Increasing Trends of Legacy and Emerging Organic Contaminants in a Dated Sediment Core From East-Africa
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Date
2022
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Publisher
Frontiers in environmental science
Abstract
Temporal trends of industrial organic contaminants can show how environmental burdens
respond to changes in production, regulation, and other anthropogenic and environmental
factors. Numerous studies have documented such trends from the Northern Hemisphere,
while there is very limited data in the literature from sub-Saharan Africa. We hypothesized
that the temporal trends of legacy and contemporary industrial contaminants in sub-
Saharan Africa could greatly differ from the regions in which many of these chemicals were
initially produced and more extensively used. For this purpose, a dated sediment core
covering six decades from a floodplain system in urban Dar es Salaam, Tanzania, was
analysed. The samples were analysed for selected legacy persistent organic pollutants
(POPs) [polychlorinated biphenyls (PCBs) and polybrominated biphenyl ethers (PBDEs)]
and chemicals of emerging concern (CECs) [alternative brominated flame retardants
(aBFRs), chlorinated paraffins (CPs), and dechloranes]. All groups of chemicals showed
a steep increase in concentrations towards the uppermost sediment layers reflecting the
more recent years. Concentrations of the individual compound groups in surface sediment
were found in the order CPs >> aBFRs ∼ ∑25PBDEs > dechloranes ∼ ∑32PCBs. Time
trends for the individual compounds and compound groups differed, with ∑32PCBs
showing presence in sediments since at least the early 1960s, while some CECs first
occurred in sediments corresponding to the last decade. Investigations into potential
drivers for the observed trends showed that socioeconomic factors related to growth in
population, economy, and waste generation have contributed to increasing
concentrations of PBDEs, aBFRs, CPs, and Dechlorane Plus. Further monitoring of
temporal trends of industrial organic contaminants in urban areas in the Global South
is recommended.
Description
This research article was published by Frontiers in environmental science in 2022