The accumulation of arsenic in paddy soils and rice plants with arsenic-containing irrigation water
| Autor: | Ko, Ya-Ting, 柯雅婷 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 The accumulation of arsenic in soils and food crops due to the use of arsenic containing groundwater for irrigation has created worldwide concern. The aims of this study are to compare the accumulation of arsenic in paddy soils by different amounts of irrigation, to understand the vertical and horizontal distribution of As content in the soils, and to measure As content in different organs of rice (Oryza sativa L.). Two plots (high irrigation, H; low irrigation, L) in the study area were located in Jiangjun District, Tainan City, Taiwan, used the same groundwater source. Rice was cultivated in the paddy fields in February 17, 2013. After 122 days, it was harvested. In the jointing stage (April and May, 2013) and the maturing stage of rice growth, we collected the groundwater, soils and rice samples and analyzed arsenic concentration by HG-AA. The concentrations of As in groundwater in January, April, May, and June, 2013 were 3.78, 5.78, 8.42 and 10 μg/L respectively. The pH values in some soil samples were higher than 8.0 corresponding to their high ECs. The rhizosphere soils showed total As content in the range of 1.03-3.54 mg/kg. In the maturing stage, total As concentrations in the H and L fields were 1.03-2.58 and 1.02-3.54 mg/kg, showing no As difference of soil between different amounts of irrigation. As was concentrated in the plow layers of the paddy soils. Ferrous iron, which is mobilized in the bulk soil solution, was oxidized to ferric iron and precipitated as iron oxides/hydroxides on the root surface, the so called iron plaque. The accumulation of As in iron plaque in H field and L field were 114.8-933.0 and 52.29-384.8 mg/kg, this difference was not correlated with As content in the roots. The arsenic content in different parts of rice are found in the order of iron plaque > root > straw > husk > grain. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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