Adsorption of antibiotic-resistant bacteria and their cell-free deoxyribonucleic acid harbouring resistance genes in drinking water with metal oxides
- Authors: Tobechukwu, Anthony Eric
- Date: 2022
- Subjects: Metallic oxides , DNA -- Synthesis , Drinking water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27787 , vital:69494
- Description: Access to cleaner water is essential to human health. The incidence of Antibiotic Resistant Bacteria ARB in drinking water and subsequent proliferation of Antibiotic Resistance Genes ARGs in drinking water is a concern for public health. The free DNA cassette harboring antibiotic resistance gene in drinking water has been linked with impaired public health. The ARGs allows bacteria to develop resistance towards antibiotics while ARB render antibiotics ineffective. Existing drinking water treatment technologies eg adsorption, ozonation and chlorination, have shown different levels of potency in the removal of conventional water pollutant. These technologies, which operating principles is based on oxidation or mass transfer, have been explored to gained an insight into their efficiency in the removal of ARB ARGs in water treatment. In general, methods that functions by mass transfer of the ARB ARGs is more effectively than bacteria oxidation. Consequently, adsorption technology was chosen using common metal oxide adsorbents. The adsorbents ZnOAg CeO2 and Al2O3 were synthesized via the self propagation combustion method. This method was selected because of the purity of the final product and the energy requirement. One of the challenges in the removal of ARB in drinking water is the release of ARGs. To address this concern, five different ZnOAg heterostructures were synthesized for the removal of Enterococci faecium. ZnOAg was chosen because of the bactericidal and bacteriostatic characteristics. The study revealed that the concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity q34.11 CFUg was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudofirst-order kinetic equation and adsorbents Ag2Zn1 Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation 6.5 – 8.5 whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDREF onto the different heterostructure. Interestingly the MDREF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal. Cerium IV oxide CeO2 was selected because of high adsorption towards phosphate, backbone base for DNA. To prevent the problem of antibiotic resistance, we have synthesized a CeO2 adsorbent that exhibit highly positive character in a wide pH range, via the simple self-propagation combustion protocol, for the removal of free DNA harboring antibiotic resistance genes. Molecular characterization of the extracted genes showed that the sizes for E. coli and inherent gyrB genes are 147 and 460 bp with a purity between 19 2.0. The XRD SEM TEM, and PZC results of the as-synthesized CeO2 showed an agglomerate of pure cubic-faced centered material and highly crystalline, with a net charge at pH 6.2. Experimental results revealed that the reaction proceeded via pseudo first-order kinetic, and it is governed by electrostatic attraction. The free- DNA solution pH electrolyte, and competing ions impacted on the adsorption process. Further experimental results showed that the as-synthesized CeO2 adsorbent has the potential to be used for the removal of free DNA harboring ARGs from tap-water even under oxic conditions. Alumina Al2O3 is an abundant adsorbent that has also shown high removal capacity towards phosphate. The highly pure synthesized Al2O3 adsorbent exhibit fluid-like behaviour under Scanning Electron Microscope SEM. The XRD pattern corresponds to αAl2O3. The adsorption kinetics was described by pseudo second orderadsorption capacity 11.7 μgg implying chemisorption, which agrees with the electrostatic force of attraction caused by opposing ions. This result was evident by the effect of different ions in the tap water. The synthesized α-Al2O3 has the potential for the removal of cell free DNA harbouring multiply resistant genes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
- Authors: Tobechukwu, Anthony Eric
- Date: 2022
- Subjects: Metallic oxides , DNA -- Synthesis , Drinking water
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27787 , vital:69494
- Description: Access to cleaner water is essential to human health. The incidence of Antibiotic Resistant Bacteria ARB in drinking water and subsequent proliferation of Antibiotic Resistance Genes ARGs in drinking water is a concern for public health. The free DNA cassette harboring antibiotic resistance gene in drinking water has been linked with impaired public health. The ARGs allows bacteria to develop resistance towards antibiotics while ARB render antibiotics ineffective. Existing drinking water treatment technologies eg adsorption, ozonation and chlorination, have shown different levels of potency in the removal of conventional water pollutant. These technologies, which operating principles is based on oxidation or mass transfer, have been explored to gained an insight into their efficiency in the removal of ARB ARGs in water treatment. In general, methods that functions by mass transfer of the ARB ARGs is more effectively than bacteria oxidation. Consequently, adsorption technology was chosen using common metal oxide adsorbents. The adsorbents ZnOAg CeO2 and Al2O3 were synthesized via the self propagation combustion method. This method was selected because of the purity of the final product and the energy requirement. One of the challenges in the removal of ARB in drinking water is the release of ARGs. To address this concern, five different ZnOAg heterostructures were synthesized for the removal of Enterococci faecium. ZnOAg was chosen because of the bactericidal and bacteriostatic characteristics. The study revealed that the concentration of the precursors influences the microstructures of the adsorbents; however, it did not significantly affect the adsorption efficiency. The maximum adsorption capacity q34.11 CFUg was obtained for Ag1Zn3.5. The kinetic studies revealed that Ag1Zn1 and Ag1Zn2 adsorbents agreed to the pseudofirst-order kinetic equation and adsorbents Ag2Zn1 Ag3.5Zn1 and Ag1Zn3.5 agreed to the pseudo-second-order kinetic equation. Initial tap-water pH range was beneficial for the adsorption and the pH of the treated tap-water was within the WHO tap water recommendation 6.5 – 8.5 whereas the effect of ionic strength, anionic and cationic interference was insignificant in the adsorption of MDREF onto the different heterostructure. Interestingly the MDREF could retain its cell membrane integrity and resistance genes, suggesting that surface adsorption was the primary mechanism for the removal. Cerium IV oxide CeO2 was selected because of high adsorption towards phosphate, backbone base for DNA. To prevent the problem of antibiotic resistance, we have synthesized a CeO2 adsorbent that exhibit highly positive character in a wide pH range, via the simple self-propagation combustion protocol, for the removal of free DNA harboring antibiotic resistance genes. Molecular characterization of the extracted genes showed that the sizes for E. coli and inherent gyrB genes are 147 and 460 bp with a purity between 19 2.0. The XRD SEM TEM, and PZC results of the as-synthesized CeO2 showed an agglomerate of pure cubic-faced centered material and highly crystalline, with a net charge at pH 6.2. Experimental results revealed that the reaction proceeded via pseudo first-order kinetic, and it is governed by electrostatic attraction. The free- DNA solution pH electrolyte, and competing ions impacted on the adsorption process. Further experimental results showed that the as-synthesized CeO2 adsorbent has the potential to be used for the removal of free DNA harboring ARGs from tap-water even under oxic conditions. Alumina Al2O3 is an abundant adsorbent that has also shown high removal capacity towards phosphate. The highly pure synthesized Al2O3 adsorbent exhibit fluid-like behaviour under Scanning Electron Microscope SEM. The XRD pattern corresponds to αAl2O3. The adsorption kinetics was described by pseudo second orderadsorption capacity 11.7 μgg implying chemisorption, which agrees with the electrostatic force of attraction caused by opposing ions. This result was evident by the effect of different ions in the tap water. The synthesized α-Al2O3 has the potential for the removal of cell free DNA harbouring multiply resistant genes. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022
Investigation of pharmaceutical residues and polybrominated diphenyl ethers in selected river estuaries and canal in Eastern Cape Province, South Africa
- Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Authors: Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Date: 2021-09
- Subjects: Marine pharmacology
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21545 , vital:48878
- Description: The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
- Authors: Ohoro, Chinemerem Ruth https://orcid.org/ 0000-0002-8167-6314
- Date: 2021-09
- Subjects: Marine pharmacology
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/21545 , vital:48878
- Description: The increasing global pollution by contaminants of emerging concern due to industrialization, development, and improper handling of industrial and domestic waste is alarming. Some of these emerging contaminants are endocrine disruptors and persistent organic pollutants. Two groups of compounds (pharmaceuticals and polybrominated diphenyl ethers (PBDEs)) were considered for this study. Pharmaceuticals are drugs which we take to cure and nourish human and animal bodies, ranging from antibiotics, stimulants, psychiatric, to hormonal recipes among others. They are potentially toxic and comprise chemicals or active ingredients capable of disrupting hormones. They have been related to human and aquatic organisms' ecological risks, such as feminization and masculinization of fish, cancer, and disruption of the immune system. In recent times, pharmaceuticals are being tested in the Rivers of South Africa. PBDEs are human influential chemicals usually incorporated into products such as flame retardants, which can travel over a long distance. They are hydrophobic, lipophilic, environmentally persistent, and easily absorbed by aquatic organisms. About 209 congeners exist, and BDE- 17, 47, 66, 100, 153, 154, and 183 are frequently detected in the environment. The higher brominated congeners can debrominate to more toxic and lower congeners. Though they have low acute toxicity, their effect of interfering with the thyroid gland is long-term. They pose a risk such as immunological, neurological, carcinogenicity, and reproductive disruption. Water and sediment samples considered for investigation were collected from five different sites (Buffalo River Estuary, Sundays River Estuary, Swartkops River Estuary, Nahoon River Estuary, and Markman Canal stormwater). These sites are located in the two major cities hosting the two major Ports (East London and Port Elizabeth) in the Eastern Cape Province of South Africa. Five sampling points were chosen for the collection of both water and sediment samples across three seasons that span from August to December in each of the mentioned sites. Nahoon River Estuary that was not sampled in winter seasons due to logistics and the global pandemic of year 2020; sediment sample was not collected at point NH5 for the spring season because of inaccessibility and topography of the sampling point. Ultrasonic extraction was utilized for sediment samples while SPE method with C-18 cartridges, was used to extract pharmaceuticals in water samples and for the purification of sediment extracts. A chromatographic column was employed for sediment purification. Analytes considered in this study were carbamazepine, caffeine, trimethoprim, sulfamethoxazole, and testosterone. Nahoon River Estuary and Markman canal were considered for investigation of water and sediments for PBDEs. The samples were processed for analysis immediately on arrival to the laboratory after being stored in an ice chest at 4 oC. Physicochemical properties of water samples were taken on site. The temperature ranges from 15.5-24.5 oC for Markman and 24.5- 26.6 oC. Nahoon River Estuary. There was a correlation among the congeners except for BDE-153, which do not correlate with BDE- 17, 47, and 183 in Markman. However, BDE- 153 correlated with BDE-66 in Markman. The Ʃ5PBDE for water and Ʃ6PBDE sediment for all seasons were BDL – 1357 ng/L and BDL – 408.14 ng/g, respectively. The PBDEs mean concentrations in Nahoon water samples ranges from BDL-247 ng/L (spring). The dominant congeners in Nahoon Estuary and Markman Canal samples were BDE- 17 and BDE – 66. The temperature and pH of Swartkops River Estuary range from 16.66 – 25.15 oC, and 8.1 – 10.4, respectively. The pH of the Estuary was higher than that of the Markman Canal. The concentrations of pharmaceuticals in water samples were below detection limit. However, carbamazepine gave the highest concentration in sediment samples (23.86 μg/kg). SLF was not detected in sediment samples. The range of temperature for Buffalo River Estuary was lower than the other sites (18.10 – 20.22 oC); however, the pH showed no difference. Human and ecotoxicological risks were estimated for Markman Canal, Nahoon, Swartkops, Buffalo and Sundays River estuaries. The concentrations obtained for the two classes of contaminants in this study showed that PBDEs in Markman Canal sediment could pose a potential risk to humans, while Nahoon River Estuary poses no risk from PBDEs. Furthermore, the concentrations of caffeine in surface water of Sundays Estuary indicates low ecotoxicological risk to aquatic organisms (fish). Also, carbamazepine and trimethoprim levels (BDL – 9.50 and 1.39-2.00 μg/kg, respectively) suggest a high risk to aquatic organisms (bacteria, invertebrate, algae) in sediment of Buffalo, Sundays, and Swartkops estuaries, as well as Markman Canal. The situation report shows that the estuaries and canal in East London and Port Elizabeth are polluted by organic pollutants such as pharmaceuticals and polybrominated diphenyl ethers. Measures has to be taken to monitor the pollution of these rivers that are of economic value to South Africa. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-09
Investigation of the levels of PBDEs and PCNs in the surface water and sediments from selected waterbodies in the Eastern Cape Province, South Africa
- Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Authors: Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Date: 2021-06
- Subjects: Persistent pollutants , Water -- Purification -- Organic compounds removal , Organic water pollutants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22699 , vital:52660
- Description: Studies have revealed that persistent organic pollutants (POPs) are omnipresent in our environment; almost all human beings have definite levels of POPs in their bodies. Even fetus and embryos are not spared; they have been found to bear certain levels of POPs. So far, there are about 28 chemicals listed as POPs among which are polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs). PCN and PBDE distributions have been reported from different sources around the world, but studies relating to PCNs occurrence and distribution in Africa, especially South Africa is still minimal. PBDEs have been reported to cause diabetes, cancer, damage to reproductive system, thyroid, liver and other vital organs in the body, while PCNs have been linked to chloracne (severe skin reactions/lesions) and liver disease (yellow atrophy) in humans, chicken oedema and X-disease in cattle. Hence, this study evaluates PCN levels in water and sediment samples from three waterbodies: North End Lake (NEL), Chatty River (CHA) and Makman Canal (MMC), while PBDE levels was reported in NEL and CHA samples. The three sites are located in Port Elizabeth, Eastern Cape Province (ECP) of South Africa. The lake serves as a recreational resort while the latter two waterbodies are tributaries discharging into the Swartkop Estuary, an important estuary in ECP. Water samples were extracted with C18 cartridges (solid phase), while soxhlet was employed for the extraction of sediments. Water and sediment extricates were purified and quantified with gas chromatography-micro electron capture detector (GC-μECD). Forty-seven (47) water samples and 44 sediment samples were collected in August until December 2020 from six sampling points in NEL, five points in each of CHA and MMC. All the samples were evaluated for physicochemical properties, PBDEs and PCNs using validated standard methods. The sampling period covered three South Africa seasons: August (winter), October (spring) and December (summer). The physicochemical parameters (PP) of NEL water samples for the three seasons generally varied as follows: temperature (15.3–23°C), pH (7.9–10.3), oxidation-reduction potential, ORP (23.4-110 mV), atmospheric pressure, AP (14.52-15.56 PSI), turbidity (15.1–167 NTU), electrical conductivity, EC (114–1291 μS/cm), total dissolved solids, TDS (55-645 mg/L), total suspended solids, TSS (20–107 mg/L) and salinity (0.05–0.65 PSU). All the PPs except for turbidity and TSS are within acceptable limits. NEL sediments had moisture content (MC), organic matter (OM) and organic carbon (OC) in the range of 0.04–8.0percent, 0.08–2.2percent and 0.05–1.8percent, respectively. The sum of eight PCN congeners Σ8PCNs and six PBDE congeners Σ6PBDEs in NEL water samples ranged from 0.164–2.934 μg/L and 0.009-1.025 μg/L individually. The values for Σ8PCNs and Σ6PBDEs in NEL sediment samples varied from 0.991–237 μg/kg and 0.354-28.850 μg/kg, respectively. The calculated hazard quotient (HQ) corresponding to the non-carcinogenic health risk associated with PBDEs in NEL water samples was 2.0×10-3-1.4×10-1, while the TEQ values due to PCNs varied from 6.10×10-7- 3.12×10-3 μg/L in NEL water samples and 3.70×10-5-1.96×10-2 μg/kg dw in sediments. The PP values for CHA water samples include temperature (15.4–22.9°C), pH (7.7–10.5), TDS (991–1771 mg/L), TSS (6–41 mg/L), turbidity (1.0–198 NTU), EC (1981–3542 μS/cm), AP (14.60–14.80 PSI), ORP (-339.1-51.3 mV), and salinity (1.02–1.87 PSU). The EC, TDS and salinity exceeded acceptable values at certain points. The sediments of CHA have MC, OM and OC contents ranging from 0.01-10.2percent, 0.2-1.3percent and 0.1-0.8percent in that order. Sum of Σ8PCNs, Σ6PBDEs in CHA water and sediment samples ranged from 0.026–1.054 μg/L, 0.007-0.079 μg/L and 0.429–1888.468 μg/kg, 0.347-6.468 μg/kg individually. The HQ in CHA water samples was 1.6×10-3-7.7×10-3 and the estimated TEQ was 1.0×10-7-6.62×10-5 μg/L and 1.10×10−5-6.40×10−2 μg/kg in water and sediments, respectively. The temperatures for MMC water samples ranged from 15.6-24.5°C, while other PPs recorded were as follows: pH (8.4-10.2), TDS (943–4002 mg/L), TSS (7-491 mg/L), turbidity (2.9-154.2 NTU), EC (1885-8004 μS/cm), AP (14.53–14.82 PSI), ORP (7.8-130 mV) and salinity (0.96-4.47 PSU). MMC’s sediments recorded MC, OM and OC varying as 0.4- 18.9percent, 0.2-4.5percent and 0.1-2.6percent, respectively across the three seasons. The Σ8PCNs for MMC water and sediment samples were 0.035–0.699 μg/L and 0.260–6744 μg/kg. The TEQ values in MMC water and sediment samples were 1.19×10-7-1.47×10-4 μg/L and 4.43×10−5- 4.19×10−1 μg/kg, respectively. The results are all less than one, and this suggests that the selected water is safe. Results showed that NEL water had highest TEQ, PCN and PBDE concentrations, while MMC sediments recorded maximum TEQ and PCN levels in this study. PBDE concentrations in NEL sediments were above the other site. In conclusion, NEL water was most polluted with both pollutants (PCNs and PBDEs), but MMC sediments contained more PCNs. There is need for the immediate remediation of these selected waterbodies. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-06
- Authors: Agunbiade, Idowu Victoria https://orcid.org/0000-0001-5605-0312
- Date: 2021-06
- Subjects: Persistent pollutants , Water -- Purification -- Organic compounds removal , Organic water pollutants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22699 , vital:52660
- Description: Studies have revealed that persistent organic pollutants (POPs) are omnipresent in our environment; almost all human beings have definite levels of POPs in their bodies. Even fetus and embryos are not spared; they have been found to bear certain levels of POPs. So far, there are about 28 chemicals listed as POPs among which are polybrominated diphenyl ethers (PBDEs) and polychlorinated naphthalenes (PCNs). PCN and PBDE distributions have been reported from different sources around the world, but studies relating to PCNs occurrence and distribution in Africa, especially South Africa is still minimal. PBDEs have been reported to cause diabetes, cancer, damage to reproductive system, thyroid, liver and other vital organs in the body, while PCNs have been linked to chloracne (severe skin reactions/lesions) and liver disease (yellow atrophy) in humans, chicken oedema and X-disease in cattle. Hence, this study evaluates PCN levels in water and sediment samples from three waterbodies: North End Lake (NEL), Chatty River (CHA) and Makman Canal (MMC), while PBDE levels was reported in NEL and CHA samples. The three sites are located in Port Elizabeth, Eastern Cape Province (ECP) of South Africa. The lake serves as a recreational resort while the latter two waterbodies are tributaries discharging into the Swartkop Estuary, an important estuary in ECP. Water samples were extracted with C18 cartridges (solid phase), while soxhlet was employed for the extraction of sediments. Water and sediment extricates were purified and quantified with gas chromatography-micro electron capture detector (GC-μECD). Forty-seven (47) water samples and 44 sediment samples were collected in August until December 2020 from six sampling points in NEL, five points in each of CHA and MMC. All the samples were evaluated for physicochemical properties, PBDEs and PCNs using validated standard methods. The sampling period covered three South Africa seasons: August (winter), October (spring) and December (summer). The physicochemical parameters (PP) of NEL water samples for the three seasons generally varied as follows: temperature (15.3–23°C), pH (7.9–10.3), oxidation-reduction potential, ORP (23.4-110 mV), atmospheric pressure, AP (14.52-15.56 PSI), turbidity (15.1–167 NTU), electrical conductivity, EC (114–1291 μS/cm), total dissolved solids, TDS (55-645 mg/L), total suspended solids, TSS (20–107 mg/L) and salinity (0.05–0.65 PSU). All the PPs except for turbidity and TSS are within acceptable limits. NEL sediments had moisture content (MC), organic matter (OM) and organic carbon (OC) in the range of 0.04–8.0percent, 0.08–2.2percent and 0.05–1.8percent, respectively. The sum of eight PCN congeners Σ8PCNs and six PBDE congeners Σ6PBDEs in NEL water samples ranged from 0.164–2.934 μg/L and 0.009-1.025 μg/L individually. The values for Σ8PCNs and Σ6PBDEs in NEL sediment samples varied from 0.991–237 μg/kg and 0.354-28.850 μg/kg, respectively. The calculated hazard quotient (HQ) corresponding to the non-carcinogenic health risk associated with PBDEs in NEL water samples was 2.0×10-3-1.4×10-1, while the TEQ values due to PCNs varied from 6.10×10-7- 3.12×10-3 μg/L in NEL water samples and 3.70×10-5-1.96×10-2 μg/kg dw in sediments. The PP values for CHA water samples include temperature (15.4–22.9°C), pH (7.7–10.5), TDS (991–1771 mg/L), TSS (6–41 mg/L), turbidity (1.0–198 NTU), EC (1981–3542 μS/cm), AP (14.60–14.80 PSI), ORP (-339.1-51.3 mV), and salinity (1.02–1.87 PSU). The EC, TDS and salinity exceeded acceptable values at certain points. The sediments of CHA have MC, OM and OC contents ranging from 0.01-10.2percent, 0.2-1.3percent and 0.1-0.8percent in that order. Sum of Σ8PCNs, Σ6PBDEs in CHA water and sediment samples ranged from 0.026–1.054 μg/L, 0.007-0.079 μg/L and 0.429–1888.468 μg/kg, 0.347-6.468 μg/kg individually. The HQ in CHA water samples was 1.6×10-3-7.7×10-3 and the estimated TEQ was 1.0×10-7-6.62×10-5 μg/L and 1.10×10−5-6.40×10−2 μg/kg in water and sediments, respectively. The temperatures for MMC water samples ranged from 15.6-24.5°C, while other PPs recorded were as follows: pH (8.4-10.2), TDS (943–4002 mg/L), TSS (7-491 mg/L), turbidity (2.9-154.2 NTU), EC (1885-8004 μS/cm), AP (14.53–14.82 PSI), ORP (7.8-130 mV) and salinity (0.96-4.47 PSU). MMC’s sediments recorded MC, OM and OC varying as 0.4- 18.9percent, 0.2-4.5percent and 0.1-2.6percent, respectively across the three seasons. The Σ8PCNs for MMC water and sediment samples were 0.035–0.699 μg/L and 0.260–6744 μg/kg. The TEQ values in MMC water and sediment samples were 1.19×10-7-1.47×10-4 μg/L and 4.43×10−5- 4.19×10−1 μg/kg, respectively. The results are all less than one, and this suggests that the selected water is safe. Results showed that NEL water had highest TEQ, PCN and PBDE concentrations, while MMC sediments recorded maximum TEQ and PCN levels in this study. PBDE concentrations in NEL sediments were above the other site. In conclusion, NEL water was most polluted with both pollutants (PCNs and PBDEs), but MMC sediments contained more PCNs. There is need for the immediate remediation of these selected waterbodies. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021-06
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