Metal concentrations in water, sediment and three fish species from the Danube River, Serbia: a cause for environmental concern

Biomonitoring of toxic and essential trace elements in different tissues of fish species in Türkiye

Concentrations of toxic and essential trace elements (Hg, Ni, Cu, Pb, Cr, Cd, Mn, As and Se) were determined in different tissues (muscle, skin and liver) of three commercial fish species (Diplodus sargus, Zeus faber, Pomatomus saltatrix). The concentration of the elements was measured by ICP-MS. Arsenic was the most accumulated element in fish tissues. As concentrations in tissues of all fish species, except muscle and skin of John Dory fish, were higher than the maximum limits (MLs). The highest Se concentrations in all fish tissues were in found in the liver. Mn levels were higher than the maximum limits in all tissues of Sargoz fish, skin of John Dory fish, livers of Bluefish and Big Bluefish. In addition, Cr concentrations in tissues of all fish species were found to be higher than the maximum limits of FEPA and WHO.

Evaluation of sediment dredging in remediating toxic metal contamination - a systematic review

Toxic metal pollution is a leading environmental concern for aquatic systems globally, and remedial dredging has been widely employed to mitigate its harmful impacts. In terms of the short-term impacts of remedial dredging, mixed results are reported in several studies. Despite its immediate negative impacts including saturation of water with toxic metals, increased turbidity, and sediment resuspension, positive impacts can be recorded over a stabilization period of 6-24 months after dredging. Nevertheless, the sustainability of these recorded positive effects cannot be ascertained as some studies have reported long-term regression in remediated sites' conditions. Evaluation of success determinants, site-measure compatibility, and determination of supplementary measures are keys to achieving and sustaining the projected benefits of remedial dredging and justifying its overall cost. This multicomponent study reviewed published literatures that documented the outcomes of short- and long-term dredging projects in toxic metal-polluted systems globally with a broad goal of examining how sediment removal impacts toxic metal dynamics in the aquatic system and understanding why the sustenance of positive impacts is controversial. In the meantime, this study also explored the preventative and remedial management strategies for attaining and sustaining positive dredging outcomes. The purpose of this study is to provide key recommendations for decision-making and policy development in aquatic toxic metal remediation.

Bioaccumulation of potentially toxic elements in fish species of Serbia: a review

In the first review of potentially toxic elements (PTEs) in fish in water ecosystems in Serbia, 40 studies related to fish contamination with PTEs were identified and evaluated. Studies of concentrations of PTEs in fish tissues covered 28 ecosystems (108 localities). The main studied river ecosystems were the Danube and the Sava, and the Međuvršje reservoir was the most studied standing water ecosystem. Among the most studied fish species were catfish (Silurus glanis), followed by pikeperch (Sander lucioperca), bream (Abramis brama), carp (Cyprinus carpio), and barbel (Barbus barbus). There were 48 "hot spot" sampling sites where concentrations of Hg, Cd, Pb, As, Ni, Fe, and/or Cu exceeded the maximum permitted concentrations (MPCs) prescribed by legislation. Elevated concentrations of these elements were the most detected in fish species sampled in the Danube, Sava, and rivers belonging to the Velika Morava basin. Hg concentrations were the most common above MPC in muscle tissue of species sampled from the Danube and Sava rivers. On the other hand, we can single out the species Vimba bream (Vimba vimba), sampled in Danube River in Zemun near Belgrade, as the safest species for human consumption due to the largest number of elements in fish meat below detection limits. Finally, having in mind all the criteria prescribed by U.S. EPA (2000), we identify and recommend two predatory fish species pikeperch (S. lucioperca) and catfish (S. glanis), and bottom-feeding fish species barbel (B. barbus) as bioindicators of PTEs contamination in Serbian waters.

Development of a Sensitive Method for Cadmium Determination in Fish Tissue and Drinking Water Samples by FAAS Using SQT In Situ Atom Trapping

A sensitive and robust trap method was developed for the determination of cadmium (Cd) by using a slotted quartz tube. Using this method at a sample suction rate of 7.4 mL/min for 4.0 min collection, a 1467-fold increase in sensitivity was obtained compared to the flame atomic absorption spectrometry method. Under the optimized conditions, a limit of detection of 0.075 ng mL^-1 was obtained for the trap method. The interference effects of hydride-forming elements, transition metals, and some anions on the Cd signal were investigated. The developed method was evaluated by analyzing "Sewage Sludge-industrial origin (BCR no: 146R)", "NIST SRM 1640a Trace elements in natural water", and "DOLT: 5 Dogfish Liver". There was a good agreement between the certified and found values at the 95% confidence level. This method was applied successfully for the determination of Cd in drinking water and some fish tissue samples (liver, muscle, and gill) obtained from Muğla province.

Seasonal variations of macro-, micro-, and toxic elements in tissues of vimba bream (Vimba vimba) from the Danube River near Belgrade, Serbia

Vimba bream (Vimba vimba) individuals were collected from the Danube River near Belgrade, from May 2016 to May 2017. Samples of muscle and liver tissue were analyzed for concentrations of 25 elements (macro-, micro-, and toxic elements) using inductively coupled plasma optical emission spectrometry (ICP-OES). For both tissues, the highest concentrations of most elements were observed in late spring/early summer (months of May and June). Majority of statistically significant correlations between elements were positive in both tissues. Contributions of Ca, K, and Mg to human diet were in a similar range. The lowest contribution of all macroelements was observed for Na, while the contribution of Se was well above the recommended dietary allowance for this element. Levels of detected elements were well below MAC values prescribed by national and international regulations. The highest value of Hg liver/muscle index (>1) was observed in August, which could indicate a higher contamination of the sampling location in that month. Se:Hg molar ratio never drops below 1, which could indicate that Hg toxicity is prevented. THQ values showed little variation thought the year and were well below the threshold of 1, with the exception of THQ for Al in May (0.92). This element also strongly affects the hazard index.

Distribution and Ecotoxicological Risk Assessment of Heavy Metals in Streams of Amanos Mountains from Southern Turkey

Assessing the potential ecological risks of chemical pollutants like heavy metals is a key tool of a sustainable environment. With this goal, ecotoxicological significant metal (Al, As, Cd, Cr, Cu, Fe, Hg, Ni, Pb, and Zn) levels of the water (n = 32) and sediment (n = 32) samples of streams [rural (8 points) and urban (8 points) sides] on Amanos Mountains were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and ecotoxicological risk assessment was performed through the potential ecological risk index (RI). The study region with intense urban activities has also ecological importance with regards to wildlife. It is located on the migration route of birds, hosts loggerhead and green sea turtles, Mediterranean seals, and some terrestrial species like mountain gazelle and striped hyena. All calculated RI values were below the potential risk limits and the ecotoxicological risk was observed to be very low. Metal levels should be monitored periodically, and necessary measures should be taken before the reflection of the increase to be determined by the risk assessment on the ecosystem.

Spatial distribution of multielements including lanthanides in sediments of Iron Gate I Reservoir in the Danube River

Recent studies show that lanthanides (Ln) are becoming emerging pollutants due to their wide application in new technologies, but their environmental fate, transport, and possible accumulation are still relatively unknown. This study aims to determine major and trace elements including Ln in the Danube River sediment which either belong or close to the Iron Gate Reservoir. The Iron Gate Reservoir is characterized by accumulation of sediments as an effect of building hydropower dam Iron Gate I. The surface sediments were collected on the Danube River-1141 to 864 km and three tributaries along this waterway. Two samples of deep sediments were used for comparison. The results indicate the significant upward enrichment of Zn, Sb, Cr, Nd, and Dy in sediments belongs to the Iron Gate Reservoir. The sample 4-Smed is labelled as a hot spot of contamination with Zn, Cr, As, Sb, Nd, and Dy. Also, a trend of increasing concentration in the time period from 1995 to 2016 was found for elements Zn, Cr, and Ni in sediment samples in the Iron Gate Reservoir. Chemometric analysis shows the grouping of sample sites into clusters characterized by the following properties: (i) increased concentration of all measured elements (samples within the Iron Gate Reservoir); (ii) increased Cu concentration (11-Pek); and (iii) lower concentrations of the measured elements (deep sediments). The data presented hereby contribute to the monitoring of pollution of the River Danube sediments and give the first view of Ln profile in the studied sediments.

Metals Distribution, Histopathological Alterations, and Health Risk Assessment in Different Tissues of Fish (Ctenopharyngodon idella)

Grass carps were exposed to the established lethal concentration (LC) values of copper (Cu), chromium (Cr), and lead (Pb) each for the exposed period of 24, 48, 72, and 96 h respectively. Concentrations of these metals were determined in the brain, liver, muscles, gills, kidneys, and intestinal tissues of exposed and control fish through the atomic absorption spectrophotometer after the wet digestion process. The metals accumulation inside these tissues confirmed the absorption of metals from media into the tissues of the model organism. The accumulated concentration in fish tissues was confirmed to be concentration-dependent with significant (p < 0.05) elevated mean values seen for the lead followed by chromium and copper as compared with the mean concentration values of their respective control group. Levels of metals were found above the permissible standards suggested by the regulatory authorities in the fish's body. Histological sections of the same targeted organs exposed to the three exposure concentration groups were studied and compared with the sections of the healthy group. The histopathological lesions were scored to rank the deleterious effects of metals. The histopathological changes were recorded in concentration and progressive time-related series where gills had the greatest number of scored lesions followed by the kidneys and intestines, muscles, brain, and finally the liver as the least affected organ. Moreover, the organs were not affected uniformly by the metals; in fact, every studied organ has given mild to severe responses towards the toxic metals where lead had proven to cause more severe lesions as compared with copper and chromium. The histological lesions recorded mostly were thus concentration-dependent as revealed in the bioaccumulation of these metals with the effects ranked as lead > chromium > copper with a few exceptions. The findings can be used as a benchmark for the evaluation of the fate and effects of the toxic metals in the expanded aquaculture production of grass carp nationwide. Further investigations with respect to other potentially toxic metals like arsenic, mercury, and cadmium could address the problem towards additional studies.

Concentrations, Distribution, and Pollution Assessment of Metals in River Sediments in China

This study conducted a review on the concentrations, spatial distribution and pollution assessment of metals including As, Hg, Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in 102 river sediments in China between January 2008 and July 2020 based on the online literature. The geo-accumulation index (Igeo) and potential ecological risk index (RI) were used for the pollution assessment of the metals. The results showed that the ranges of metals were: 0.44 to 250.73 mg/kg for As, 0.02 to 8.67 mg/kg for Hg, 0.06 to 40 mg/kg for Cd, 0.81 to 251.58 mg/kg for Co, 4.69 to 460 mg/kg for Cr, 2.13 to 520.42 mg/kg for Cu, 39.76 to 1884 mg/kg for Mn, 1.91 to 203.11 mg/kg for Ni, 1.44 to 1434.25 mg/kg for Pb and 12.76 to 1737.35 mg/kg for Zn, respectively. The median values of these metals were descending in the order: Mn > Zn > Cr > Cu > Pb > Ni > Co > As > Cd > Hg. Compared with the SQGs, As and Cr manifested higher exceeding sites among the metals. Metals of river sediments manifested a significant spatial variation among different regions, which might be attributed to the natural weathering and anthropogenic activity. The mean Igeo values of the metals presented the decreasing trends in the order: Cd > Hg > Zn > Cu > As > Pb > Ni > Co > Cr > Mn. Cd and Hg manifested higher proportions of contaminated sites and contributed most to the RI, which should be listed as priority control of pollutants. Southwest River Basin, Liaohe River Basin, and Huaihe River Basin manifested higher ecological risks than other basins. The study could provide a comprehensive understanding of metals pollution in river sediments in China, and a reference of the control of pollutant discharge in the river basins for the management.

The Toxic Element Concentration in Fish Tissues from Saničani Lake, an Urban Environment, in Bosnia and Herzegovina

Concentrations of toxic elements (lead, cadmium, mercury, and arsenic) were measured in water, sediment, and four commercial fish species (Cyprinus carpio, Hypophthalmichthys molitrix, Silurus glanis, and Esox lucius) and their tissues (muscle, liver, and kidney) from Saničani Lake, Bosnia and Herzegovina. The concentration of toxic elements was measured by atomic absorption spectrometry. Toxic element concentrations were significantly affected by the fish species and tissues sampled. The lead was the most heavily deposited element in lake sediments and waters. The highest concentrations of Pb and Cd were in the kidney in all four fish species. Concentrations of Hg and As were higher in the muscle than in the kidney and liver in all four fish species. The toxic element concentrations in all examined tissues were significantly higher in Silurus glanis and Esox lucius than in the other fish species examined. Concentrations of all tested elements were present in the fish muscle at different levels, but these levels were under the maximum levels allowed by the European Union and FAO/WHO. Accordingly, fish meat from this lake is acceptable for human consumption.

Determination of the Level of Selected Elements in Canned Meat and Fish and Risk Assessment for Consumer Health

The objective of the study was to determine the content of cobalt, silver, tin, antimony, lead, mercury, cadmium, arsenic, vanadium, chromium, manganese, nickel, and uranium in canned meat and canned fish by means of ICP-MS apparatus and mercury analyzer. Also, probabilistic risk assessment (non carcinogenic) was estimated by models including target hazard quotient (THQ). It was found that Mn was the element with the highest concentration in the analyzed products, with average concentration of 0.216 mg·kg^-1 in canned meat and 1.196 mg·kg^-1 in canned fish. The average contents of other elements were as follows (respectively, for canned meat and fish): Co 0.018 and 0.028 mg·kg^-1, Ag 0.0386 and 0.0053 mg·kg^-1, Sn 0.059 and 0.200 mg·kg^-1, Sb 0.0268 and 0.0377 mg·kg^-1, Pb 0.202 and 0.068 mg·kg^-1, Hg 0.00003 and 0.02676 mg·kg^-1, Cd 0.00496 and 0.0202 mg·kg^-1, As 0.002 and 0.857 mg·kg^-1, V 0.0003 and 0.095 mg·kg^-1, Cr 0.244 and 0.590 mg·kg^-1, Mn 0.216 and 1.196 mg·kg^-1, Ni 0.004 and 0.088 mg·kg^-1, and U < LOQ and 0.047 mg·kg^-1. The concentration of As was the highest among other toxic elements in canned fish; therefore, the THQ value of this element revealed the highest level amounting up to 0.77576 (THQ_max).

Seasonal distributions of heavy metal concentrations in different snail (Helix pomatia) tissues from an urban environment in Serbia

The aim of this study was to evaluate the differences between concentrations of heavy metals (cadmium, copper, zinc, iron, and manganese) in terrestrial gastropods, Helix pomatia, collected in four different environment locations in Pančevo city, Serbia. Metal concentrations in the foot and in the digestive gland were measured. Heavy metals cadmium, copper, zinc, iron, and manganese were measured in triplicate by atomic absorption spectrophotometry. Also, this study investigated correlations between the trace element content in the soft tissues and different seasons (summer and fall). The results showed that heavy metal concentrations of the measured elements in both snail tissues were significantly higher in polluted sites when compared to the background levels in the city. In digestive gland tissues, the concentration of heavy metals was higher compared with that in foot tissues. The bioaccumulation (heavy metal concentrations in soft tissues) of heavy metals (Cd, Cu, Zn, Fe, and Mn) in snails, Helix pomatia, has been assessed and related to seasons and sites. Heavy metal accumulation in the soft tissues of snails could provide a powerful monitoring tool for the assessment of environmental heavy metal pollution.

Heavy metal and arsenic concentrations in rainbow trout (Oncorhynchus mykiss) farmed in a dam reservoir on the Firat (Euphrates) River: Risk-based consumption advisories

The concentrations of ten metals in rainbow trout (Oncorhynchus mykiss) farmed in the Karakaya Dam Reservoir (Turkey) on the Firat River were determined. The metal concentrations in rainbow trout did not exceed the maximum permissible levels. Biomagnification factors (BMF) of ten metals were <1, indicating that these metals were not biomagnified. The estimated daily intake (EDI) of each metal was much lower than the respective tolerable daily intake (TDI). The target hazard quotient (THQ) for individual metal and total THQ for combined metals were lower than 1, indicating no health risk for consumers due to the intake of either individual metal or combined metals. The cancer risk (CR) value for toxic inorganic As was below 10^-6, indicating no carcinogenic risk. According to the calculated maximum allowable consumption rates (CR_mm), an adult may safely consume 28 meals of rainbow trout from the dam reservoir per month with no adverse carcinogenic and non-carcinogenic health effects. According to these results, the consumption of rainbow trout farmed in this dam reservoir is completely safe for human health.

Heavy metals and minerals contents in pikeperch (Sander lucioperca), carp (Cyprinus carpio) and flathead grey mullet (Mugil cephalus) from Sidi Salem Reservoir (Tunisia): health risk assessment related to fish consumption

The aim of this study was to investigate heavy metals and selected minerals contents in filets of pikeperch (Sander lucioperca), carp (Cyprinus carpio) and flathead grey mullet (Mugil cephalus), the major fish species produced in Sidi-Salem reservoir; the largest Tunisian freshwater ecosystem. Concentrations of Ca, Mg, Fe, Zn, Cd, Pb and Hg were determined by inductively coupled plasma-optical emission spectrometry, while concentrations of Na and P were determined by flame photometry and spectrophotometry, respectively. Results concerning heavy metals are considered quantitatively reliable for Hg and Cd but must be taken with precautions concerning Pb levels as the LOD (limit of detection) of the analytical process was higher than acceptable limit. They showed greater accumulations of both Hg and Cd in filets of pikeperch than in filets of carp and mullet, but none of the values exceeded the normative maximum levels (0.500 and 0.050 mg kg^-1 w.w., respectively). Considering provisional intakes, target hazard quotient and hazard index, estimated for a fish portion per week, consumption of any of the species did not appear to be potentially hazardous for the health as they were far below threshold values. A fish portion would provide substantial amounts (>15% of daily requirements) in essential mineral nutrients (P, Mg and Fe) and thus should be considered an interesting contribution to a healthy diet. It is strongly advocated to authorities including freshwater fish in the official national annual control survey of contaminants in fishery products, which in addition to guaranteeing security of consumers, would also allow diversifying valorisation opportunities and thus increase the economic value of this fish production.

Determination of heavy metals in muscle tissue of six fish species with different feeding habits from the Danube River, Belgrade-public health and environmental risk assessment

The aim of this study was to investigate the presence of heavy metals/metalloids (Pb, Cd, Hg, Cu, Fe, Zn, As) in the muscle tissue of fish from the Danube River (two locations: Zemun and Grocka). For the purpose of heavy metal determination in fish muscle, 120 samples of six different fish species, Prussian carp, barbel, bream, carp, pike perch, and catfish were collected. For determining heavy metals, we used microwave oven digestion and atomic absorption spectrometer methods. The highest average content of Pb (0.084 ± 0.004 mg kg^-1), Cd (0.082 ± 0.003 mg kg^-1), Hg (0.466 ± 0.006 mg kg^-1), and As (0.333 ± 0.007 mg kg^-1) was found in the muscle of carp (an omnivorous fish) from Grocka, while the highest average level of Fe (13.60 ± 0.03 mg kg^-1) was deposited in bream (also omnivorous) from Zemun. Also, the average Cu level (1.62 ± 0.13 mg kg^-1) was the highest in catfish muscle (a carnivorous fish) from Grocka, while the highest Zn content (11.16 ± 0.17 mg kg^-1) was determined in muscle of Prussian carp (an omnivorous fish) from Zemun. The highest content of heavy metals (Cu, Fe, and Zn, respectively) in muscle of the six different types of fish from both locations was symmetrically arranged by species (catfish, barbel, and Prussian carp, respectively). Concentrations of Pb, Hg, and As in the Danube River fish muscle were under the maximum residual levels prescribed by the European Union (EU) and the maximum allowed concentrations (MAC) for Serbia. On the other hand, in all fish muscle from both locations (Zemun and Grocka), higher concentrations of Cd than prescribed (MAC) were found, with the exception of bream and pike perch.