Concentration of heavy metals in the food chain components of the nearshore coastal waters of Kalpakkam, southeast coast of India

Assessment of heavy metals and environmental stress conditions on the production potential of polyunsaturated fatty acids (PUFAs) in indigenous microalgae isolated from the Gulf of Mannar coastal waters

The present study evaluated the effects of heavy metals, viz., lead, mercury, and cadmium, on growth, chlorophyll a, b, c, carotenoids, and PUFA content of marine microalgae Chlorella sp. and Cylindrotheca fusiformis. At 96-h exposure, the IC50 values for Hg2+, Pb2+, and Cd2+ were 0.85 mg/L, 2.4 mg/L, and 5.3 mg/L respectively, in Chlorella sp. In C. fusiformis, IC50 values for Hg2+, Pb2+, and Cd2+ were 0.5 mg/L, 1.2 mg/L, and 3 mg/L respectively. The pigment contents of both microalgae were significantly affected upon heavy metal exposure. In Chlorella sp. and C. fusiformis, the exposed concentrations of Hg2+ averagely decreased the PUFA content by 76.34% and 78.68%, respectively. Similarly, Pb2+-exposed concentrations resulted in 54.50% and 82.64% average reductions in PUFA content of Chlorella sp. and C. fusiformis, respectively. Cd2+-exposed concentrations showed 32.58% and 40.54% average reduction in PUFA content of Chlorella sp. and C. fusiformis, respectively. Among the environmental stress conditions, the dark treatment has increased total PUFA content by 6.63% in Chlorella sp. and 3.92% in C. fusiformis. It was observed that the 50% nitrogen starvation (two-stage) significantly improved the PUFA production from 26.47 ± 6.55% to 40.92 ± 10.74% in Chlorella sp. and from 11.23 ± 5.01 to 32.8 ± 14.17% in C. fusiformis. The toxicity for both microalgae was followed in the order Hg2+ > Pb2+ > Cd2+. Among the two species, Chlorella sp. has shown a high tolerance to heavy metals and can be effectively utilized in PUFA production.

Potentially toxic metals in seawater, sediment and seaweeds: bioaccumulation, ecological and human health risk assessment

This study assesses the bioaccumulation, ecological, and health risks associated with potentially toxic metals (PTMs), including Pb, Hg, Cd, As, and Cr in Hare Island, Thoothukudi. The results revealed that the concentration of PTMs in sediment, seawater, and S. wightii ranged from 0.095 to 2.81 mg kg-1, 0.017 to 1.515 mg L-1, and 0.076 to 5.713 mg kg-1, respectively. The highest concentrations of PTMs were found in the S. wightii compared to seawater and sediment. The high bioaccumulation of Hg and As in S. wightii suggests that it can be used as a bioindicator for these elements in this region. The ecological risk indices, which include individual, complex, biological, and ecological pollution indices, suggest that Hare Island had moderate contamination with Hg and Cd. However, there are no human health risks associated with PTMs. This study examines the current ecological and health risks associated with PTMs and emphasizes the importance of regular monitoring.

Toxicity risks associated with heavy metals to fish species in the Transboundary River - Linked Ramsar Conservation Site of Tanguar Haor, Bangladesh

The presence of trace metals in aquatic ecosystems can have detrimental effects on fish survival. The Tanguar haor, a Ramsar conservation wetland, receives sediment and water from multiple transboundary rivers. However, there have been limited studies on the metal concentrations in fish species in this sediment-rich wetland. This study aimed to analyze the concentrations of iron (Fe), manganese (Mn), chromium (Cr), copper (Cu), zinc (Zn), cadmium (Cd), and lead (Pb) in water, sediment, and fish tissues. Higher concentrations of Cd and Pb were found in the water and sediment. All these metals were detected in eight fish species, including benthic and pelagic species. Among them, Systomus sarana, a pelagic fish that also consumes benthic organisms, exhibited a higher metal pollution index than other fish, particularly benthic species. The release of higher metal concentrations from sediment into the water has the potential to impact the accumulation of metals in fish. SYNOPSIS: This study on metal concentrations in fish species will aid policymaking on ecotoxicology research for transboundary river-connected wetlands.

Are iron ore microparticles toxic for the European clam Ruditapes decussatus? Response elements from biomarker activities and in silico modeling

Inevitably, high concentrations of iron, the most widely produced ore globally, can be found in aquatic environments. To assess the toxicity of iron on aquatic organisms, Ruditapes decussatus specimens were subjected to microparticles derived from two types of iron ore (hematite and magnetite) at four different concentrations (0.5, 1, 1.5, and 5 g/L). The findings revealed that both types of iron ore were absorbed by clams in a concentration-dependent manner. Biomarkers analysis demonstrated significant and organ-specific impacts on the health of the clams caused by these microparticles, which was further supported by computational analyses on bioavailability. Within seven days of exposure, changes were observed in the activities of several enzymes, including catalase, acetylcholinesterase, and glutathione S-transferases, as well as in the rate of lipid peroxidation in both the digestive gland and gills. This study provides an environmental perspective on the toxicological effects of iron ore microparticles.

Assessment of heavy metals contamination of sediments and surface waters of Bitter lake, Suez Canal, Egypt: Ecological risks and human health

The concentrations of heavy metals in the surface waters and sediments of Bitter Lake were investigated to assess the level, distribution, and source of pollution and the associated ecological and human health risks. The ecological indices of the lake water indicate low contamination degrees by heavy metals. A dermal exposure-based health risk evaluation revealed no carcinogenic or non-carcinogenic impact on human health. The contamination factor (CF) for Cu, Ni, Pb, Mn, Fe, and Zn (CF < 1) indicate low contamination levels, while Cd reaches very high contamination in most sediment sites (CF ranges from 6.2 to 72.4). Furthermore, the potential ecological risk factor (Erⁱ) and modified hazard quotient (mHQ) indicate low ecological risk for all metals except Cd, revealing high to very high-level ecological risk in most sites (Erⁱ ranges from 185 to 2173 and mHQ from 1.8 to 6.3). This emphasizes the urgency of prompt actions to improve the environment in Bitter Lake.

Highly sensitive and specific detection of silver ions using a dual-color fluorescence co-localization strategy

Ag⁺ ions are widely used in various fields of human life due to their unique properties and they threaten the environment and human health. The traditional methods for Ag⁺ detection commonly suffer from disadvantages including limited sensitivity, expensive equipment and complicated operating steps. Herein, we developed a highly specific dual-color fluorescence co-localization (DFC) strategy based on the C-Ag⁺-C structure for Ag⁺ detection. In this strategy, Ag⁺ ions can be captured to form C-Ag⁺-C base pairs, and these ions enable single-stranded DNAs to form double strands. The DFC strategy can exclude nonspecific interaction sites and greatly improve the sensitivity and specificity. By DFC of the QDs and Cy5 linked to the DNA strands, highly sensitive Ag⁺ detection was achieved in the concentration range from 0.14 pM to 200 nM, with a limit of detection (LOD) of 0.14 pM. Moreover, this method has been applied for the detection of Ag⁺ ions in real environmental samples with satisfactory recoveries. We believe that the DFC strategy is promising for Ag⁺ detection.

Pollution and Potential Ecological Risk Evaluation Associated with Toxic Metals in an Impacted Mangrove Swamp in Niger Delta, Nigeria

Anthropogenic activities along coastal areas have contributed to the unwarranted discharge of toxic metals into mangrove swamps, posing risks to marine deposits and ecological environments. In this research, we studied the Isaka−Bundu tidal swamp area in the Niger Delta, which is an impacted mangrove creek located along the Bonny river, exposed to pollution pressures. The ecological risks (Er) of toxic metals in the sediments and water of the Isaka−Bundu tidal mangrove swamp followed a decreasing order (Cu > Zn > Cd > Cu > Pb > As), according to our results, while the potential ecological risk index (PERI) of the toxic metals in the sediments and water of the Isaka−Bundu tidal mangrove swamp can be said to have a very high ecological risk (PERI ≥ 600). The sediment pollution load index (PLI) was higher than 1 in all three analyzed stations, suggesting extremely toxic pollution. The enrichment evaluation shows that the studied stations have a moderate potential ecological risk of Cd, with the enrichment value for Pb showing low potential ecological risk. Our study shows that the Isaka−Bundu tidal mangrove swamp has a significant level of toxic metal pollution, which is evidence of the illegal activities performed in the Niger Delta.

Synthetization and characterization of SnCaAl2O3 nanocomposite and using as a superior adsorbent for Pb, Zn, and Cd ions in polluted water

The presence of heavy metals in drinking water or wastewater poses a serious threat to the ecosystem. Hence, the present study focused on synthesizing SnCaAl2O3 core-shell nanoparticles (C.N.P.s) in the α-Alumina phase by thermal annealing a stacked structure sandwiched between two Al2O3 layers at low temperatures. The obtained structure showed Sn N.P. floating gate with an Al2O3 dielectric stacked tunneling barrier to remove the excess of these heavy metals from polluted water. To characterize the prepared composites, X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HR-TEM) were used. The synthesized SnCaAl2O3 C.N.P.s composite was examined to utilize it as an adsorbent for removing Zn, Cd, and Pb divalent cations. The removal efficiency was studied by various parameters such as adsorbent dose, pH, contact time, metal concentrations, temperature, and coexisting ions. The experimental results were tested via Langmuir and Freundlich isotherm models. The obtained results were convenient to the Freundlich isotherm model. Moreover, the adsorption thermodynamic behavior of Zn+2, Cd+2, and Pb+2 on the synthesized composite was examined, and the process is endothermic and spontaneous under experimental conditions. The results illustrated that the adsorption efficiency of the SnCaAl2O3 core-shell nanoparticles (C.N.P.s) ranged from 88% to about 100% for all cations.

Non-proportional distribution and bioaccumulation of metals between phytoplankton and zooplankton in coastal waters

Metal concentrations were concurrently quantified in seawater, phytoplankton, and zooplankton from a heavily impacted coast of southern Taiwan. Combined size and density fractionation were used to accurately quantify metal concentrations in phytoplankton. Cr, Co, Ni, Cu, As, and Pb were analyzed using an inductively coupled plasma mass spectrometer (ICP-MS). As expected, metals significantly increased with an order of seawater < phytoplankton < zooplankton (p < 0.05); but did not differ between estuarine, nearshore, and offshore sites (p > 0.05). Metals were higher along Kaohsiung Harbor and marine outfall diffusion sites, highlighting their major impacts on plankton metal contamination. Notably, phytoplankton (Cr BCF > 100; half of the sites) significantly accumulated more metals contrary to zooplankton (BAF < 10). Metal concentrations and bioaccumulation factors between phytoplankton and zooplankton showed significant negative correlations. This demonstrates a non-proportional distribution and bioaccumulation of metals in phytoplankton and zooplankton-corroborating laboratory findings on zooplankton ability to control metals, irrespective of significantly high bioaccumulation in phytoplankton.

Separate and combined effects of cadmium (Cd) and nonylphenol (NP) on growth and antioxidative enzymes in Hydrocharis dubia (Bl.) Backer

Cadmium (Cd) is considered a priority pollutant, and nonylphenol (NP) is a common organic pollutant in water environments. However, the ecological risks of combined Cd and NP pollution have not been fully elucidated. In this study, the effects of Cd, NP, and Cd-NP on the growth and physiology of Hydrocharis dubia (Bl.) Backer were studied. The results indicated that Cd-NP joint toxicity is concentration-dependent. The joint toxicity of Cd and NP on H. dubia was antagonistic when the concentrations of Cd + NP were 0.01 + 0.1/1 mg/L. At 0.5 + 0.1/1 mg/L, Cd and NP had a strong synergistic effect on H. dubia. In addition, plant growth was significantly inhibited, and the chlorophyll contents were significantly reduced under Cd, NP, or Cd-NP exposure. The plant's antioxidant enzyme system was destroyed. The activities of superoxide dismutase (SOD) and catalase (CAT) were significantly decreased under NP-only exposure. The activity of SOD was significantly decreased under Cd-only and under joint exposure. Compound pollution exceeded the oxidative defense capacity of the plants, so the H₂O₂ content increased significantly. Our results indicated that the ecotoxicity of NP combined with Cd may be exacerbated in aquatic environments and cause obvious damage to H. dubia.

Accumulation potential of heavy metals at different growth stages of Pacific white leg shrimp, Penaeus vannamei farmed along the Southeast coast of Peninsular India: A report on ecotoxicology and human health risk assessment

This study compared the heavy metal concentration in water, sediment, and shrimp at different growth stages of culture and subsequently evaluated the ecotoxicological and human health risk status. Total trace element concentration in the water, sediment and shrimp ranged from not detected (ND) (Hg) to 91.05 (Fe) μg/L, 0.01 (Hg) to 19, 246.33 (Fe) mg/kg, and ND (Hg) to 13.98 (Fe) mg/kg, respectively. Toxic metals such as, Cd, Hg, and Pb in shrimps ranged from ND to 2.11 mg/kg, ND to 0.158 mg/kg, ND to 0.088 mg/kg, and ND to 0.469 mg/kg, respectively. Toxic heavy metals at all the growth stages of shrimps (days of culture (DOC)-01 to DOC-90) were found below the maximum residual limit (MRL) of 0.5 mg/kg set by the European Commission (EC). Similarly, Cu, Zn, and As concentrations in shrimp were also far below the MRLs of 30 mg/kg, 100 mg/kg, and 76 mg/kg set by the World Health Organization and Food Safety and Standard Authority of India, respectively. The concentration of heavy metals increased from DOC-01 to DOC-90 and was positively correlated with the length and weight of the shrimps (p < 0.05). The risk assessment was estimated for both Indians and Americans and found no carcinogenic (lifetime cancer risk (LCR) < 10^-4) and non-carcinogenic (THQ and TTHQ<1) health risks through consumption of shrimp cultured in this region. The hazard quotient (HQ_dermal < 1), hazard index (HI < 1), and LCR (<10^-4) values of the heavy metals indicated that the dermal absorption might not be a concern for the local fishermen and marine fish/shrimp farmworkers. Water and sediment quality indices were applied to assess the surface water and sediment quality, and their results were found nil to low levels of heavy metal contamination at all the sampling sites. All heavy metals studied in sediments were < effect range low (ERL) and < threshold effect level (TEL), indicating no adverse biological effects on aquatic organisms. Therefore, regular monitoring of the shrimp aquaculture system throughout the crop will provide evidence of heavy metals bioaccumulation in shrimps. This research will provide baseline data to help farmers establish the optimal aquaculture practices and regulatory authorities to formulate legislation and strategies to reduce heavy metal biomagnification in shrimps from farm to fork.

Assessment of heavy metal distribution in seawater of Kakinada Bay, a tropical mangrove-rich coastal environment

The main objective of the present study is to estimate the heavy metal concentrations and ecological risk index (ERI) in the seawater of Kakinada Bay. Turbidity, suspended particulate matter (SPM), pH, salinity, dissolved oxygen, along with heavy metals were recorded from twelve locations of the Bay to understand its hydrographical conditions. The distribution of environmental variables and heavy metal concentrations was noticed mostly from the south to north gradient. Significant positive correlations were detected in some pairs of metals such as Cu with Zn (R² = 0.515; p < 0.05), Pb with both Cr (R² = 0.810; p < 0.01) and Cd (R² = 0.511; p < 0.05), and Cr with Ni (R² = 0.573; p < 0.05) indicating their common origin. The ERI values (7.93-35.2) of seawater of Kakinada Bay in the present study were in the ecologically high-risk category. Industrial operations, domestic sewage, and natural processes are the major contaminant sources of Kakinada Bay leading its environment to a potential ecological concern.

Feasibility of Remediation of Heavy-Metal-Contaminated Marine Dredged Sediments by Active Capping with Enteromorpha Biochar

Enteromorpha biochar (BC) has been proposed as a potential absorbent in the marine environments. This study attempts to understand the process of active capping using Enteromorpha BC to prevent the release of heavy metals (Pb and Cd) from contaminated marine dredged sediments. The capping efficiency was assessed with a series of lab-scale column experiments. Results showed that the Enteromorpha BC exhibits rough pore structure and higher specific surface area, as well as more surface organic functional groups, which is favorable for its adsorption capacity and selectivity towards heavy metals. The capping thickness of 2 cm for Enteromorpha BC was sufficient to prevent the release of heavy metals from sediments, with the capping efficiency of 47% for Pb and 62% for Cd. Kinetic studies showed that heavy metals released into the overlying water can be described by a three-parameter sigmoidal kinetic model. Importantly, the fractions of heavy metals in the dredged sediments below the capping layer were analyzed to reveal the capping remediation mechanism. The outcomes of the present study indicate that capping with Enteromorpha BC is a promising method to regulate the water environment by preventing the release of heavy metals from the contaminated dredged sediments.

Metal-associated human health risk assessment due to consumption of pelagic and benthic ichthyofaunal resources from the highly contaminated Cuddalore coast in Southern India

We present seasonal variation of four metals (Cd, Cu, Pb, and Zn) in nine pelagic and three benthic fish species from the highly polluted Cuddalore coast in Tamil Nadu, India. Metals were assessed using atomic absorption spectrometry and detected in all fish species, in at least one season, except Iniistius cyanifrons where cadmium was not detected throughout. In both benthic and pelagic fish, order of metal concentration was Zn > Cu > Pb > Cd. Multivariate statistical analysis revealed that metals may have originated from both natural and anthropogenic sources. Health risk assessment revealed that consumption of fish from Cuddalore coast does not pose health risk for now; however, hazard index values (pelagic = 0.97; benthic = 0.90) are in borderline. Even a slight increase in metal concentration in fish can prove hazardous for human consumption. Sooner or later, eating fish from Cuddalore coast may pose a considerable health risk to humans if metal pollution is not held at Bay.

Trace element concentrations in water and Clupeonella cultriventris caspia in the Southern Caspian Sea and Assessment of Potential Risk to Human Health

Despite the fishing pressure on common kilka (Clupeonella cultriventris caspia) and the importance of the Caspian Sea, there are little data on trace element levels in those. Therefore, the concentrations of 27 trace elements were measured in water (n=15) and C. cultriventris (n=1050) collected from the southern Caspian Sea. The concentrations of Cd, Hg, and Zn in the water exceeded permissible limits and posed potential ecological risks to the aquatic biota, especially in the southeastern region of the Caspian Sea. The estimated daily intakes of As, Cd, Co, Hg, Mn, Pb, Sb, and V from the consumption of C. cultriventris were higher than the acceptable daily intake recommended by the JECFA and USEPA. However, the target hazard quotients and hazard index values were lesser than one. It appears that C. cultriventris provides a small amount of essential element nutrition for consumers. In conclusion, this study revealed that consumers are exposed to As, Co, Hg, Mn, Mo, Sb, and, V through the consumption of C. cultriventris. Also, the concentrations of Cd, Hg, and Zn in water showed significant ecological risk.

Metal-Organic Frameworks-Based Sensors for Food Safety

Food contains a variety of poisonous and harmful substances that have an impact on human health. Therefore, food safety is a worldwide public concern. Food detection approaches must ensure the safety of food at every step of the food supply chain by monitoring and evaluating all hazards from every single step of food production. Therefore, early detection and determination of trace-level contaminants in food are one of the most crucial measures for ensuring food safety and safeguarding consumers' health. In recent years, various methods have been introduced for food safety analysis, including classical methods and biomolecules-based sensing methods. However, most of these methods are laboratory-dependent, time-consuming, costly, and require well-trained technicians. To overcome such problems, developing rapid, simple, accurate, low-cost, and portable food sensing techniques is essential. Metal-organic frameworks (MOFs), a type of porous materials that present high porosity, abundant functional groups, and tunable physical and chemical properties, demonstrates promise in large-number applications. In this regard, MOF-based sensing techniques provide a novel approach in rapid and efficient sensing of pathogenic bacteria, heavy metals, food illegal additives, toxins, persistent organic pollutants (POPs), veterinary drugs, and pesticide residues. This review focused on the rapid screening of MOF-based sensors for food safety analysis. Challenges and future perspectives of MOF-based sensors were discussed. MOF-based sensing techniques would be useful tools for food safety evaluation owing to their portability, affordability, reliability, sensibility, and stability. The present review focused on research published up to 7 years ago. We believe that this work will help readers understand the effects of food hazard exposure, the effects on humans, and the use of MOFs in the detection and sensing of food hazards.

Removal of Sb(III) by 3D-reduced graphene oxide/sodium alginate double-network composites from an aqueous batch and fixed-bed system

We created 3D-reduced graphene oxide/sodium alginate double network (GAD) beads to address the problem of local water pollution by antimony. GAD is a novel material with the high specific surface area of graphene and biosecurity of sodium alginate. Due to the introduction of graphene, the thermal stability and specific surface area of GAD are enhanced, as shown from the FTIR, TGA, BET, Raman, and XRD characterizations. The influence of different environmental variables-such as the pH, dosage, temperature, contact time, and sodium chloride concentration on the Sb(III) sorption with GAD-was investigated. The adsorption results fit well with both the pseudo-second order (R² > 0.99) and Freundlich (R² > 0.99) isotherm models. The temperature rise has a negative influence on the adsorption. The Langmuir adsorption capacity is 7.67 mg/g, which is higher than many adsorbents. The GAD results from the fixed-bed adsorption experiment were a good fit with the Thomas model (R² > 0.99). In addition, GAD appears to be a renewable and ideal adsorbent for the treatment of antimony pollution in aqueous systems.

Concentrations and health risks of heavy metals in five major marketed marine bivalves from three coastal cities in Guangxi, China

Seafood consumption provides essential elements to humans while also posing risks to human health. A total of 2610 individuals of five edible marine bivalve species (Ruditapes philippinarum, Paphia undulata, Meretrix meretrix, Sinonovacula constricta and Meretrix lyrata) were randomly sampled from six farmer markets in three cities (Beihai, Qinzhou and Fangchenggang) in the southernmost coastal region of China. The concentrations of heavy metals (Cu, Pb, Zn, Cd, Cr, Hg and As) were determined by inductively coupled plasma mass spectrometry (ICP-MS). The estimated daily intake (EDI), target hazard quotient (THQ), total hazard index (HI), and target cancer risk (TR) were calculated to evaluate potential human health risks from bivalve consumption. The mean concentrations of metals in the tissues of bivalves descended in the order Zn > Cu > As > Cd > Cr >Pb > Hg in descending order, and the concentrations varied substantially among the five bivalves. Heavy metal concentrations in edible tissues of most bivalve samples were below the safety limits set by national and international regulations, and there were significant correlations between certain metal concentrations. The EDI values for each metal in each bivalve were significantly lower than the corresponding PTDI (provisional tolerable daily intake) values. Health risk assessment showed that although there is no noncarcinogenic health risk for local residents exposed to individual or combined metals from these bivalves, there is a carcinogenic risk from Cd and Cr exposure. Thus, in the long term, monitoring and controlling bivalve consumption will be important. Although current accumulation levels of bivalves are safe, continued and excessive lifetime consumption over 70 years may pose a target cancer risk.

Evaluating artisanal fishing of globally threatened sharks and rays in the Bay of Bengal, Bangladesh

Sharks and rays are at risk of extinction globally. This reflects low resilience to increasing fishing pressure, exacerbated by habitat loss, climate change, increasing value in a trade and inadequate information leading to limited conservation actions. Artisanal fisheries in the Bay of Bengal of Bangladesh contribute to the high levels of global fishing pressure on elasmobranchs. However, it is one of the most data-poor regions of the world, and the diversity, occurrence and conservation needs of elasmobranchs in this region have not been adequately assessed. This study evaluated elasmobranch diversity, species composition, catch and trade within the artisanal fisheries to address this critical knowledge gap. Findings show that elasmobranch diversity in Bangladesh has previously been underestimated. In this study, over 160000 individual elasmobranchs were recorded through landing site monitoring, comprising 88 species (30 sharks and 58 rays) within 20 families and 35 genera. Of these, 54 are globally threatened according to the IUCN Red List of Threatened Species, with ten species listed as Critically Endangered and 22 species listed as Endangered. Almost 98% juvenile catch (69-99% for different species) for large species sand a decline in numbers of large individuals were documented, indicating unsustainable fisheries. Several previously common species were rarely landed, indicating potential population declines. The catch pattern showed seasonality and, in some cases, gear specificity. Overall, Bangladesh was found to be a significant contributor to shark and ray catches and trade in the Bay of Bengal region. Effective monitoring was not observed at the landing sites or processing centres, despite 29 species of elasmobranchs being protected by law, many of which were frequently landed. On this basis, a series of recommendations were provided for improving the conservation status of the elasmobranchs in this region. These include the need for improved taxonomic research, enhanced monitoring of elasmobranch stocks, and the highest protection level for threatened taxa. Alongside political will, enhancing national capacity to manage and rebuild elasmobranch stocks, coordinated regional management measures are essential.

Potential health risk assessment of some bioaccumulated metals in Nile tilapia (Oreochromis niloticus) cultured in Kafr El-Shaikh farms, Egypt

In Egypt, using agricultural drainage water is a serious challenge for fish farming, due to water scaristy. Metals could be a potential threat to the quality of the cultured fish. Thus, this study aimed to assess the content of the metals in the cultured fish, their effect on the fish tissues, and the possible human health risk upon their consumption. This accomplished firstly, by determining the levels of essential Fe, Mn, Zn, Cu, beside the top three most toxic metals (Cr, Cd, and Pb) in the edible muscles and liver of 200 samples of Oreochromis niloticus cultured at three fish farms, using inductively coupled plasma optical emission spectroscopy (ICP-OES). The results showed the order of abundance: Fe > Zn > Cu ≥ Cr > Mn > Pb > Cd. Levels of Fe, Zn, Mn, and Cu in the fish liver were higher than corresponding values of muscles by 3, 3, 5, 9 order of magnitude, respectively. The histopathological examination showed alternations in muscles and liver tissues of fish farms irrigated with drainage water. However, the risk assessment indicated the safe human consumption of cultured fish produced from these fish farms.

Comprehensive Assessment and Potential Ecological Risk of Trace Element Pollution (As, Ni, Co and Cr) in Aquatic Environmental Samples from an Industrialized Area

A global assessment of arsenic (As), nickel (Ni), cobalt (Co) and chromium (Cr) was performed in environmental samples from an important industrial bay. Different fractions of water, sediments and tissues from four species of fish were analysed. Samples were collected from selected sampling sites during four consecutive samplings in spring and autumn seasons, in order to evaluate concentrations and their possible correlations among the aquatic compartments. While a higher availability of Cr and Ni was found in water, Co and As were the most available elements in sediments. In fish, the liver was the tissue with the highest proportion of As and Co, and gills showed the highest concentrations of Ni and Cr. Significance differences were observed among sites showing the pollution sources. In sediments, high correlations were found between total Co content and the most available fractions. Total Ni content highly correlated with the oxidisable fraction, while Cr total content tightly correlated with the least available fractions. Quality guideline values for sediments were frequently exceeded. In sediments and biota, concentrations were slightly higher than in other ecosystems, indicating that maritime, industrial and urban activities are affecting this type of ecosystem with great anthropogenic influence.

A Near Standard Soil Samples Spectra Enhanced Modeling Strategy for Cd Concentration Prediction

Visible and near-infrared (VNIR) spectroscopy technology for soil heavy metal (HM) concentration prediction has been widely studied. However, its spectral response characteristics are still uncertain. In this study, a near standard soil Cd samples (NSSCd) spectra enhanced modeling strategy was developed in order to to reveal the soil cadmium (Cd) spectral response characteristics and predict its concentration. NSSCd were produced by adding the quantitative Cd solution into background soil. Then, prior spectral bands (i.e., the bands with higher variable importance in projection (VIP) score in NSSCd spectra) were used for predicting Cd concentration in soil samples collected from the Hengyang mining area and Baoding agriculture area. The partial least squares (PLS) and competitive adaptive reweighted sampling-partial least squares (CARS-PLS) were used for validation. Compared to using entire VNIR spectral ranges, the new modeling strategy performed very well, with the coefficient of determination (R2) and the ratio of prediction to deviation (RPD) showing an improvement from 0.63 and 1.72 to 0.71 and 1.95 in Hengyang and from 0.54 and 1.57 to 0.76 and 2.19 in Baoding. These results suggest that NSS prior spectral bands are critical for soil HM prediction. Our results represent an exciting finding for the future design of remote sensing sensors for soil HM detection.

Heavy metal- and organic-matter pollution due to self-heating coal-waste dumps in the Upper Silesian Coal Basin (Poland)

This study provides potential insight between self-heating coal-waste dumps and related environmental pollution in southern Poland. Samples collected from dumps in the Upper Silesian Coal Basin were used to quantify released contents of organic- and inorganic pollutants, i.e., polycyclic aromatic hydrocarbons (PAHs) and trace elements (Pb, Cd, Cr, Cu, Zn, Ni, Hg, As). Elevated Hg concentrations (~100-1078 mg/kg) and Pb (~600-2000 mg/kg) attest to the evaporation of these metals from deeper parts of the dumps. The acidic pH levels (3.0-4.5) may help to mobilize these elements. Pearson's correlation coefficients for samples analyzed by AAS and ICP-MS indicate a similar origin for Cd, Zn, and As. Mostly 2- and 3-ring PAHs, especially anthracene in burnt soil, dominate in the samples. Chlorinated PAHs, thiophenol, pyridines, quinolines (and derivatives) in thermally-altered samples, and waste containing pyrolytic bitumen indicate coking conditions. The high levels of Hg, Pb, and Cd, and chlorinated PAHs and nitrogen heterocycles formed or enriched during self-heating in these dumps should be deemed a significant environmental hazard. Calculating the lifetime cancer risks due to PAHs and heavy metals accumulations in the dumps are substantial, and access to these dumps should be prohibited.

Metal and metallothionein levels in zooplankton in relation to environmental exposure: spatial and temporal variability (Saronikos Gulf, Greece)

Metal and metallothionein (MT) in mixed zooplankton were investigated as means of monitoring metal availability regarding environmental exposure. Spatial and temporal variability of Cd, Cu, Ni, Zn, Fe, Mn and Pb in zooplankton and seawater were studied in Saronikos Gulf (Aegean Sea, Eastern Mediterranean), once every second month during an annual cycle (2011-2012). Particulate organic carbon and chlorophyll α were also measured in seawater samples. Median zooplankton metal concentrations were 0.65, 32.4, 7.1, 864, 1420, 40.2 and 26.8 μg g^-1 dw for Cd, Cu, Ni, Zn, Fe, Mn and Pb, respectively, and 109 μg g^-1 ww for MTs. Metal levels in zooplankton and MTs were higher at sites influenced by human-derived pressures. Additionally, metal concentrations in pelagic fish flesh from the Greek MED-POL data base were used for bioconcentration and biomagnification factors calculation. Bioconcentration from water to zooplankton was higher than metal transfer from either seston to zooplankton or zooplankton to fish.

Macromineral and heavy metal profiles of selected deep-sea fish from the Kochi coast of the Arabian Sea, India

Deep-sea fish from the Arabian Sea in the south western coast of India have been gaining attention as a new edible fish source. Mineral profile of ten selected deep-sea fish from the south west coast of India were assessed for heavy metal and macro mineral content for safety and nutritional quality assessment, respectively. Heavy metal levels were below permissible limits for most of the species studied. But in some species, the levels slightly exceeded the permissible limit of 0.3 mg/kg for Pb, a major heavy metal contaminant in fish, according to the European Union and FSSAI regulations for heavy metals in food. Interestingly, significant content of macro minerals was observed in all the species studied. In conclusion, deep-sea fish were observed to be good source of minerals and were found to be safe for human consumption; except for a couple of species which possess slightly higher Pb content, which may be because of its presence in their habitat.

Organochlorine pesticides and heavy metals in the zooplankton, fishes, and shrimps of tropical shallow tidal creeks and the associated human health risk

Studies on organochlorine pesticides (OCPs) and heavy metals (HMs) from tidal creeks are scarce. Sixteen OCPs and seven HMs were measured in the surface water, zooplankton, two fishes (Harpadon nehereus and Pampus argenteus), and one shrimp (Penaeus indicus) collected from three tidal creeks of the Indian Sundarban. The surface water was polluted by hexachlorocyclohexane isomers (ΣHCH: 525-1581 ng l^-1), dichlorodiphenyltrichloroethane congeners (ΣDDT: 188-377 ng l^-1), endosulfan congeners (ΣEND: 687-1474 ng l^-1), and other OCPs (512-1334 ng l^-1). However, the mean HM concentrations in the surface water were <1 μg l^-1. The zooplankton community exhibited bioaccumulation of both OCPs and HMs. Aldrin, Heptachlor, and α-HCH levels in the edible biotas could lead to cancer. Co and Cd levels could lead to non-cancerous risks, and Pb levels could pose a cancerous risk. This study showed that creeks could be potential sites of both OCP and HM pollution.

An amplified fluorescent biosensor for Ag+ detection through the hybridization chain reactions

Ag is widely distributed in nature and it is used in almost all areas of human life. However, due to the widespread use of Ag materials, Ag⁺ pollution seriously threatens the human health and environment. The traditional detection methods for Ag⁺ suffer from disadvantages including high operational cost, complicated operating unit and instrument, and high requirements for professionals. Thus, in this study, a new type of Ag⁺ detection biosensor based on the hybridization signal amplification was designed to overcome these problems. Combining cytosine-Ag⁺-cytosine mismatch structure with the hybridization chain reaction, this biosensor converted the conventional detection signal into the nucleic acid amplification signal, which realized efficient, rapid, sensitive, and specific detection of Ag⁺. The limit-of-detection of this sensor reached 0.69 pM, which is much less than the maximum concentration (0.1 mg L^-1, 927 nM) suggested for drinking water by the World Health Organization, and the maximum concentration (0.05 mg L^-1, 464 nM) suggested by the United States Environmental Protection Agency. This method provides a promising new platform for detecting Ag⁺ concentrations at ultralow levels.

Accumulation and risk assessment of heavy metals employing species sensitivity distributions in Linggi River, Negeri Sembilan, Malaysia

The constant increase of heavy metals into the aqueous environment has become a contemporary global issue of concern to government authorities and the public. The study assesses the concentration, distribution, and risk assessment of heavy metals in freshwater from the Linggi River, Negeri Sembilan, Malaysia. Species sensitivity distribution (SSD) was utilised to calculate the cumulative probability distribution of toxicity from heavy metals. The aquatic organism's toxicity data obtained from the ECOTOXicology knowledgebase (ECOTOX) was used to estimate the predictive non-effects concentration (PNEC). The decreasing sequence of hazardous concentration (HC₅) was manganese > aluminium > copper > lead > arsenic > cadmium > nickel > zinc > selenium, respectively. The highest heavy metal concentration was iron with a mean value of 45.77 μg L^-1, followed by manganese (14.41 μg L^-1) and aluminium (11.72 μg L^-1). The mean heavy metal pollution index (HPI) value in this study is 11.52, implying low-level heavy metal pollutions in Linggi River. The risk quotient (RQ) approaches were applied to assess the potential risk of heavy metals. The RQ shows a medium risk of aluminium (RQ_m = 0.1125) and zinc (RQ_m = 0.1262); a low risk of arsenic (RQ_m = 0.0122) and manganese (RQ_m = 0.0687); and a negligible risk of cadmium (RQ_m = 0.0085), copper (RQ_m = 0.0054), nickel (RQ_m = 0.0054), lead (RQ_m = 0.0016) and selenium (RQ_m = 0.0012). The output of this study produces comprehensive pollution risk, thus provides insights for the legislators regarding exposure management and mitigation.

Spring-neap tides influence on bioavailability of metals and bioaccumulation in edible biota of the Zuari (tropical) Estuary

Role of spring and neap tides on metal bioavailability and bioaccumulation in edible biota was studied in the Zuari Estuary. Moderate to very high range of contamination factor for Fe, Mn, Cr, Zn, Cu, Cd, and Pb at one or more stations and tides suggesting their anthropogenic origin. The anthropogenic input of metals was supported by pollution load index. Relatively high bioavailable concentration of Fe, Mn, Cr, Zn, Cu, Cd, and Pb indicated their toxicity to biota. Total metal concentration, viz., Fe, Mn, Cr, Zn, Cu and Cd, and bioavailable content Mn, Cd, and Pb were higher during spring tide than neap tide at one or more stations which revealed their low mobility under flooded conditions. The above observation was well supported by higher concentration of Fe, Mn, Cr, Zn, Cu, and Pb in Polymesoda erosa at the middle estuary during neap tide than subsequent spring tide. Further, an increase in concentration of metals bound to certain bioavailable fractions toward the surface of the cores revealed their possible bioavailability to the biota with changes in the physicochemical properties of the Zuari estuary. Biota sediment accumulation factor revealed macro level accumulation of Cd and suggested its toxicity to marine biota.

Prescribing sea water quality criteria for arsenic, cadmium and lead through species sensitivity distribution

Water quality standards are essential for regulation of contaminants in marine environment. Seawater quality criteria (SWQC) for arsenic (As), cadmium (Cd) and lead (Pb) have not been developed for India. The aim of this study is to derive the SWQC for the metals based on Species Sensitivity Distribution (SSD). Eight species of sensitive marine organisms belonging to five phyla were assessed for their sensitivity to toxicity of As, Cd and Pb. Median effective concentrations (EC₅₀) and Median Lethal Concentrations (LC₅₀) were derived from the acute toxicity bio-assays. No Observed Effect Concentrations (NOEC), Lowest Observed Effect Concentrations (LOEC) and chronic values were derived from chronic toxicity bio-assays. Diatoms were more sensitive to As with 96 h EC₅₀ of 0.1 mg/l and copepods were more sensitive to Cd and Pb with 96 h EC₅₀ of 0.019 mg/l and 0.05 mg/l respectively. Estimated NOECs ranged from 4.87 to 21.55 µg/l of As, 1.0 to 120 µg/l of Cd and 5.67 to 91.67 µg/l of Pb. Similarly, chronic values (µg/l) were in the range of 6.71-26.1, 1.38-170, and 7.67-91.67 of As, Cd and Pb respectively. The Criterion Maximum Concentration (CMC), Criterion Continuous Concentration (CCC) and Predicted No Effect Concentration (PNEC) values were prescribed as SWQC. The CMC (µg/l) of 19, 1.7 and 17 for As, Cd, and Pb were derived respectively for acute exposure during accidental marine outfalls. The CCC (µg/l) for As was 4.6, 1.1 for Cd and 5.9 for Pb are recommended as SWQC for protection of 95% of marine organisms. PNEC (µg/l) of 3.8 for As, 0.92 for Cd and 4.3 for Pb are suggested for highly disturbed ecosystems, shell fishing and mariculture uses of water bodies. These values are recommended as a baseline for site specific water quality criteria for the coastal waters of the country.

Peptide-Based Gel in Environmental Remediation: Removal of Toxic Organic Dyes and Hazardous Pb2+ and Cd2+ Ions from Wastewater and Oil Spill Recovery

A dipeptide-based synthetic amphiphile bearing a myristyl chain has been found to form hydrogels in the pH range 6.9-8.5 and organogels in various organic solvents including petroleum ether, diesel, kerosene, and petrol. These organogels and hydrogels have been thoroughly studied and characterized by different techniques including high-resolution transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and rheology. It has been found that the xerogel obtained from the peptide gelator can trap various toxic organic dyes from wastewater efficiently. Moreover, the hydrogel has been used to remove toxic heavy metal ions Pb²⁺ and Cd²⁺ from wastewater. Dye adsorption kinetics has been studied, and it has been fitted by using the Freundlich isotherm equation. Interestingly, the gelator amphiphilic peptide gels fuel oil, kerosene, diesel, and petrol in a biphasic mixture of salt water and oil within a few seconds. This indicates that these gels not only may find application in oil spill recovery but also can be used to remove toxic organic dyes and hazardous toxic metal ions from wastewater. Moreover, the gelator can be recycled several times without significant loss of activity, suggesting the sustainability of this new gelator. This holds future promise for environmental remediation by using peptide-based gelators.

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.

Ecological risk assessment of heavy metals to aquatic organisms in the Lhasa River, Tibet, China

The Lhasa River is the largest and most important tributary of the Yarlung Tsangpo River on the Tibetan Plateau, China. It is an important source of drinking water and irrigation for the inhabitants living in the watershed. Despite the increasing focus on water chemistry, the ecological risk assessment (ERA) caused by heavy metals to aquatic organisms in the Lhasa River has not been performed before. Based on the documented monitoring data for heavy metals, the species sensitivity distributions (SSDs) method was applied in this study. The potential ecological risks induced by eight major heavy metals (including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), manganese (Mn), lead (Pb), and zinc (Zn)) in the Lhasa River to four typical categories of freshwater organisms, including insects, crustaceans, fish, and mollusks, were assessed in different water periods (e.g., high, normal, and low water-periods). Results suggested that the downstream part of the Lhasa River and the Meldromarchu and Tölungchu tributaries are the principal zones for the high aquatic ecological risks. For most of the monitoring sites, the ecological risks decreased in the following order: high-water period > normal-water period > low-water period. During the high-water period, Cu had the highest ecological risks for all selected species. For the insects, the ecological risks were quite low (< 1%) throughout the year. These results suggested that particular attention should be paid to the contamination of certain heavy metals (e.g., Cu and Cr) in the future water management in the Lhasa River.

Spatial-seasonal variations and ecological risk of heavy metals in Persian gulf coastal region: case study of Iran

PURPOSE

This study aimed to perform a systematic review to analyse the seasonal concentration and ecological risk assessment of heavy metals (HMs) in seawater and sediment samples collected from the coastline of Jam city in Bushehr, Iran.

METHODS

A total of 96 sediment and seawater samples were collected from 16 sampling stations during the spring, summer, autumn, and winter of 2017. Then, the concentrations of Pb, Ni, Cd, Cr, Cu, Zn, and Fe were determined. Finally, the pollution load index (PLI), ecological risk (Er), and environmental risk (RI) were calculated to assess the HM ecological risk.

RESULTS

The results showed that the mean concentrations of HMs were lower than the maximum acceptable concentration by SQG and NOAA. In addition, the PLI assessed a low pollution load level in the region. The ER and RI results also showed that the region was at low risk, and the metal risk was classified as Cd > Cu > Pb > Ni > Zn > Cr. In some samples, the mean concentrations of HM were found to be higher with a statistically significant difference (P˂0.05). The results also showed that sediments were engaging in a moderate Er by Cd.

CONCLUSIONS

Generally, the rapid growth of urbanization, as well as industrial and human activities, along this coastline and area has increased the pollutants dumped into the seawater and sediments. Thus, it is necessary to take regular monitoring programs and develop better management strategies to minimize the amount of HMs entering into this coastal area.

Potential of green/brown algae for monitoring of metal(loid)s pollution in the coastal seawater and sediments of the Persian Gulf: ecological and health risk assessment

The current investigation evaluates metal (loid)s biomonitoring using algae as well as the metal(loid) pollution of seawaters and sediments in the northern part along the Persian Gulf. Algae, seawater, and sediment samples were collected from four coastal areas with different land applications. The concentration of Ni, V, As, and Cd in abiotic samples (seawater and sediment) and four species of algae (Enteromorpha intestinalis, Rhizoclonium riparium, Cystoseira myrica, and Sargassum boveanum) was measured using an ICP-AES device. Concentrations of potentially toxic elements in seawater, sediments, and algae species followed the trend of "Ni˃V˃As˃Cd." The area of Asaloyeh (with the highest industrial activity) and the Dayyer area (with the lowest industrial activity) provided the highest and lowest amounts of metal(loid)s pollution, respectively. The average concentrations of V and As in four algae species significantly differed for all sampled areas. Obtaining the bio-concentration factor (BCF) > 1 for seawater and < 1 for sediment indicated that the studied algae have the ability to efficiently concentrate metal(loid)s from seawater and the limited accumulation of metals in sediments. According to the Nemerow pollution index, the order of metal(loid)s pollution for the studied areas estimated as Asaloyeh>Ganaveh>Bushehr>Dayyer. Algae species of C. myrica and E. intestinalis can often serve as suitable biological tools for monitoring seawater and sediment quality.

Elemental distribution in urban sediments of small waterbodies and its implications: a case study from Kolkata, India

The impacts of elemental pollution in sediments of freshwater bodies are of particular concern in rapidly urbanizing cities of the developing world and have been extensively studied in rivers and lakes. The current study is an attempt to highlight the importance of smaller waterbodies, which happen to form a natural network in cities, for assessing the contamination status of sediments. The distribution of elements (Al, Ca, Fe, K, Mg, S, Si, Ti, Ba, Mn, Sr, V, As, Cr, Cu, Ni, Pb and Zn) in sediments of 15 ponds and 6 canals was studied to understand the overall pollution status and the associated ecological risk to aquatic organisms. Geochemical indices revealed Cr, Cu, Pb and Zn to be the principal elements of concern. The mean concentration of Cr, Cu, Pb and Zn was 308, 174, 76.9 and 446 mg kg^-1, respectively. Ecological risk assessment revealed that Cr in 86% sites, Ni in 52% sites, Cu and Zn in 28% sites and Pb in 10% sites were associated with possible ecological toxicity. The findings suggest that multielemental concentration in sediments of ponds and canals could effectively distinguish between pristine and polluted sites and suitably identify the main elements of concern to support cost-efficient waste management solutions customized to both the sites and elements of concern.

Geochemical and probabilistic human health risk of chromium in mangrove sediments: A case study in Fujian, China

Deciphering the mobility and transfer of heavy metals in transition buffers is vital to understanding their behavior in mangrove forests. As one of the most redox-sensitive metals, the geochemical fractionation of sediment Chromium in mangrove forests and its health risks to the coastal fishermen folk is not clearly understood. This study investigated the current levels, enrichment, geochemical fractionation, and eco-toxicity on organisms of sediment Chromium from three mangrove forests in southeast China. A health risk assessment for different exposure pathways were also determined with Monte Carlo simulations technique. The results revealed that the concentration of sediment Chromium ranged from 30.75 mg kg^-1 to 99.28 mg kg^-1. The geochemical fractionations of sediment Chromium were mainly associated with amorphous Fe fraction, crystalline Fe fraction and residual fraction. Notably, 83.12% of samples analyzed in the residual phases of Chromium exceeded the background value of 40.7 mg kg^-1. Adverse effect index revealed a considerably negative effect on benthos occurrence in the mangroves. Values of non-carcinogenic risks were below unity at all samples, whereas the cancer risks associated with Cr(VI) exposure via fish consumption at median were close to 1.73 ×10^-5. A sensitivity analysis indicated that sediment Cr(VI) concentration and exposure frequency were the most relevant variables in the risk model. As the first attempt to provide information on the human health risks of sediment Chromium in mangrove forests in China, findings from this study can help track potential adverse effects and avoid risks from sediment Chromium.

Single and combined exposures of waterborne Cu and Cd induced oxidative stress responses and tissue injury in female rare minnow (Gobiocypris rarus)

Copper (Cu) and cadmium (Cd) are two kinds of abundant toxic metals in aquatic ecosystem. The present study evaluated the effects of waterborne Cu and Cd on oxidative stress responses and histological alterations in female rare minnow (Gobiocypris rarus). Fish were exposed for 7 days to: (i) control (no added Cu or Cd), (ii) waterborne Cu (39.2 μg L^-1), (iii) waterborne Cd (299.6 μg L^-1), and (iv) Cu and Cd in mixture (19.6 and 149.8 μg L^-1, respectively). Antioxidant enzyme activities and gene mRNA abundance in fish tissues (gills, liver, and ovaries) were induced by Cu and Cd exposures, both individually and in mixture, at day 1, but an asynchronous response was observed between most enzyme activities and gene mRNA abundance following 7 days exposure. Biochemical analysis and histological observation indicated that exposure to Cu and Cd, alone and in combination, caused evident damage to lipids and tissue structure in gills, liver and ovaries. Comparing with single Cu or Cd exposure, Cu and Cd co-exposure induced greater increase in the mRNA expression of most antioxidant genes and caused more severe lesions in fish tissues, which suggested that exposure to waterborne Cu and Cd in mixture might increase their individual toxicity. Furthermore, positive relationships between nuclear factor erythroid 2-related factor (Nrf2) expression and expression of manganese superoxide dismutase (Mn-SOD) and catalase (CAT) were also observed in the present study, which suggested that Cu or/and Cd induced expression of these antioxidant genes were might through activation of Nrf2.

Quantification of multi-classes of endocrine-disrupting compounds in estuarine water

Emerging pollutants known as endocrine-disrupting compounds (EDCs) are a contemporary global issue, especially in aquatic ecosystems. As aquaculture production through mariculture activities in Malaysia supports food production, the concentration and distribution of EDCs in estuarine water ecosystems may have changed. Therefore, this current study aims to prepare a suitable and reliable method for application on environmental samples. Besides, this study also presented the occurrence of EDCs pollutant in Pulau Kukup, Johor, where the biggest and most active mariculture site in Malaysia takes place. Analytical methods based on a combination of solid-phase extraction with liquid chromatography tandem mass spectrometry (Solid-phase extraction (SPE)-LC-MS/MS) have been modified and optimised to examine the level of targeted EDCs contaminant. In the current study, this method displays high extraction recovery for targeted EDCs, ranging from 92.02% to 132.32%. The highest concentration detected is diclofenac (<0.47-79.89 ng/L) followed by 17β-estradiol (E2) (<5.28-31.43 ng/L) and 17α-ethynylestradiol (EE2) (<0.30-7.67 ng/L). The highest percentage distribution for the targeted EDCs in the current study is diclofenac, followed by EE2 and dexamethasone with the percentages of 99.44%, 89.53% and 73.23%, respectively. This current study can be a baseline assessment to understand the pollution profile of EDCs and their distribution in the estuarine water of the mariculture site throughout the world, especially in Malaysia. Owing to the significant concentration of targeted EDCs detected in water samples, the need for further monitoring in the future is required.

Distribution, Source and Risk Assessment of Heavy Metal(oid)s in Water, Sediments, and Corbicula Fluminea of Xijiang River, China

A total of 43 water and sediment samples, and 34 Corbicula fluminea samples were collected in Xijiang River in southern China to determine the spatial distribution and sources of 12 metals/metalloids (V, Co, Cr, Ni, Cu, Mn, Zn, Cd, Pb, As, Sb, and Tl) and to assess the pollution levels and ecological risks of the pollutants. The results showed that the levels of the metals/metalloids (except for Tl) in the river water from almost all of the sampling sites met the Chinese national surface water quality standards. However, the concentrations of the metals/metalloids in the sediments exceeded the background values by a factor of 1.03–56.56 except for V, Co, and Mn, and the contents of Zn, Cd, and Pb in the Corbicula fluminea soft tissue exceeded the limits of the Chinese Category I food Quality Standards. The spatial distribution analysis showed that the concentrations of the contaminants in the lower reaches of Xijiang River were higher than in the upper reaches. The bioaccumulation factor (BAF), biota-sediment accumulation factor (BSF), geo-accumulation index (I_geo), and the potential ecological risk index (RI) were obtained to assess the pollution levels and ecological risks. The results indicated that Cu, Cd, and Zn were the most prone to bio-accumulation in the Corbicula fluminea soft tissue, and the lower reaches showed a much higher pollution level and risk than the upper reaches. The metals/metalloids in the sediments posed serious threat on the aquatic ecosystem, of which Cd, As, and Sb are the most risky contaminants. The results of principal component analysis (PCA) indicated Cr, Ni, Cu, Mn, Cd, Pb, and As in the sediments came from relevant industrial activities, and V and Co originated from natural sources, and Sb from mining activities, Zn and Tl came from industrial activities and mining activities.

Ecotoxicological Effect of Single and Combined Exposure of Carbamazepine and Cadmium on Female Danio rerio: A Multibiomarker Study

In aquatic environments, organisms are exposed to mixtures of pollutants which may change the toxicity profile of each contaminant, compared to its toxicity alone. Carbamazepine (CBZ) and cadmium (Cd) are among the pollutants that co-occur in aquatic environments. To date, most research about their toxicity towards aquatic vertebrates is based on single exposure experiments. The present study aims to evaluate single and combined effects of CBZ and Cd on biomarkers in female Danio rerio (zebrafish) by exposing them to environmentally relevant concentrations of these two pollutants for ten days. Four kinds of biomarkers involved in antioxidant systems, energy metabolism, nervous system, and endocrine disruption, respectively, were studied. Our research results coincided with those of former studies in single exposure experiments. However, the combined exposure of CBZ and Cd exerted different responses from other studies in which these two contaminants were examined alone in zebrafish. The present study evidenced the need to conduct more coexposure studies to enhance the environmental relevance of these experimental results.

Joint effects of chronic exposure to environmentally relevant levels of nonylphenol and cadmium on the reproductive functions in male rockfish Sebastiscus marmoratus

Nonylphenol (NP) and Cadmium (Cd) are two common contaminants that can be detected in aquatic environments. Nevertheless, the combined toxicity of NP and Cd at environmentally relevant concentrations in aquatic organisms has not been thoroughly characterized to date. In the present study, the interactions between NP and Cd on male Sebastiscus marmoratus were studied. After 21 days of exposure, the brain aromatase activity was observed to be significantly induced by 100 ng/L NP and 40 μg/L Cd, whereas all of the concentrations of co-treatment resulted in an increase in brain aromatase activity. Additionally, NP could also reduce plasma testosterone concentration, while NP, Cd and their mixture could induce plasma 17β-estradiol (E2) concentration and VTG concentration. The interactions between NP and Cd on the reproductive physiology were antagonism. Our results also support the notion of using these indicators as biomarkers for exposure to EDCs and further extend the boundary of biomonitoring to environmental levels.

Spatio-temporal variations in physico-chemical parameters and potentially harmful elements (PHEs) of Uchalli Wetlands Complex (Ramsar site), Pakistan

Uchalli Wetlands Complex (UWC) is located in District Khushab, Pakistan, which comprised of three lakes named Khabeki, Uchalli, and Jahlar. The UWC Pakistan is one of the Ramsar sites of international importance. However, the information regarding water quality parameters and concentration of potentially harmful elements (PHEs) is relatively short. Present study focused on spatio-temporal variations in the physico-chemical parameters and PHE (Cd, Pb, Ni, Cu, Zn, Cr, As, Mn) concentrations in water and fish samples using inductively coupled plasma. Sampling was done in summer (August 2016) and winter (January 2017) seasons. The overall concentrations of PHEs in water were in the following order: Mn > Zn > Cu > Cr > Ni > Cd > Pb > As for Khabeki; As >Ni > Cr > Mn > Zn > Cu > Cd > Pb for Uchalli; and Mn > Zn > Ni > Cu > As > Cr > Cd > Pb for Jahlar Lake. PHE concentration in fish followed the order Ni > Cd > Mn > Pb > Cu > Zn > Cr > As. PHEs analysis showed that Mn; Ni and As; and Ni and Mn in summer were above the Pakistan Environmental Quality Standards (PEQS) and World Health Organization (WHO) standards in Khabeki, Uchalli, and Jahlar Lakes respectively while in winter, Mn; Cd, Ni, and As; and Ni and Mn were higher than standard values in Khabeki, Uchalli, and Jahlar Lakes respectively. In fish samples, only Cd (0.0942) was higher in summer as compared to winter (0.0512) while other seven PHEs observed were higher in winter. Conclusively, the metal pollution index showed that water quality of UWC is not very fit for human consumption directly. The bioconcentration factor results indicated potential to accumulate PHEs, i.e., Cd (29.4375 and 9.4814), Pb (16.66 and 4.375), and Ni (4.9875 and 6.206), in fish during both sampling campaigns. Target hazard quotient (THQ), target carcinogenic risk (TR), hazard index (HI), estimated daily intake (EDI), and international safe standard limits of PHEs for fish species indicated that fish from UWC is safe for human consumption. Variations in physic-chemical parameters and PHE concentration were observed spatially and temporally that could be caused by precipitation amount or natural geochemistry of the lakes' crust. The water quality was not suitable for direct human consumption. Fish was only found in Khabeki Lake that had potential to accumulate Cd, Pb, and Ni more as compared to other studied PHEs.

First record of bioaccumulation and bioconcentration of metals in Scleractinian corals and their algal symbionts from Kharg and Lark coral reefs (Persian Gulf, Iran)

Metal pollution is nowadays a serious threat worldwide for ecosystem and human health. Despite that, there is still a paucity of data on metal impact on coral reef ecosystems. Herein, the levels of eleven metals (Mn, Zn, Cu, Cr, Co, Ni, V, As, Cd, Hg, Pb) were assessed in surface sediments, seawater samples, Scleractinian corals (tissue and skeleton) and their algal symbionts collected from Kharg and Lark coral reefs in the Persian Gulf, Iran. At Kharg, surface sediments and seawater showed higher concentrations of metals than Lark, attributable to the higher metal loads and petrochemical activities in the area. Sediment quality guidelines indicated Hg as a serious threat to biota both at Kharg and Lark. Accordingly, metals bioaccumulation and bioconcentration was higher in corals from Kharg relatively to Lark Island. Interestingly, as supported by values of BCFs and BSAFs, metal accumulation was higher in coral tissues in respect to skeletons, and in zooxanthellae relatively to coral tissues at both coral reefs. Differential metal bioaccumulation was found among Scleractinian species, indicating that corals have distinct selectivity for assimilating metals from ambient sediments and seawater. Overall, metal accumulation in corals and zooxanthellae is an appropriate tool for environmental monitoring studies in coral reefs. Noteworthy, the use of Porites lutea, among Scleractinian corals, seems to be as a good bioindicator in monitoring studies of metal pollution.

Impact of the Coal Mining on the Spatial Distribution of Potentially Toxic Metals in Farmland Tillage Soil

Coal mining areas are prone to hazardous element contamination because of mining activities and the resulting wastes, mainly including Cr, Ni, Cu, Zn, Cd and Pb. This study collected 103 samples of farmland tillage soil surrounding a coal mine in southwestern Shandong province and monitored the heavy metal concentrations of each sample by inductively coupled plasma mass spectrometer (ICP-MS). Statistics, geostatistics, and geographical information systems (GIS) were used to determine the spatial pattern of the potentially toxic metals above in the coal mining area. The results show that the toxic metal concentrations have wide ranges, but the average values for Cr, Ni, Cu, Zn, Cd and Pb are 72.16, 29.53, 23.07, 66.30, 0.14 and 23.71 mg Kg-1, which mostly exceed the natural soil background contents of Shandong Province. The element pairs Ni-Cu, Ni-Zn, and Cu-Zn have relatively high correlation coefficients (0.805, 0.505, 0.613, respectively). The Kriging interpolation results show that the contents of soil toxic metals are influenced by coal mining activities. Moreover, micro-domain variation analysis revealed the toxic metals in the typical area of the coal transportation line. These findings offer systematic insight into the influence of coal mining activities on toxic metals in farmland tillage soil.

Heavy Metal Concentration in Largehead Hairtail (Trichiurus lepturus Linneaus, 1758) and Savalai Hairtail (Lepturacanthus savala (Cuvier, 1829)) Obtained from Karachi Fish Harbour, Pakistan

In this study, muscle samples gathered from Largehead hairtail (Trichiurus lepturus Linneaus, 1758) and Savali hairtail [Lepturacanthus savala (Cuvier, 1829)] from the Karachi Fish Harbour, Pakistan were analyzed to determine heavy metal concentrations (iron [Fe], zinc [Zn], copper [Cu], manganese [Mn], lead [Pb] and cadmium [Cd]) between January and December 2016. All samples were analyzed using the AAnalyst 700 Flame Atomic Absorption Spectrophotometer. It was observed that the average measured level of Fe, Zn, Cu, Mn, Pb and Cd in muscle were 77.72 ± 47.84 µg/g, 20.34 ± 8.49 µg/g, 2.23 ± 1.16 µg/g, 0.57 ± 0.36 µg/g, 0.20 ± 0.16 µg/g and 0.42 ± 0.19 µg/g for T. lepturus, respectively. Besides, the average level of the same metal concentrations in muscle for L. savala were 85.11 ± 57.64 µg/g, 16.63 ± 9.25 µg/g, 2.53 ± 1.90 µg/g, 0.47 ± 0.27 µg/g, 0.23 ± 0.18 µg/g and 0.47 ± 0.20 µg/g, respectively. The correlation between size groups and metal accumulation in muscle tissues were investigated for both fish. In terms of public risk assessment, the provisional tolerable weekly intake's of various heavy metals were compared with the consumption of both fish. As a result of the analysis, Fe, Zn, Cu, Mn, Pb and Cd accumulations in muscle tissues of T. lepturus and L. savala collected from Karachi Fish Harbour Pakistan did not exceed limit values.