Вплив важких металів на прісноводні екосистеми. Тематична англомовна бібліографія

Heavy metals contamination in freshwater ecosystems has drawn attention worldwide. It is necessary to investigate heavy metals content and assess their ecological risk in order to protect the aquatic ecosystems. In this study, we collected surface sediment samples from the freshwater ecosystem of the city of Zhenjiang, in China, in both winter and summer. Then, we analyzed the seasonal and spatial distribution patterns of lead (Pb), chromium (Cr), cadmium (Cd), zinc (Zn), and copper (Cu). The contamination factor (CF), enrichment factor (EF), geo-accumulation index (Igeo), and potential ecological risk (Eri) were jointly used to assess the pollution degree and the ecological risk posed to the freshwater ecosystem by the aforementioned elements. Multivariate statistical analysis, including Pearson’s correlation and principal component analysis and cluster analysis, were used to identify potential sources of the investigated metals in this research area. Study results showed that: (1) the average concentrations values were 1.81 mg/kg and 1.15 mg/kg for Cd, 55.3 mg/kg and 62.2 mg/kg for Cu, 88.0 mg/kg and 52.5 mg/kg for Cr, 27.3 mg/kg and 22.8 mg/kg for Pb, 87.0 mg/kg and 271 mg/kg for Zn, in winter and summer, respectively. Amongst the investigated elements, the average concentrations of Cd, Cu, Cr, and Pb, were above the local background values in winter, whereas, Cd, Cu and Zn concentrations were higher than the background values in Zhenjiang; (2) The CF and EF indicated that Cd had a high contamination degree and a significant enrichment compare to others investigated metals in the surface sediment of in this research area. (3) Cd posed moderate, considerable, or very high ecological risks in different sites, while the other elements (i.e., Cu, Cr, Pb, and Zn) presented a low degree of ecological risk. (4) Multivariate statistical analyses results indicated Pb, Cu, and Zn had similar geochemical characteristics, while, Cd and Cr had significant differences with the above elements. Therefore, Pb, Cu, and Zn probably originate from the same sources, while Cd and Cr might have mixed sources, including both natural sources and human activities. Overall, more attention should be paid to Cd for risk assessment in the current study area. The findings of this study provide fundamental information for the evaluation and management of the heavy metals investigated in the freshwater ecosystem of Zhenjiang.

Domestic wastewater is a crucial source of contamination in freshwater ecosystems, with an estimated global production of 127.13 billion tons annually. Various sewage treatment facilities put in place for treatment of municipal wastewater generate sewage sludge, which accumulates contaminants from wastewater, posing risks to waterbodies upon discharge. Although biological, and chemical treatment methods are employed for treatment, they have limitations, and environmental concerns. Despite the recommendation for sludge reuse in agriculture, it may contain harmful heavy metals like Zn, Cd, and Pb, threatening ecosystems, and human health. The discharge of wastewater in the river poses substantial risk due to the heavy metal concentration as well as physicochemical contaminants. Index approach for assessing ecological risks, and extent of contamination of sludge, and water from heavy metals is recommended. A decommissioned sewage treatment plant in Thimphu, Bhutan poses risks due to wastewater leakage into rivers, necessitating the need for a study to evaluate heavy metal concentrations, and physicochemical contaminants, and determine the ecological risks of sludge, and wastewater to the river water. The study was conducted at Babesa Sewage Treatment Plant in Thimphu city, sampling sludge, and wastewater from the plant based on different biological treatment methods, and river water upstream, and downstream. The physicochemical parameter and heavy metals concentration were analyzed, and water quality indices were used to assess pollution, and ecological risk. Statistical analysis of the data for heavy metals and physicochemical parameters was conducted using ANOVA, and Pearson's correlation. Results indicated that the physicochemical parameters were within permissible limits for sludge, and wastewater, thereby affirming agricultural application. Heavy metal concentrations for sludge also differed among ponds, and correlation analysis revealed positive associations. Zn, and Cd had moderate contamination but Cd, and Cu posed more ecological risk in sludge. The wastewater had higher contamination of Pb, and the river water upstream as well as downstream showed the same. River water downstream showed elevated levels of heavy metals compared to upstream establishing significant deterioration in quality. Positive correlations among heavy metals suggest a common pollution source, likely effluents from the sewage treatment plant.

Freshwater ecosystems represent hotspots for the world’s total diversity and human well-being. However, they are also subjected to threats across the globe as a result of localised human activities, broad scale catchment clearance, climate change and invasive species. The increased degradation of freshwater habitats and their ecological functions as a consequence of these threats, at local and global scales, has led to significant freshwater problems for human existence and the world’s biodiversity. There is growing evidence that the loss of biodiversity is one of the most complex environmental issues facing the world; however, the importance of understanding species distribution patterns and the ecological differentiation among species that are reflected as species-specific responses or tolerances to environmental drivers is less well understood. In particular, when a morphological approach is used as a taxonomic tool for investigating species diversity and species level responses to environmental drivers, the diversity of responses hidden within species complexes may not be realized, and the conclusion of generality may mask specific cryptic species responses. In South-East Queensland, Australia, European occupation since the mid 1800’s has seen large scale clearing of native vegetation along streams and rivers in nearly all catchments. As a consequence of this land-use change catchment hydrology has been substantially altered, which, combined with the presence of dams and weirs, has resulted in a decline in water quality of streams in some catchments, which is of growing concern for conservation of species biodiversity. This study aimed to explore cryptic diversity in two species complexes of freshwater aytid shrimps common in South-East Queensland and elucidate species level responses to environmental variation that could explain their spatial distribution. This broad aim was met through three specific studies. First, using regional scale data of cryptic species diversity and water quality, the importance of species-specific responses to environmental conditions in determining spatial distribution patterns and environmental relationships of cryptic species in the Caridina indistincta and Paratya australiensis species complexes was examined. To accomplish this aim, DNA sequences were used to identify shrimp specimens from 89 sites in 17 catchments spanning the study area. In addition, an assessment of eight morphological traits was used to test whether these cryptic species could be morphologically identified. Use of these eight traits did allow species level identification, at least in South-East Queensland. However, caution is suggested in the use of these morphological traits for recognising species, due to the probability of morphological plasticity within a species across broad spatial scales. Ordination analysis of presence-absence data showed that the five cryptic species within the two species complexes showed spatially distinct distributions across streams in SEQ, with each cryptic species displaying different relationships with individual environmental variables. For species in the Caridina indistincta complex, C. indistincta sp. B was significantly associated with elevation, C. indistincta sp. D was significantly correlated with dissolved oxygen range, whilst, individuals of C. indistincta sp. A were negatively associated with elevation and dissolved oxygen range. This may indicate that C. indistincta sp. A tended to inhabit sites with low elevation and perhaps having a higher tolerance to a low range of dissolved oxygen. For the Paratya australiensis species complex, P. australiensis lineage 4 and 6 showed significant correlations with elevation and conductivity, respectively. The second broad aim of the study was to explore these spatial patterns at smaller geographical scales and with greater detail about water quality to understand and quantify the fundamental environmental factors (e.g., physical chemical water parameters and concentrations of heavy metals) that are potentially shaping the current distribution patterns and abundance of cryptic species within the two species complexes. To explore this aim, sediment samples from 22 sites in 13 catchments in SEQ were analysed to determine concentrations (mg/kg dry weight) of 11 heavy metals. Additionally, a number of water quality variables were measured in situ, including: elevation, stream width, stream temperature, dissolved oxygen, conductivity, pH, total dissolved solids, and turbidity. Also, a water sample was taken from each site for laboratory analysis of: Ammonium nitrogen (NH4-N), Dissolved oxidized nitrogen (Nitrate+Nitrite) (NOX-N), Total nitrogen (TN), Total kjeldahl nitrogen (TKN), Total kjeldahl phosphorus (TKP), Orthophosphate-P (PO4-P). Shrimps were collected from each site and identified to species using both morphology and DNA sequencing. The morphological identification of each adult individual (except juveniles which were genetically analysed) was used as a measure of absolute abundance and the genetic ‘checking’ of a set number of individuals in each sample was used to compute relative abundance. Redundancy analysis (RDA) showed that the spatial distribution and absolute and relative abundance of C. indistincta sp. D and sp. B were significantly positively influenced by elevation, while the relative abundance of P. australiensis Lin.6 was significantly positively affected by the concentration of manganese (Mn). Stream Total nitrogen (TN) was significantly positive driver of the spatial distribution and relative abundance of C. indistincta sp. A, while Orthophosphate-P (PO4-P) was significantly positive driver for the absolute and relative abundance of this species. Further analysis, this study confirms that P. australiensis Lin.6 was more tolerant of heavy metal concentrations compared with other cryptic species, as its distribution and absolute and relative abundance were significantly positively correlated with the concentrations of manganese, iron and cobalt. In contrast, C. indistincta sp. A was more sensitive to these metals than other study species. These results demonstrated that cryptic species of freshwater atyid shrimps of the C. indistincta and P. australiensis species complexes were different in their environmental requirements. As well, the cryptic species of both complexes were identified to have different associations with heavy metal concentrations, indicating that these species were different in their tolerance to toxicants. Finally, the third aim of the study was to further examine the differences in sensitivity to heavy metals (Copper and Zinc) among cryptic species of the two study complexes experimentally in the laboratory. Two cryptic species of each complex were used as study species, C. indistincta sp. A and sp. D and P. australiensis Lin.4 and Lin.6. The field studies showed differences among these species in their correlations with metal concentrations, and therefore they were seen as good candidate species for testing differences in the sensitivity to metal toxicants. Each cryptic species was exposed to six concentrations of each metal Cu or Zn using an acute (96-h) toxicity test. The results from this study were generally showed contrasting correlation between species and heavy metals; P. australiensis Lin.6 was the most tolerant species to both study metals, while C. indistincta sp. A was more sensitive to copper, and C. indistincta sp. D was more sensitive to Zn compared with the other tested species. Furthermore, the exposure of individuals of each species to the heavy metals caused changes in both their behaviour and their colour during exposure time. Overall, this study has shown cryptic species within broad species complexes can vary in their spatial distribution and their tolerance and response to water quality parameters. This highlights the advantage of using analyses of biotic and abiotic variables for ecological management and biodiversity conservation and the need to understand true species diversity when looking at species level responses to environmental degradation.

Aquaculture is a vital pillar of global food security, particularly for Egypt, as it is the principal fish-producing sector. Heavy metal contamination in aquatic environments represents one of the most significant environmental hazards. A 90-day feeding experiment was conducted to evaluate the effects of sublethal concentrations of heavy metals: Cu (0.125 ppm), Hg (0.005 ppm), Pb (1.5 ppm), and Cd (1 ppm) on the Nile tilapia. The investigation focused on evaluating growth performance, somatic indices, metal accumulation in tissues, and key physiological parameters. 144 fish (initial weight, 17 ± 0.4 g) were divided at random in triplicate into 12 glass aquaria (90 L each), placed into four treatment groups for heavy metals and control. Fish received a commercial feed containing 30% crude protein, administered at 3% of their body weight per day. Heavy metal exposure resulted in dramatic decreases (P≤ 0.05) in the mean weight gain, specific growth rate, and percentage survival compared to control. Both feed conversion ratio and protein efficiency ratio were markedly reduced, indicating a decline in feed utilization efficiency. Residue analysis revealed the greatest accumulation of heavy metals in the kidney and liver, with lesser amounts detected in the gills and muscles, highlighting the liver's role in detoxification. Significant changes (P≤ 0.05) in hepato-, spleen-, and kidney-somatic indices are indicative of organ injury. Moreover, biochemical examination revealed a decrease in total protein and globulin concentration. In addition, increased serum activities of hepatic enzymes (ALT and AST) indicate hepatocellular damage. Hemogram profile examination established that hemoglobin concentration, packed cell volume, and counts of erythrocytes and leukocytes were significantly higher (P ≤ 0.05) in control fish compared to those exposed to heavy metals. Results indicate the acute physiological distress and hematobiochemical change resulting from metal exposure, and highlight their bioaccumulation and toxicological effects in freshwater habitats.

Ceratophyllum demersum-An accretion biotool for heavy metal remediation

Road salts are altering and mobilizing heavy metals away from roadside soils, potentially into freshwater systems. Despite numerous studies investigating the mobilization of heavy metals by road salts, few studies have investigated (a) the movement rate and fate of heavy metals mobilized by road salts, (b) how road salts alter the bioavailable fraction of heavy metals, and (c) how road salts and heavy metals interact to affect freshwater organisms or human health. In this article, we discuss the consequences of increased concentrations of heavy metals and road salts, examine the mechanisms of heavy-metal mobilization, and highlight areas for future research. Future studies should investigate how metals and road salts alter ecosystem function and ecosystem services in freshwater habitats. Finally, increased research efforts will help assess whether the fate of heavy metals mobilized by road salts increases risks to human health by contaminating drinking water and water used for agriculture.

An Algorithm was designed and implemented to evaluate the toxicity of heavy metals to aquatic organisms of fresh water habitats. The evaluation criteria were chosen according to environmental factors that can enhance or reduce the toxicity of heavy metals using a certain point system that gives values in terms of points to each environmental factor. A computer algorithm and user friendly software package to evaluate heavy metals toxicity to fresh water organisms were developed and implemented.

Monitoring water and sediment quality in freshwater ecosystems is essential for sustainable management and ecological protection. This study assessed heavy metal contamination in water and sediments from five sampling stations in Asejire Reservoir, Oyo State, Nigeria. A range of pollution indices was employed to quantify contamination levels. Principal Component Analysis (PCA) and Cluster Analysis (CA) were used to identify potential sources of pollution, while the Water Quality Index (WQI) provided an overall evaluation of water quality. The WQI score of 74.23 indicated generally good water quality, although localized contamination was observed. PCA results suggested that most heavy metals originated from anthropogenic activities, and CA grouped pollution sources into two main clusters. The geo-accumulation index showed low cadmium (Cd) levels at most stations, with slight to moderate pollution recorded at Station 5. Chromium (Cr), copper (Cu), and lead (Pb) exhibited moderate to strong pollution levels. Ecological risk assessment indicated no significant risk from Cr, low risk from Cu and Pb, and a very high ecological risk from Cd. The Heavy Metal Pollution Index (HPI), ranging from 290.35 to 294.75, further confirmed substantial human-related input. These findings highlight the need for routine monitoring and targeted remediation to prevent further degradation, safeguard aquatic ecosystems, and protect public health.

Exposure to heavy metal-contaminated sediments disrupts gene expression, lipid profile, and life history traits in the midge Chironomus riparius

The spatial and temporal interaction and accumulation of heavy metals (HMs) in microplastics (MPs) were studied in sediment samples from the Noyyal River of the southern Indian Peninsula. The sedimentary MP concentrations ranged from 0.20 to 12.70 g kg −1 . Polystyrene, nylon, polypropylene, and polycarbonate were dominant MPs containing high concentrations of Al and Fe. Heavy metal speciation was carried out in sedimentary MPs using Tessier's method: exchangeable (F1), carbonate (F2), and Mn‐oxide (F3). Al and Ba showed high concentrations in the F1 and F2 fractions, while F3 had high for Fe, Mn, and Zn. HMs are primarily adsorbed by π–π interactions, electrostatic interactions, and ion exchange processes, and their adsorption varies with particle size, surface area, polymer type, and aging as inferred from the literature. Risk Assessment Code indicates high risk for metals Mo, Ba, and Ag with RAC >50. Cluster analysis indicates that metals tend to accrue in MPs mostly from the release of industrial effluent and weathering. Consumer plastics, organic/inorganic pigments, packaging materials, natural and synthetic rubbers, and antimicrobial compounds promote metal–MP interactions in the environment, leading to environmental deterioration. The study finds that the metal fractionation method can be used to understand the adsorption and scavenging capacity of HMs by MPs. The fractionation results imply that microplastics can act as secondary sources of metals, facilitating their release into the water column and influencing metal cycling and toxicity in freshwater ecosystems.

Biodiversity, the variety of life within a particular ecosystem or habitat, has been a growing concern in freshwater ecosystems. Streams become more polluted as a result of industrial and agricultural runoff, specifically through heavy metals found in industrial waste as well as pesticides. The impact of pollution on stream health could be studied through bioindicator macroinvertebrates, as their health and mortality reflects the quality of their environment. If an a bioindicator organism’s environment were in poor health conditions, it would reflect on the organism by creating health issues and defects. This study aims to determine the combined effects of heavy metals Copper sulfate and Zinc nitrate on stream health through investigating the oxidative stress levels of macroinvertebrates Lymnaea stagnalis. This involved exposure of Lymnaea stagnalis to the following experimental groups: 15 g/L Zinc nitrate, 15 ug/L Copper sulfate, and regular pond water that will be created in the lab. The disparity between oxidative stress levels of each group would be evaluated. This would be done through a thiobarbituric acid reactive substances assay, which measures the creation of lipid peroxidation products that result from oxidative stress. The creation of lipid peroxidation products indicates oxidative stress through producing a pink color, which will be measured through aspectrophotometer. Additional work is needed to corroborate preliminary results and draw final conclusions. This study may be able to support the creation of new water treatment methods through evaluating the extent to which heavy metals play a significant role in water pollution.

Comprehensive environmental assessment of heavy metal contamination of surface water, sediments and Nile Tilapia in Lake Nasser, Egypt

A review on microplastic pollution research in India

<p>Rivers are vital parts of the hydrosphere, providing ecosystem services and water for drinking and agriculture. However, rapid industrialisation and urbanisation globally leads to increasing pollution in many rivers. On their own, many in-river monitoring efforts in lower middle income countries do not yet provide enough information to adequately understand the general state or trends in freshwater ecosystems, presenting difficulties in efforts to mitigate water quality degradation. However, new sources of data such as satellites, drones and sondes provide better spatial and temporal coverage of the river network. This talk presents a statistical downscaling approach for the fusion of data from these different sources into a single product with improved accuracy and coverage compared to that of an individual source, through a Bayesian hierarchical modelling approach. The model development is motivated by the Ramganga river in northern India, a source of irrigation for crops and drinking water that supports millions of people, but suffers from heavy metal and nutrient pollution from population pressures, intensive agriculture and industries along its length, leading to water quality degradation and biodiversity loss. The work takes place as part of the Ramganga Water Data Fusion Project, funded by the UK Global Challenges Research Fund with the aim of informing work such as risk-based modelling and developing future monitoring design to improve mitigation efforts.</p>

This laboratory-based study determined the consequences of heavy metal exposure using zebrafish Danio rerio. Embryos were transiently exposed to environmentally-relevant concentrations of cadmium or nickel until 72 h postfertilization (hpf), then they were returned to system water and allowed to grow until 7, 9, and 11 days postfertilization (dpf), when they were examined morphologically and behaviorally. Morphological measures of notochord length, eye diameter, and inter-eye distance were not different across treatments; however, significant differences in optomotor responses were observed in treated larvae at all ages tested. These results suggest that initial developmental exposure to cadmium and nickel significantly impacts visually-guided larval behavior. The absence of significant differences in gross morphology suggests that the effects of these metals are subtle and may occur at the cellular level. By using this ecologically relevant model and pollutant type, this study has broad application and implications with regard to safe levels of contaminant in drinking water and freshwater ecosystems.