Influence of soil properties and aging on arsenic phytotoxicity.

Bioavailability of As varies among soils, and this needs to be taken into account during environmental risk assessment. Using a standardized barley root elongation assay, we investigated the phytotoxicity of arsenate added to 16 European soils that varied widely in their physicochemical properties. The effective concentrations of As causing 10% (EC10) and 50% (EC50) inhibition were estimated based on the concentrations of total added As or As extracted with 0.

Phytotoxicity of nickel in a range of European soils: influence of soil properties, Ni solubility and speciation.

We investigated the influence of soil properties on Ni toxicity to barley root and tomato shoot growth, using 16 European soils. The effective concentration of added Ni causing 50% inhibition (EC(50)) ranged from 52 to 1929mgkg(-1) and from 17 to 920mgkg(-1) for the barley and tomato test, respectively, representing 37- and 54-fold variation among soils. Soil cation exchange capacity was the best single predictor for the EC(50).

Biofortification of UK food crops with selenium.

Se is an essential element for animals. In man low dietary Se intakes are associated with health disorders including oxidative stress-related conditions, reduced fertility and immune functions and an increased risk of cancers. Although the reference nutrient intakes for adult females and males in the UK are 60 and 75 microg Se/d respectively, dietary Se intakes in the UK have declined from >60 microg Se/d in the 1970s to 35 microg Se/d in the 1990s, with a concomitant decline in human Se status.

Comparison of soil solution speciation and diffusive gradients in thin-films measurement as an indicator of copper bioavailability to plants.

The toxicity effect concentrations (10% effective concentration [EC10] and 50% effective concentration [EC50]) of total added Cu derived from barley root elongation and tomato growth assays varied widely among 18 European soils. We investigated whether this variation could be explained by the solubility or speciation of Cu in soil solutions or the diffusive gradients in thin-films (DGT) measurement. Solubility and Cu speciation varied greatly among the soils tested.

Soil factors controlling the expression of copper toxicity to plants in a wide range of European soils.

The impact of soil properties on metal bioavailability to plants is well recognized. However, the effect of soil bioavailability parameters on toxicity threshold values for Cu in plants needs quantification. Eighteen European soils varying widely in soil properties were amended with CuCl2 to obtain a range of seven concentrations including an unamended control.

Effect of soil characteristics on Cd uptake by the hyperaccumulator Thlaspi caerulescens.

The influence of soil characteristics on the phytoremediation potential of Thlaspi caerulescens is not well understood. We investigated the effect of soil pH and Cd concentration on plant Cd uptake on one soil type, and the variation in Cd uptake using a range of field contaminated soils. On soils with total Cd concentrations of 0.

Scale and causes of lead contamination in Chinese tea.

We investigated the scale and causes of Pb contamination in Chinese tea. Lead concentrations in 1,225 tea samples collected nationally between 1999 and 2001 varied from <0.2 to 97.

Identification of the form of Cd in the leaves of a superior Cd-accumulating ecotype of Thlaspi caerulescens using 113Cd-NMR.

Thlaspi caerulescens (Ganges ecotype) is a known Cd hyperaccumulator, however, the ligands which coordinate to Cd ions in the leaves have not been identified. In the present study, the chemical form of Cd was investigated by using 113Cd-nuclear magnetic resonance (NMR) spectroscopy. Plants were grown hydroponically with a highly enriched 113Cd stable isotope.

Pollution-induced community tolerance of soil microbes in response to a zinc gradient.

The long-term accumulation of Zn in soils provides the microbial community time to adapt to this heavy metal. To assess the effects of long-term exposure to Zn on the metabolic diversity and tolerance to Zn of soil microbial community, the pollution-induced community tolerance (PICT) method, based on the Biolog microtitre plate system, was used. It especially is useful to study gradients of pollutants for detecting PICT.

Subcellular localisation of Cd and Zn in the leaves of a Cd-hyperaccumulating ecotype of Thlaspi caerulescens.

Thlaspi caerulescens (Ganges ecotype) is able to accumulate large concentrations of cadmium (Cd) and zinc (Zn) in the leaves without showing any toxicity, suggesting a strong internal detoxification. The distribution of Cd and Zn in the leaves was investigated in the present study. Although the Cd and Zn concentrations in the epidermal tissues were 2-fold higher than those of mesophyll tissues, 65-70% of total leaf Cd and Zn were distributed in the mesophyll tissues, suggesting that mesophyll is a major storage site of the two metals in the leaves.

Copper uptake by Elsholtzia splendens and Silene vulgaris and assessment of copper phytoavailability in contaminated soils.

Tolerance and metal uptake are two essential characteristics required for phytoextraction of metals from contaminated soils. We compared tolerance and Cu uptake of Elsholtzia splendens (reported previously to be a Cu hyperaccumulator) with Silene vulgaris (the Imsbach population, a well-known Cu-tolerant excluder species), using 30 soils varying widely in total Cu concentration (19-8645 mg kg(-1)). We further investigated the effectiveness of different soil testing methods for predicting plant metal uptake.

Phytoextraction of metals and metalloids from contaminated soils.

The removal of inorganic contaminants by plants is termed phytoextraction. Recent studies have looked at the feasibility of phytoextraction, and demonstrate that both good biomass yields and metal hyperaccumulation are required to make the process efficient. Adding chelating agents to soil to increase the bioavailability of contaminants can sometimes induce hyperaccumulation in normal plants, but may produce undesirable environmental risks.

Mechanisms of arsenic hyperaccumulation in Pteris vittata. Uptake kinetics, interactions with phosphate, and arsenic speciation.

The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata.

Arsenic distribution and speciation in the fronds of the hyperaccumulator Pteris vittata.

•  Pteris vittata is the first plant reported to be a hyperaccumulator of arsenic (As), and little is known about the mechanisms of As hyperaccumulation in this plant. •  Arsenic distribution at the whole plant (fronds) and cellular level was investigated using chemical analyses and energy dispersive X-ray microanalyses (EDXA). Speciation of As in the fronds was determined using X-ray absorption near edge spectroscopy (XANES) analyses.

In situ fixation of metals in soils using bauxite residue: biological effects.

Soils polluted with heavy metals can cause phytotoxicity and exhibit impared microbial activities. In this paper we evaluate the responses of different biological endpoints to in situ remediation processes. Three soil amendments (red mud, beringite and lime) were applied to two soils polluted by heavy metals.

In situ fixation of metals in soils using bauxite residue: chemical assessment.

Contamination of soils with heavy metals and metalloids is a widespread problem all over the world. Low cost, non-invasive, in situ technologies are required for remediation processes. We investigated the efficiency of a bauxite residue (red mud) to fix heavy metals in two soils, one contaminated by industrial activities (French soil), and one by sewage sludge applications (UK soil).

Influence of iron status on cadmium and zinc uptake by different ecotypes of the hyperaccumulator Thlaspi caerulescens.

We have previously identified an ecotype of the hyperaccumulator Thlaspi caerulescens (Ganges), which is far superior to other ecotypes (including Prayon) in Cd uptake. In this study, we investigated the effect of Fe status on the uptake of Cd and Zn in the Ganges and Prayon ecotypes, and the kinetics of Cd and Zn influx using radioisotopes. Furthermore, the T.

Characteristics of cadmium uptake in two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens.

Uptake of Cd and Zn by intact seedlings of two contrasting ecotypes of the hyperaccumulator Thlaspi caerulescens was characterized using radioactive tracers. Uptake of Cd and Zn at 2 degrees C was assumed to represent mainly apoplastic binding in the roots, whereas the difference in uptake between 22 degrees C and 2 degrees C represented metabolically dependent influx. There was no significant difference between the two ecotypes in the apoplastic binding of Cd or Zn.

Trends in (13)C/ (12)C ratios and C isotope discrimination of wheat since 1845.

Archived wheat grain and straw samples from the unfertilised plot of the Broadbalk Continuous Wheat Experiment at Rothamsted, England, were used to investigate the trends in stable C isotope ratios since 1845. Grain δ(13)C was higher than straw δ(13)C. Both grain and straw δ(13)C have decreased by approximately 2.