Lower Course Of River Research Articles

Riparian vegetation entraps macroplastics along the entire river course: Implications for eco-safety activities and mitigation strategies

Macroplastic litter causes detrimental effects on freshwater biota affecting human health. Despite the significant role of rivers in transporting plastic waste, most plastics remain in fluvial ecosystems, accumulating in infrastructure, river sediment, and (riverbank) vegetated areas. However, the entrapment of plastics by riparian vegetation was overlooked, particularly in upper and middle river courses. For the first time, we aimed to quantify the entrapment of plastics by riparian vegetation along the entire river course. Sampling riparian areas in the upper, middle, and lower river courses in central Italy, we found 1548 macrolitter items, with vegetation entrapping 93.9% of total litter. Riverbank and riparian plastics acted as long-term indicators of river plastics. We emphasized the trapping efficiency at the species level highlighting that the best plastic trapper species were trees, shrubs and reeds (Populus spp., Salix spp., Rubus ulmifolius, Phragmites australis, and Ficus carica), blocking 85.4% of the total macrolitter entrapped by plants. Plastic pieces, bags, bandages, sanitary items, and packaging were among the most trapped types. Furthermore, vegetation in the lower river course exhibited greater plastic entrapment compared to the upper and middle courses, following the fact that all the river courses contribute to plastic pollution. Recognizing the potential of riparian vegetation as a valuable ecosystem service in trapping macroplastics, further research should explore the characteristics and structures of riparian communities involved in this process. By developing eco-safe practices and mitigation strategies based on these findings, we might contribute significantly to managing, conserving, and restoring riverine ecosystems.

FIRST RECORD OF <i>BRANCHIURA SOWERBYI</i> BEDDARD, 1892 (OLIGOCHAETA) IN SHEKSNINSKOE RESERVOIR (UPPER VOLGA)

In August 2021, two specimens of invasive oligochaete of tropical origin Branchiura sowerbyi were found in the Sheksna reservoir of the Vologda region (59°45ʹ21ʺN, 38°21ʹ28ʺE). For today, this is the northernmost finding of this species. Probably, this species penetrated with the ballast waters from the Don River lower course through the Volgo-Don canal and the Volgo-Baltic waterway. The temperature regime of the water bodies of the Vologda region allows reproduction of this oligohaeta.

Patterns of Structural and Functional Bacterioplankton Metacommunity along a River under Anthropogenic Pressure

Bacteria, an integral part of aquatic ecosystems, are responsible for the circulation of matter and flow of energy. Since bacterioplankton rapidly responds to any natural and human-induced disturbances in the environment, it can serve as a bioindicator of these changes. Knowing factors that shape the microbial community structure may help the sustainable management of the water environment. However, the identification of environmental signals affecting the structure and function of bacterioplankton is still a challenge. The study analyses the impact of environmental variables on basic microbial parameters, which determines the effectiveness of ecological processes in rivers. Measurements of bacterioplankton abundance (BA) and extracellular enzyme activity (EEA) were based on fluorescent markers. The bacterial community structure was determined by 16S rRNA gene amplicon sequencing (Illumina). The results indicate spatial variation in bacterioplankton abundance. Temporal variation was not significant. Lipase and aminopeptidase had the highest level of activity. EEA was not correlated with bacterial abundance but was significantly correlated with temperature. Moreover, differences in lipase, α-glucosidase and β-glucosidase activity levels between spring and summer were noted. At the same time, the location of sampling site had a significant influence on aminopeptidase activity. The taxonomic analysis of bacterioplankton communities in the Brda River indicated that, although different numbers of OTUs were recorded in the studied river sections, bacterioplankton biodiversity did not change significantly along the river with distance downstream. Anthropogenically modified river sections were characterized by the dominance of Flavobacterium (Bacterioidetes) and hgcl clade (Actinobacteria) taxa, known for their ability to produce extracellular enzymes. PCoA analysis revealed that the sites located in the lower river course (urban area) had the most similar bacterial community structure (β-diversity). The study provides new insight into the changes in microbial communities along the river and emphasizes the potential impact of anthropogenization on these processes.

НОВЫЕ МЕСТОНАХОЖДЕНИЯ И СОСТОЯНИЯ ОБНАРУЖЕННЫХ ЦЕНОПОПУЛЯЦИЙ РЕДКОГО ВИДА POTENTILLA FREYNIANA BORNM. (ROSACEAE) ЛУГОВЫХ СООБЩЕСТВ ДОЛИНЫ НИЖНЕГО ТЕЧЕНИЯ Р. УССУРИ

The paper presents data on new locations of the rare species Potentilla freyniana Bornm. (Rosaceae) of the meadow communities in the Ussuri River lower course valley. The author gives the characteristics of phytocenoses in the places of this species growth. It is provided the data on the number of individuals in coenopopulations, frequency of occurrence, age spectrum, vitality, as well as morphometric parameters of individuals to assess their condition. Some measures are proposed to protect the Potentilla freyniana species.

Why analysing microplastics in floodplains matters: application in a sedimentary context.

Microplastics in the environment are a relatively new form of anthropogenic contamination. Right now, the research focus is on the detection of microplastic accumulation in different environmental compartments and understanding the processes that have led to its transport. Detailed information on microplastics in floodplain areas and their distribution in depth are still missing to better understand accumulation points. Therefore, this study presents on the one hand microplastic detection in fluvial sediments from nine sampling sites along a river course. Polymers were determined with infrared spectroscopy and additional sedimentary analysis of the grain size and heavy metal concentration was performed. In total, there was less microplastic in the upper than in the lower river course and slip-off slopes were identified as accumulation hotspots also in deeper sediment layers. Mostly, microplastic particles were detected in fine sediment and heavy metal concentrations along the river were similar to those of microplastics. On the other hand, besides the spatial distribution of microplastics and accumulation in floodplain areas, microplastic analysis offered information in a sedimentary context. Sedimentation rates (0.29-4.00 cm a-1) and patterns between temporal deposition and microplastic polymers were identified. The basis for the development of a dating method by detection of MPs in sediments was thus established. Microplastics as a contaminant provide, in addition to the identification of deposition areas, further data in a temporal and sedimentary perspective.

Phytoplankton response to water quality seasonality in a Brazilian neotropical river.

Tropical wet-dry climate seasonality is widely recognized as an important condition to phytoplankton communities' structure in freshwater ecosystems; however, there are few studies in that field in northeast Brazilian rivers. This study aimed to evaluate the influence of water quality seasonal variability over the phytoplankton dynamics and identify seasonality in eutrophication phenomena in a poorly studied neotropical river. Water quality variables and phytoplankton were examined within the Jequitinhonha River lower course, Bahia (Brazil) from 2010 to 2012. A 3-year time series was analyzed for both rainy and dry seasons. Descriptive, inferential, and multivariate analyses (CCA) were performed. Results indicated that chemical oxygen demand, dissolved aluminum, and turbidity were the main factors which influenced phytoplankton community structure and composition. Dry season was favorable for diatoms and Chlorophyceae (chlorophylls) while rainy season was favorable for cyanobacteria. Still, it was revealed that, in dry season, lower values for turbidity, chemical oxygen demand, dissolved aluminum, and dissolved iron were related with an eutrophication phenomenon.

CONSIDERATIONS ON THE MORPHOLOGICAL CHANGES ON MOLDOVA RIVER LOWER COURSE AND THE EVOLUTION OF REGULARIZATION WORKS

The paper presents an analysis of the morphological changes created on the Moldova River lower course. The studies and researches were carried out on the sector around Pildeşti locality, where Roman water catchment is located. The successive floods from 1994 to 2018 have morphologically modified the Moldova River minor river bed, which determined supply parameters of the wells located on the left bank of the river. The minor river bed moves horizontally during floods due to the degradation of the jetties and the enclosure beams. The floods of 2016 and 2018 partially and totally destroyed some of the riverbed's shore protections. Also, part of the shore protection works have been degraded, which has influenced the stability of the Moldova River left bank. The floods in the past ten years have led to the displacement of the minor river bed towards the right riverbank by breaking the old enclosure dikes and the jetties. Studies conducted during 2012-2018 analysed hydrological, hydraulic, morphological and topographic parameters on the considered river sector. The research analysed the concurrence of regulation and protection works in the water catchment area during floods. The flood of 2016 forced the restoration of the Moldova River minor river bed, to ensure the optimum wells operation.

Trophic segregation in multispecies community of salmonids in the Penzhina River lower course (Kamchatsky Krai, Russia)

Trophic segregation in multispecies community of salmonids in the Penzhina River lower course (Kamchatsky Krai, Russia)

Lanthanides and yttrium in the sediments of the lower Minho River (NW Iberian Peninsula): imprint of tributaries

Rare earth elements have been used as sediment tracers in river, estuarine and coastal environments but rarely applied as fluvial tributary tracers. Lanthanides (Ln) and yttrium (Y) were quantified in fluvial sediments of the Minho River lower course (NW Iberian Peninsula), where the catchment contains heterogeneous lithologies, to define the characteristic imprints of tributaries and their relevance in the riverine system. Surface sediments were sampled at 36 points in the lower Minho riverbed and its nine main tributaries.The < 2-mm fraction was sieved and ground, and ≈ 100 mg was completely acid-digested with HF and aqua regia in closed Teflon bombs at 100 °C for 1 h. The residue was evaporated, re-dissolved with HNO3 and Milli-Q water, heated 20 min at 75 °C and diluted to 50 cm3 with Milli-Q water. Lanthanides and yttrium were determined using a quadrupole ICP-MS equipped with a Peltier impact bead spray chamber and a concentric Meinhard nebuliser. Blanks accounted for less than 1% of the element concentrations in the samples. The precision and accuracy of the analytical procedures were controlled through reference materials AGV-1 and MAG-1. Contents ranged from 22 to 153 mg Ln kg−1 and 1.5–22.9 mg Y kg−1 and ES-normalised light-heavy Ln fractionation, (LN/HN), varied between 0.6 and 2.6. These wide ranges, together with Eu and Ce anomalies and element-by-element Ln, varied with changes in parental rocks of the lower Minho basin. Minho sediments showed negative Ce anomalies (0.81 ± 0.29) and positive Eu anomalies (1.23 ± 0.18). Sediments received traces of granitic pegmatites and gneissic peralkaline rocks from two tributaries: the Gadanha (22.9 mg Y kg−1; 83 mg Ln kg−1; 0.60 LN/HN; 0.51 Eu/Eu*; 0.88 Ce/Ce*) and the Louro (15.9 mg Y kg−1; 110 mg Lnkg−1; 0.97 LN/HN; 0.69 Eu/Eu*; 1.49 Ce/Ce*). The Tamuxe tributary, flowing through a slate and quartzite fault, provided the lowest source (1.6 mg Y kg−1; 28 mg Ln kg−1; 2.48 LN/HN; 1.01 Eu/Eu*; 0.55 Ce/Ce*). Lanthanide and Y signatures in sediments may be used to trace land-tributary-river influences. The imprints are observed downstream of fluvial confluences but not in all cases, responding to basin lithological changes, particularly for pegmatites and peralkaline rocks. The general REE trend is described using Y contents only. Tributaries, which are responsible for one-fifth of the Minho water load, provide one-half of their sediments. Non-homogeneous sediment patterns may be magnified in dammed rivers such as the Minho.

Can beaver impact promote river renaturalization? The example of the Raba River, southern Poland

The European beaver (Castor fiber) was reintroduced in the Polish Carpathians in the 1980s after a few centuries of absence. It gradually colonized suitable habitats in the Raba River valley and elsewhere. The question arises as to whether beaver activity can play a role in the local improvement of hydromorphological conditions and spontaneous renaturalization of the Raba River channel. Field surveys were performed in morphodynamically and structurally homogeneous reaches of the river. Traces of beaver activity were identified and used to estimate the studied beaver population. Local beaver impact on the studied river channel was also determined. The Raba channel is trained along about 80% of its length and considerably incised. Traces of beavers activity were found in 16 out of 31 river reaches, mainly in the upper and lower river course. The study showed that relatively flat channel gradient, small maximum bed-material grain size, and high channel sinuosity favour beaver presence. The largest number of beaver habitats was identified in river reaches strongly altered by man and characterized by a uniform channel structure. Beaver impact on channel structure varies depending on differences of the river channel features in upper and lower reaches of the Raba River channel. In upper reaches, the impact of beaver activity (mostly dams) is reflected in increased lateral erosion, while slower water current reduces the tendency for bed degradation. In lower reaches, beaver impact is mostly limited to bank fragmentation (slides and burrows). Lateral erosion, accumulation of material at the toe of riverbanks, and wood debris accumulation all produce a local impact on river channel width. These beaver-initiated processes mostly alter artificially homogenized river reaches. Beavers may actually play a substantial role in future renaturalization of both upper and lower reaches of the Raba River.

The possibilities of reconstructing the composition of vegetation communities on the basis of conjugated palynological, phytolith and carpological analyses for Kolyma River lower course area.

The possibilities of reconstructing the composition of vegetation communities on the basis of conjugated palynological, phytolith and carpological analyses for Kolyma River lower course area.

State of the environment of urban and mining areas in the Selenga Transboundary River Basin (Mongolia Russia)

The pollution of the soil cover, river water and bottom sediments in the Ulaanbaatar and Ulan-Ude cities and the Erdenet and Zakamensk mining centers was assessed using the data of geochemical surveys in 2011–2015. In Ulaanbaatar, the highest pollution with Pb, Cd, Zn, Mo, Cr, and Cu is revealed in the central industrial–transport–residential area. Emissions from thermal power plants and motor vehicles are the main sources of pollutants. In Ulan-Ude, the highest concentrations of Pb, Cd, Sb, and Sn are observed in the soils of the industrial zone with various engineering and manufacturing enterprises. The topsoils in the mining centers are contaminated with ore and accompanied elements: Mo, Cu, As, Sb in Erdenet, and W and Mo, W, Bi, Cd, Pb, and Sb in Zakamensk. The extremely hazardous level of the soil pollution in Erdenet was revealed in the mining complex area, while in Zakamensk, it occupies about half of the city’s territory. The Ulaanbaatar city’s effect on the trace element composition of water and bottom sediments in the Tuul River during the summer floods is insignificant, in low-water season content of dissolved Pb, Cd, Zn, Co, Sr, Ni and Cu, Co, V in suspension increase many times. In the Selenga River lower course near Ulan-Ude, the floodwater has high concentrations of dissolved Cu, Co, V, Ni and is slightly enriched with suspended V, Bi, Sb, Sn, Mo; the concentrations of heavy metals in bottom sediments remain unchanged. The mining centers exert a local impact on the river network.

Pace of life, predators and parasites: predator-induced life-history evolution in Trinidadian guppies predicts decrease in parasite tolerance.

A common evolutionary response to predation pressure is increased investment in reproduction, ultimately resulting in a fast life history. Theory and comparative studies suggest that short-lived organisms invest less in defence against parasites than those that are longer lived (the pace of life hypothesis). Combining these tenets of evolutionary theory leads to the specific, untested prediction that within species, populations experiencing higher predation pressure invest less in defence against parasites. The Trinidadian guppy, Poecilia reticulata, presents an excellent opportunity to test this prediction: guppy populations in lower courses of rivers experience higher predation pressure, and as a consequence have evolved faster life histories, than those in upper courses. Data from a large-scale field survey showed that fish infected with Gyrodactylus parasites were of a lower body condition (quantified using the scaled mass index) than uninfected fish, but only in lower course populations. Although the evidence we present is correlational, it suggests that upper course guppies sustain lower fitness costs of infection, i.e. are more tolerant, than lower course guppies. The data are therefore consistent with the pace of life hypothesis of parasite defence allocation, and suggest that life-history traits mediate the indirect effect of predators on the parasites of their prey.

The diversity and longitudinal changes of zooplankton in the lower course of a large, regulated European river (the lower Vistula River, Poland)

AbstractThe diversity and longitudinal variation of zooplankton in the lower Vistula River were analyzed. Samples were taken from 40 stations located along a 272-km long section of the lower river course. During the study the unique technique of taking samples from “the same water” was used. The zooplankton community was dominated by rotifers and nauplii — larval stages of copepods. The most abundant species were: Brachionus angularis, Brachionus calyciflorus and Brachionus budapestiensis. The zooplankton species diversity in the main channel of the lower Vistula River was similar to other large European rivers; however, its abundance was lower. The diversity, abundance and biomass of potamoplankton steadily decreased downstream. This could be related both to scarcity of storage zones for potamoplankton development in the river due to the extensive regulation processes, and changes in hydrological conditions of the main channel (by the straightening of riverbed) where the samples were collected.

Possible Abstraction Sites along Osun River Lower Course in Ogun and Lagos State, Nigeria For Sustainable Supply Of Potable Water

Water scarcity remains a major challenge in all the developing nations of the world; not because of paucity of surface water (rivers and streams) that could be abstracted for treatment, but, finding a suitable and sustainable abstraction site. The main objective of this research is to identify good locations, where water treatment plant could be sited along Osun River in Ogun and Lagos State for sustainable production of potable water. To achieve this, water quality of Osun River upstream Lekki lagoon was investigated at three sampling stations; Ogbere, Igbonla and Lekki. Water parameters such as physical (temperature, solids, turbidity) chemicals (pH, electrical conductivity (EC), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, phosphate, chloride and sulphate, alkalinity, potassium, lead, chromium, iron) and bacteriological (feacal coliform) were determined using standard procedures. The results revealed that Ogbere and Igbonla stations are better locations where water could be abstracted from Osun River than Lekki stations due to low measured parameters (indicators of water pollution), which were within World Health Organization (WHO) acceptable limits. The findings also showed that while raw water abstraction from Osun River at Ogbere and Igbonla stations would require a conventional treatment, raw water from the Lekki lagoon (station) would require special treatment especially desalination due to high chloride and EC contents with expected cost implication.

NATURAL REGENERATION OF FISH ASSEMBLAGES IN THE PILICA RIVER AFTER A REDUCTION OF POINT‐SOURCE POLLUTION

ABSTRACTElectrofishing was conducted along the Pilica River, the biggest West tributary of the Vistula, Poland. This paper presents a comparison between the 1990s (1994–1995, 63 sites) and 2000s (2003–2005, 64 sites), that is, because the water quality started improving after 1989. In the Pilica, there is an increased risk of masking relationships between fish distribution and abiotic factors because a dam without a fish pass was constructed in the middle course of the river in 1973, perhaps resulting in fewer possibilities for potential colonizers reaching river fragments fit for colonization. The main aim of this study was to check if natural fish fauna regeneration took place in the river following a significant sewage input reduction. The fish samples were classified with a Kohonen artificial neural network and assigned to two main clusters (X and Y) and, respectively, two pairs of subclusters (X1, X2; Y1, Y2) of neurons. No species attained its significantly highest biomass and/or frequency (expressed as IndVal) in X2 (in which samples from the 1990s dominated), whereas 21 species did so in Y1 or Y2 (containing almost all of the samples from the 2000s), better testifying to the aquatic environment at the sites where the samples assigned to two latter subclusters come from. Moreover, significantly higher values for Y1 and/or Y2 when compared with X2 were recorded in the richness of the fish species, the total fish biomass and total rheophilic fish biomass. In summary, the positive reaction of ichthyofauna to the improvement of the water quality, stated after 1989, was not recorded during the sampling in 1994–1995, but with a considerable delay in 2003–2005. It should be emphasized that the improvement in fish assemblages was recorded in the Pilica both upstream and downstream from the dam reservoir. A good ecological status was recorded even for some samples from the 1990s. They were collected in the lower river course, where the fish could move freely from the Vistula. This testifies the combined role of the presence of potential colonizers and the functioning ecological corridors for fish assemblages in a river system under human impact. Copyright © 2012 John Wiley &amp; Sons, Ltd.

Spatio‐temporal variations in fish assemblages in a tropical regulated lower river course: an environmental guild

AbstractFish assemblage patterns were studied in the lower river reach of the Uthokawiphatprasit anti‐salt dam, 6 km upstream from the Pak Panang River mouth, Southern Thailand, where the dam was opened occasionally depending on the upstream water level. Matrix data of the presence–absence of 71 fish species in 102 surveys was used in the analysis by applying a self‐organizing map (SOM) model. The trained SOM (lattice 8 × 7) showed that after 6 years of operation, five assemblage patterns were distinguished. These patterns described the probability of the occurrence of fish in each fish environmental guild, which according to changes in flow and water geomorphology. Clusters Ia and Ib were mostly the surveys in upstream stations and occupied by fish in potamonic guilds, whereas the fish in the estuarine guild and marine guilds showed a high probability of occurring in clusters IIa, IIb and IIc, which belonged to the surveys in downstream stations. The surveys of the stations near the dam (i.e. stations 5 and 6) during the opening phase were contained in cluster IIb. The Kruskal–Wallis test showed that there was no statistical difference in the probability of occurrence among assemblages of the diadromous, catadromous and semi‐anadromous fishes but not the amphidromous fishes, which had a low probability of occurrence in clusters Ia and Ib. The fish assemblages were arrayed along a longitudinal gradient, where salinity and pH were the most important controlling variables and explained 94.0% of the total inertia. Copyright © 2009 John Wiley &amp; Sons, Ltd.

Evaluation of Sinos River water genotoxicity using the comet assay in fish

The Sinos River, in southern Brazil, is polluted by industrial discharges and untreated urban wastes. Fish genotoxicity biomarkers are valuable parameters for environmental risk assessment. In this study, we used the comet assay to detect genotoxicity due to multiple sources of pollution in the peripheral blood of a native fish species (Hyphessobrycon luetkenii). In addition, we analysed possible DNA damage from aluminum, lead, chromium, copper, nickel, iron and zinc contamination. Water samples were collected seasonally from three sampling sites and the fish were assessed under laboratory conditions. Water chemical analysis showed an increased level of aluminum and iron in most of the samples at sites 2 and 3, located in the middle and lower river course, respectively. The index of DNA damage assessed by the comet assay demonstrated no significant differences in different seasons or at the different sampling sites, while the frequency of cells with DNA damage was higher in water samples collected at sites 1 and 2 during the spring season. None of the metals studied seems to be associated with the increase in the frequency of cells with DNA damage observed during the spring season. The results of this study indicate that the Sinos River is contaminated with substances that are genotoxic to fish, including the waters near the river spring.

Distribution, origin and cycling of carbon in the Tana River (Kenya): a dry season basin-scale survey from headwaters to the delta

Abstract. The Tana River basin (TRB) is the largest in Kenya (~120 000 km2). We conducted a survey during the dry season throughout the TRB, analyzing a broad suite of biogeochemical parameters. Biogeochemical signatures in headwater streams were highly variable. Along the middle and lower river course, total suspended matter (TSM) concentrations increased more than 30-fold despite the absence of tributary inputs, indicating important resuspension events of internally stored sediment. These resuspended sediment inputs were characterized by a lower and 14C-depleted OC content, suggesting selective degradation of more recent material during sediment retention. Masinga Dam (a large reservoir on the upper river) induced a strong nutrient retention (~50% for inorganic N, ~72% for inorganic phosphate, and ~40% for dissolved silicate). Moreover, while DOC pools and δ13C signatures were similar above, in and below the reservoir, the POC pool in Masinga surface waters was dominated by 13C-depleted phytoplankton, which contributed to the riverine POC pool immediately below the dam, but rapidly disappeared further downstream, suggesting rapid remineralization of this labile C pool in the river system. Despite the generally high turbidity, the combination of relatively high oxygen saturation levels, low δ18O signatures of dissolved O2 (all &lt;+24.2‰), and the relatively low pCO2 values suggest that in-stream primary production was significant, even though pigment data suggest that phytoplankton makes only a minor contribution to the total POC pool in the Tana River.

Fluxes of Heavy Metals from a Highly Polluted Watershed During Flood Events: A Case Study of the Litavka River, Czech Republic

The Litavka River (length 56 km, watershed area 630 km2, average flow at the outlet to the Berounka River 2.57 m3 s−1) drains the historical mining, ore processing, and smelting region of Přibram. This Ag–Pb–Zn±Sb ore district (production from the thirteenth century to 1978, locally to 1980) is known for extensive heavy metal contamination. Recent contamination of the Litavka River system is mostly related to the erosion of contaminated soils and fluvial floodplains sediments, especially from a low-gradient river section located immediately below the ore district, where the fine-grained floodplain sediments are from 1.0 to 1.7 m thick. Radiocarbon accelerator mass spectrometry dating of charcoal fragments separated from one floodplain profile showed calibrated 14C age in the range AD 1220–1284 at a depth of 1.2 m below the surface, while depths of 0.4 and 0.8 m yielded ages in the range AD 1680–1939. Formation of this floodplain was related to disturbance of the river equilibrium resulting from deforestation and the influx of fine-grained material from ore processing, including historical failures of settling ponds. Fluxes of heavy metals during flood events in the Litavka River were studied 35 km downstream below the ore district. Metals are transported here mostly (more than 99% for Pb) in the form of suspended particulate matter (SPM), which at the outlet of the Litavka River contains 2,016 mg kg−1 Zn, 918 mg kg−1 Pb, and 25.5 mg kg−1 Cd on average. During a snowmelt-related minor flood event between March 25 and 29, 2006 (peak flow 36.6 m3 s−1), the river transported 2,400 tonnes of SPM during 4 days, containing 74 kg of Cd, 2,954 kg of Pb, and 5,811 kg of Zn. During larger floods (water flows above 55 m3 s−1 have occurred here 27 times during the last 77 years), the contamination is more diluted by material eroded in the floodplain along the middle and lower river course.