Particle size distribution behavior of polycyclic aromatic hydrocarbons in contaminated sedimentary environment of Likas River Estuary, Malaysia

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants, which are hazardous to the environment. Due to their low water solubility and hydrophobic nature, they easily adhered to the organic fraction of sediment rather than bind to the inorganic fraction. PAHs tend to be adsorbed in different particle sizes of sediments. The concentration of PAHs is also influenced by the presence of black carbon (BC) in the sediments. The main objective of this study was to characterize the distribution and identify the source of PAHs in different particle size. The samples in this study were taken from the Likas River Estuary, Sabah, Malaysia using Ekman dredge. Prior to the analysis, the sediments were freeze dried and sieved into different size fractions. The samples were then extracted for PAHs using Soxhlet apparatus, purified and fractionated with column chromatography before analysis with GC-MS. The results show that the highest concentration of PAHs, 10,900 mg/kg d.w., was obtained in particle size of 250-500 μm in Sample 3. Among four samples, the highest PAHs concentrations appear to be obtained in intermediate grain size fractions, except for Sample 4, where highest concentration appeared in 63-125 μm fraction. Source recognition index of MP/P indicated that PAHs in most of the particle size fractions are of pyrogenic origins, which was also supported by the BaA/(BaA+Chry) ratio. A better correlation an bind to the inorganic fraction. PAHs tend to be adsorbed in different particle sizes of sediments. The concentration of PAHs is also influenced by the presence of black carbon (BC) in the sediments. The main objective of this study was to characterize the distribution and identify the source of PAHs in different particle size. The samples in this study were taken from the Likas River Estuary, Sabah, Malaysia using Ekman dredge. Prior to the analysis, the sediments were freeze dried and sieved into different size fractions. The samples were then extracted for PAHs using Soxhlet apparatus, purified and fractionated with column chromatography before analysis with GC-MS. The results show that the highest concentration of PAHs, 10,900 mg/kg d.w., was obtained in particle size of 250-500 μm in Sample 3. Among four samples, the highest PAHs concentrations appear to be obtained in intermediate grain size fractions, except for Sample 4, where highest concentration appeared in 63-125 μm fraction. Source recognition index of MP/P indicated that PAHs in most of the particle size fractions are of pyrogenic origins, which was also supported by the BaA/(BaA+Chry) ratio. A better correlation