Patterns of toxic metals bioaccumulation in a cross-border freshwater reservoir

Assessment of Essential and Potentially Toxic Elements in Water and Sediment and the Tissues of Sciaena deliciosa (Tschudi, 1846) from the Coast of Callao Bay, Peru

The lorna drum Sciaena deliciosa is a coastal demersal species and one of the underlying artisanal fisheries in some areas of Peru, and is also a source of protein for Peruvian coastal dwellers. The investigation addresses concern about the environmental impact on this fish species and the potential risks to human health through the consumption of contaminated seafood. This research endeavors to assess the concentration of potentially toxic and essential elements in the muscle and liver tissues of S. deliciosa, in addition to the presence thereof in water and sediment capture areas on the coast of Callao, Peru. The study revealed that, in water samples, Ag, Ni, and Zn exceed Peruvian standards, but were below international standards, and Ba, P, Se, and Sn exceed international standards. In the sediments, As, Cd, Pb, Fe, and Zn were above international standards. In the fish, S. delicious muscle demonstrated As, Hg, and Pb exceeding at least one international standard. In the liver, As, Hg, Pb, and Cu exceed international standards. The study approach increased accuracy in risk assessments, offering crucial insights into the interplay between heavy metal pollution, water quality, and animal health, informing risk management strategies. Future studies can explore the long-term effects of heavy metal exposure on different organisms and consider their cumulative impact on health.

Mercury and Organic Pollutants Removal from Aqueous Solutions by Heterogeneous Photocatalysis with ZnO-Based Materials

The removal of four Contaminants of Emerging Concern, namely bisphenol A, sulfamethoxazole, diclofenac and benzotriazole; two odorous compounds, geosmin and 2-methylisoborneol, frequently detected in recirculating aquaculture systems; and Hg(II) was investigated using ZnO-based materials doped or co-doped with Ce and Cu under simulated solar radiation. Photocatalysts were synthetized via a hydrothermal route and their efficiency was assessed by changing some operational parameters in different water matrices of increasing complexity. The mixture of contaminants was successfully degraded in just 1 h, while the complete mineralization was achieved in a few hours; experiments performed in an actual aquaculture water confirmed the efficiency and broad versatility of the synthesized materials.

Assessment of Some Heavy Metals and Their Relationship with Oxidative Stress and Immunological Parameters in Aquatic Animal Species

Heavy metal accumulation changes the immune system and leads to oxidative damage in aquatic animals. The present study evaluated the correlation between heavy metal accumulation, with immunological and oxidative stress parameters, in various species in the aquatic environment of Western Iran. Fresh samples included fish (trout and carp) and shrimp obtained from Sanandaj aquaculture. After blood sampling and serum isolation for immunological study, meat sections of these animals were used to measure heavy metal concentrations to determine the oxidative stress and immunological parameters. The highest concentrations of Pb (0.82 ± 0.10), As (0.53 ± 0.18), Hg (0.47 ± 0.08), and Zn (28.77 ± 1.88) (µg/g) were found in trout, while the lowest accumulation of heavy metals except for Cd (0.24 ± 0.11) and Se (1.57 ± 0.42) (µg/g) were observed in shrimp. The antioxidant enzymes glutathione peroxidase (GPx) (1.89 ± 0.13) and superoxide dismutase (SOD) (1.96 ± 0.62) U/mg showed the highest concentrations in shrimp and lowest in the trout. Significant negative correlations were found between these enzymes with As and Pb in trout and carp. A significant positive correlation was determined between Se and Zn with GPx and a negative correlation with malondialdehyde (MDA) in shrimp. Immunological biomarkers indicated the concentrations of IL-6, TNF-α, and IFN-Ƴ were higher in fish than in shrimp, and the lowest IgM level was obtained in Shrimp. Increased Pb and Cd showed a significant relationship with increased IL-6 and TNF-α in trout compared to shrimp and carp. An increase in As and Se concentration beyound maximum permissible limits (MPL) were recorded in fish and shrimp, while a Zn level less than MPL was recorded. The target hazard quotients (THQ) and target cancer risk (TR) values of non-essential heavy metals were obtained under acceptable ranges. We suggest reducing the As and Pb content under aquaculture farms and increase in the amount of Zn through diets to keep healthy immunological and physiological conditions for aquatic species in the west of Iran.

Integrating indices based on different chemical extractions and bioaccumulation in Bellamya aeruginosa to assess metal pollution and ecological risk in sediment

Various indices based on metal chemical data are used to evaluate pollution and ecological risk, but the consistency of the assessment results is usually unsatisfactory, and it is unclear if the ecological risk from sediment metals is accurately represented in in situ zoobenthos. Herein, the pollution and ecological risk associated with As, Cd, Cr, Cu, Ni, Pb and Zn in the sediments of two adjacent lakes (Datun (DT) and Changqiao (CQ)) were comprehensively evaluated by integrating metal concentrations, chemical forms and bioaccumulation in Bellamya aeruginosa (B. aeruginosa). The metal concentrations and chemical compositions varied widely in the sediments. Over 50% of the Cd, Pb and Zn in the sediments was present in bioavailable forms, followed by 28% of Cu and less than 25% of As, Cr and Ni. According to the enrichment factor (EF) and concentration enrichment ratio (CER) assessments, Cr and Ni were natural in origin, while the other metals were at minor to extremely high pollution levels, with average EFs of 1.5-77.6 and CERs of 1.1-113.4. The pollution levels for Cd, Cu and Pb from the EF and CER assessments were similar, while those for As and Zn were higher according to CER than EF (p = 0.05), likely due to the baseline underestimation associated with the potential diagenetic remobilization of bioavailable metals. The ecological risk index (Er), sediment quality guidelines (SQGs) and risk assessment code (RAC) showed a high eco-risk for Cd, while no similar risk was found for the other metals. By integrating risk indices with the chemical forms and pollution levels of metals, we deduced high eco-risks for As and Pb and moderate eco-risks for Cu and Zn in DT Lake and moderate eco-risks for As, Pb and Zn in CQ Lake. The other metals in the sediments of the two lakes presented low eco-risks. No significant positive correlations (p = 0.05) between metal accumulation in B. aeruginosa and the indices of pollution and eco-risk were observed except for the case of As, implying that measuring the metal concentrations in B. aeruginosa would not accurately characterize the metal pollution and ecological risk of sediments.

Contamination level, source identification and health risk assessment of potentially toxic elements in drinking water sources of mining and non-mining areas of Khyber Pakhtunkhwa, Pakistan

Accelerated mining activities have increased water contamination with potentially toxic elements (PTEs) and their associated human health risk in developing countries. The current study investigated the distribution of PTEs, their potential sources and health risk assessment in both ground and surface water sources in mining and non-mining areas of Khyber Pakhtunkhwa, Pakistan. Water samples (n = 150) were taken from selected sites and were analyzed for six PTEs (Ni, Cr, Zn, Cu, Pb and Mn). Among PTEs, Cr showed a high mean concentration (497) μg L^-1, followed by Zn (414) μg L^-1 in the mining area, while Zn showed the lowest mean value (4.44) μg L^-1 in non-mining areas. Elevated concentrations of Ni, Cr and a moderate level of Pb in ground and surface water of Mohmand District exceeded the permissible limits set by WHO. Multivariate statistical analyses showed that the pollution sources of PTEs were mainly from mafic-ultramafic rocks, acid mine drainage, open dumping of mine wastes and mine tailings. The hazard quotient (HQ) was the highest for children relative to that for adults, but not higher than the USEPA limits. The hazard index (HI) for ingestions of all selected PTEs was lower than the threshold value (HI_ing < 1), except for Mohmand District, which showed a value of HI >1 in mining areas through ingestion. Moreover, the carcinogenic risk (CR) values exceeded the threshold limits for Ni and Cr set by the USEPA (1.0E-04-1.0E-06). In order to protect the drinking water sources of the study areas from further contamination, management techniques and policy for mining operations need to be implemented.

Assessment of the Anthropogenic Impact and Distribution of Potentially Toxic and Rare Earth Elements in Lake Sediments from North-Eastern Romania

Chemical analysis was performed on sediment samples collected in two sampling sessions (July and October) from Podu Iloaiei Dam Lake, one of the most important water resources used for aquaculture in north-eastern Romania. The concentration of 15 trace elements (TEs), 8 refractory elements (REs), and 15 rare earth elements (REEs)—determined using inductively coupled plasma mass spectrometry—showed variability largely dependent of the sampling points and collection time. Manganese was the most abundant TE, V and Cr were the most abundant REs, while Ce was one of the most abundant REEs. The cerium negative anomaly and Gd positive anomaly were observed in the Chondrite-normalized distributions. In October, the Ce anomaly showed significant negative correlation with Mn, emphasizing the water body oxidation potential. The identified positive Gd anomaly was most likely associated with the use of Gd-chelating agents in magnetic resonance imaging in Iasi, the largest medical hub in north-eastern Romania. Principal component analysis extracted three factors explaining 96.0% of the observed variance, i.e., rock weathering, leaching from soil surface, contributions from urban stormwater and atmospheric deposition (50.9%), pedological contributions (23.7%), and mixed anthropogenic sources (e.g., traffic, waste discharge, agricultural activities; 21.4%). The evaluation of pollution indices highlighted low and moderate degrees of contamination for most of the elements and a considerable degree of contamination for Cd. Assigned Cd sources included fertilizers and pesticides used in the near agricultural areas or the high traffic road located near the lake. Since contamination of aquatic ecosystems with harmful elements is a human health concern, further monitoring of specific vectors in the food chain of the investigated dam lake will be of the utmost importance.

Emerging and Persistent Pollutants in the Aquatic Ecosystems of the Lower Danube Basin and North West Black Sea Region—A Review

The tremendous impact of natural and anthropogenic organic and inorganic substances continuously released into the environment requires a better understanding of the chemical status of aquatic ecosystems. Water contamination monitoring studies were performed for different classes of substances in different regions of the world. Reliable analytical methods and exposure assessment are the basis of a better management of water resources. Our research comprised publications from 2010 regarding the Lower Danube and North West Black Sea region, considering regulated and unregulated persistent and emerging pollutants. The frequently reported ones were: pharmaceuticals (carbamazepine, diclofenac, sulfamethoxazole, and trimethoprim), pesticides (atrazine, carbendazim, and metolachlor), endocrine disruptors—bisphenol A and estrone, polycyclic aromatic hydrocarbons, organochlorinated pesticides, and heavy metals (Cd, Zn, Pb, Hg, Cu, Cr). Seasonal variations were reported for both organic and inorganic contaminants. Microbial pollution was also a subject of the present review.

Bird's feather as an effective bioindicator for detection of trace elements in polymetallic contaminated areas in Anhui Province, China

Environmental pollution, especially because of trace metals, seriously affects ecological safety, and bird feathers are often used as bioindicators to monitor this risk in various environments. However, the feasibility of feathers as bioindicators for trace metals in polymetallic contaminated areas has not been extensively studied. In this study, we used inductively coupled plasma mass spectrometry (ICP-MS) to quantify and compare the contents of nine trace metal(loid)s (V, Cr, Mn, Co, Cu, Zn, As, Cd and Pb) among soil, plants, insects and birds (feathers and internal tissues) sampled in the mining area of Tongling, a polymetallic contaminated area in Anhui Province, eastern China. We detected significant trace metal pollution in the abiotic and biotic materials. The contents of Cr, Cu, Zn, As and Pb in feathers differed among bird species and among sampling sites, with higher contents often recorded in tree sparrows (Passer montanus). The metal(loid)s V, Mn, Co, Zn, and As had higher contents in feathers than in internal tissues including heart, liver, kidneys, muscles and bones. The contents of some elements in feathers were positively correlated with those in internal tissues, for example, Co, As, and Cd in the heart, V and Co in the kidneys, Cd in the liver, Pb in bones, and As in muscles. Furthermore, the contents of V, Cr, As and Pb in feathers were higher than those in other biomaterials, implying an increasing trend from plants, insects, and feathers. Our study indicates that bird feathers can be used as effective, non-destructive bioindicators to monitor trace metal(loid) pollution, especially for V, Co, As, Cd and Pb, in polymetallic contaminated areas, providing reliable information for ecological assessment.

Environmental monitoring and impact assessment of Prut River cross-border pollution

The cross-border rivers management is a challenge for the involved countries, especially if they do not have the same type of legislation. The negative effects on water quality are quantified by using environmental impact assessment tools. Thus, the quantification of impacts that could affect the human health, ecosystem equilibrium, and biodiversity is based on monitoring of the water quality indicators. An increased attention should be paid to the toxic pollutants resulted from various activities that may affect the aquatic environment and human health on short and long term. This study approaches the cross-border impact assessment of heavy metals, organic, and nutrient pollution in the case of two countries (Romania and Republic of Moldova), the Prut River being the natural border. The methodology considered a specific area of the Prut River on both river sides, based on specific water quality indicators. The studied area covers sampling points from North to South within Iasi County and Republic of Moldova, in the Prut River cross-border section. To assess the pollutants' impacts, the improved Leopold Matrix and the Rapid Impact Assessment Matrix were adapted and applied. The results offered an overview on water pollution level and impacts on the Prut River cross-border area, for the 5-year period (2015-2019). There is a major negative impact generated in the Southern part of the studied area, in the case of the following indicators: copper, selenium, organic substances, with an increased level of pollution recorded in the last 2 years (2018, 2019). The conclusion of this research is that even if both countries follow the international protocols concerning cross-border pollution, they still have to comply to different environmental standards which approach differently the pollution levels and the significant impacts on water quality.

Metal contamination, bioaccumulation, ROS generation, and epigenotoxicity influences on zebrafish exposed to river water polluted by mining activities

Epigenetic mechanisms are important for gene expression regulation, which is closely related to human health, and epigenetic effects of polluted water bodies have gained increasing research attention. Le'an River suffers from severe trace metal pollution owing to mining activities. In this study, zebrafish was used as a biological model to study pollution of Le'an River after seven consecutive days of exposure. The results showed that midstream and downstream sections of the river were seriously polluted by trace metals. The liver and gill of zebrafish were enriched with trace metals, and cadmium had the highest bioaccumulation factor. Trace metals caused oxidative stress in zebrafish cells, with increases in reactive oxygen species levels. Significant increase of global DNA methylation in liver of middle and downstream section were observed, with values from 125.67% to 165.45% compared with control. Changes in DNA methylation in the promoter region cause significant increase or decrease of the expression of repair genes and apoptosis genes in liver and gill. In summary, Le'an River water exhibited significant epigenetic effects, and it is necessary to consider epigenetic effects in the evaluation of pollution and health risks of river water.

Preliminary investigation of lower Danube pollution caused by potentially toxic metals

The current study aims to assess the pollution status of the European river-sea system lower Danube River-Danube Delta-North West Black Sea, through an integrated analysis of metal concentrations in water, sediments and fish community. The Danube flows through numerous industrial cities and receives a significant amount of pollutants due to the reception of urban and industrial emissaries, as well as agricultural land runoff. Samples of water, sediments and fish (10 species) were collected from 7 representative sites along Danube River, Danube Delta and Black Sea shore. For the analysed fish species, potentially toxic and essential elements (Pb, Cd, As, Cu, Fe, Zn, Mg, Ca, Na, K) from muscle and liver samples were measured and discussed. Measurement of elements and other environmental quality parameters were determined for water and sediments. The Black Sea area, represented by S6 and S7, received sediments from Danube with the lowest concentrations of Cd (0.05 ± 0.01 μg g^-1, respectively 0.01 ± 0.001 μg g^-1), Pb (3 ± 0.03 μg g^-1, respectively 2 ± 0.03 μg g^-1), As (2 ± 0.02 μg g^-1, respectively 1.4 ± 0.3 μg g^-1), Ni (8.9 ± 0.1 μg g^-1, respectively 5.2 ± 0.2 μg g^-1), Cr (8 ± 0.7 μg g^-1, respectively 5 ± 0.2 μg g^-1), Cu (3 ± 0.1 μg g^-1, respectively 2 ± 0.04 μg g^-1), Fe(6 ± 0.3 μg g^-1, respectively 3 ± 0.1 μg g^-1) and Zn (0.03 ± 0.003 μg g^-1, respectively 0.017 ± 0.001 μg g^-1). These results suggest that the Danube Delta system plays an important role in filtering the pollutants. Based on the biota and water analysis, there was no correlation observed between Cd, respectively Pb concentration in the environment and fish body (Person Coef. = -0.02 in muscle tissue and -0.01 in liver tissue, respectively Pearson Coeff. = -0.06 in muscle tissue and 0.1 in liver tissue). Cadmium remained an active element in the pollution of the Danube area (S1 and S2), with high concentration in the water matrix (0.14 ± 0.02 μg L^-1, respectively 0.05 ± 0.01 μg L^-1) and fish muscle (0.15 ± 0.03 μg g^-1f.w. in C. carpio - S2). This fact was confirmed by several other studies.

Carboxyl-functionalized hollow polymer microspheres for detection of trace metal elements in complex food matrixes by ICP-MS assisted with solid-phase extraction

In this work, carboxyl-functionalized hollow polymer microspheres (CHPMs) was successfully fabricated using poly (styrene-itaconic anhydride) particles as the core template and itaconic anhydride and trans-anethole cross-linked with divinylbenzene as the shell. The desirable microspheres and hollow structure of CHPMs were demonstrated by scanning and transmission electron microscopies, respectively. The characterized CHPMs as an adsorbent was packed into a solid phase extraction column to simultaneously detect the V(V), Cr(III), Cu(II), Cd(II), and Pb(II) in digested food samples by inductively coupled plasma-mass spectrometry (ICP-MS). A series of experimental parameters of solid-phase extraction (SPE) were investigated through vast experiments to improve sensitivity of the proposed method in metal ions detection. The detection limits of the method reached 0.8-3.2 ng L^-1 for the target elements, and the relative standard deviations (RSDs) ranging from 1.2% to 3.5% were obtained from eleven parallel experiments using a 1.0 μg L^-1 sample solution. The stability allowed the material to withstand more than 15 cycling while the recoveries remained above 88%. In food samples, the detection limits were at 0.20-0.80 μg kg^-1, and satisfactory recoveries of 85-104% were obtained in spike tests of laver, fish as well as chicken.

Seasonal variations on trace element bioaccumulation and trophic transfer along a freshwater food chain in Argentina

Río Tercero Reservoir (RTR) is the largest artificial reservoir in the province of Córdoba (Argentina). Water, sediment, plankton, shrimp (Palaemonetes argentinus), and fish (Odontesthes bonariensis) were collected during the wet season (WS) and dry season (DS) from this reservoir. Concentrations of Ag, Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, P, Pb, Se, U, and Zn were determined to investigate their respective bioaccumulation pattern and trophic transfer in the food chain. Results showed that their concentrations in water were rather low except Pb, which exceed the limits considered as hazardous for aquatic life. The enrichment factor (EF) in sediments showed that most of the element were derived from anthropogenic sources. Furthermore, the bioaccumulation factor (BAF) determined that the elements undergo bioaccumulation, especially in organisms such as plankton. The invertebrates were characterized by the highest BAF for Cu, P, and Zn in both seasons; Ag, As, and Hg during WS; and Se during DS. Fish muscle registered the highest BAF for Hg (DS) and Se (WS). A significant decrease in Al, As, Cd, Cr, Cu (DS) Fe, Mn, Ni, Pb, Se, U, and Zn (DS) concentrations through the trophic chain was observed, indicating biodilution. Some notable exceptions were found as Cu (WS), Hg (DS), and P (both season) that showed biomagnification. Further studies are needed to establish differential behavior with different species and pollutant, particularly when the potential transfer is to edible organisms.

The Duckweed, Lemna minor Modulates Heavy Metal-Induced Oxidative Stress in the Nile Tilapia, Oreochromis niloticus

A two-fold integrated research study was conducted; firstly, to understand the effects of copper (Cu) and zinc (Zn) on the growth and oxidative stress in Nile tilapia, Oreochromis niloticus; secondly, to study the beneficial effects of the duckweed Lemna minor L. as a heavy metal remover in wastewater. Experiments were conducted in mesocosms with and without duckweed. Tilapia fingerlings were exposed to Cu (0.004 and 0.02 mg L−1) and Zn (0.5 and 1.5 mg L−1) and fish fed for four weeks. We evaluated the fish growth performance, the hepatic DNA structure using comet assay, the expression of antioxidative genes (superoxide dismutase, SOD; catalase, CAT; glutathione peroxidase, GPx and glutathione-S-transferase, GST) and GPx and GST enzymatic activity. The results showed that Zn exhibited more pronounced toxic effects than Cu. A low dose of Cu did not influence the growth whereas higher doses of Cu and Zn significantly reduced the growth rate of tilapia compared to the control, but the addition of duckweed prevented weight loss. Furthermore, in the presence of a high dose of Cu and Zn, DNA damage decreased, antioxidant gene expressions and enzymatic activities increased. In conclusion, the results suggest that duckweed and Nile tilapia can be suitable candidates in metal remediation wastewater assessment programs.

Determination of cadmium and lead in tomato (Solanum lycopersicum) and lettuce (Lactuca sativa) consumed in Quito, Ecuador

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Cadmium content was lower than 0.100 mg/kg (tomato) and 0.200 mg/kg (lettuce).

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Lead content above or close to 0.100 mg/kg was found in 25 % of tomato samples.

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Organic products had similar lead and cadmium content as nonorganic ones.

Vegetables are one of the most important components in the human diet, but despite their multiple nutritional components, studies have demonstrated the presence of trace metals in their edible parts. In Ecuador, two of the most consumed crops are tomato (Solanum lycopersicum) and lettuce (Lactuca sativa). The importance of these two crops in the Ecuadorian diet, especially in large and touristic locations like the Metropolitan District of Quito, implies food safety-related concerns for locals and visitors. However, no previous studies have quantified the cadmium and lead levels in these two vegetables using samples from Quito markets. Thus, the aim of this study was to determine the cadmium and lead content in both tomato and lettuce products from main nonorganic and organic markets in Quito using a graphite furnace atomic absorption spectrophotometer. The results showed that the cadmium levels were lower than 0.058 in tomatoes and 0.034 mg/kg in lettuce, which are under the respective threshold values (0.100 and 0.200 mg/kg). Regarding lead, levels lower than 0.066 mg/kg were detected in lettuce, which did not exceed the CXS 193–1995 threshold value, while levels in tomatoes were near or exceeded the threshold value (0.100 mg/kg) from four markets (0.209, 0.162, 0.110, 0.099 mg/kg), suggesting a possible risk from tomato consumption. In addition, most vegetables marketed as organic had higher metal content than those coming from nonorganic markets. Based on these results, local health and commercial control authorities should monitor contaminants in food products sold in Quito and other places in Ecuador to ensure their safety.

Environmental benchmarks based on ecotoxicological assessment with planktonic species might not adequately protect benthic assemblages in lotic systems

Freshwater ecosystems face widespread diffuse and point-source contamination. Species Sensitivity Distributions (SSDs) have been used as a tool to determine chemical concentration benchmarks that represent protective levels for most species in the environment. Here we used a SSD approach to assess on the adequacy of standard planktonic organisms to reflect the response of benthic communities, critically supporting the structure and function of lotic ecosystems. For the purpose, SSDs reflecting non-lethal responses of standard planktonic and selected benthic organisms were built based on EC50 values (collected in the literature or estimated following testing herein) regarding three model contaminants: potassium dichromate (PD), 3,5-dichlorophenol (DCP) and lead chloride (LC). The derived HC5 estimates were discriminatory between chemicals and the uncertainty associated with the estimate was remarkably low. The HC5 estimates with corresponding uncertainty were generally within the same order of magnitude for the three chemicals tested, with better discrimination between chemicals regarding their hazardous potential being achieved for benthic organisms: DCP was clearly less hazardous than PD, but LC tends to be as hazardous as PD and DCP (assuming the confidence interval ranges). Moreover, benthic communities were more sensitive to both DCP and PD, in this later case the HC5 being lower by more than one order of magnitude than that found for planktonic communities; for LC, confidence intervals overlapped, preventing a feasible assumption regarding differential sensitivity of the compared communities. Microphytobenthos was highlighted as the most sensitive group to the three tested chemicals in SSDs covering the benthic compartment, while SSDs with planktonic organisms did not consistently show trends in sensitivity ordering. Overall, our results suggest that protective benchmarks retrieved from SSDs built with the responses of standard planktonic organisms (which are the most commonly used for regulation purposes) do not adequately protect benthic communities.