Abstract
The seasonal variability of persistent organic pollutants in Hartbeespoort Dam, South Africa, was investigated using semipermeable membrane devices (SPMDs) as passive samplers. Freely dissolved waterborne polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were sampled to investigate seasonal changes in their concentrations. Exposure of the passive samplers was done for 14 days at the same sampling site in each of the four seasons of the year, in 2011. The SPMD-derived analyte amounts enabled the calculation of time-weighted averages of free dissolved waterborne levels of the contaminants. Concentrations ranged from 30.0 ng∙l -1 to 51.5 ng∙l -1 for PAHs, 38 pg l-1 to 150 pg∙l-1 for PCBs, 9.2 to 10.4 ng∙l-1 for HCHs and 0.3 to 0.8 ng∙l-1 for DDTs, respectively. It was also noted that the winter season generally exhibited higher contaminant concentrations for most compounds studied, which likely reflects the seasonality of their atmospheric deposition. An attempt was also made to identify possible sources of PAH contaminants in the dam by examining PAH ratios. These diagnostic ratios were inclined towards pyrogenic sources of pollution, except for the winter season where both pyrogenic and petrogenic sources likely contribute to the contamination pattern.
Highlights
Huge quantities of organic pollutants, including persistent organic pollutants (POPs), are released into the environment
This study was aimed at determining the water-dissolved concentrations of the 16 US EPA priority polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in Hartbeespoort Dam, South Africa, using semipermeable membrane devices (SPMDs)
Characteristic ions (m/z values) used in the analysis of polycyclic aromatic hydrocarbons in single ion monitoring (SIM) mode by GC/MS and characteristic MRM transitions (m/z values of parent and daughter ions) used in the analysis of PCBs and OCPs are given in the Appendix (Tables A1 and A2)
Summary
Huge quantities of organic pollutants, including persistent organic pollutants (POPs), are released into the environment. Due to their ubiquitous nature, hydrophobic organic compounds such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) have been identified as environmental contaminants in almost every compartment of the global system (ATSDR, 2009). PAHs, PCBs and OCPs are of particular interest because of their potential toxicity, carcinogenicity, possible mutagenicity as well as tendency to bioaccumulate. They are present in the aquatic environment both as truly dissolved and particle-bound. The concentration of freely-dissolved POPs in the water column is directly proportional to their chemical activity and fugacity in the water phase and is an important parameter in modelling their fate in the environment (Mayer et al, 2003)
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