Bioavailable cadmium and zinc in soil in sugarcane cultivation area: Mae Sot, Tak province

Abstract

There are several methods for determination of metals in soil. Among these, EDTA, DTPA and CaCl2 as a single extractant and another sequential extract using the first step of Community Bureau of Reference (BCR) procedure (using acetic acid) were selected for this study to determine bioavailable of cadmium (Cd) and zinc (Zn) from contaminated soil samples from Mae Sot, Tak Province. In order to examine which procedure is the most suitable for this contaminated area, sugarcane samples were also collected from the same site of soil sampling. Total Cd and Zn concentrations were analyzed from six parts of sugarcane; root, underground stem, bagasse, juice, leave and top. Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) was used for determination concentrations of the metals. In addition, soil properties were measured such as pH, oxidation-reduction potential (Eh) and organic matter content (OM). The result shows that for the underground part (root) has highest concentration of Cd and Zn. However, if it is considered in term of metal accumulated in mass, both total quantities of the two metals accumulated more in above ground parts. The correlation coefficient analysis was performed using SPSS version 11.5. Spearman correlation coefficient was determined by correlating total metal contents in soil and sugarcane with extractable metals from soil by four different extraction procedures. To examine the most suitable extraction procedures used in this area at Mae Sot, Tak province. The results shows that most suitable extraction method that yield high correlation with the bioavailable Cd and Zn are BCR1 and EDTA extraction procedure. The result gives a significant correlation both; between total Cd and Zn in soil with available Cd and Zn in soil; as well as available Cd and Zn in soil with Cd and Zn in sugarcane. This may indicate that to predict Cd and Zn uptake to sugarcane, BCR1 and EDTA methods may be the suitable procedures in order to avoid complication of determination in sugarcane.