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STORMWATER SAMPLING OF OIL PRODUCTS USING
SEMIPERMEABLE MEMBRANE DEVICES (SPMDs)
Per-Anders Bergqvist, *Lina Ulčinienė, *Viktoras Račys and *Audronė Žaliauskienė
Environmental Chemistry, Umeå University, Sweden and
*Kaunas University of Technology, Kaunas, Lithuania
•
Introduction
Non-point source (NPS) water pollution is a growing threat to the
environment (rivers, lakes and ground water) and public health. It is the
accumulation of sediment, chemicals, toxics, nutrients, debris and
pathogens that are carried by rain water and snow melt into the nearby
water body. Polycyclic aromatic hydrocarbons (PAHs) are among most
frequently detected and most important contaminants of urban runoff.
Important contribution to PAH contamination is via oil and
combustion products in stormwater. Attention must be paid even to low
concentration pollutants because of their potential high toxicity.
Commonly the PAH pollution of pyrogenic and petrogenic origin is
distinguished by additional analysis of methylated PAH (Ngabe et. al.
2000, Science of Total Env.). In this study PAH contamination of Tvärån
stream flowing through industrial and urban areas is investigated using
semipermeable membrane devices (SPMDs).
• Results and discussion
Concentrations (ng/L) of petrogenic and pyrogenic pollutants
Concentration, ng/L
PAH
0,00
0,20
0,40
0,60
0,80
1,00
1,20
1,40
1,60
1,80
2,00
2,20
2,40
2,60
2,80
Naphthalene
2-methylnaphthalene
1-methylnaphthalene
Acenaphthylene
1 site
2 site
3 site
Biphenylene
Acenaphthene
2,6-dimethylnaphthalene
2,3,5-trimethylnaphthalene
Fluorene
1-methylphenanthrene
Phenanthrene
Anthracene
Benz(a)anthracene
Chrysene
Fluoranthene
Pyrene
Benzo(b)fluoranthene
Benzo(k)fluoranthene
•
Benzo(e)pyrene
Materials and methods
Benzo(a)pyrene
Perylene
Benzo(g,h,i)perylene
Indeno(c,d)pyrene
Dibenzo(a,h)anthracene
Comparison of petrogenic and pyrogenic pollutants
Concentrations, ng/L
The quality of Tvärån stream was evaluated using SPMDs. These
are diffusive samplers that are used for measuring the truly dissolved
concentration of pollutants in water and air. A standard SPMD consists
of low-density polyethylene membrane contained 1 ml (0,915 g) of pure
triolein. They mimic the uptake of bioavailable organic compounds by
organisms. Storm water is one example of sampling condition where
flow and concentrations are fluctuating. The SPMD technology performs
continuous sampling during an extended period of time (several weeks)
and makes it possible to calculate a TWA (time weighted average)
concentration of dissolved (bioavailable) compounds.
In this study SPMDs were deployed at three sites in the Tvärån
stream (Umeå, Sweden) upstream (site 1), after the industrial area (site 2)
and after urban area (site 3) during 23 days. Schematic map of sampling
places is below.
The determined concentrations of
pyrogenic (19 compounds) and
petrogenic (5 methylated compounds)
PAHs at three sampling sites are shown
in figure (columns in red indicates the
methylated PAHs). Overall trend is that
concentrations of PAHs in the storm
water fed stream are increasing in the
industrial and urban area. Heavy PAH
compounds
are
commonly
not
dissolved in water and thus not sampled
in the SPMD. The composition of
incoming pollutants is thus different
between the two areas. Most of the
lighter methylated compounds are
added into the stream at site 2 whereas
heavier methylated compounds displays
an additional increase in the urban area.
10
9
8
7
6
5
4
3
2
1
0
Figure shows the comparison of sum
of 18 PAHs and sum of 5 methylated
PAHs. At sampling site 1 the petrogenic
influence is really low which is in
agreement with the forest and
agricultural environment upstream site 1.
The total amounts of PAHs and
methylated PAHs do not significantly
differ between site 2 and 3, but there is a
change of composition as previuosly
described.
sum 5 methyl-PAHs
sum 18 PAHs
1
2
3
Sampling places
The samples were treated according to scheme presented below.
S18 PAH concentration ng/L
Relationship between the concentration
of sumPAHs and the ratio of 1-methyl-PHE and PHE
10
9
8
7
6
5
4
3
2
1
0
0,00
0,05
0,10
0,15
0,20
0,25
Ratio 1-methyl-PHE/PHE
0,30
Figure shows the relationship
between
the
concentration
of
sumPAHs and the ratio of 1-methylPHE and PHE (PHE is phenanthrene).
Pyrogenic PAHs increase as the stream
is passing industrial and also urban
areas. However, after sampling site 2
the concnetration of the petrogenic
indicator (1-methyl-PHE/PHE) are
increasing more than the concentration
of pyrogenic PAHs. This indicates
continuos source of petrogenic PAHs
in the urban area but the source is
different compared to the industrial
area.
Influence of unknown oil related compounds
scan (FS) and
• Full
Conclusions
selective ion monitoring (SIM) mass
spectrometry was used for the determination of compounds of petrogenic
origin All
and three
SIM sampling
was also sites
usedshow
for determining
pollutants
of pyrogenic
different pollution
profiles
related
to the probable industrial and urban activities in the drainage
origin.
regions.
When the clean water after site 1 entered the site 2 notable
increase of petrogenic and pyrogenic pollution were seen. There
were no significant change in the pollutant levels when reaching site
3, however change in composition.
Non-destructive sampling with SPMD provides a fingerprinting
tool for identifying point-sources.
SPMDs is very usefull for testing bioaccumulative pollutants
and potentially toxic pollutants independent on flow variations and
ocasional factors. The described methodology is suitable for
stormwater investigations.
SPMDs method was succsesfully used to show the impact of
industrial and urban areas on the stream water quality but still it
needs futher investigations for general application and specific
evaluation.
Figure
compares
GC-MS
chromatograms at the three sampling
sites. The chromatograms (m/z 133)
shows the influence of a group of
unknown oil related compounds
(possibly trimethylbenzenes). The
amount of these compounds are
increasing in the stormwater during
industrial area. Another significant
increase (2 times) could be seen even
at site 3 (after urban area). The
sources of these compounds are still
to be identified. Also other
compounds in the stormwater
increased at site 2 and 3.
Acknowledgements
We thank Umeå university,
EU Socrates-Erasmus program and
Kaunas University of Technology
for financial support.