Heavy Metal Content in Paddy Soils of Ketara, Besut, Terengganu, Malaysia

A study to determine the heavy metal content in paddy soils was carried out at KETARA, Besut, Terengganu, Malaysia. The objective of the study was to determine the heavy metal content of the soil types in the study area. The heavy metals studied were Pb, Cd, Cu, Zn, Fe, Mn and Cr. Heavy metals in the soil were extracted using the sequential extraction method, which consists of four fractions namely the easily leachable and ion exchange (EFLE), acid reducible (AR), oxidizable organic (OO) and resistant (RR). Heavy metals were detected using an inductively coupled plasma mass spectrometer (ICP-MS). The study showed that the highest concentration of heavy metals was found in the resistant fraction (RR) for all the studied soils. Fe was the most dominant metal whereas Cd had the lowest concentration for all studied soil types. With the exception of Fe and Mn, the soils were naturally low in the respective heavy metals (Zn, Cu, Cr, Pb, Cd). The high amount of soil Fe and Mn in the studied soils could be attributed to the occurrence of Fe-Mn hydrous-oxide mottles. Meanwhile, the higher levels of Mn in the ELFE and AR fractions suggest that the continuous usage of agrochemical materials for paddy cultivation activities, rendered high bioavailable Mn in the soils. The elevated levels of Pb and Cd in the soils could possibly be attributed to anthropogenic sources.