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| Titel |
Studies on the accumulation and transformation of arsenic in ecosystem in Guandu Wetland, Taiwan |
| VerfasserIn |
Y. Y. Chen, C. W. Liu, Y. H. Kao |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061938
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| Zusammenfassung |
| High arsenic (As) is naturally occurred in geothermal areas, it may result in pollution of
downstream wetland and estuary ecosystem. Arsenic concentration is up to 4.32 mg/L in
geothermal spring water and overly exceeded the drinking water guideline of WHO (0.01
mg/L) that may result in wetland ecosystem damage. The influence of aqueous,
solid and plant phase on As mobility in Guandu wetland, Taiwan, is not properly
distinguished yet. The mangroves are particularly growing in study area and Kandelia
obovata is one of the most dominant plant species. The purpose of this study is to
discriminate that integration of aqueous, solid and plant phase is affected by As
redox cycling. The chemical compounds (As, Fe, Mn, TOC, SO42-, FeS2) and
isotopic compositions (δ34S ) in surface water and soil samples were analyzed, to
characterize of As distribution. The sequential extraction of As and total As in plant
samples were analyzed, to estimate the bioconcentration factor (BCF) and transfer
factor (TF), and understand the accumulation and transformation of As for Kandelia
obovata in aqueous and solid phase. The As concentration in plants (23.69 mg/kg) are
higher than the surrounding water (0.0028 mg/L) and soils (16.33 mg/kg). Arsenic
concentration in various plant tissues at maturity follow the order: roots (19.74 mg/kg) >
stems (1.76 mg/kg) > leaves (1.71 mg/kg) > seedlings (0.48 mg/kg), and they are
mostly accumulated in the roots. However, the result of As sequential extraction in
the sediments indicate uptake of chemical compound in plant from sediments is
difficult, depending on low bioavailability in plants. Besides, low transfer factor
(TFstems-roots=0.088, TFleaves-roots=0.088 and TFseedlings-roots=0.024) indicate
that the transformation of As in various plant tissues is very low. The results show
that Kandelia obovata content low As bioavailability and low TF, cause of easy
adaption to grow on As contaminated wetland ecosystem. BCFplants-porewater
(10742.68) is higher than BCFplants-soil (1.49). High BCF between plant and pore water
or soil indicates that uptake and bioaccumulation of As of Kandelia obovata are
significant, therefore, Kandelia obovata is an As hyperaccumulator. The mechanism of
plant uptake might be depending on the oxidation of As-contained FeS2 in the
aerial roots, causing that uptake of As in the plants is from water rather than soil. |
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