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Sediments are known to be the ultimate sink for most pollutants in the aquatic environment. In this study, the concentrations of both legacy polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs) were measured in sediments samples from the Vaal River catchment. The concentrations of Σ7BDE-congeners ranged from 2...
Citations
... The e-waste recycling is one of the fastest-growing waste streams around the developing world (Chan and Wong 2013;Akortia et al. 2018;Chokwe et al. 2019). The presence of halogenated compounds in e-wastes results in the formation of persistent organic pollutants like PCBs, PCDD/Fs during recycling processes. ...
... Globally, the top countries producing e-waste are Canada, France, the USA, and the UK (Andeobu et al. 2021). In Africa, the top three countries producing highest e-waste are South Africa, Nigeria, and Egypt (Chokwe et al. 2019) with Ghana receiving most of the e-waste from developed countries (Akortia et al. 2018). There are many different materials and additives found in these unwanted electronic products, some of which are toxic. ...
Polychlorinated dibenzo- p -dioxins and dibenzo-furans (PCDD/Fs) are notorious pollutants classified as persistent organic pollutants (POPs), which even at trace levels can bio-accumulate in the environment and have negative effects on organisms. Due to their adverse health effects, countries around the globe have introduced stringent emission standards to reduce the formation of PCDD/Fs. Using data in the literature over the past two decades (2001 to 2023), this review discussed the PCDD/F emissions from incineration facilities, E-waste recycling, iron sintering, secondary metal smelting plants, and crematories. But the review only focused on pollutants and remediation strategies from the incineration processes. There are two heterogeneous mechanism pathways that lead to the formation of PCDD/Fs, firstly, the De novo phase, using macromolecules of carbon or polycyclic aromatic hydrocarbons to begin the synthesis, and secondly, the condensation reaction beginning with the rearrangement of the molecular structure of the precursor compound. On the remediation strategies, adsorption injections were the most preferred method; however, recent studies reported other strategies such as catalytic filtration systems, an electron beam system, and good combustion practices. This review concluded that a lot has been done to manage and prevent PCDD/F formation efficiently to the level which no longer poses a hazard to human health and the environment.
Graphical abstract
... BDE-209 was also the dominant congener of PBDEs having 85% of the total PBDEs at the site (La Guardia et al., 2013). The average concentrations of PBDEs in the sediment samples of Vaal River were higher than those detected in Llobregat and Ebro River in Spain (Barón et al., 2014;Chokwe et al., 2019). The levels of PBDEs in the sediment samples from the Markman canal were also investigated by Ohoro et al (2021) and the total concentration of PBDEs ranged between 175 and 408 ng/g dw. ...
Trace elements (TEs) originated from geogenic and anthropogenic sources while additive legacy
brominated flame retardants (ALBFRs) come from man-made sources. The co-occurrence of TEs and
ALBFRs in the aquatic environment has recently become a major concern because of their health
implications on humans. In this review, we compile some published data on the levels of these two
groups of pollutants in water, and sediment, around the world. This study reveals that a lot of studies
have been separately conducted to determine the concentration of TEs and ALBFRs in aquatic
environments, but few studies have been conducted to determine the co-occurrence of these two sets
of contaminants of emerging concerns. This review also demonstrates that the co-existence of
ALBFRs and TEs in water and sediment may result in the development of complex compounds that
are more harmful to aquatic species and, by extension, people than when they exist separately. Hence,
there is an urgent need to elucidate the structures of these complexes and to determine the health
implications of their co-existence in the aquatic environment. This is the first review of the cooccurrence
of TEs and ALBFRs in water and sediment of the aquatic environment.
... Wastewater treatment plants (WWTPs) were identified by Münze et al. [15] as important point sources of chemicals discharged in the aquatic environments, resulting in a much greater concentration of chemicals downstream of the effluent. Since wastewater is treated by microbes through a metabolic process [16], the water quality of a WWTP is highly dependent on parameters such as pH, COD, E. coli, and other contaminants [12,14,17]. Water treatment plants were established as central units to reduce pollution loads to acceptable levels before the resultant effluent was discharged into receiving water bodies to prevent potential health threats that might result from the occurrence of microbial pollutants in water resources. ...
... Moreover, a small but growing number of researchers have additionally started assessing the influence of climatic and environmental variables on water quality in surface water [3,13,14,31]. Some of the studies discovered that the variation of physicochemical parameters demonstrates a general trend of higher concentrations during the wet season and lower concentrations during the dry season [8,14,17,32]. ...
The declining state of municipal wastewater treatment is one of the major contributors to the many pollution challenges faced in most parts of South Africa. Escherichia coli and Chemical Oxygen Demand are used as indicators for the performance of wastewater treatment plants. Wastewater treatment plant (WWTP) efficiency challenges are associated with susceptibility to seasonal variations that alter microbial density in wastewater. This study sought to investigate the effect of rainfall
on E. coli and COD in the effluent wastewater discharged from the Crocodile River, Mpumalanga Province, South Africa. To cover the spatial distribution of the pollutant in the Crocodile River, water samples were collected from 2016 to 2021 at three strategic sites. The rainfall data was acquired from the South AfricanWeather Services from 2016 to 2021, which contains daily rainfall measurements for each sampling site. Data analysis was carried out using Microsoft Excel 2019, Seaborn package, and Python Spyder (version 3.8). The White River, which is located on the upper stream, recorded the highest COD levels of 97.941 mg/L and 120.588 mg/L in autumn and spring, respectively. Matsulu
WWTP was found to have the highest E. coli concentration per milliliter (72.47 cfu/100 mL) in the spring compared to any other location or time of year. The results also indicated that each of the sampling sites recorded above 60 (cfu)/100 mL of E. coli in Kanyamazane (spring), Matsulu (summer), and White River (winter). It was noted that the rainfall is a significant predictor (p < 0.004) of E. coli. Additionally, it was discovered during the data analysis that the rainfall parameter did not significantly affect COD prediction (p > 0.634), implying that rain was not a reliable predictor of COD.
... 5 Industrial wastewater contamination is a significant issue in South Africa -a fast-growing country with limited freshwater resources. The country is currently designated as water-stressed 5,6 with just over 1200 m 3 /person/year of fresh water available for a population of about 58.89 million people 7 . Effluents generated from both industrial and home activities are the second most common source of chemical and microbiological pollution of South Africa's water sources. ...
Excessive discharge of poorly treated effluent has impacted global water resource systems intensely. The declining state of wastewater treatment plants (WWTPs) is a significant source of pollution in water resources. There is evidence of water resource quality deterioration in natural environments caused by effluent discharges. We assessed the impact of wastewater treatment effluent on the quality of the Crocodile River. For spatial distribution, we collected data from three WWTPs discharging effluent into the Crocodile River and from three points situated downstream of each WWTP. Physicochemical and microbiological parameters such as pH, electrical conductivity, chemical oxygen demand, phosphates, nitrates, ammonia, and Escherichia coli were analysed using standard methods of the American Public Health Association.
The water quality index was also calculated to give an overall indication of pollution within the catchment. The results show that WWTPs were not complying with the effluent standards set out in their water use licence. The WWTP effluent had a negative impact on downstream water quality, with the water quality index indicating low quality of discharged effluent. It is recommended that a regular and consistent water resource
quality monitoring programme be implemented, particularly in areas where effluent discharges are prevalent.
... Its disadvantages are high solvent consumption and low efficiency, which is why repeated extractions are sometimes needed to extract enough analytes. However, the method has been successful in extracting PBDEs from sediment and bivalve samples with a solvent mixture of dichloromethane and n-hexane (1:1, v/v) (13) and in extracting PBDEs and PBBs from sediment with a solvent mixture of n-hexane and acetone (4:1, v/v) (52). It has also been successfully combined with SPE and DMIP to purify and concentrate PBDEs from sediment (40). ...
... The retention time of elemental sulphur on the GC column can be equal to the retention time of the analysed compounds, but also elemental sulphur may disrupt the operation of the MS. Elemental sulphur is most often removed by adding Cu powder directly to the sample or extract (32,34,52). ...
... GC coupled to an MS detector (GC-MS) or an electron capture detector (GC-ECD) is the most common method to determine PBDEs (12,13,39,47,52) and PBBs (50,52). HBCD, TBBPA, and TBPPS are most often analysed with LC coupled to an MS detector (LC-MS) (13,37) or HPLC coupled to MS detector (19,20,55) or UV detector (2,22). ...
The most common and consequently analysed brominated flame retardants (BFRs) are polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs), tetrabromobisphenol A (TBBPA), tetrabromobisphenol S (TBBPS), and hexabromocyclododecane (HBCD). As these persistent organic pollutants are widespread in the environment and have a number of harmful effects on human health, the production and use of most has been banned for several years. The aquatic environment is polluted by these compounds through their deposition from the atmosphere, sewage sludge, wastewater treatment plants, and landfills, and higher levels are found in areas with developed industry and agriculture and near landfills. Each compound also seems to show preference for specific compartments of the aquatic environment, i.e. water, sediment, or aquatic organisms, according to their physicochemical properties. The aim of this review was to take a closer look at the analysis of BFRs, as without reliable analysis we would not be able to determine their levels and distribution across the aquatic compartments and assess human exposure and health risks. Particularly worrying are the health risks associated with PBDEs in fish, whose levels generally exceed the permitted values.
... The ecological risks of PBDEs in the soils were assessed using the hazard quotient. The risk quotients (RQ) were obtained as a ratio of the measured PBDEs concentrations in the soils to the guideline values (Hakanson 1980;Chokwe et al., 2019). ...
... There is no quality guideline for PBDEs in Nigeria; however, the Federal Environmental Quality Guideline (FEQG) for PBDEs established by Environment Canada was adopted. The FEQG values for tri, tetra, penta, hexa, octa, and deca-BDEs are 44, 39, 0.4, 440, 5600, and 19, ng g À1 , respectively (Chokwe et al., 2019). The concentrations of the tri-BDEs, tetra-BDEs, penta-BDEs, hexa-BDEs, octa-BDEs, and deca-BDEs in this study were below the FEQG standards and the USEPA screening levels for residential and industrial soils (EPA, 2017) while the concentrations of the penta-BDEs in 61% of the soil samples were above the FEQG standards. ...
The usage of polybrominated diphenyl ethers (PBDEs) as fire-resistant additives was banned several years ago; however, they persist in several environmental compartments. This study determined the concentrations and associated exposure risks of Ʃ39PBDEs in soil depth samples from selected metals and plastics scrap catchments in the Niger Delta region, Nigeria. Samples extraction was performed by the Soxhlet extraction method followed by GC-MS analysis. The mean concentrations of ∑39PBDEs-congeners ranged from 0.01 ± 001 to 25 ± 11.0 ng g⁻¹ in the topsoil and 0.01 ± 0.01 to 6.50 ± 4.7 ng g⁻¹ in the subsoil. The PBDE homologue profiles were dominated by di, penta, hexa, and tri-BDEs. The PBDEs cancer and non-cancer risk for infants were higher than those in adults, expressed in the following order: ingestion > dermal contact > inhalation. In general, the sum for the three exposure pathways was within the allowable threshold limit, suggesting a low lifetime cancer risk from soil exposures. The technical mixture used for paints, plastics, hydraulic, and dielectric insulating fluids for transformers, capacitors, cable wires, and power capacitors is a potential source of Ʃ39PBDEs in the study area. With the increase in metals scrap enterprise in Nigeria, this study provides empirical data useful for the development of efficient strategies to strengthen and enforce existing regulations for metals and plastics scrap land use in Nigeria and other similar catchments around the world.
... Currently, there is a scarcity of information on the production and use of deca-BDE in South Africa (Daso et al., 2013a). However, Deca-BDE has been detected in Rubik's cube in South Africa (DiGangi et al., 2017), which is suspected to be from the plastic industry (Chokwe et al., 2019). ...
... This can be attributed to the fresh release of effluent from the industry on the sampling day. The concentration of contaminants in the sediment of this study (Table S4) was R 6 278 ng/g, R 6 408 ng/g, and R 6 175 ng/g in winter, and spring, summer, respectively, higher than the concentrations detected (48 ng/g) by Chokwe et al. (2019) in South Africa and 0.5-3 ng/g in the USA (Song et al., 2004). The concentrations of R 5 PBDE in water samples of winter and summer (Table S4) are BDL-724 ng/L (R 5 1061 ng/L) and 2.98-28.56 ...
This study investigates the pollution of Markman stormwater runoff, which is a tributary to Swartkops River Estuary. Solid-phase and ultrasonic extraction methods were utilized in the extraction of water and sediment samples, respectively. The pH of the sampling sites was above the EU guideline. The ranges of concentration of \(\Sigma_{6}\)PBDE obtained in water and sediment samples for all the seasons were 58.47–1357 ng/L and 175–408 ng/g, respectively. Results also showed that BDE-66 was the dominant congener, specifically in the industrial zone, where its concentrations ranged from 2 to 407 ng/g in sediment. Consequently, the high concentration of BDE- 66 in the sediment of stormwater calls for concern. Penta-BDE suggests potential moderate eco-toxicological risk, as evident in the calculated risk assessment. The result showed possible photodegradation along the contaminant's travel time, as only 7% of the PBDE was detected at the point of entry into the Swartkops River Estuary. Markman stormwater may be contributing heavily to the pollution load of Swartkops River, as evident in the alarming concentrations of PBDEs obtained. The industries at this zone should eliminate the contaminants before discharging their effluents into the canal.
... ng/g; Ganci et al., 2019). These ranges were narrower than those found in samples collected from e-waste recycling workshops in Bui Dau, northern Vietnam (<0.2-35 ng/g; Matsukami et al., 2017); the Jinjiang River, China (ND -39.1 ng/g; Hou et al., 2019); and the Vaal River, South Africa (ND -45 ng/g; Chokwe et al., 2019). Low detection frequencies and concentrations of PBEB and BB-153 were also documented elsewhere (Matsukami et al., 2017;Ganci et al., 2019;Hou et al., 2019). ...
... ; and the Vaal River, South Africa (59-350 ng/g;Chokwe et al., 2019). Meanwhile, DBDPE was not detected in surface sediments from the Jinjiang River, China(Hou et al., 2019) and was found at insignificant concentrations in ...
... ng/g; Ganci et al., 2019). These ranges were narrower than those found in samples collected from e-waste recycling workshops in Bui Dau, northern Vietnam (<0.2-35 ng/g; Matsukami et al., 2017); the Jinjiang River, China (ND -39.1 ng/g; Hou et al., 2019); and the Vaal River, South Africa (ND -45 ng/g; Chokwe et al., 2019). Low detection frequencies and concentrations of PBEB and BB-153 were also documented elsewhere (Matsukami et al., 2017;Ganci et al., 2019;Hou et al., 2019). ...
... ; and the Vaal River, South Africa (59-350 ng/g;Chokwe et al., 2019). Meanwhile, DBDPE was not detected in surface sediments from the Jinjiang River, China(Hou et al., 2019) and was found at insignificant concentrations in ...
Comprehensive and updated information about polychlorinated biphenyls (PCBs) and brominated flame retardants (BFRs) in surface sediments from Hanoi, the capital city of Vietnam, is rather scarce. In this study, concentrations and profiles of 209 PCBs, 41 polybrominated diphenyl ethers (PBDEs), 2,2′,4,4′,5,5′-hexabromobiphenyl (BB-153), hexabromocyclododecane (HBCD), pentabromoethylbenzene (PBEB), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), and decabromodiphenyl ethane (DBDPE) were determined in sediment samples collected from the Red River and some inner-city rivers of Hanoi. Concentrations (ng/g dry weight, median and range) of pollutants decreased in the order: DBDPE (28; not detected ND – 59) ≈ PCBs (27; 1.7–50) > PBDEs (23; 0.20–61) > HBCD (1.2; ND – 5.2) > BTBPE (0.46; ND – 3.6) > BB-153 (0.004; ND – 0.014) > PBEB (ND). Pollutant levels in the inner-city river sediments were about one to two orders of magnitude higher than those measured in the Red River main stream sediments. Tri-to hexa-CBs are major homologs but detailed profiles vary between individual samples, reflecting source and/or seasonal variations. CB-11 and CB-209 were found at higher proportions in sediments than in technical PCB mixtures, suggesting their novel sources from pigments. Deca-BDE and DBDPE are the most predominant BFRs with an increasing trend predicted for DBDPE. A preliminary ecological risk assessment was conducted for these pollutants in sediments. Total PCBs and deca-BDE in a few inner-city river sediments may exhibit adverse effects on benthic organisms, but no serious risk was estimated in general.
... To our knowledge, this is among the first datasets reporting the occurrence of DBDPE in sediment samples from Japan. Concentrations of DBDPE in our sediment samples (up to 850 pg g À1 ) were generally lower than those measured in other locations in the world such as three major state lakes in eastern China (1020e3640 pg g À1 ; Wu et al., 2012) and Dongjang River in southern China (62,000e210,000 pg g À1 ; Zhang et al., 2009); lakes and coastal areas of Sweden (230e11,000 pg g À1 ; Ricklund et al., 2010); and Vaal River, South Africa (59,000e350,000 pg g À1 ; Chokwe et al., 2019). The increasing DBDPE concentrations towards decreasing sediment depths were reported by Zhang et al. (2009) Chinese sediment cores, which were relatively similar to the trend observed in surface layers (i.e., 2004e2011) of our core. ...
... The risk quotients (RQ) of selected PBDE homologs and DBDPE in the sediment samples from Beppu Bay were estimated as ratios of their measured concentrations and respective benchmarks, which were previously applied elsewhere (Wang et al., 2015;Chokwe et al., 2019;Yuan et al., 2020). For PBDEs, we used the Canadian Federal Sediment Quality Guidelines (FSeQG) derived for the protection of aquatic life such as sediment dwelling and pelagic animals that may bioaccumulate PBDEs from sediments (Environment Canada, 2013). ...
... Levels of risk were classified into three groups: RQ ! 1.0 (high risk); 0.1 RQ < 1.0 (medium risk); and RQ < 0.1 (low risk) (Wang et al., 2015;Chokwe et al., 2019;Yuan et al., 2020). ...
Contamination levels and temporal trends of polybrominated diphenyl ethers (PBDEs) and some alternative brominated flame retardants (BFRs) were examined in a dated sediment core from the deepest part of the Beppu Bay, southwestern Japan. PBDEs were found in the upper layers of 0–15 cm depth at concentrations ranging from 5200 to 32,600 pg g–1 with the peak estimated at 1995. Decabromodiphenyl ether (BDE-209) was the most abundant congener, accounting for 96% in average of total PBDEs. The vertical profile of BDE-209 observed in our sediment core generally agreed with the historical pattern of domestic demand of commercial deca-BDE mixtures in Japan, and perfectly matched with maximum stock of these products (i.e., 42,000 tons in 1995). Among alternative BFRs, only decabromodiphenyl ethane (DBDPE), a replacement of deca-BDE, was found at significant levels with concentrations of 69 to 850 pg g–1 in sediment layers dated between 1991 and 2011. Ratios of DBDPE to BDE-209 gradually increased during this period, implying opposite trends of these two compounds and the role of DBDPE as a deca-BDE’s alternative. The occurrence of deca-BDE components in sediments may pose medium risk to benthic aquatic life, while the ecological risk of other PBDE homologs and DBDPE was negligible.
