Evaluation of Mercury Contamination in Iranian Wild Cats Through Hair Analysis

Comparative analysis between mercury levels in fish tissues evaluated using direct mercury analyzer and inductively plasma-coupled mass spectrometer

Recent ecotoxicological studies have indicated mercury (Hg) contamination in aquatic ecosystems in the Amazon Basin. Although Hg contamination can be associated with small-scale gold mining, the soils of the Amazon region have naturally high Hg concentrations, and can be transported to aquatic ecosystems via deforestation and mining activities. Biomagnification of Hg can pose risks to the local human population; therefore, its concentration in fish tissues must be monitored consistently. Fast and sensitive Hg determination is required for continuously monitoring ecosystems impacted by mineral exploration. The direct mercury analyzer (DMA-80) is widely used for determining total Hg levels in tissue samples; it is fast and cost-effective, without requiring sample preparation. Here, we determined the sensitivity and specificity of Hg detection accomplished using DMA-80, and whether these results are reliable compared to those obtained using Inductively Coupled Plasma Mass Spectrometer (ICP-MS), which is the gold standard. We obtained 106 paired dried samples of muscle tissue from fish species occupying different trophic levels in the Lower Amazon region, and analyzed them using both equipment (DMA-80 and ICP-MS). The results obtained using DMA-80 had an overall Hg mean of 1.90 ± 0.18 mg/kg which was higher (p < 0.05) than the mean of those obtained using ICP-MS (1.55 ± 0.13 mg/kg). Linear regression analysis comparing the Hg levels obtained using both devices was within the 95% prediction interval, and a high coefficient of correlation showed agreement between the devices (r = 0.979; 0.069 to 0.986, 95% CI). Bland-Altman analysis showed that DMA-80 had a positive bias of 6.5% in relation to ICP-MS, which is more evident in samples with high Hg concentrations. DMA-80 was efficient in determining whether the Hg levels exceeded the maximum allowed levels required by the European Union, USA, and Brazil, showing a specificity and sensitivity of above 95%.

Pets, Genuine Tools of Environmental Pollutant Detection

In a shared environment, our companion animals became unintended sentinels for pollutant exposure consequences, developing even earlier similar conditions to humans. This review focused on the human-pet cohabitation in an environment we all share. Alongside other species, canine and feline companions are veritable models in human medical research. The latency period for showing chronic exposure effects to pollutants is just a few years in them, compared to considerably more, decades in humans. Comparing the serum values of people and their companion animals can, for example, indicate the degree of poisonous lead load we are exposed to and of other substances as well. We can find 2.4 times higher perfluorochemicals from stain- and grease-proof coatings in canine companions, 23 times higher values of flame retardants in cats, and 5 times more mercury compared to the average levels tested in humans. All these represent early warning signals. Taking these into account, together with the animal welfare orientation of today's society, finding non-invasive methods to detect the degree of environmental pollution in our animals becomes paramount, alongside the need to raise awareness of the risks carried by certain chemicals we knowingly use.

Wildlife hair as bioindicators of metal exposure

Animal hair is a useful biomonitoring tool for assessing the occurrence of trace elements in ecosystems. Essential (chromium, copper, iron, manganese, nickel, and zinc) and nonessential (aluminum, arsenic, cadmium, mercury, lead, palladium, platinum, rubidium, tin, and vanadium) elements were investigated in hair of badger (Meles meles), wild boar (Sus scrofa), marmot (Marmota marmota), wolf (Canis lupus), fox (Vulpes vulpes) and deer (Cervus elaphus) from Northwestern Italy. Badger was found to be the highest bioaccumulator of metals, while wolf, fox and deer recorded the lowest values. Essential elements contribute in higher degree to the sum of metals for all species except for wild boar. Results have shown that animals with omnivorous diet such as badger, marmot and wild boar have metal content (especially Al, As, Cr, Cu, Fe, Ni, V) higher than carnivores (wolf and fox) and herbivores (deer) and could represent an effective sentinel of environmental exposure to metals.

Rational synthesis and characterization of highly water stable MOF@GO composite for efficient removal of mercury (Hg2+) from water

The present study is aimed at adsorptive removal of Mercury (Hg²⁺) using highly functionalized nanomaterials based on Graphene Oxide Zeolitic Imidazolate Framework composite (ZIF-67@GO). Solvothermal methodology was used to synthesize ZIF-67@GO composite. Synthesized compounds were confirmed by FTIR, SEM, PXRD and EDX analysis. The as-prepared ZIF-67@GO was tested as efficient adsorbent for effective removal of Mercury (Hg²⁺) from aquatic environment. The atomic adsorption spectrophotometer was used to monitor the process of adsorption of Hg⁺² on ZIF-67@GO. From the adsorption data, the maximum removal efficiency achieved was 91.1% using 10 mg amount of composite for 50 mL using 20 ppm Mercury (Hg²⁺) solution. Different parameters like pH, contact time, concentration, adsorption kinetics and isotherm were also examined to explore adsorption process. Adsorption data fitted well for Freundlich Model having R² value of 0.9925 than Langmuir Isotherm with R² value of 0.9238. Kinetics were rapid and excellently described via 2nd order model with R² = 0.99946 than 1st order model with R² value of 0.8836. Freundlich and pseudo 2nd order models validated that multilayer chemisorption occurs during adsorption process due to the presence of highly functionalized sites on ZIF-67@GO composite. The synthesized composite material has shown excellent reusability. Thus, water stable ZIF-67@GO composites can efficiently be used for Mercury (Hg²⁺) confiscation from water.

Non-destructive mercury exposure assessment in the Brandt's hedgehog (Paraechinus hypomelas): spines as indicators of endogenous concentrations

Due to its persistence, bioaccumulation characteristics, and toxicity, environmental contamination with mercury (Hg) is of high concern for human health, living organisms, and ecosystems, and its biological monitoring is highly relevant. In this study, the levels of total Hg were measured in organs, tissues, and spines of 50 individuals of Brandt's hedgehog collected in Iran in 2019. The Hg median levels in kidneys, liver, muscle, and spines were 156, 47, 47, and 20 ng/g dry weight, respectively. The results showed a significant positive correlation between the levels of Hg in kidneys and liver (r = 0.519; p < 0.01) and in spines and muscle (r = 0.337, p < 0.01) and kidneys (r = 0.309, p < 0.05). Significant differences (p < 0.05) in Hg levels in organs and tissues were also observed depending on the sex, weight, length, and age of the individuals. In addition, the median levels of total Hg in kidneys of Brandt's hedgehogs from an agricultural ecotype (median 190 ± 65) were significantly higher (p < 0.05) than those collected from a forest ecotype (median 126 ± 50), suggesting that the habitat could have a significant impact on animal contamination.

Toxic and essential metal levels in the hair of red deer (Cervus elaphus) and wild boar (Sus scrofa) for monitoring the contamination in protected areas of South-Western Spain

Contaminant monitoring in tissues of wild species can help in the knowledge not only of their health, but also of the environmental health conditions in the zones where they live. In this study, concentrations of toxic metals (As, Cd, Hg, and Pb) and an essential metal (Zn) were measured in the hair of red deer (Cervus elaphus) and wild boar (Sus scrofa) inhabiting in protected areas of South-Western Spain. Zn (69.02 ± 1.03 mg kg^-1, 70.31 ± 2.22 mg kg^-1), Pb (0.61 ± 0.05 mg kg^-1, 0.68 ± 0.08 mg kg^-1), and As (0.33 ± 0.03 mg kg^-1, 0.53 ± 0.08 mg kg^-1) were detected in the hair of red deer and wild boar, respectively. The other metals (Cd and Hg) were under the quantification limit (0.1 mg kg^-1). No differences in the level of elements between both species were found. The levels of the detected elements in the hair showed low concentrations and similar to those observed in animals of the same species from unpolluted zones, reflecting a lack of contamination by these elements in the studied areas. Based on critical values of these elements established for organs of mammals, red deer and wild boar from the studied territories did not suffer toxicosis by the studied elements. Age-related differences in the content of As in the hair of red deer and age- and gender-related differences in the content of As in the hair of wild boar were detected, which should be considered for biomonitoring purposes. Finally, positive (Pb-As in both species) and negative (Zn-Pb in wild boar) interrelationships between elements were found.