期刊名称：Journal of Environmental Science and Technology
印刷版ISSN：1994-7887
电子版ISSN：2077-2181
出版年度：2014
卷号：7
期号：3
页码：154-165
DOI：10.3923/jest.2014.154.165
出版社：Asian Network for Scientific Information
摘要：The study discusses iron speciation in upland and lowland agricultural soils of Peninsular Malaysia. Generally, iron speciation in upland soils is influenced by the formation of iron oxyhydroxides and iron precipitates, due to intense chemical weathering processes. The bioavailability of iron (easily leacheable and exchangeable, ELFE fraction) is very low and this could be attributed to its occurrence in the insoluble form. In the lowland soils, however, iron speciation varied widely due to varied soil composition, redox conditions and agricultural practices. Generally, soils in lowland regions are more clayey and silty compared to those in upland regions. The iron speciation in the Organic Oxizable (OO) fraction is also higher, due to the higher organic carbon content in soils. As with upland soils, the biovailability of iron in the lowland soil is also very low. In riverine alluvial deposits, iron tends to accumulate in the RR fraction, followed by the OO and Acid Reducible (AR) fractions. In the non-paddy areas, soils in the lowland region were found to be highly oxidized. Due to the shallow water table, these soils were exposed to the alternate submergence and exposure cycles during the wet and dry seasons respectively, resulting in the formation of iron and manganese mottles. Iron in these soils is concentrated mainly in the resistant fraction (RR), followed by the OO fraction. Due to the high organic carbon content, iron in peat soils is fixed mainly by organic matter (OO fraction) but it also existed in the resistant form (RR fraction).
