Occurrence and Concentration of Phthalate Esters in River Sediment Around Covenant Oxidation Ponds, Covenant University, Ota, Ogun State

Abstract

Phthalate Esters (PEs) are well known environmental pollutants with wide application as plasticizers in plastic production. Concentrations of 8 PEs were determined in sediment samples collected from upstream and downstream of Covenant University Oxidation Pond (COP) between March and June 2013. Samples were extracted using the mechanical shaking method with double distilled dichloromethane. The prepared extracts were cleaned using activated silica gel-packed column chromatography and analyzed with high capillary gas chromatography equipped with flame ionization detector (GC-FID). The mean concentrations over the study period for the PEs, monoethylphthalate (MMP), dimethylphthalate (DMP), diallylphthalate (DAP), diethylphthalate (DEP), diisobutyl- (DIBP), di-n-butylphthalate (DBP), butyl-benzylphthalate (BBP), and di-(2-ethyl)hexyl phthalate (DEHP) are 23.1 mgkg -1 , 273 mgkg -1 , 28.9 mgkg -1 , 150 mgkg -1 , 26.5 mgkg -1 , 264.5 mgkg -1 , 41.7 mgkg -1 , and 20.9 mgkg -1 for upstream samples. Mean concentrations for the downstream samples are 24.2 mgkg -1 , 280 mgkg -1 , 33.4 mgkg -1 , 176 mg kg -1 , 26.9 mgkg -1 , 264 mgkg -1 , 41.8 mgkg -1 , and 18.2 mgkg -1 , respectively. Generally, the PEs’ concentration in downstream samples was significantly higher ( p >0.05) than upstream except for DIBP, BBP, and DBP whose DEHP concentrations were significantly higher ( p >0.05) upstream than downstream. The distribution pattern of PEs in the sediment is in the order DMP> DBP> DEP> BBP> DAP> DiBP> MMP> DEHP. The occurrence of PEs in the samples analyzed further supports their ubiquity in the environment.