Assessment of Heavy Metals in Sediment at Saphan Hin, Phuket

Abstract

This study was conducted to assess the level of metal pollution in sediment samples at two different locations at Saphan Hin, which received water from Bang-Yai canal. The total content of Tin (Sn), Lead (Pb), and Zinc (Zn) were measured using inductively coupled plasma optical emission spectrometer (ICP-OES) by aqua regia digestion. The ranges of metal concentration (mg kg^-1) were 9.04 - 32.17 mg kg^-1 and 6.33 - 36.52 mg kg^-1 of Pb in Core A and B; and 32.83 - 68.49 mg kg^-1 and 21.63 - 73.59 mg kg^-1 of Zn in Core A and B, which is below the Sediment Quality Guidelines of Threshold Effects Concentration (TEC) (35.8 mg Pb kg^-1 and 121 mg Zn kg^-1). Sn was not detected (< 0.03 mg kg^-1). Analysis of the geo-accumulation index (I_geo) clearly indicated that most of the analysed sediment samples were not contaminated with the studied metals since low I_geo values were observed (I_{geo Pb} and I_{geo Zn} < 0). The detected enrichment factor (EF_Pb) values between2.0 and 6.0 indicated moderate enrichment, while most of the sediments had EF_Zn values below 2 which exhibited deficiency to minimal enrichment. The EF values in this study (EF > 1.5) indicates a significant portion of the trace metals was delivered from non-crustal materials and that may be delivered by other sources. Correlation analysis showed positive relationships between Pb and Zn in both cores (r = 0.5** Core A and 0.941** Core B). The association of Pb and Zn is possibly because they originated from the same sources. The determination of other metals should be considered further.