摘要
In the present study,the seasonal concentrations of polybrominated diphenyl ethers(PBDEs)in leachate and sediment samples,and the influence of geomembrane liners on PBDE levels and the extent of their infiltration into groundwater on selected landfill sites in Gauteng Province,South Africa were determined.Leachate and sediment samples were collected from seven operational landfill sites namely:Goudkoppies,Robinson Deep,Marie Louis,Soshanguve,Onderstepoort,Hatherly and Garankuwa from Johannesburg and Pretoria,in winter and summer.Groundwater samples were collected from monitoring boreholes from two landfill sites.Liquid-liquid and Soxhlet extraction techniques were employed for the extraction of leachate and groundwater,and sediment respectively using dichloromethane.The extracted samples were subjected to column clean up and,thereafter,analysed using gas chromatographyemass spectroscopy(GC-MS).PBDEs selected for the study were:BDE-17,-28,-47,-100,-99,-153,-154,-183 and-209.The P9PBDE concentrations in leachate samples for winter and summer ranged from 0.316e1.36 ng L-1 and 0.560e1.08 ng L-1 respectively.The P9 PBDE concentrations obtained for sediment in winter and summer were 3.00e4.91 ng g-1 and 2.50e3.71 ng g-1 respectively.Winter samples exhibited higher(p<0.05)concentrations for both leachate and sediment samples compared to summer samples.This trend was attributed to high precipitation rate in summer which may have infiltrated into the landfills,subsequently diluting the leachate and sediment samples.In contrast,the winter period is generally dry and PBDEs are,therefore,more likely to be concentrated.The concentrations of PBDEs in leachate and sediment samples were higher in landfill sites with geomembrane liners compared to those without liners.Groundwater samples taken from the vicinity of selected landfill sites without geomembrane liners exhibited high concentrations of P9PBDEs,indicating possible migration of PBDEs from landfill site into groundwater.Pearson correlation(r)and statistical significant t-test(p)for the PBDE congeners versus dissolved organic carbon(DOC)resulted in positive moderate interactions with a statistical significance for most congeners.Suggesting that there is a possible influence of organic carbon on the levels of PBDEs.
基金
The authors acknowledge the Water Research Commission(WRC-K8-850)
South Africa for funding this research and Tshwane University of Technology for the facilities
financial support for Sibiya IV for her masters'programme.
