Metals and polycyclic aromatic hydrocarbons (PAHs) in stormwater sediments: particle distribution and catchment area emission factors (CAEFs)
Paper i proceeding, 2010
Emissions from traffic and construction materials contaminate stormwater with both metals and organic
pollutants, and techniques for efficient removal of contaminants are reguested. The purpose of this study
was to determine the particle distribution of some selected metals and polycyclic aromatic hydrocarbons
(PAHs) in a stormwater sedimentation facility, and to caiculate the emitted amounts of these contaminants
in the studied catchment area. Chemical analysis and determination of physical parameters were
performed on sediments sampled at a stormwater treatment facility consisting of seven sedimentation
chambers connected in series. The facility is located in central Gothenburg, Sweden, and receives runoff
from the E6 and E20 motorway, with a daily traffic bad of approximately 86 000 vehicies. The
concentrations of the PAHs and metals showed a trend with sediment concentrations increasing from the
first to the last chamber. The pollutant concentrations were weil correlated with the particle size
distribution, dry densities, water and organic content of the sediments. in two or more of the chambers, the
concentrations of Cd, Pb, Cu, Zn, Ni, Cr and carcinogenic PAHs were higher than the given guideline vaiues
for contaminated soil. The relative composition of the PAHs in sediment, with a dominance of pyrene,
phenanthrene, fluoranthene and chrysene, indicates that rubber tyres, diesel exhaust and road asphalt
could be important sources of PAH pollution. The calculated catchment area emission factors (CAEFs)
showed, in Wyear ha, the following order: petroleum hydrocarbons Cio - C4o (15 000) > Zn (3200) > Ni
(~3000) > Cu (1500) > Sb (930) > Cr (820) > V (640)> Pb (260) > Co (120) > As (87) > Sn (25)> Mo (43)
> ~16-EPA PAH (13) > Cresols (3.4) > Cd (1.3)> Hg (0.43). The results show that large parts of the finest
sediment particle fractions, with high concentrations of the contaminants, are released with outiet water
from the sedimentation facility. The treatment facility could be more efficient if a filter was installed after
the sedimentation steps, before discharge of water to the nearby stream.
urban sediments
metals
particle distribution
PAH
road runoff
Catchment area emission factors (CAEFs)