| 1. |
- Bergqvist, Claes, 1977-, et al.
(författare)
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Accumulation and speciation of arsenic in vegetables cultivated in soils with various As availability
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The toxicity of arsenic (As) in the environment is controlled by its concentration, availability and speciation. The aims of the study were to evaluate the accumulation and speciation of As in three vegetables (carrot, lettuce, spinach) cultivated in both contaminated and natural soils with various As concentrations and to estimate the concomitant health risks associated with the consumption of the vegetables. Arsenic concentration and speciation in plant tissues and soils was analysed by HPLC, AAS and X-ray absorption near-edge structure (XANES) spectroscopy. To estimate the plants influence in the rhizosphere, organic acids in lettuce root exudates were analysed by ion chromatography. The results showed that the As accumulation was higher in plants cultivated in soil with higher As extractability. Arsenate predominated in the soils, rhizosphere and root exudates of lettuce. Succinic acid was the major organic acid in lettuce root exudates. Arsenite was the predominating As species in the shoots of healthy looking plants. In plants showing signs of phytotoxicity, arsenate was predominating. Ingestion of the tested vegetables may result in an intake of elevated levels of As.
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| 2. |
- Bergqvist, Claes, 1977-
(författare)
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Arsenic accumulation in plants for food and phytoremediation : Influence by external factors
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Arsenic (As) appears in the environment as various As species, which may vary in plant uptake and toxicity. Moreover, As exposure may vary between habitat due to availability and speciation, both of which are influenced by redox potential. To decrease As uptake, addition of silicate may be a tool.The aim of the study was to investigate how the external factors As availability, plant habitats, silicon and oxygen level, influenced the accumulation and speciation of As in plants for food and phytoremediation in a temperate region. The external factors were chosen due to their previously showed influence on As in plants.The risks with dietary As was investigated by plant As accumulation and speciation in carrot, lettuce and spinach grown in alum shale and glassworks soils, and by the influence of silicon on As accumulation in lettuce in hydroponics. Suitable plants for As phytoremediation was investigated by analysing plants from various habitats, and by the O2 influence on phytofiltration.The results showed that vegetables accumulated more As in soils with higher As extractability, and the As extractability in the rhizosphere was higher than in bulk soil. Also, the As concentration in lettuce was higher in hydroponics than in soil, but silicon reduced the accumulation of As in lettuce in hydroponics. Also, the more toxic inorganic As were the main As species detected in vegetables, compared with the less toxic organic As. For phytoremediation, the results showed a low As accumulation in emergent and terrestrial plants. Submerged plants had had a higher shoot As concentration. In general, the habitat had a major influence on the As accumulation in plants. The results also showed that the As accumulation properties in Elodea canadensis was reduced at higher O2.In conclusion, consumption of vegetables cultivated in As polluted soils can result in an elevated intake of inorganic As, and E. canadensis is a promising candidate for As phytofiltration in a temperate region.
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| 3. |
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| 4. |
- Bergqvist, Claes, 1977-, et al.
(författare)
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Oxygen influences on arsenic behaviour in sediment-water-plant system of Elodea canadensis
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Phytofiltration can be used to remove arsenic (As) from water using the submerged macrophyte Elodea canadensis. To understand the effects of aeration on this system, we investigated the influence of different O2 levels on the As concentration and speciation in sediment, water and E. canadensis,and the efficiency of phytofiltration of As by this plant. The water in pots with As, E. canadensis and/or sediment were aerated with N2, air or left unmodified to create low, high and medium O2 levels, respectively. Analyses of As concentration and species were performed with HPLC-AAS. The results showed that the As accumulation properties by E. canadensis decreased at high O2. Medium O2 had the lowest As release from sediment to water and among the highest plant As accumulation. Arsenate predominated in the sediment-water-plant system, but arsenite increased with decreasing O2. To create conditions favouring the binding of As in sediment and accumulation from water by E. canadensis, the O2 concentration should be medium.
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| 5. |
- Greger, Maria, 1956-, et al.
(författare)
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Influence of silicon on arsenic uptake and toxicity in lettuce
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Lettuce grown in soil is found to contain high concentration of the toxic element arsenic (As). The aim was therefore to investigate uptake and speciation of As in lettuce as well as the influence of silicon (Si) on As uptake, since Si may diminish the As uptake. Plants were cultivated in nutrient solution containing arsenite or arsenate with or without silicate. Uptake and distribution of As between roots and shoots, As accumulation in cell walls, As speciation and toxic effect on biomass were analysed. Results show that arsenite was more toxic to lettuce than arsenate. Silicate decreased the toxicity to arsenate but very little of the arsenite toxicity was changed by Si. On the other hand, Si diminished the arsenite uptake more than the arsenate uptake. There was higher concentration of arsenate than of arsenite in the plant independent which As species added. When arsenate was added, the As concentration in shoot was half of that in the root and this distribution did not change with Si addition. When arsenite was added, about 10% of As was found in the shoots and 90% in the roots, but changed in the presence of Si to be evenly distributed in the plant. In both roots and shoot, about 40% of the As was found in the cell wall fraction, and only in the shoot when arsenite was added, Si increased this fraction to 47%. The extraction efficiency when analysing the As-species was lower in shoot than in roots, especially in the presence of arsenite and Si. The opposite was found for the As concentration in pellets after extraction. This pointed towards variations in the strength of binding of arsenite and arsenate between roots and shoots and between Si and non-Si treated plants.
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