The aim of this study was to assess the impact of the Brno agglomeration on the distribution of risk elements (Pb, Cd, Cu, Zn, As) in tissues of a total of 50 chub (Leuciscus cephalus L.). Contamination by metals was monitored in fish from different sites on the Svitava and Svratka rivers in the urban agglomeration of Brno in 2008. Metal concentration was determined in the muscle, liver and kidney by high-resolution atomic absorption spectrometry. Electrothermic technique was used to assess lead, cadmium and copper concentrations; zinc content was determined by flame technique and arsenic by hydride generation. The highest concentrations of cadmium, lead, arsenic and zinc in individual tissues, ranked in a descending order as follows: kidney > liver > muscle; for copper it was liver > kidney > muscle. The highest concentrations of cadmium, arsenic and zinc were determined in chub kidney from the locality of Kníničky (1.35 ± 0.97, 0.186 ± 0.076, and 299.7 ± 123.4 mg·kg -1 respectively); the highest concentration of lead was on the Svratka before junction (0.28 ± 0.19 mg·kg -1 ). The highest contamination with risk metals was found in chub from the Svratka. The assessed concentrations have shown minimum participation of the Brno agglomeration in the accumulation of metals. The concentrations of all risk elements in chub from all of the monitored localities do not pose any environmental or health threat. This study updates published data on chub from the Rivers Svitava and Svratka on concentration of risk elements.

Rainbow trout (Oncorhynchus mykiss) was monitored for the duration of one year, from 2 to 14 months of age (n = 120). The study was performed on a farm with through-running water from the basin of water processing plant in the years 2007 and 2008. During the first months of fish life, we analyzed homogenized samples (n = 12) of rainbow trout bodies. From the 8 th month the samples of twelve rainbow trouts were analysed. The total contents of arsenic and arsenobetaine were quantified in muscle, liver, spleen and bile separately. The total arsenic was determined by hydride technique AAS and arsenobetaine by high performance liquid chromatography combined with detection using atomic fluorescence spectrometry. The concentration of arsenic in homogenized body samples grew (P < 0.01) during the first months of life, from the 6 th month of rearing no significant difference was found. The concentration of arsenobetaine in homogenized bodies was low during the first months and from the 6 th month the concentration stayed on invariable level and amounted to 46 ± 6% of total arsenic. The highest concentrations of arsenic and arsenobetaine in tissues ranked in the order muscle, liver, spleen and bile. In summer months the total arsenic in muscle was bonded in the form of arsenobetaine, in winter months the content of arsenobetaine dropped to 50% of total arsenic. The content of arsenic in liver samples remained the same during the entire monitoring, however, the ratio of arsenobetaine content altered. In summer months it reached the maximum 27%, in winter months it dropped to 7% of arsenic. The concentration of arsenic in spleen and bile decreased in winter months, arsenobetaine corresponded to the value assessed in liver. This study proved the effect of the small content of arsenic in feedstuff on accumulation of total arsenic and arsenobetaine in the tissue of rainbow trout during the growing period and season. Arsenobetaine, tissue, atomic absorption spectrometry, hydride generation, atomic fluorescence spectrometryArsenic compounds enter the environment naturally by volcanic eruptions, forest fires and weather impacts such as erosion. The most serious anthropogenic sources of arsenic (including industrial emissions) are the ore mining and processing industry, thermal power plants, agriculture (application of insecticides, herbicides, algicides) and the wood-working industry (chemical preservation of wood) (Tamaki and Frankenberger 1992). Arsenic exists in a wide variety of chemical forms and oxidation states, which influences its bioavailability and toxicity. In recent years a number of publications have appeared dealing with the arsenic content in marine organisms (Agusa et al. 2008;Grotti et al. 2010;Francesconi 2010) and freshwater organisms (Čelechovská et al. 2005;Ciardullo et al. 2010). More than 50 arsenic compounds were detected in marine organisms. Arsenobetaine (AsB), which is stable, metabolically inactive and non-toxic, predominates over all the arsenic species in edible parts of fish (Sloth et al. 2...