In the present study, microplastics (MPs) and metal concentrations were studied in the widely consumed tilapia (Oreochromis niloticus) fishes (n = 15) collected from a metropolitan reservoir of the ...Atoyac River basin, Mexico. Nearly 139 fibers were extracted from the gastrointestinal tracts and assessed using optical microscopy to evaluate their physical characteristics. The colour distribution of the fibers was mainly black (40%), blue (19%), red and white (14%). SEM images represented the surface morphology, while the elemental composition of the fibers was studied using EDX spectra. Polymer characterization using μFTIR aided in confirming the fibers as plastics (polyamide, polyester, and synthetic cellulose) and non-plastics (natural cellulose). Henceforth, ∼33% of the fibers, provisionally thought to be plastics, were natural fibers. The total metal concentrations were higher in the liver (259.24 mg kg−1) than the muscle (122.56 mg kg−1) due to diverse metabolic functions in the hepatic tissues. Human health risk assessment in terms of Hazard Index (HI) presented Pb and Zn values above unity in both adults and children, prompting regulatory measures. Statistical tests between MPs and fish biometry did not present any substantial correlations. The present study also affirmed that the presence of MPs and metals in fishes of a highly contaminated region is not only governed by their bioavailabilities, but also on the physiological characteristics of the individual organism.
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•Microplastic prevalence of 53.67% was found in Freshwater Tilapia from a metropolitan reservoir.•HI values > 1 for Pb and Zn in adults and children prompt remedial actions.•No significant correlations between MPs and fish biometry/metal levels.
Accumulation of trace metals (Fe, Mn, Cr, Cu, Ni, Co, Pb, Zn, Cd) were investigated in water, sediment (n=20) along with six fish of diverse feeding guilds (Sillago sihama, Liza parsia, Etroplus ...suratensis, Oreochromis mossambicus, Arius parkii and Gerres oyena) from the Ennore creek, northern part of Chennai metropolitan megacity, southeast coast of India. Dissolved trace metals (DTMs) in surface water samples and total trace metals (TTMs) in surface sediments (top 0–10cm) indicate that concentration pattern of metals was higher in the discharge point of the river/channels entering the main creek. The maximum mean values of DTMs exhibited the following decreasing order (expressed in µg/L): Fe (1698)>Mn (24)>Zn (14.50)>Pb (13.89)>Ni (6.73)>Cu (3.53)>Co (3.04)>Cr (2.01) whereas the trend is somewhat different in sediments (µgg−1): Fe (4300)>Mn (640)>Cr (383)>Zn (155)>Cu (102)>Ni (35)>Pb (32)>Cd (0.51) are mainly due to the industrial complexes right on the banks of the river/channels. Species-specific heterogeneous patterns of tissue metal loads were apparent and the overall metal enrichment exhibited the following decreasing order (expressed in µgg−1): Cu (7.33)>Fe (6.53)>Zn (4.91)>Cr (1.67)>Pb (1.33)>Ni (0.44)>Mn (0.43)>Co (0.36)>Cd (0.11). This indicates that metals are absorbed onto the different organs, which is also endorsed by the calculated values of bioaccumulation factor (BAFs) (avg. muscle 117, gill 126, liver 123, intestine 118) in fishes. The high calculated biota sediment accumulation factor (BSAF) (0.437) for the species Arius parkii is considered to be a potential bioindicator in this region. The enrichment of trace metals is also supported by the association of metals in water, sediments and different body organs (muscle, gill, liver, intestine) of fish samples. Comparative studies with other coastal regions indicate considerable enrichment of DTMs & TTMs in sediments as well as in various organs of fish samples. Holistic spatial, temporal monitoring and comprehensive regional strategies are required to prevent health risks and ensure nutritional safety conditions.
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•Bioaccumulation of metals in fishes in creek region of Chennai Metro, SE coast of India.•Identifying the toxicity level of metals based on comparative studies from established values.•Fishes absorbing anthropogenic metals from water and sediments in creek region.
Mercury (Hg) is a global pollutant that is a major public health concern due to its mobility, stability and toxicity behavior in the environment. In this study Hg concentrations were determined in ...beach sediment samples (n = 43) collected from the South Durban Coast, South Africa. A human health risk assessment was also carried out to comprehend the potential health effects of incidental ingestion/direct contact with contaminated sediments in a recreational setting. Hg concentrations ranged between 0.62 and 4.88 mg kg−1 dw., exceeding all background and regulatory limits. Numerical values of calculated exposure pathways represented dermal contact with the sediments as one of the potential paths in both adults and children. Hazard Index (HI) values were found to be less than unity signifying no adverse health effects. This study validates the critical need for long-term monitoring of Hg in various scenarios in order to incorporate better public health management strategies.
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•Human health risk assessment via recreational activities at tourist beaches•Hg levels exceeded all background and regulatory levels.•Dermal contact is the most potential exposure pathway of Hg in both adult and child.
The study evaluated the spatial and seasonal variations of microplastic abundances in water, sediments, and commercial fishes of a semi-urban tourist impacted estuary in the Gulf of Mexico, Mexico. ...The prevalence of microplastics (MPs) elucidated diffuse sources namely long-range transport, domestic, agricultural, fishing, industrial and recreational activities and the local climatic conditions. Seasonally, the mean abundances of MPs in both water and sediments were high during Nortes (strong winds) followed by the dry and rainy seasons. Overall, black and blue colored MPs dominated the region and all the recovered plastics were fibers. The commercial fishes (n = 187) contained 881 MPs in their gastrointestinal tracts, suggesting that the food web of the estuary is highly prone to microplastic contamination. SEM images of extracted plastic fibers presented surface morphologies that are impacted by physical strains. Further, the elemental characterization of fibers using EDX displayed significant peaks of Al, As, Cl, Cr, Cu, Pb, and Zn that were used as additives during the production of plastics. The main types of polymers included low-density polyethylene, polyester, polypropylene, polycarbonate, rayon, polyvinyl chloride, polyacrylonitrile, polyamide, nylon and polyethylene terephthalate. MP abundances demonstrated in this study elucidate that estuaries are a major conduit for land-derived plastics to the ocean and the results will aid in implementing remedial/clean up actions of the estuary for better conservation of the ecosystem.
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•Seasonal differences of MP accumulation were studied in a semi-urban estuary.•Strong winds are considered to be the major force on MP abundances.•Primary use of plastic materials by tourists are observed based on the type and morphological characters of MPs.•Presence of nearly 881 MPs in 187 commercial fish samples suggest potential risks to human health.
Pelagic thresher shark (Alopias pelagicus) is a circumglobal species with high ecological and economic importance. Concentrations of mercury, selenium and cadmium in the muscle and liver tissues of ...A. pelagicus captured from Baja California Sur, Mexico were determined for assessing the potential human hazard. Results revealed that the average concentrations of Hg (0.76 mg kg−1) and Cd (0.18 mg kg−1) in muscle tissues were below the maximum permissible limits for human consumption. Se in the muscles were relatively low (mean: 0.30 mg kg−1 −1) resulting in a molar excess of Hg over Se. Average levels of hepatic Cd were extremely higher than the maximum limit for consumption. Organotropism of Hg was muscle > liver, whereas Se and Cd presented an order of liver > muscle. Biomagnification Factor (BMF) emphasized the trophic transfer of elements. Selenium Health Benefit value was negative (−3.76) posing potential health risks demanding regular monitoring for health risks.
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•Muscular Hg > hepatic Hg liver, whereas inverse for Cd and Se•Hg and Cd levels in the muscles less than the permissible limits for consumption•Trophic accumulation of Hg, Se and Cd from the preys
A study on mercury (Hg) and selenium (Se) concentrations in the liver and muscle of brown smooth-hound shark Mustelus henlei and its principal prey items, was conducted in the western coast of Baja ...California Sur, Mexico. Average Hg concentrations were found to be high in the muscle than in the liver; however, Hg concentrations were below the maximum permissible limits, and hence, the consumption of this species does not constitute a risk to human health. The mean Se concentrations were higher in the liver than in the muscle. The results of Hg: Se molar ratio revealed that Se counteracts the toxicity of Hg in hepatic tissues, whereas the contrary occurs in the muscle. Significant differences in Hg and Se accumulation were observed between females and males. Biomagnification factor values >1 demonstrate a biomagnification process from its principal prey species (i.e., red crab, Pleuroncodes planipes and Pacific mackerel, Scomber japonicus).
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•Consumption of this shark species does not constitute a risk to human health.•The shark tissues contained Hg and Se levels lower than other shark species.•Mercury levels in shark muscles and liver are below Mexican permissible limits.•Biomagnification in prey indicates magnification along the food chain.•The prey red crab was the major contributor of Hg to M. henlei.
Mercury- Selenium concentrations were determined in 136 samples of Carcharhinus falciformis (Silky shark) sampled from the Chiapas coast, Gulf of Tehuantepec, Mexico during August 2014 – January ...2015. Average Hg concentrations in neonates and juveniles (all values in μg g−1 w.w.) were found to be 0.115 and 0.129 respectively, below the maximum permissible limit of 1 μg g−1 set by the Mexican government. However, excess Se values (all values in μg g−1 d.w.) observed in neonates (5.366) and juveniles (2.815) prove to maintain antioxidant ability by inducing Hg excretion and reducing its toxicity. Calculated Biomagnification Factor (BMFTL) denoted high values for the prey C.hippurus, signifying absolute magnification of Hg and Se along the food chain. This study provides key toxicological evidences of Hg- Se interaction and their effects in marine systems and human health.
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•Hg and Se concentrations in neonates, juveniles silky sharks and toxicology issues•Mercury levels were below in the species than the permissible limits of the Mexican government.•Biomagnification in preys indicate magnification along food chain.
The aim of the study was to evaluate the bioavailability of trace metals (Chromium, Copper, Nickel, Lead, Zinc, Cadmium, Arsenic, and Mercury) in the commercially consumed Crassostrea gigas oysters ...collected over a 12-month growth period (2011–12) from an experimental cultivation farm in La Pitahaya, Sinaloa State, Mexico. Sediment and water samples were also collected from four different zones adjacent to the cultivation area to identify the concentration patterns of metals. The results revealed that sewage disposals, fertilizers used for agricultural practices and shrimp culture are the major sources for the enrichment of certain toxic metals. The metal concentrations in oysters presented a decreasing order of abundance (all values in mg Kg−1): Zn (278.91 ± 93.03) > Cu (63.13 ± 31.72) > Cr (22.29 ± 30.23) > Cd (14.54 ± 4.28) > Ni (9.41 ± 11.33) > Pb (2.22 ± 1.33) > As (0.58 ± 0.91) > Hg (0.04 ± 0.06). Bioconcentration Factor (BCF) and Biota Sediment Accumulation Factor (BSAF) exhibited that C. gigas in the region are strong accumulators for Zn and Cd respectively. Thus, the present study proves to fulfill the gap in understanding the rate of bioaccumulation of metals in C. gigas which is regarded as the most sought after oyster species globally.
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•Elevated metal levels in oyster species (C. gigas) from a cultivation site in SW Gulf of California Coast, Mexico.•High affinities of oyster to accumulate Zn and Cd from the ambient water and sediment fractions.•Impact of effluents from agriculture, aquaculture and domestic waste disposals.
Polycyclic aromatic hydrocarbons (PAHs) were assessed in sediments (n = 7) collected from the mouth of the Balsas River, Pacific Coast, Mexico. The total PAH levels ranged between 142.1 and ...3944.07 μg kg−1 in the summer and 137.65–3967.38 μg kg−1 in the winter, probably reflecting the anthropogenic activities of the region. Calculation of the four analytical ratios of Anthracene/(Anthracene + Phenanthrene): Fluoranthene/(Fluoranthene + Pyrene), Fluoranthene/Pyrene: Fluoranthene/(Fluoranthene + Pyrene), Indeno 123-cdPyrene/(Indeno 123-cdPyrene + Benzo ghiPerylene): Benzo aanthracene/(Benzo aAnthracene + Chrysene), and Anthracene/Phenanthrene: Fluoranthene/(Fluoranthene + Pyrene) revealed a mixed PAH source, from petroleum and biomass combustion. Significant statistical correlations (r2 = 0.90) between the 4 and 5 ringed PAHs denote that adsorption is the principal mechanism for accumulation in sedimentary archives. Ecotoxicological indices (Mean Effect Range Medium Quotient and Mean Probable Effect Level Quotient) indicated moderate pollution with adverse biological impacts on ambient benthonic organisms. The calculations of Toxicity Equivalent Quotient and Mutagen Equivalent Quotient values proposed that the region is highly polluted by mutagenic and carcinogenic PAH compounds. The genotoxic evaluation of Lutjanus guttatus (Spotted rose snapper) presented significant DNA damage and discrepancies in Ethoxyresorufin-O-Deethylase activity. Based on the toxicological and genotoxicological evaluation of PAHs in sediments, the region was observed to be largely impacted from biological damage.
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•PAHs mainly sourced from petroleum and biomass combustion and ranged between 139.88 and 3955.73 μg kg−1.•Spotted rose snapper fish presented significant DNA damage due to high cPAHs exposure.•Moderate to high PAH pollution indicate adverse biological effects on the benthos.
River Atoyac is considered to be one of the most polluted rivers in Mexico due to the discharges of untreated or partially treated wastewater from industrial and municipal activities. In order to ...improve the river water quality, it is obligatory to identify the possible contaminant sources for upholding a well-balanced ecosystem. Henceforth, the present study incorporates the application of a continuous real-time monitoring system to identify the provenance of pollutants of the river mainly from anomaly events. Four monitoring stations were installed all along the River Atoyac in the State of Puebla, Central Mexico. The real-time monitoring systems have an ability to measure various water quality parameters for every 15 minutes such as Temperature (T), pH, Conductivity (EC), turbidity (TURB), Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP) and Spectral Absorption Coefficient (SAC). In total, eight water samples of anomaly events (i.e.) 2 per monitoring station during rainy (August–September) and winter seasons (November–December), that were detected using the parameters previously mentioned were procured and also analyzed in the laboratory for evaluating almost 54 physicochemical, inorganic and organic characteristics. Statistical results of factorial analysis explained that 30% of the total variance corresponded to textile effluents, 23% related to discharges produced by automobile and petrochemical industries, and 18% of the total variance defined the agricultural activities. Additionally, indices like Overall Index Pollution, Heavy Metal Evaluation Index, Screening Quick Reference Table and Molecular ratios of hydrocarbons for PAH sources was also calculated to estimate the grade of pollution and associated ecotoxicological risks. The present study also enlightens the fact that the assessed results will definitely provide valuable information for the management of river water quality by developing stringent public policies by governmental agencies for the sustainable conservation of Atoyac River.
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•Real time monitoring is regarded to be a fundamental tool for wastewater management.•Identification of pollutant sources is vital to improve river water quality.•River Atoyac is highly impacted by industrial and agricultural effluents.•Pb, Hg and Cd reflect acute toxicity.
