Content of heavy metals in the muscle tissue of fish from two rivers

Overview

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with the highest concentration reaching 5029.9 µg/kg. In comparison, nickel concentrations
in roach and perch were generally low and often below the detection limit (14.8 µg/kg). Mercury
significant, with concentrations in the Bečva mostly under the detection limit (1.49 µg/kg). Lead
in which chromium concentrations exceeded 159.94 µg/kg. In general, aside from nickel, heavy
(EC) No 2023/915 with the maximum content of Pb in fish meat set at 0.30 mg/kg wet
weight, Cd at 0.05 mg/kg wet weight and Hg at 0.50 mg/kg wet weight.
1% Pd/Mg(NO3)2 was used as a modifier.
Calibration standards consisted of 1000 mg/l of stock Cd, Pb, Cr, Ni and Hg solutions (Merck & Co, Inc.,
USA), while ultrapure 69% HNO3 m/m (Sigma Aldrich, USA) and Milli Q water with a maximum resistivity
agreed with the certified values. Limits of detection for the heavy metals were as follows: 0.1 µg/l (0.1 µg/kg) for
Hg, 0.052 mg/l (1.49 µg/kg) for Cd, 0.65 mg/l (18.57 µg/kg) for Pb, 0.12 mg/l (3.43 µg/kg) for Cr and 0.52 mg/l
(14.8 µg/kg) for Ni.
recalculated for fish biomass, i.e. 0.05 µg/kg for Hg, 0.745 µg/kg for Cd, 9.285 µg/kg for Pb, 1.715 µg/kg for
Cr and 7.4 µg/kg for Ni.
those at Bečva 4 (Table 1). Body weight varied according to total length (Kruskal-Wallis
Bečva (Table 2). Not only were mean concentrations of Ni in chub muscle tissue highest
in the Svratka, the highest concentration recorded in the study (5029.87 µg/kg) was also
found there (Table 3). Significant differences were recorded between Ni concentrations at
df = 4, P < 0.001; Table 3). Concentrations of Hg in all chub muscle samples were
above than the limit of detection (14.3–249.4 µg/kg), with both mean and highest Hg
Cr, Pb, and Cd concentrations were often below the limit of detection (Table 3). Mean
one sample with the highest Cd concentration recorded (13 µg/kg). While most samples
Bečva 3 had a value 93.3 times above the limit of detection (159.94 µg/kg). Lead
Table 1. Characteristics of fish caught in the rivers Bečva and Svratka for heavy metals analysis.
Table 2. Concentrations of heavy metal pollutants in water and sediment from the rivers Bečva and Svratka (mean ± SD).
Table 3. Concentrations of heavy metal pollutants in muscle of chub from the rivers Bečva and Svratka (mean ± SD).
Numbers in parentheses: number of samples above limit of detection (LOD) analysed (n = 10 in total). Different
Table 4. Concentrations of heavy metal pollutants in muscle tissue of different fish species from the river Svratka
Numbers in parentheses: number of samples above limit of detection (LOD) analysed (n = 10 in total). Different
20 ± 10 µg/kg, i.e. slightly lower than in the present study, and similar results have also been
regulations, i.e. 50 µg/kg for Cd and 300 µg/kg for Pb (Commission Regulation (EC)
the upstream locality had muscle Hg concentrations of 110 ± 40 µg/kg in 2007 and
70 ± 30 µg/kg in 2008, while the downstream locality had slightly higher concentrations
at 100 ± 30 µg/kg in 2007 and 120 ± 143 µg/kg in 2008. Aside from the upstream locality
(14.8 µg/kg). In contrast, others had Ni concentration up to 5.3 mg/kg). Nickel leakage
relatively often. Uysal et al. 2009 found high variability in Ni content (6.21–887.1 mg/kg)
(0–0.441 mg/kg), while the variability was low on the later sampling (4.41–15.41 mg/kg).
samples, in their study area, however, the highest sediment concentration was 63.3 mg/kg
attributed to the relatively high Ni content in sediment in the Svratka (mean = 40.56 mg/kg).
all localities. Andreji et al. (2005) reported a mean muscle tissue Cr concentration

Methods (brief)

human health. However, the samples with the highest nickel content could represent a potential
river basin. During this study, some fish muscle samples exceeded the maximum Hg levels
poisoning, in the autumn of 2020. Fish samples were acquired in October 2021 by electrofishing from four sites:
Fish were sampled from the Svratka in March 2022 from a trapezoidal regulated stretch of the river, with more
the Bečva (2020–2022) were obtained from the Povodí Moravy State Enterprise. Sediment samples from the
Samples of sediments were taken from 2 places upstream of the locality on the Svratka (49.1852786N,
The resulting value of the pollutant content in the sediments is the average of the values from these samples.
Heavy metals were analysed in river sediments and fish muscles. Sediment samples were first lyophilised
mineralised through microwave digestion (Ethos ONE, Milestone, Italy). Concentrations of Cd, Cr, Pb and Ni
were then determined using a 280Z AA graphite furnace atomic absorption spectrometer (Agilent Technologies,
pre-treatment of the sample (i.e. no decomposition or separation), 100 ± 0.1 mg of fresh muscle or dry sediment
sample being directly analysed under optimal measurement conditions, i.e. drying at 120 °C for 90 s, followed by
sample (pre)treatment and sample dilution, respectively.
Republic) was used for validating Cd, Pb, Cr, Ni and Hg analysis of sediment samples. In all cases, our results
df = 4, P < 0.001; Table 3). Concentrations of Hg in all chub muscle samples were
one sample with the highest Cd concentration recorded (13 µg/kg). While most samples
from all localities had Cr concentrations below the limit of detection, one sample from
in muscle tissue samples from chub and roach, and chub and perch (Table 4).

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised