The source, composition and fate of selected PAHs in the River Derwent, Derbyshire, and in associated biota
This work was undertaken in order to determine the
extent and nature of PAH pollution In a freshwater riverine
environment. An extensive survey of sediment, water and
aquatic organisms was carried out to investigate sources of
PAH, physicochemical relationships occurring in the water
and sediment, the extent of bioaccumulation and the
potential for bioconcentration through the food chain.
Laboratory studies were designed to investigate the likely
mode and extent of uptake of PAH by Noemacheilus barbatulus
(L.), Glossiphonia complanata (L.) and Lymnaea peregra
(MUller), the ability of these species to metabolise PAH
compounds and the extent of depuration.
All sediment PAH profiles were similar and
indicative of an anthropogenic pyrolytic origin. Urban/road
runoff was considered to be a major influence on sediment
PAH concentrations. point sources consisted of industrial
waste sewage and runoff containing used engine oil.
, All sites were affected by diffuse PAH pollution. At
certain sites and at times of heavy rainfall this is overlain
by a greater input of PAH to the sediment from point
Positive linear relationships have been demonstrated
between total and individual PAH content and organiC matter
content in sediments throughout a range of particle sizes.
A similar PAH profile was found in each sediment size
fraction, thus organisms selectively removing certain sized
particles are not being exposed to differing ratios of PAH
The river system seems to be in a state of nearequilibrium
with regard to the partitioning of PAH between
bedload sediment, suspended sediment, water and interstitial
water. Adsorption and desorption processes occur in two
phases, the first being almost instantaneous and the second
being a slower approach to equilibrium.
There is no- evidence of PAH's being bioconcentrated
through the food chain. Uptake by tubificid worms occurs by
the ingestion of contaminated sediment. Uptake by Cottus
goblo (L.), N. barbatulus, L. peregru, G. complanata and
Erpobdella octoculata (t.) occurs mainly through water and
was shown to be rapid. N. barbatulus, L. peregra and G.
complanat~ have the capacity to metabolise PAH compounds to
harmful derivatives and it is likely that C. gobio and E.
octoculata also have this capability. Depuration of BaP and
metabolite compounds was relatively slow. Prolonged exposure
to low levels of BaP in the environment may lead to a buildup
of DaP and metabolite compounds in these organisms.