measurement showed the heavy metal diffusion fluxes from soil to solution decreased by greater than 84% after remediation. X-ray diffraction analysis indicated the mobile metals were mainly deposited as their silicates, phosphates and hydroxides in amended treatments. Moreover, it was found metal translocation from stem to leaf was dramatically restrained by adding amendments, which might be due to the increase of silicon concentration and co-precipitation with heavy metals in stem. Finally, a field experiment showed the trace element concentrations in polished rice treated with amendments complied with the food safety standards of China. These results demonstrated fly ash and steel slag could be effective in mitigating heavy metal accumulation in rice grown on multi-metal contaminated acidic soils.     

Acute and chronic effects of nano- and non-nano-scale TiO2 and ZnO particles on mobility and reproduction of the freshwater invertebrate Daphnia magna

Among the emerging literature addressing the biological effects of nanoparticles, very little information exists, particularly on aquatic organisms, that evaluates nanoparticles in comparison to non-nanocounterparts. Therefore, the potential effects of nano-scale and non-nano-scale TiO₂ and ZnO on the water flea, Daphnia magna, were examined in 48-h acute toxicity tests using three different test media, several pigment formulations – including coated nanoparticles – and a variety of preparation steps. In addition, a 21-d chronic Daphnia reproduction study was performed using coated TiO₂ nanoparticles. Analytical ultracentrifugation analyses provided evidence that the nanoparticles were present in a wide range of differently sized aggregates in the tested dispersions. While no pronounced effects on D. magna were observed for nano-scale and non-nano-scale TiO₂ pigments in 19 of 25 acute (48-h) toxicity tests (EC50 > 100 mg L⁻¹), six acute tests with both nano- and non-nano-scale TiO₂ pigments showed slight effects (EC10, 0.5–91.2 mg L⁻¹). For the nano-scale and non-nano-scale ZnO pigments, the acute 48-h EC50 values were close to the 1 mg L⁻¹ level, which is within the reported range of zinc toxicity to Daphnia. In general, the toxicity in the acute tests was independent of particle size (non-nano-scale or nano-scale), coating of particles, aggregation of particles, the type of medium or the applied pre-treatment of the test dispersions. The chronic Daphnia test with coated TiO₂ nanoparticles demonstrated that reproduction was a more sensitive endpoint than adult mortality. After 21 d, the NOEC for adult mortality was 30 mg L⁻¹ and the NOEC for offspring production was 3 mg L⁻¹. The 21-d EC10 and EC50 values for reproductive effects were 5 and 26.6 mg L⁻¹, respectively. This study demonstrates the utility of evaluating nanoparticle effects relative to non-nano-scale counterparts and presents the first report of chronic exposure to TiO₂ nanoparticles in D. magna.     

Comparison of EDTA-enhanced phytoextraction and phytostabilisation strategies with Lolium perenne on a heavy metal contaminated soil

Phytoremediation is a promising and cost-effective strategy to manage heavy metal polluted sites. In this experiment, we compared simultaneously phytoextraction and phytostabilisation techniques on a Cd and Zn contaminated soil, through monitoring of plant accumulation and leaching. Lolium perenne plants were cultivated for 2 months under controlled environmental conditions in a 27.6 dm³-pot experiment allowing the collect of leachates. The heavy metal phytoextraction was promoted by adding Na-EDTA (0.5 g kg⁻¹ of soil) in watering solution. Phytostabilisation was assessed by mixing soil with steel shots (1%) before L. perenne sowing. Presence of plants exacerbated heavy metal leaching, by improving soil hydraulic conductivity. Use of EDTA for phytoextraction led to higher concentration of heavy metal in shoots. However, this higher heavy metal extraction was insufficient to satisfactory reduce the heavy metal content in soil, and led to important heavy metal leaching induced by EDTA. On the other hand, addition of steel shots efficiently decreased both Cd and Zn mobility, according to 0.01 M CaCl₂ extraction, and leaching. However, improvement of growth conditions by steel shots led to higher heavy metal mass in shoot tissues. Therefore, soil heavy metal mobility and plant metal uptake are not systematically positively correlated.     

Seabird feathers as monitors of the levels and persistence of heavy metal pollution after the Prestige oil spill

We measured heavy metal concentrations in yellow-legged gulls (n = 196) and European shags (n = 189) in order to assess the temporal pattern of contaminant exposure following the Prestige oil spill in November 2002. We analysed Pb, Cu, Zn, Cr, Ni and V levels in chick feathers sampled at four colonies during seven post-spill years (2003-2009), and compared results with pre-spill levels obtained from feathers of juvenile shag corpses (grown in spring/summer 2002). Following the Prestige wreck, Cu (4.3-10 μg g⁻¹) and Pb concentrations (1.0-1.4 μg g⁻¹) were, respectively, between two and five times higher than pre-spill levels (1.5-3.6 and 0.1-0.4 μg g⁻¹), but returned to previous background concentrations after three years. Our study highlights the suitability of chick feathers of seabirds for assessing the impact of oil spills on heavy metal contamination, and provides the best evidence to date on the persistence of oil pollution after the Prestige incident.     

钝化剂在烟草植物修复铅镉污染土壤中的作用

重金属钝化剂可以改变土壤中重金属的形态,降低其在土壤中的有效浓度、植物毒性及生物有效性,影响污染土壤中植物的生长及其对重金属的吸收。在温室盆栽条件下研究了施加羟基磷灰石（HA）、纳米羟基磷灰石（nHA）、纳米零价铁（nFe0）和纳米TiO2（nTiO2）对烟草植物修复铅镉污染土壤的作用。结果表明,HA降低土壤中Ph、cd的有效性、促进烟草生长、增加了烟草叶、茎、根中cd的吸收量和根系中Pb的吸收量,有利于Ph、cd的钝化和植物修复。nHA也可以降低土壤中Pb、cd的有效性,增加了烟草叶中cd的吸收量,有利于Pb、cd的钝化和cd的植物提取。nFe0和nTiO2：对于土壤Pb和cd的钝化作用和植物修复均没有显著影响。综合来看,HA最适合应用于烟草植物修复铅镉污染土壤。     

Effect of endophyte-infection on growth parameters and Cd-induced phytotoxicity of Cd-hyperaccumulator Solanum nigrum L

The aim of this work was to evaluate effects of endophytic bacterium inoculation on plant growth and assess the possible mechanism of endophyte in heavy metal phytoremediation. Seeds of Solanum nigrum L. were inoculated with endophyte Serratia nematodiphila LRE07 and were subjected to Cd in the growing medium. Cd produced a significant inhibition on plant growth and a reduction in the content of photosynthetic pigments. The inoculation of endophytic bacterium alleviated the Cd-induced changes, resulting in more biomass production and higher photosynthetic pigments content of leaves compared with non-symbiotic ones. The beneficial effect was more obvious at relatively low Cd concentration (10 μM). Based on the alteration of nutrient uptake and activated oxygen metabolism in infected plants, the possible mechanisms of endophytic bacterium in Cd phytotoxicity reduction can be concluded as uptake enhancement of essential mineral nutrition and improvement in the antioxidative enzymes activities in infected plant.     

Dynamic changes of rhizosphere properties and antioxidant enzyme responses of wheat plants (Triticum aestivum L.) grown in mercury-contaminated soils

A pot experiment was conducted to investigate the dynamic changes in the rhizosphere properties and antioxidant enzyme responses of wheat plants (Triticum aestivum L.) grown in three levels of Hg-contaminated soils. The concentrations of soluble Hg and dissolved organic carbon (DOC) in the rhizosphere soil solutions of the wheat plants were characterised by the sequence before sowing > trefoil stage > stooling stage, whereas the soil solution pH was found to follow an opposite distribution pattern. The activities of antioxidant enzymes in wheat plants under Hg stress were substantially altered. Greater superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activities were observed in the wheat plants grown in a highly polluted soil than in a slightly polluted soil (with increases of 11–27% at the trefoil stage and 26–70% at the stooling stage); however, increasing concentrations of Hg up to seriously polluted level led to reduced enzyme activities. The present results suggest that wheat plants could positively adapt to environmental Hg stress, with rhizosphere acidification, the enhancement of DOC production and greater antioxidant enzyme activities perhaps being three important mechanisms involved in the metal uptake/tolerance in the rhizospheres of wheat plants grown in Hg-contaminated soils.     

Breeding performance of blue tits (Cyanistes caeruleus) and great tits (Parus major) in a heavy metal polluted area

We compared heavy metal levels, calcium levels, breeding parameters and condition of nestling and adult Cyanistes caeruleus and Parus major along a heavy metal pollution gradient. Both species started laying earlier and showed inferior nestling growth and smaller fledging probability in the polluted areas, which are phenologically advanced in spring due to sparse forests. The major inter-specific difference in the responses was that the clutch size and hatching success were decreased in the polluted area in P. major, but not in C. caeruleus. Heavy metal profiles in nestling feces were relatively similar in the two species, though Ni and Pb levels were higher in C. caeruleus than in P. major. However, the latter species showed markedly higher fecal calcium concentrations. Lower calcium levels and higher levels of some heavy metals in C. caeruleus suggest that in Ca-deficient environments this species might be more susceptible to negative pollution effects than P. major.     

Zinc tolerance and uptake by <Emphasis Type="Italic">Arabidopsis halleri ssp. gemmifera</Emphasis> grown in nutrient solution

Background, aim, and scope  

Zinc is an essential micronutrient element but its concentrations found in contaminated soils frequently exceed those required by the plant and soil organisms, and thus create danger to animal and human health. Phytoremediation is a technique, often employed in remediation of contaminated soils, which aims to remove heavy metals or other contaminants from soils or waters using plants. Arabidopsis (A.) halleri ssp. gemmifera is a plant recently found to be grown vigorously in heavy metal contaminated areas of Japan and it contained remarkably high amount of heavy metals in its shoots. However, the magnitude of Zn accumulation and tolerance in A. halleri ssp. gemmifera need to be investigated for its use as a phytoremediation plant.     

Remediation of contaminated agricultural soils near a former Pb/Zn smelter in Austria: batch, pot and field experiments

Metal contaminated crops from contaminated soils are possible hazards for the food chain. The aim of this study was to find practical and cost-effective measures to reduce metal uptake in crops grown on metal contaminated soils near a former metal smelter in Austria. Metal-inefficient cultivars of crop plants commonly grown in the area were investigated in combination with in-situ soil amendments. A laboratory batch experiment using 15 potential amendments was used to select 5 amendments to treat contaminated soil in a pot study using two Barley (Hordeum vulgare L.) cultivars that differed in their ability to accumulate cadmium. Results from this experiment identified 3 of these amendments for use in a field trial. In the pot experiment a reduction in ammonium nitrate extractable Cd (<41%) and Pb (<49%) compared to the controls was measured, with a concurrent reduction of uptake into barley grain (Cd<62%, Pb<68%). In the field extractable fractions of Cd, Pb, and Zn were reduced by up to 96%, 99%, and 99%, respectively in amended soils.     

The arbuscular mycorrhizal fungus Glomus mosseae can enhance arsenic tolerance in Medicago truncatula by increasing plant phosphorus status and restricting arsenate uptake

A pot experiment examined the biomass and As uptake of Medicago truncatula colonized by the arbuscular mycorrhizal (AM) fungus Glomus mosseae in low-P soil experimentally contaminated with different levels of arsenate. The biomass of G. mosseae external mycelium was unaffected by the highest addition level of As studied (200 mg kg⁻¹) but shoot and root biomass declined in both mycorrhizal and non-mycorrhizal plants, indicating that the AM fungus was more tolerant than M. truncatula to arsenate. Mycorrhizal inoculation increased shoot and root dry weights by enhancing host plant P nutrition and lowering shoot and root As concentrations compared with uninoculated plants. The AM fungus may have been highly tolerant to As and conferred enhanced tolerance to arsenate on the host plant by enhancing P nutrition and restricting root As uptake.