2. ENVIRONMENTAL ChEMISTRy & TEChNOLOGy 2.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Environmental Chemistry & Technology
P18 DISTRIbuTION PATTERNS OF ORGANIC
POLLuTANTS IN bRNO LAKE wITh
RESPECT TO ITS DEPOSITIONAL hISTORy
eVA FRAnCůa , JAn SCHWARZBAUERb , MATHIAS
RICKInGc , RADIM LánAa , PAVEL MüLLERa , JURAJ
FRAnCůa and SLAVOMIR nEHYBAd aCzech Geological Survey, Leitnerova 22, 658 69 Brno, Czech
Republic,
bInstitute of Geology and Geochemistry of Petroleum and
Coal, Aachen University of Technology (RWTH), Lochnerstr.
4–20, 52056 Aachen, Germany,
c Working Group Hydrogeology and Applied Geochemistry,
Free University Berlin, Malteserstr. 74–100 – Raum B117,
12249 Berlin, Germany,
dDepartment of Geology and Mineralogy, Masaryk University,
Kotlarska 2, 611 37 Brno,
eva.francu@geology.cz
Introduction
The contamination of the environment with persistent
organic pollutants (POPs) has been of great concern since the
1960s. Polychlorinated biphenyls (PCBs) or organochlorine
pesticides (OCPs) are found mainly in water, sediments and
aquatic biota throughout the world 1,2 . Owing to an intensive
agricultural and industrial production in past few decades, in
particular, river and lake sediments in the Czech Republic are
loaded with POPs and their levels are only partly decreasing 3 .
Brno Lake is situated on the Svratka River upstream from the
city of Brno and belongs to the most important water reservoirs
in the SE Czech Republic. Undisturbed sediment deposits
in lacustrine systems can act as environmental archive after
radiodating 4,5 . Since there are only a few studies dealing
with the levels of organochlorine contaminants in dated sediment
cores 6–9 , this pilot study is focused on the occurrence
of risk elements and organic pollutants in vertical profiles of
the sediment layers of the Brno Lake in order to restore the
pollution history of these trace organic pollutants.
Experimental
The first sampling campaign in Brno Lake covered nine
1m-deep cores with 52 sediment samples. A 3 m-long core
was drilled during the period of time when the reservoir was
empty in the early 2008. The detailed sampling includes
120 samples in total; detailed sedimentological investigation
and geochemistry were applied to the whole 3 m profile.
All samples were analyzed using screening methods
such as magnetic susceptibility (Kf) measured on KLY-2,3
and 3S kappabridges, elemental analysis of total organic and
inorganic carbon (TOC, TIC, respectively), high performance
liquid chromatography (HPLC) of 16 EPA priority polycyclic
aromatic hydrocarbons (PAH), and gas chromatography
with flame ionization detector (GC-FID) to measure the total
extractable hydrocarbons (TEH). Seven indicative PCB congeners
and organochlorine pesticides were determinated by
means of gas chromatograph HP 6890 equipped with µECD
s371
63 ni, cool-on-column injector and capillary column HP-5ms
(60 m × 0.25 mm i.d.). From the screening results 20 samples
were selected for gas chromatography coupled with mass
spectrometry (GC/MS) in full scan mode to characterize the
distribution of the alkylated aromatic and parent hydrocarbons
and in selected ion monitoring mode (SIM) for the saturated
fraction (SAT).
Results
The sedimentological visual examination together with
elemental analysis of the total organic and inorganic carbon
(TOC and TIC) and of the magnetic susceptibility (Kf) indicate
a stratigraphic archive with roughly 5 cycles each about
60 cm thick marked by increased magnetic susceptibility,
increased sand content and lowered organic carbon (Fig. 1.).
These coarser grained intervals formed probably during major
flooding events and migration of the lake bottom channel.
Fig. 1. Total organic carbon and magnetic susceptibility in the
deep well core profile from the Brno Lake (2008)
The early phase of the depositional history has sedimentary
structures suggesting more fluviatile environment
and sandy lithology. The later phases are characteristic by
increasing portion of fine-grained sediments. Laminated
sediments with organic carbon of up to 7.18 % mark the highstand
phases with stratified water column, which persisted
over long periods of the existence of the lake. A Th-U(Ra)-K
gamma-spectrometric survey shows that a probable source
of these elements is in the weathered granitic material of the
Brno Massif while the contribution from the U-mines is negligible.