Biomonitoring of Trace Metals in the Keban Dam Reservoir (Turkey) Using Mussels (Unio elongatulus eucirrus) and Crayfish (Astacus leptodactylus)

Holistic perilous index-based environmental appraisal of Metal(oid)s in the sole coral-bearing island of northeastern bay of Bengal

This study aimed to evaluate the concentration, distribution, along with the environmental and human health impact of eight heavy metals-Pb, Cr, Cu, Cd, Zn, Mn, Ni, and As-on St. Martin's Island in the northeastern Bay of Bengal, and in doing so to help implement new legislations to protect the island. Focusing on the island's significance as a tourist destination, with seafood being a prominent dietary component, three sample types (sediment, seawater, and crustaceans) were selected for a comprehensive assessment, considering seasonal variations. Concentration of metals was observed to be lower than the established standards in sediment samples, but in seawater samples, Pb, Cr, Cd and Zn were higher than US-EPA values for natural marine water. The metals displayed a decreasing trend of Zn > Ni > Pb > Cu > Mn > As > Cd > Cr in crustacean samples for both seasons. Crustacean samples displayed higher metal concentrations in winter than in monsoon. Pb exceeded the maximum allowable limit for crustaceans with a concentration of about 3 and 4 mg kg-1 in monsoon and winter respectively; being more than 6-8 times the standard for Bangladesh which is only about 0.5 mg kg-1. Health indices displayed that although adults may suffer less from carcinogenic/non-carcinogenic health effects, the risks are far greater for children. For both age groups, As and Ni displayed possibilities of developing cancer. Principal Component Analysis (PCA)shed light on the sources of metals and showed that most of them were from anthropogenic sources. Overall, this study found that the quality of the environment of the island was better in comparison to previous studies made before the pandemic, and so, if the trend continues, it may lead to a better environment for the organisms around the island and help to keep the negative physiological impacts from the consumption of these organisms to a minimal.

Monthly variation of fatty acids, lipid quality index and metal content of Pontastacus leptodactylus (Eschscholtz, 1823) in Atikhisar Dam Lake (Çanakkale, Türkiye)

This study aims to investigate the metal content, fatty acid composition, lipid quality, and potential health risks of Pontastacus leptodactylus crayfish inhabiting Atikhisar Dam Lake. The research covers a 12-month period and includes both male and female individuals. The study investigated the metal content of crayfish specimens. In female individuals, the metal concentrations were ranked as Fe > Zn > Al > Cu > Mn > Se > As > Hg > Cd > Pb, while in male individuals, the ranking was Fe > Al > Zn > Cu > Mn > Se > As > Hg > Pb > Cd. The results demonstrate that Atherogenicity Index (AI) values for both genders range between 0.21 and 0.31, and Thrombogenicity Index (TI) values fall within 0.14 and 0.20. This indicates that crayfish meat is composed of healthy and high-quality fatty acids. In male individuals, omega-3 values range from 25.28 ± 0.380% to 28.34 ± 0.430%, and in female individuals, they vary from 22.98 ± 0.195% to 28.73 ± 0.871%. These findings underscore the absence of significant health risks associated with mercury levels in crayfish meat. Monthly meal calculations reveal that consuming female crayfish at an average of 4.35 servings per month for adults and 2.24 servings per month for children presents no health hazards. Similarly, the consumption of crayfish meat at an average of 5.29 servings per month for adult males and 2.72 servings per month for male children is deemed safe for health. Based on these results, the lipid quality of both male and female individuals from this species is found to be beneficial, as confirmed by risk-benefit assessments.

Ecological and human health risk from exposure to contaminated sediments in a tropical river impacted by gold mining in Colombia

Despite being one of the most important tropical biomes in the world, the Atrato River basin has experienced a critical ecological deterioration due to gold mining, posing a significant threat to wildlife and human health. In this study, we measured the concentrations of mercury (Hg) and arsenic (As) in sediments at various swamps within the basin. Classical indices were employed to assess the associated ecological and human health risks linked to exposure to these elements. The concentrations of Hg and As in the sediments ranged between 0.09 and 0.23 mg/kg and 0.59-2.68 mg/kg, respectively. The highest Hg values were found at upstream stations impacted by gold mining activities. For As, the highest levels were found near river mouth (except for station B), where agricultural practices are taken place. The contamination factor (CF) indicated that most of the sediments exhibited moderate contamination levels of Hg and As, depending on the specific sampling area. Conversely, the pollution load index (PLI) suggested a contamination level ranging from basic to moderate, with the exception of station B, which showed a progressive deterioration of the site. The geoaccumulation index (Igeo) indicated that the sediments were moderately contaminated with Hg, while showing signs of increasing contamination for As. According to the criteria for limiting effect concentrations (TEC), Hg concentrations exceeded the TEC at stations B and C, indicating a potential toxic risk to aquatic biota. A moderate potential ecological risk (PERI) was detected at downstream stations (D and E), and a high risk was detected at upstream stations (A, B and C). The hazard index (HI), used for non-carcinogenic risk assessment, suggested a risk of adverse effects on the population, particularly in children, with HI values exceeding 1. However, all lifetime cancer risk (TLCR) values fell within the acceptable range (1 × 10-6 to 1 × 10-4), indicating a negligible risk. Oral ingestion and inhalation were identified as the two primary routes of concern. This study serves as a valuable reference for risk assessment regarding exposures to environmental matrices that may not pose an immediate risk to human health.

Bioaccumulation and Health Risk Assessment of Metals in Small-Sized Fish (Rhodeus sinensis, Ctenogobius giurinus) and Mussel (Cristaria plicata) from a River Reservoir, Southwest China

In order to assess the bioaccumulation and health risk of metals in a river reservoir, concentrations of copper (Cu), zinc (Zn), lead (Pb), cadmium (Cd), arsenic (As), and mercury (Hg) in the water, sediments, two small-sized fish, and a freshwater mussel from the Zhoubai reservoir were examined. The results indicated that all of these metals conform with class one of environmental quality standards for surface water (State Environmental Protection Administration of China, GB 3838-2002). There were no significant differences for total metal concentrations in sediment between the three sampling sites (p > 0.05), but the bioavailable concentrations in S3 were the lowest. The Cd was dominated with exchangeable fraction and showed considerable risk. All metal concentrations except for Pb in Rhodeus sinensis were significantly higher than those in Ctenogobius giurinus (p < 0.05). The metal concentrations in Cristaria plicata showed a similar pattern of bioavailable metals in sediment, indicating that the metal concentrations in aquatic organisms were determined by the bioavailable forms of metals. Negative correlations were observed between the size of fish and concentrations of Cu, Zn, Pb, Cd, and As. However, significant positive correlations were found between the size of mussel and concentrations of Cd (p < 0.01), As (p < 0.05), and Hg (p < 0.01). Zn had the highest BCF values in fish and mussel. The aquatic organisms showed lower ability of metal bioaccumulation from the sediment. Low values of target hazard quotient (THQ), hazard index (HI), and carcinogenic risk (CR) indicated that these metals do not pose a health risk to public through fish and mussel consumption in this study area.

Evaluation of metal pollution related to human health risk in freshwater snail Viviparus contectus (Millet, 1813) as a potential bioindicator species in Lake Habitat (Turkey)

Freshwater mollusks are employed as bioindicators for the assessment of water quality in biomonitoring studies since the water quality of natural resources is crucial for humans. The freshwater snail species known as Viviparus contectus (Viviparidae: Gastropoda) is one that people eat. Here, the levels of heavy metals (Cd, Cr, Pb, As, Zn, and Cu) in water and V. contectus samples were determined. An Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES, Spectro Arcos, vertical plasma) was used for the analysing the heavy metal concentrations in water and freshwater snail samples. The results of the current investigation demonstrated that freshwater snails accumulated metals in their water and soft tissues in the following orders: Pb > Cr = Zn = Cu = Cd = As and Zn > Cu > Pb > Cd > As = Cr. Autumn was the time of year when higher amounts of heavy metals (As, Cr, Cu, Zn, and Hg) were found. Pb content in the freshwater snail samples was strongly impacted by seasonal fluctuations (P 0.05). For adults, the EDI (estimated daily intake) values were lower than the TDI (tolerable daily intake) values, and the HI (hazard index) values were below 1. Freshwater snail samples had Zn and Pb levels that were over the FAO/WHO, Turkish Food Codex, JECFA, and EC limit values. Except for Pb, the water study shows mean metal concentrations below the USEPA, Turkish Pollution Control Regulation, and World Health Organisation maximum allowed levels. Aquatic ecosystems were negatively impacted by anthropogenic activities overall, and this study can provide a helpful data set for investigations on metallic contamination in water bodies and biomonitoring in freshwater ecosystems.

Factors influencing accumulation of Zn, Cu, and Ca in the tissues of spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817)

Both physicochemical and biological factors affect the degree of metal accumulation in crayfish tissues. The content of metals and correlations between the metal concentrations in different tissues and the total length of crayfish is suitable indicators of contamination of the aquatic environment. The aim of the study was to analyse the effect of age and sex of crayfish on the degree of accumulation of Ca, Cu, and Zn in the muscle and exoskeleton. A total of 100 individuals of the spiny-cheek crayfish (Faxonius limosus, Rafinesque, 1817) were caught from Głowińsk reservoir (Poland) in October 2019 using fyke nets. Metal concentrations were determined in freeze-dried samples of the abdominal muscle, exoskeleton, bottom sediment, and water using atomic absorption spectroscopy (AAS). Here, we show that the highest concentrations of Zn were found in the muscle of 4-year-old females, Cu in 3-year-old males, and Ca in 4-year-old males. Sex was a significant factor affecting the content of Ca in the muscle and Zn in the exoskeleton. Age was a significant factor affecting the content of Zn, Cu, and Ca in the muscle and Zn and Cu in the exoskeleton. The bioconcentration factor (BCF) of Zn and Cu in the muscle and exoskeleton of spiny-cheek crayfish was much higher from water than from sediments, unlike Ca. Furthermore, we found significant correlation for muscle between Zn and total length in 3-year-old females and 4-year-old males and between Cu and TL in 3-year-old males. Analysing the recommended daily intake (RDI) for the investigated minerals confirmed that the consumption of 100 g of spiny-cheek crayfish muscle could meet daily requirement for Zn up to 27.5%, for Ca in 12.4%, and over 100% for Cu. The conducted analyses confirmed that the consumption of crayfish meat was safe for the health of potential consumers in terms of the analysed metal content.

Sex and seasonal differences in metal accumulation of selected tissues in red swamp crayfish from Lake Trasimeno (Umbria, Italy)

Concentrations of essential metals (Cu, Co, Cr, Fe, Ni, Mn, and Zn) and non-essential and toxic metals (Ag, Cd, Hg, and Pb) were quantified in hepatopancreas and abdominal muscle for 73 specimens (37 males and 36 females) of Procambarus clarkii from Lake Trasimeno (Italy) in a year's campaign (July 2018 to June 2019). Elemental concentrations determined in crayfish differed in tissues, seasons, and gender. Both sexes showed lower concentrations in abdominal muscle than in hepatopancreas. Essential metals accumulated in higher concentrations in both tissues than non-essential elements, while associations between essential metals were stronger, especially for females; however, a strong correlation was also observed between Cu and Ag in both sexes. No significant differences in concentrations were recorded between sexes for all seasons; contrarily, significant differences among the total seasonal concentrations (males plus females) were observed only for essential metals and for Ag. Seasonal Toxic Contamination Index (TCI) for Cr, Ni, Cu, Zn, Cd, Pb, and Hg were calculated to assess the toxicity level of metals in the sediments. TCI higher than 1 was detected for Ni only in summer, confirming the close connection between the fluctuating hydrological levels of the shallow Lake Trasimeno, strongly dependent on precipitation, and the metal contamination levels of sediments.

A global synthesis of ecosystem services provided and disrupted by freshwater bivalve molluscs

Identification of ecosystem services, i.e. the contributions that ecosystems make to human well-being, has proven instrumental in galvanising public and political support for safeguarding biodiversity and its benefits to people. Here we synthesise the global evidence on ecosystem services provided and disrupted by freshwater bivalves, a heterogenous group of >1200 species, including some of the most threatened (in Unionida) and invasive (e.g. Dreissena polymorpha) taxa globally. Our systematic literature review resulted in a data set of 904 records from 69 countries relating to 24 classes of provisioning (N = 189), cultural (N = 491) and regulating (N = 224) services following the Common International Classification of Ecosystem Services (CICES). Prominent ecosystem services included (i) the provisioning of food, materials and medicinal products, (ii) knowledge acquisition (e.g. on water quality, past environments and historical societies), ornamental and other cultural contributions, and (iii) the filtration, sequestration, storage and/or transformation of biological and physico-chemical water properties. About 9% of records provided evidence for the disruption rather than provision of ecosystem services. Synergies and trade-offs of ecosystem services were observed. For instance, water filtration by freshwater bivalves can be beneficial for the cultural service 'biomonitoring', while negatively or positively affecting food consumption or human recreation. Our evidence base spanned a total of 91 genera and 191 species, dominated by Unionida (55% of records, 76% of species), Veneroida (21 and 9%, respectively; mainly Corbicula spp.) and Myoida (20 and 4%, respectively; mainly Dreissena spp.). About one third of records, predominantly from Europe and the Americas, related to species that were non-native to the country of study. The majority of records originated from Asia (35%), with available evidence for 23 CICES classes, as well as Europe (29%) and North America (23%), where research was largely focused on 'biomonitoring'. Whilst the earliest record (from 1949) originated from North America, since 2000, annual output of records has increased rapidly in Asia and Europe. Future research should focus on filling gaps in knowledge in lesser-studied regions, including Africa and South America, and should look to provide a quantitative valuation of the socio-economic costs and benefits of ecosystem services shaped by freshwater bivalves.

The effects of invasive epibiont Dreissena polymorpha on the narrow-clawed crayfish (Astacus leptodactylus, Astacidae) in Eğirdir Lake, Turkey: a case study

In aquatic ecosystems, organisms are in a close relationship with each other. While this relationship is sometimes beneficial for both species, it can sometimes be harmful to one species. This study aimed to investigate the effects of colonized zebra mussels Dreissena polymorpha on the growth parameters and total hemocyte counts of the narrow-clawed crayfish Astacus leptodactylus from Eğirdir Lake (Turkey). Zebra mussels were found on various body parts of crayfish and the most intense (44.7%) colonization was in the carapace region. There were significant differences between various biometric data and ratios of the narrow-clawed crayfish with epibiont D. polymorpha and without epibiont D. polymorpha (the control group) in terms of total length, abdomen width, arm length and chelae length, carapace width/carapace length, carapace length/abdomen length, abdomen width/carapace width, and chelae width/chelae length (p < 0.05). When the total hemocyte counts were examined, lower values ​were obtained in the narrow-clawed crayfish with zebra mussels compared to the control group (p < 0.05). As a result, epibiont organisms have negative effects on the health and growth status of the host organisms considering total hemocyte counts and biometric data.

Novel strategies and advancement in reducing heavy metals from the contaminated environment

The most contemporary ecological issues are the dumping of unprocessed factories' effluent. As a result, there is an increasing demand for creative, practical, environmentally acceptable, and inexpensive methodologies to remediate inorganic metals (Hg, Cr, Pb, and Cd) liquidated into the atmosphere, protecting ecosystems. Latest innovations in biological metals have driven natural treatment as a viable substitute for traditional approaches in this area. To eliminate pesticide remains from soil/water sites, technologies such as oxidation, burning, adsorption, and microbial degradation have been established. Bioremediation is a more cost-effective and ecologically responsible means of removing heavy metals than conventional alternatives. As a result, microorganisms have emerged as a necessary component of methyl breakdown and detoxification via metabolic reactions and hereditary characteristics. The utmost operative variant for confiscating substantial metals commencing contaminated soil was A. niger, which had a maximum bioaccumulation efficiency of 98% (Cd) and 43% (Cr). Biosensor bacteria are both environmentally sustainable and cost-effective. As a result, microbes have a range of metal absorption processes that allow them to have higher metal biosorption capabilities. Additionally, the biosorption potential of bacterium, fungus, biofilm, and algae, inherently handled microorganisms that immobilized microbial cells for the elimination of heavy metals, was reviewed in this study. Furthermore, we discuss some of the challenges and opportunities associated with producing effective heavy metal removal techniques, such as those that employ different types of nanoparticles.

Accumulation and Distribution of Nanoparticles (Al2O3, CuO, and TiO2) in Tissues of Freshwater Mussel (Unio tigridis)

Freshwater mussels are used as an effective bioindicator of metal pollution. There is no data on the accumulation of any metal-oxide nanoparticles (NPs) in tissues of Unio tigridis. Thus, this study was undertaken to investigate accumulation of Al₂O₃, CuO, and TiO₂ NPs following exposure to different concentrations (0, 1, 3, and 9 mg/L) of NPs for 14 days. Metal concentrations in tissues were determined by ICP-MS, while NP presence was demonstrated by transmission electron microscope (TEM) images. During the experiments, mussels were fed with cultured algae (Chlorella vulgaris). TEM images demonstrated the presence of NPs in digestive gland and muscle. TEM images also suggested that NPs were taken via the lysosomes or endosomes. Highest mean concentrations (µg/g d.w.) of aluminium (76.51), copper (111.63) and titanium (113.83) occurred in the gills and followed by the digestive glands and muscles. Algae consumption of mussels did not significantly differ among controls and NP-exposed groups.

Sediment contamination by trace elements and the associated ecological and health risk assessment: A case study from a large reservoir (Turkey)

Although Keban Reservoir (KR) is Turkey's the second largest man-made reservoir, limited data are available on the contents of trace elements (TEs) in sediments of the KR. The concentrations of 23 less- and commonly-monitored TEs in the sediments from 49 sites in the reservoir were measured to assess health risks, contamination levels and ecological risks of TEs. Concerning median Enrichment Factor values of TEs, chromium (Cr), strontium (Sr) and nickel (Ni) showed moderate enrichment, while other TEs showed minimal enrichment. Pollution Load Index values ranged from 0.33 to 0.63, indicating no a multi-element contamination case in the study area. Low ecological risk was found at 47 sites, while moderate ecological risk was recorded at two sites. The PEC (probable effect concentration) values were exceeded for Ni and Cr. Although wastewater from leather processing factory partly contributed to Cr enrichment at site 2, all TEs mainly originated from lithogenic sources. Median hazard quotient (HQ) values of zirconium (Zr) and lanthanum (La) for children from sediment ingestion were above the risk threshold of unity (HQ = 4.81 and 1.39) and contributed 62.9% and 18.2% of the total health risk. Such high HQ values of Zr and La have never been reported in the literature. Hazard index values for children exceeded those for adults, indicating that children are more vulnerable to health risks than adults. Carcinogenic risk values of arsenic (As) were within the acceptable limits. Our findings indicated that in a multi-element sediment study, some less-monitored elements such as Zr and La may have an important role in health risk assessment even if they are found in the sediment at low concentrations. Therefore, this study can be a model for future similar studies evaluating the health risks of multi-elements in sediments.

Partitioning of trace elements in the tissues of Mediterranean mussels (Mytilus galloprovincialis) sampled from industrial sites along the Algerian coast

This research was aimed at evaluating the seasonal partitioning of Zn, Se, As, Cu, and Co in the tissues of Mytilus galloprovincialis sampled at two industrial sites along the Algerian coast. Adult mussels were seasonally collected from two sites over the course of a whole year. The gills, digestive glands, gonads, and remaining soft tissues were analyzed through ICP-MS. The observations led to identifying metals ranges (μg g^-1_{Dry Weight}) of 67.17-395.51 (Zn), 2.18-12.74 (Se), 7.81-28.61 (As), 3.32-155.91 (Cu), and 0.10-3.59 (Co) in the various tissues. The highest concentrations were found in the digestive glands and gills as compared to the gonads and remaining soft tissues. Distinct patterns of metals partitioning were found: indeed, As and Co concentrations were higher in the digestive glands, while Se and Zn concentrations were higher in the gills. Many of the mussels samples resulted contaminated, therefore potentially posing a considerable health risk to consumers.

Characterization of ATPases in the gill of freshwater mussel (Unio tigridis) and effects of ionic and nanoparticle forms of aluminium and copper

Mussels are often used to monitor the aquatic systems for different ecological aims, as they are one of the best bioindicator animals. However, the characterization of biomarkers should be known before using them in environmental monitoring and toxicology studies. There is no study to our knowledge on the characterization of Na-ATPase and Ca-ATPase in tissues of freshwater mussel (Unio tigridis). Thus, this study was undertaken to characterize the optimum working conditions of Na-ATPase and Ca-ATPase in the gill of mussels, determining the highest levels of parameters (Na⁺, Mg²⁺, Ca²⁺, ATP, pH, temperature, enzyme amount, incubation time) to obtain maximum activity. The present study also aimed to investigate in vitro effects of ionic and nanoparticle (Al₂O₃, CuO) forms of aluminium and copper (0, 30, 90, 270 μg/L) on the activities of Na-ATPase and Ca-ATPase. Data showed that there was no ouabain-sensitive ATPase activity in the gill up to 10 mM ouabain concentrations. Na-ATPase and Ca-ATPase activities in the gill of control mussels were 5.124 ± 0.373 and 3.750 ± 0.211 μmol Pi/mg pro./h, respectively. Exposure to different concentrations of nanoparticles did not alter significantly (P > 0.05) the activities of Na-ATPase and Ca-ATPase in vitro, whereas the same concentrations of ionic aluminium and copper significantly decreased (P < 0.05) the enzyme activities. Data emphasized that there were different modes of action between ionic and nanoparticle forms of aluminium and copper. Data also suggested that in vivo studies should also be carried out to estimate better the effects of nanoparticle and ionic forms of metals on ATPases of U. tigridis.

Human health risk assessment of selected metal(loid)s via crayfish (Faxonius virilis; Procambarus acutus acutus) consumption in Missouri

Farmed crustaceans are an important component in addressing the rising animal protein demand. The present study determined the concentrations of fourteen elements (Ag, As, Be, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Sn, Pb, and Zn) in the edible abdominal muscle of cultured freshwater crayfish species (Faxonius virilis; Procambarus acutus acutus) from Missouri. Also, this paper describes the dietary intake and the human health risks from the consumption of crayfish muscle in the adult population. Overall, 172 animals were captured between February 2017 and January 2018 for assessment. Concentrations of metals (Ag, Be, Cd, Cu, Co, Cr, Fe, Mn, Ni, Pb, Sn, Mo, and Zn) and metalloid (As) in the muscle tissue were determined after microwave-assisted acid digestion by ICP - OES. Health indices (EDI/EWI: estimated daily/weekly intakes; THQ: target hazard quotient; TTHQ: total target hazard quotient; ILCR: incremental lifetime cancer risk; and ∑ILCR: cumulative lifetime cancer risk) were calculated and compared to thresholds. Of all samples, the highest concentrations (mg kg -1 wet weight) of metal(loid)s in muscle were Ag (0.11), As (3.15), Be (0.21), Cd (0.11), Co (0.32), Cr (1.22), Cu (107), Fe (23.0), Mn (8.54), Mo (0.62), Ni (2.65), Pb (1.76), Sn (5.91), and Zn (19.2). In both species, the average As, Cd, and Zn concentrations were below the legal limits. However, the levels of Cu, Pb, and As, in some samples, were in exceedance of the maximum levels. In both species, a significant correlation (p < 0.05) was observed between the carapace length (CL) and animal body weight (BW). In P. acutus, CL, BW, and animal total length were homogenous (p > 0.05) among the sexes. Non-parametric Kruskal-Wallis test results indicated significant differences (p < 0.05) in the levels of As, Be, and Zn in F. virilis, and Be and Cr in P. a. acutus among the genders. Significant inter-species differences (p < 0.05) were observed in the levels of Be, Ni, and Pb and the growth factors. The EDI/EWI values were below the permissible limits. THQ and TTHQ values, being below 1.0, indicated no probabilistic health risk. Regarding carcinogenic risk, only As and Ni indicated cancer risk (ILCR >10-5 and ∑ILCR >10-5) to the adult population. High metals/metalloid exposure from crayfish muscle consumption posed potential health hazards to the adult population.

Antioxidant system biomarkers of freshwater mussel (Unio tigridis) respond to nanoparticle (Al2O3, CuO, TiO2) exposures

PURPOSE

Mussels are known as the natural filters of the aquatic systems and are accepted as one of the best bioindicator organism. There is no data on the response of Unio tigridis to metal-oxide nanoparticle (NP) exposures. This study aimed to investigate the response of the antioxidant enzymes of U. tigridis following exposure to NPs.

MATERIALS AND METHODS

The mussels were exposed to different concentrations (0, 1, 3, 9 mg NP/L) of Al₂O₃, CuO and TiO₂ NPs for 14 days and subsequently, the activities of CAT (catalase), SOD (superoxide dismutase), GPx (glutathione peroxidase), GST (glutathione S-transferase) and GR (glutathione reductase) were measured in the gill and digestive gland. Mussels were fed with cultured unicellular algae (Chlorella vulgaris) during experiments.

RESULTS

Data showed that algae consumptions of mussels were not significantly (p>0.05) altered by NPs. However, all enzyme activities in the digestive gland and gill altered significantly (p<0.05) after NP exposures. The activities of CAT and SOD decreased, while the activities of enzymes belonging to glutathione metabolism (GPx and GST) increased in both tissues.

CONCLUSION

This study representing the first record on the antioxidant system response of U. tigridis toward NP exposures suggests that NP toxicity should be investigated thoroughly in organisms and some regulations must be done on their usages.

A Commentary on the Use of Bivalve Mollusks in Monitoring Metal Pollution Levels

The objective of this commentary is to promote the use of bivalves as biomonitors, which is a part of the continual efforts of the International Mussel Watch. This commentary is an additional discussion on "Bivalve mollusks in metal pollution studies: From bioaccumulation to biomonitoring" by Zuykov et al., published in Chemosphere 93, 201-208. The present discussion can serve as a platform for further insights to provide new thoughts and novel ideas on how to make better use of bivalves in biomonitoring studies. The certainty of better and more extensive applications of mollusks in environmental monitoring in the future is almost confirmed but more studies are urgently needed. With all the reported studies using bivalves as biomonitors of heavy metal pollution, the effectiveness of using Mussel Watch is beyond any reasonable doubts. The challenge is the development of more accurate methodologies for of heavy metal data interpretation, and the precision of the biomonitoring studies using bivalves as biomonitors, whether in coastal or freshwater ecosystems. Lastly, inclusion of human health risk assessment of heavy metals in commercial bivalves would make the research papers of high public interest.

Trace metals geochemistry for health assessment coupled with adsorption remediation method for the groundwater of Lorong Serai 4, Hulu Langat, west coast of Peninsular Malaysia

The research study was carried out to evaluate trace metals (Pb, Cd, Se, Al, Mn, Cu, Zn, Fe, As, Ni, Cr, and Ag) concentrations in groundwater of Lorong Serai 4, Hulu Langat, Selangor, Malaysia. Additionally, the research study focused on determining non-carcinogenic and carcinogenic health risks, sources of the contaminants, and effective remediation methods. The results show that the concentration levels of Pb, Cd, Se, Al, Cu, Zn, Ni, Cr, and Ag are lower than their corresponding permissible limits, while Fe, Mn, and As concentrations exceed their acceptable limit. The hazard index of the groundwater in the area exceeded the acceptable limit, showing the rate of carcinogenic and non-carcinogenic health effects associated with the water. The findings also indicate that the lifetime cancer risk is high compared to the maximum limits of lifetime cancer risk from the drinking water (10^-6 to 10^-4). The groundwater geochemical data of the area are used in establishing the source of Fe, Mn, and As metal ions. Evaluation of Fe²⁺/Fe³⁺ and S^2-/SO₄^2- redox couples and thermodynamic modelling indicates that the groundwater of the area is in redox disequilibrium. The groundwater samples contain aqueous iron sulphate, which is supersaturated, ferrous carbonate and aluminium sulphate that are saturated. The main state of redox disequilibrium is governed by mineral precipitation and dissolution. Aqueous arsenic and manganese are possibly derived from the dissolution of pyrite (arsenopyrite) and amorphous oxide-hydroxides, respectively. The high concentration of iron in the shallow groundwater in the area is primarily the result of silicate rock weathering of ferroan igneous and metamorphic minerals with a minor contribution from the oxidation of iron sulphides. Magnetite coated with graphene oxide (Fe₃O₄-GO) nanoparticles (NPs) was synthesized and characterized, and the adsorption preliminary experiments were carried out; and the Fe₃O₄-GO NPs show enhanced removal (Fe > As > Mn) capacity over graphene oxide (GO).

Macroelements and Trace Elements in Invasive Signal Crayfish (Pacifastacus leniusculus) from the Wieprza River (Southern Baltic): Human Health Implications

Signal crayfish (Pacifastacus leniusculus) is an invasive species displacing native European crayfish from their natural habitats. The elemental composition of the population from the southern Baltic coastal river and the potential health hazards are not known. The aim of the conducted research was to assess the quantitative content of Al, As, Ca, Cd, Cu, Fe, K, Mg, Na, Ni, Pb, Se, and Zn in meat, hepatopancreas, and exoskeleton in a population from Wieprza River (Poland) and compare the results with the recommendations of daily human consumption. Analysis also involved the composition of water and sediments. The concentrations of elements were analyzed using an Atomic Absorption Spectrometer. The bioconcentration factor (BCF) of elements in the signal crayfish was much higher from water than from sediments. Bioaccumulation of elements differed between the particular parts of the body of crayfish, e.g., Ca showed extreme predominance in the exoskeleton, while in meat exhibited a predominance of K, Na, Ca, and Mg. Among trace elements, crayfish meat was the richest in Zn, Cu, and Fe. The concentrations of non-essential Cd, Pb, and As were low compared to other determined elements. The highest concentrations of As, Cd, Cu, Fe, Ni, and Se were found in the hepatopancreas, while the highest levels of Al and Pb were found in the exoskeleton. Generally, it was found that the meat of P. leniusculus can be a perfect supplement to the human diet, and the consumption of 100 g of meat per day did not exceed the dietary reference values for essential elements and also for Al, As, Cd, Ni, and Pb.

Correlation profile of the heavy metal distribution in the Pontastacus leptodactylus tissues

Arsenic (As), copper (Cu), nickel (Ni), zinc (Zn), manganese (Mn), lead (Pb), iron (Fe), aluminum (Al), cadmium (Cd) and chromium (Cr) accumulations were evaluated in the gills, hepatopancreas, exoskeleton, and muscles of Pontastacus leptodactylus (crayfish) (Eschscholtz, 1823). The highest metal accumulation was observed in the gills and hepatopancreas. It was detected a negative correlation between Cr-Pb, As-Cr in the muscle tissue. All other metals were displayed positive correlations with each other in the gills, hepatopancreas, and exoskeleton. Strong positive correlations were determined between Ni-Cd and As-Pb in the gills, Ni-Cd, As-Pb and Al-Zn in the hepatopancreas, Zn-Mn and Fe-Cu in the exoskeleton, Ni-Cd, As-Pb, Zn-Mn, Al-Mn, Fe-Cu and Al-Zn in the muscle (r= 1.000). PCA and cluster analysis generally were supported the correlations observed. The correlations between divalent metals may be expressed by the role of divalent metal transporter 1 (DMT1) in the gathering of these metals.