Baseline levels and trophic transfer of persistent organic pollutants in sediments and biota from the Congo River Basin (DR Congo)

Abstract

The present study aimed to evaluate the occurrence of persistent organic pollutants (POPs: (PCBs, PBDEs, DDTs, HCHs, CHLs and HCB) in sediments and biota from the middle Congo River Basin (CRB) and to investigate their trophic transfer through the aquatic food web using nitrogen stable isotope ratios. To our knowledge, no data on levels of POPs in sediment and biota from the CRB are present in the literature, and studies on trophic transfer and biomagnification profiles of POPs using δ(15)N are scarce in tropical regions. POP levels in the sediment and biota were low, with exception of total PCB levels found in fish from the Itimbiri River (1.4 to 44ng/g ww). Compared to concentrations found in fish from pristine to relatively industrial developed areas, the ∑PCB levels in fish from the Itimbiri were high, indicating the presence of a local PCB contamination source in this catchment. Based on minimum risk level criteria formulated by ATSDR, the consumption of PCB contaminated fish from the Itimbiri river poses a potential risk for humans. The POP levels in biota were not significantly related to the POP levels in sediments, and the BSAF concept (Biota-Sediment Accumulation Factor) was found to be a poor predictor of the bioavailability and bioaccumulation of environmental pollutants in the present study. With increasing trophic levels, a significant increase in PCB 95, 101, 110, 138, 146, 149, 153, 174, 180 & 187 and p,p'-DDT in Itimbiri and BDE 47 & 99 in Itimbiri, Aruwimi & Lomami river basins was observed. Trophic magnification factors were higher than 1, indicating that biomagnification occurs through the tropical food web.

Characterization of polychlorinated biphenyls in surface sediments of the North End Lake, Port Elizabeth, South Africa

“…The levels reported by Greichus et al (1977) were two-fold greater in magnitude compared to the levels detected in the present study. Compared to the concentrations reported from other developing and industrially developed countries around the world, PCB concentrations measured in the present study were similar to those reported by Guzzella et al (2005), Rajendran et al (2005), He et al (2006), El-Khady et al (2007), and Verhaert et al (2013) (Table 3). All of these studies were conducted in developing countries, namely, India, China, Egypt and Democratic Republic of Congo, respectively.…”

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

“…They were 3-fold higher than those reported in sediments from the Napoleon Gulf and Thurston Bay of Lake Victoria (Ssebugere et al, 2013b;Ssebugere et al, 2014). The PCB concentrations in the present study were comparable to data from other fresh water bodies in Africa: the Nile River in Egypt (El-Kady et al, 2007), Ghar El Melh lagoon in Tunisia (Ameur et al, 2011), Pangani River basin in Tanzania (Hellar-Kihampa et al, 2013) and Congo River basin in the Democratic Republic of Congo (Verhaert et al, 2013). The results were also in the range of data found in sediments from tropical areas in Asia: the Mekong River delta in Vietnam (Carvalho et al, 2008) and riverine and coastal waters of Surabaya in Indonesia (Ilyas et al, 2011).…”

“…To our knowledge whereas PCBs have been reported in fish and sediments from the Napoleon Gulf and Thurston Bay of Lake Victoria (Ssebugere et al, 2013a, b;Ssebugere et al, 2014) and from other water bodies in the world (Manirakiza et al, 2002;Adu-Kumi et al, 2010;Darko et al, 2008;Helm et al, 2008;Eqani et al, 2013;Verhaert et al, 2013), literature shows no work about these pollutants in the Murchison Bay. The Bay is a major hotspot for discharge of industrial outflow, urban runoff and municipal effluents from Kampala, Uganda's capital city (Banadda et al, 2009).…”

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polybrominated diphenyl ethers in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

“…The ΣPBDEs varied widely between stations, with mean values ranging from 60.8 to 179 pg g −1 dry weight (dw). The concentrations in this study were lower than the data in sediments from the Congo River Basin in the Democratic Republic of Congo (Verhaert et al, 2013), Juksei River in South Africa (Olukunle et al, 2012), Niagara River in Canada (Samara et al, 2006), Ebro river basin in Spain (Lacorte et al, 2006) and the Columbia River in the United States .…”