Persistent organic pollutants (POPs) fall under a group of synthetic chemicals known for their persistence in environmental matrices such as soil and water, and are used in industrial, domestic and agricultural applications. Because of their volatility and lipophilicity, POPs can be transported far away from their point sources and bio-accumulate in food and in fatty tissues of humans and animals. In view of their toxicity and carcinogenicity some organic pollutants such as polychlorinated biphenyl (PCBs), organochlorine pesticides (OCPs) and phenolic derivatives (chlorophenol and nitrophenol) have been classified by United State Environmental Protection Agency (USEPA) and World Health Organization (WHO) as priority pollutants. The present work evaluated the distribution patterns of 19 polychlorinated biphenyls congeners, 17 organochlorine pesticides and selected phenolic derivatives (USEPA 11-priority pollutants) in the Buffalo River, in the Eastern Cape Province, South Africa between December 2015 and May 2016. The Liquid-liquid extraction technique was used for PCBs, OCPs and phenolic derivatives in the river water samples. Silica gel and florisil clean up were carried out for PCBs and OCPs samples respectively and analyzed with gas chromatography electron capture detector (GC/ECD). Phenolic compounds were derivatized and analyzed by gas chromatography mass spectrometer (GC/MS). Limits of detection (LOD), limit of quantitation (LOQ) and relative standard deviation (RSD) for the PCBs were 10 to 330 ng/L, 20 to 1,060 ng/L and 1.18 to 14.1 percent respectively. The LOD, LOQ and RSD for the OCPs were from 20 - 60 ng/L, 110 - 530 ng/L and 0.02 - 0.06 percent, while the corresponding values for the phenolic derivatives were 10 to 70 ng/L, 33 to 222 ng/L and 1.99 - 10.86 percent. In summer, the concentrations of PCBs, OCPs and phenolic derivatives ranged from <LOD to 482 ng/L, <LOD to 4,403 ng/L and <LOD to 1,546 ng/L respectively, while in autumn they were from <LOD to 2,383 ng/L, <LOD to 858 ng/L and <LOD to 713 ng/L in that order. Also, in summer, the level of occurrence of total PCB congeners detected at the various sampling sites were Buffalo River Estuary (BRE) 11 percent, Mdantsane (MSN) 16 percent, Zwelitsha (ZW) 26 percent, King William’s Town (KWT) 47 percent, Izele (IZ) 32 percent, and Maden (MD) 21 percent. The level of occurrence of total OCPs at BRE was 65 percent, at MSN 65 percent, at ZW 82 percent, at KWT 47 percent, at IZ 29 percent, and at MD 18 percent. The level of occurrence of total phenolic derivatives at BRE was 63 percent, at MSN 63 percent, at ZW 54 percent, at KWT 63 percent, at IZ 63 percent, and at MD 54 percent. In autumn, the level of occurrence of total PCBs at BRE was 68 percent, at MSN 16 percent, at ZW 42 percent, at KWT 26 percent, at IZ 47 percent, and at MD 0 percent. The level of occurrence of total OCPs at BRE was 65 percent, at MSN 53 percent, at ZW 41 percent, at KWT 35 percent, at IZ 53 percent, and at MD 18 percent. The level of occurrence of total phenolic derivatives at BRE was 63 percent, at MSN 63 percent, at ZW 54 percent, at KWT 18 percent, at IZ 18 percent, and at MD 45 percent. In summer, the levels of PCBs in all sampling sites were below WHO recommended maximum permissible levels (500 ng/L) for humans but in autumn the levels were above the recommended values in all the sites except MD. The cancer risk assessment values were above permissible 10-6 while hazard quotients were above the USEPA maximum limits of unity. OCPs levels were above the USEPA limits (100 ng/L) in all sampling locations in both seasons. The cancer risk assessment values were below permissible 10-6 but hazard quotients were above the USEPA maximum limits. Phenolic derivatives were also above the USEPA maximum permissible limit (500 ng/L) in most of the sampling locations in summer whereas during autumn the values were notably below the permissible limit at ZW, KWT, IZ and MD. The cancer risk assessment values and hazard quotients were above USEPA maximum limits of 10-6 and unity respectively. Conclusively, the results of this study reveal that the pollutants were present in the river at concentrations higher than the tolerable limit for human and wildlife and thereby may constitute a serious risk to public health. Therefore, it is recommended that proper regulation of the use of the compounds and their safe disposal be ensured to protect aquatic resources and the well-being of humans.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:ufh/vital:29448 |
| Date | January 2017 |
| Creators | Yahaya, Abdulrazaq |
| Publisher | University of Fort Hare, Faculty of Science and Agriculture |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Doctoral, PhD |
| Format | 165 leaves, pdf |
| Rights | University of Fort Hare |
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