Acta Universitatis Carolinae Environmentalica 19 (2005): 7-20
The Influence of Agitation Conditions on the Size Characteristics of Ferric Flocs during
Water Treatment
ONDŘEJ KLOUČEK, LIBUŠE BENEŠOVÁ
Institute of Environmental Studies, Charles University in Prague, Faculty of Sciences,
Benátská 2, 128 01, Praha 2
Accepted September 14, 2005
Abstract: The effect of invariable and variable agitation intensity on the evolution of the ferric
floc size, structure and particle concentration during aggregation is investigated by image
analysis in the Couette reactor using natural raw water. Under low agitation intensity
represented by values of the mean velocity gradient of G = 40 s-1 and 60 s-1 large, tenuous and
irregular structures with wide size distribution are formed, the changes in aggregates size
procceed slower. On the other hand high shear rates (G > 150 s-1) produces relatively
homogenous, compact aggregates with narrow size distribution, attaining quickly the sizesteady state. The study of variable shear stress influences shows that only the lowest value of
gradient applied (G = 40 s-1) have regrowth effects for the aggregates after the initial formation
at the high shear rate. The reexposure to the high velocity gradients causes breakage of the
aggregates into the aggregates that are slightly smaller or almost equal as the aggregates after
the initial agitation at the high shear rates.
Keywords: aggregation, floc size characteristics, shear stress, image analysis
Acta Universitatis Carolinae Environmentalica 19 (2005): 21-32
Sequential Extraction of Brown Coals and Unburned Carbons from Small Combustion
Units
L. BARTOŇOVÁ, Z. KLIKA
Department of Analytical Chemistry and Material Testing, Faculty of Metallurgy and Material
Engineering, VŠB-Technical University of Ostrava, Tř. 17. listopadu 15,
708 33 Ostrava-Poruba lucie.bartonova@vsb.cz, zdenek.klika@vsb.cz
Accepted September 14, 2005
Abstract: In this work attention is drawn to modes of occurrence of As, Se, Co, Cu, Pb, Cr and
Ni in 3 coals (with different ash and sulphur content) and 4 unburned carbons collected at pilotscale combustion facility simulating small domestic combustion units. Modes of occurrence of
these elements have been determined using sequential extraction by leaching the samples by
solution of ammonium acetate, HCl, HF and HNO3. Elemental analysis (XRF) showed high
content of As in these samples, mineral analysis (XRD) identified in the coals above all quartz
and kaolinite, in the unburned carbons also hematite, metakaolinite and dehydroxylated
kaolinite. Comparison of modes of occurrence of trace elements in coal and unburned carbon
provides important information on trace elements behaviour during the combustion.
Acta Universitatis Carolinae Environmentalica 19 (2005): 33-90
Fish Assemblages in the Berounka River and its Tributaries (Úhlava and Mže) in 19752004, (fishery statistics and electroshocker data)
KAREL PIVNIČKA*, MIROSLAV ŠVÁTORA**, JOSEF KŘÍŽEK*, MARTIN HUMPL*,
PAVEL SÝKORA**
*Institute for Environmental Studies, Charles University in Prague, Benátská 2, 128 01 Prague
2, CZ, pivnicka@natur.cuni.cz
** Department of Zoology, Charles University in Prague, Viničná 7, 128 44 Prague 2, CZ
Accepted September 14, 2005
Abstract: The stepwise growth of the concentration of nitrates, ammonia, and chlorides up to
the end of 1980´s with its recent decrease is quite distinct. The yields of all fish with exception
of carp decreased during 1975-1999(2004) but increased in fishing wards from Plzeň to Praha
(carp 10-160, forage fish 0.5-22, carnivorous fish 0.5-10 kg/ha). In 1998-2004 altogether of
23851 fish of 26 species were caught in the Berounka River near Radnice and 2336 fish of 21
species in the Úhlava River near Předenice by electrofishing. The relative abundance of the fish
caught by electroshocker in the Berounka ranged between 758 and 4812/ha, the biomass
between 64 and 430 kg/ha, in the Úhlava between 186 and 2648 fish/ha, and between 31 and
175 kg/ha. The cluster analysis was applied to compare fish assemblages in the whole
longitudinal profile of the Berounka and Úhlava rivers, more thoroughly in sites and years of
the Berounka R. near Radnice and, Úhlava R. near Předenice, and in the fishing wards of the
Mže and Berounka rivers managed by sport fishermen.
In the Berounka near Radnice we estimated in average of 1165 barbel, 1159 chub and
709 roach and dace (total of 3033 fish/ha). Judging from the shape of catch curves of barbel
and chub it appears that the strong year classes of both species were born in flood years 1997
and 2002. The strong year classes, not associated with floods were observed in the roach. In the
Úhlava near Předenice we estimated 200-400 barbel, 330-690 chub, 250-520 dace, and 120240 roach/ha altogether 900-1860 fish/ha. In the fishing ward B7 (45 ha) 15000- 18000
fish≥15 cm was estimated; together with fish preferred by fishermen 20-24 thousands. In a
typical under weir site of the Berounka River (Třímany, ward B7) five species ≥10 cm produce
323 kg/ha/year. The production of all species with exception of stocked carp (18 kg/ha/year)
was estimated on 350 -450kg/ha. We expect about 60% of this production in the other lotic
localities and 10% in lentic habitats.
The negative influence of NH4+ and Cl- on fish evaluated by RDA and CCA showed that
both factors covered as much as 29.9% of the variability in fish yields, the positive effect of
carp yields on yields of other fish was not shown.
Keywords: water quality; fishery management; abundance and production of fish; cluster and
multivariate analysis
Acta Universitatis Carolinae Environmentalica 19 (2005): 91-96
Mercury in Vascular, Terrestrial Plants - Comparison between Finland and Slovenia in
the Years 1979-1981
MARTIN LODENIUS, PEKKA NUORTEVA & SIRKKA-LIISA NUORTEVA
Department of Biological and Environmental Sciences, P.O.Box 27 FIN-00014 University of
Helsinki, Finland
Accepted September 15, 2005
Abstract: The mercury concentrations of terrestrial, vascular plants were analysed from
different localities in Finland and Slovenia in the years 1979-1981. The background values
were low both in Finland (mean 0.02 μg/g dry weight) and in Slovenia (mean 0.07 μg/g).
Significantly elevated concentrations were found in the vicinity of a Finnish chlor-alkali works
(mean 0.69 μg/g) and near the mercury mine at Idrija, Slovenia (mean 59 μg/g). A great
variation in the mercury contents of different plant species was observed in the polluted areas.
Keywords: uptake of mercury, different environments, indication, pollution