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Influence of silicon on arsenic uptake and toxicity in lettuce
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. (Greger group)
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. (Greger group)
Dept. of Land and Water Resources Engineering, Royal Institute of Technology. (KTH-International Groundwater Arsenic Research Group)
Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. (Greger group)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

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.

Keyword [en]
Arsenic, accumulation, silicon, speciation, toxicity
National Category
Botany
Research subject
Plant Physiology
Identifiers
URN: urn:nbn:se:su:diva-87793OAI: oai:DiVA.org:su-87793DiVA: diva2:606380
Available from: 2013-02-19 Created: 2013-02-19 Last updated: 2013-02-19
In thesis
1. Arsenic accumulation in plants for food and phytoremediation: Influence by external factors
Open this publication in new window or tab >>Arsenic accumulation in plants for food and phytoremediation: Influence by external factors
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2013. 52 p.
Keyword
Arsenic, accumulation, availability, distribution, habitat, phy-toremediation, rhizosphere, redox potential, speciation
National Category
Botany
Research subject
Plant Physiology
Identifiers
urn:nbn:se:su:diva-87798 (URN)978-91-7447-653-8 (ISBN)
Public defence
2013-04-02, föreläsningssalen, Lilla Frescati, Lilla Frescativägen 5, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defence the following papers were unpublished and had a status as follows: Paper 2: Manuscript; Paper 4: Manuscript; Paper 5: Manuscript.

Available from: 2013-03-11 Created: 2013-02-19 Last updated: 2016-10-26Bibliographically approved

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