Persistent organic pollutants in the Olifants River Basin, South Africa: Bioaccumulation and trophic transfer through a subtropical aquatic food web

Abstract

This study investigates the trophic transfer of persistent organic pollutants (POPs: PCBs, PBDEs, OCPs and PFASs) in the subtropical aquatic ecosystem of the Olifants River Basin (South Africa) by means of trophic magnification factors (TMFs). Relative trophic levels were determined by stable isotope analysis. POP levels in surface water, sediment and biota were low. Only ∑DDTs levels in fish muscle (<LOQ-61ng/g ww) were comparable or higher than values from other temperate and tropical regions. Significant positive relationships between relative trophic level and PCB, DDT and HCH concentrations were observed so trophic levels play an important role in the movement of contaminants through the food web. TMFs were >1, indicating biomagnification of all detected POPs. Calculated TMFs for PCBs were comparable to TMF values reported from the tropical Congo River basin and lower than TMFs from temperate and arctic regions. For p,p'-DDT, a higher TMF value was observed for the subtropical Olifants River during the winter low flow season than for the tropical Congo river. TMFs of DDTs from the present study were unexpectedly higher than TMFs from temperate and arctic aquatic food webs. The fish species in the aquatic ecosystem of the Olifants River can be consumed with a low risk for POP contamination.

Distribution of perfluorinated compounds (PFASs) in the aquatic environment of the industrially polluted Vaal River, South Africa

“…To our knowledge, only four studies have been performed on aquatic biota in Africa, with only one in fish. Verhaert et al (2017) detected relatively low PFAS concentrations in liver and muscle tissue of fish from the Olifants River basin in South Africa. In addition, a study on PFASs in South African crocodiles in Kruger National Park detected multiple PFASs in relatively high concentrations and suggested a point source for PFOS contamination of this area (Christie et al, 2016).…”

“…Data on PFAS concentrations in water of aquatic systems in Africa are very scarce. Only two studies could be found in South African river water (Mudumbi et al, 2014a;Verhaert et al, 2017), in which PFOA and PFOS were detected in concentrations up to 314 and 182 ng/L in the Diep River, 390 and 47 ng/L in the Salt River and 146 and 23 ng/L in the Eerste River, respectively (Mudumbi et al, 2014a). In the Olifants River basin all surface water concentrations of PFAS were <LOQ (Verhaert et al, 2017).…”

Drivers of the accumulation of mercury and organochlorine pollutants in Mediterranean lean fish and dietary significance

“…The study is also aimed to ascertain whether the concentrations of Total Hg are compliant with the maximum values in fishery products established by the European Legislation. Taking into account the role of biotic and abiotic factors in the accumulation of these pollutants in fish (Verhaert et al, 2017 andStorelli et al, 2002), the dependences between pollutant concentrations, fish species and specimen weight have been also evaluated.…”

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context

“…Nevertheless, the presence of agrochemicals in many South African rivers has been well-documented (e.g. the uMngeni River ( Gakuba et al , 2018 ), Olifants River ( Verhaert et al , 2017 ), Buffalo River ( Yahaya et al , 2017 ), Luvuvhu and Letaba rivers ( Gerber et al , 2015 ), Vaal River ( Quinn et al , 2009 ), Lourens River ( Bollmohr et al , 2007 ) and the Msunduzi River ( Adeyinka et al , 2019 )). Yet, there is little research regarding the ecological impact of many of the registered products in the environment ( Van der Laan et al , 2017 ).…”