National energy consumption structures modulate PAH source apportionment
in Ethiopian soils
Abstract
Polycyclic aromatic hydrocarbons (PAHs), a ubiquitous substance in the
environment, are closely associated with human energy consumption, which
can be released to the environment from incomplete biomass combustion or
emitted from petroleum. There is currently a knowledge gap on the
relationships between energy consumption structures (ECSs) and PAH
contamination, especially in African countries. This study investigated
the distribution, sources, and risks of 16 prioritized PAH compounds
(Σ16PAHs) in Ethiopia, and explored the impact of ECSs on PAH
contamination. The concentrations of Σ16PAHs ranged from 12.51 to 435.67
ng/g, descending across an urban-rural gradient. Based on diagnostic
ratios and positive matrix factorization (PMF) model, biomass combustion
and vehicle emissions were the most important sources. By comparing the
ECSs and PAH concentrations in African countries, it was found that
differences in ECSs shaped the diverse patterns of sources and
concentrations of PAHs in Africa. The results of incremental lifetime
cancer risk assessment suggested PAHs posed a low risk to children,
adolescents, and adults at some sampling sites. The Ethiopian government
has been making continuous efforts to develop cleaner energy and
optimize ECSs to decrease soil PAH concentrations and reduce potential
risks. This study will provide support for Ethiopia to improve energy
structure management.