Dynamics of arsenic in agricultural soils: simulation by soil column experiment
Date Issued
2015
Date
2015
Author(s)
石冠倫
Abstract
Arsenic (As) in groundwater in Taiwan comes from the natural materials in the aquifers under reducing conditions. As-contaminated groundwater has long been one of the irrigation sources. Arsenic concentration of groundwater close to Dong Shan River is 0.2 mg/L, 87.8% of which is in the form of As(III). In this study, the fractionation of arsenic in soils from Dong Shan River basin was performed to shed light on the movement and transformation of arsenic species, and the allowable rate of application of As-contaminated groundwater was estimated. The arsenic level of the soils from the sampled farmland (LT) and background soil (BG) are 65.0 mg/Kg and 17.4 mg/Kg, respectively. It implies that arsenic accumulation in soil under long-term irrigation of As-contaminated groundwater. The result of sequential extraction showed that 80% of total arsenic in the soil from farmland is associated with amorphous (F3) or crystalline hydrous Fe/Al oxides (F4). There are dynamic changes of different fractions in laboratory-scale soil columns with time, and the accumulation of arsenic in topsoil within 2 cm is obvious. Arsenic added to soil through irrigation was firstly converted to non-specific bound fraction (F1) and specific bound fraction (F2), but the net change of amorphous Fe/Al hydrous oxides-bound As (F3) or crystalline Fe/Al hydrous oxides-bound As (F4) was little. Arsenic was also found being removed from soil by leaching.
Subjects
Arsenic
soil
groundwater
fractionation
sequential extraction
leaching
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-104-R02541203-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):6615885e2171a179d7900306832b85e9