Trace element concentrations (mercury, cadmium, copper, zinc, lead, aluminium, nickel, arsenic, and selenium) in some aquatic birds of the southwest Atlantic coast of France

I believe I can fly… but in polluted air, why? Bird feathers as an example of environmental contaminant monitoring

Metallic element pollution is a global environmental problem, and it is important to study various local conditions to understand the mechanisms on a larger scale. Environmental contamination can be studied in many ways, but non-destructive techniques and methods that preserve the sample are increasingly gaining attention, especially in relation to studies on living organisms. The present study aimed to analyze the feathers of the great tit (Parus major) for Al, S, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Ba and Hg content. Discriminant analysis showed that according to elemental composition young females and males make separate groups. At the same time, old birds are in the same group. From principal component analysis (PCA), elements distribution depends on age and gender and sources of elements can be natural and anthropogenic. However, not all element accumulation was dependent on both parameters: Al, Cr, Fe, and Ni were statistically significant from both parameters. Bird feathers can be regarded as promising biomonitors of air quality.

The diving beetle, Cybister lateralimarginalis (De Geer, 1774), as a bioindicator for subcellular changes affected by heavy metal(loid) pollution in freshwater ecosystems

The present study assessed Cybister lateralimarginalis as a model species for ecotoxicological studies of metal(loid) bioaccumulation in freshwater ecosystems, by optimising protocols and analysing biomarker activities and metal(loid) concentrations from different sites and investigating their association. To accomplish this, levels of arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb) were analysed, as well as a set of biomarkers were evaluated, esterase activity and oxidative stress biomarkers: fluorescence- and glutathione-based. C. lateralimarginalis were sampled in the spring/summer of 2023 along the Sava, Drava and Danube floodplains in Croatia. C. lateralimarginalis samples from Sava floodplain (Mužilovčica) showed altered carboxylesterase (CES) activity, lower glutathione (GSH) levels, and elevated Hg and As concentrations. The Weighted Pollution Index (WPI) indicated moderate pollution at the Sava floodplain, possibly due to agricultural or petrochemical impacts. At the Drava floodplain (Podravlje), higher glutathione S-transferase (GST) activity and elevated Cd, Hg, and As concentrations were observed, likely from soil accumulation, while Stara Drava beetles had lower GSH levels, suggesting agricultural impacts. Despite this, the Drava floodplain showed the lowest WPI. Higher GST activity was noted at the Danube floodplain (Kopački rit and Topoljski Dunavac), with reactive oxygen species (ROS) concentrations (Kopački rit and Podunavlje) possibly reflecting agricultural practices or illegal hunting. The present research successfully applied C. lateralimarginalis as a bioindicator species for assessing metal(loid)s in different environments, highlighting its reliability as an abundant apex predator, emphasizing the significance of integrating biomarker response evaluation into pollutant monitoring for efficient environmental risk assessment in freshwater ecosystems.

Heavy metal concentrations in feathers and metabolomic profiles in Pacific black ducks (Anas superciliosa) from Southeastern Australia

Heavy metals are cumulative toxicants that frequently create negative health effects for waterbirds inhibiting contaminated freshwater systems. Although levels of exposure to heavy metals have been well documented for many waterbird species, the adverse effects of exposure remain relatively poorly understood. One emerging field that allows the exploration of such effects is metabolomics. The aim of this study was to characterize metabolomic profiles in relation to long-term heavy metal exposure in a waterbird species. In 2021, wings from 44 Pacific black ducks (Anas superciliosa) were collected by recreational hunters at three sites in Victoria, southeastern Australia. The concentrations of seven heavy metals were measured in feathers and these data were quantified via inductive coupled plasma mass spectrometry and compared with a semiquantitative assessment of 21 metabolites identified in muscle tissues from the same birds via gas chromatography-mass spectrometry. Principal component analysis was conducted to test associations between metabolites, heavy metals, and sites. Mean heavy metal concentrations detected were copper (9.97 µg/g), chromium (0.73 µg/g), iron (123.24 µg/g), manganese (13.01 µg/g), mercury (0.58 µg/g), lead (0.86 µg/g), and zinc (183.95 µg/g; dry wt). No association was found between heavy metals and 17 metabolites, whereas four metabolites were negatively associated with some heavy metals: α-linolenic acid with iron, glucose with lead and manganese, lactic acid with mercury, and propanoic acid with mercury. There were few differences in the studied metabolites in ducks between the three sites. This study provides a novel approach to combining toxicological and metabolomic data for an ecologically important species from a relatively poorly studied global region.

Copper and its isotopes: a brief overview of its implications in geology, environmental system, and human health

Copper, a malleable and ductile transition metal, possesses two stable isotopes. These copper isotopic composition data have recently found diverse applications in various fields and disciplines. In geology, copper isotopes serve as tracers that aid in investigating ore formation processes and the mechanisms of copper deposits Likewise, it has emerged as a valuable tracer in polluted environments. In plant biology, copper acts as an essential micronutrient crucial for photosynthesis, respiration, and growth. Copper isotopes contribute to understanding how plants uptake and dispense copper from the soil within their tissues. Similarly, in animals, copper serves as an essential trace element, playing a vital role in growth, white blood cell function, and enzyme activity. In humans, copper acts as an antioxidant, neutralising harmful free radicals within the body. It also helps in maintaining the nervous and immune system. Furthermore, copper isotopes find medical applications, particularly in cancer diagnostics, neurodegenerative diseases, and targeted radiotherapy. However, excessive copper can have detrimental effects in humans such as it can cause liver damage, nausea, and abdominal pain, whilst in plants it can affect the growth of plants, photosynthesis, and membrane permeability. This review emphasises the significance of copper and its isotopes in geology, the environment, and human health.

Monitoring of toxic metals(loids) in fifteen raptor bird species of Iran

The current study was conducted to identify the contamination of 10 toxic metals(loids) (mercury (Hg), lead (Pb), cadmium (Cd), chromium (Cr), zinc (Zn), copper (Cu), selenium (Se), nickel (Ni), arsenic (As) and aluminium (Al)) in the feathers of 15 raptor bird species, which tries to analyze the adverse effects, taxonomic affiliation, spatial distribution, habitat type, and effect of age. During 2020-2022, 476 feathers of 115 birds were collected and the primary feathers of each bird were sampled and an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) was used to analyze the toxic metals(loids). It was found that there is a statistically significant difference between the concentration of metals(loids) and the studied birds (except for As) (p < 0.05). The highest average concentrations of Hg and Al in tawny owl (2.26 and 1184.75 mg/kg dry weight, respectively), Cu in spotted little owl (10.45 mg/kg), and Pb, Cd, Cr, Zn, Se, Ni, and As in pallid scops owl (5.44, 0.19, 3.93, 251.99, 4.84, 5.45, and 0.52 mg/kg, respectively) were observed. According to the threshold level of elements, the status of Pb, Cr, Ni, and Al can be reported as unfavorable. In the current project, there was a statistically significant difference between the concentration of Hg, Cr, and Ni in the studied birds and spatial distribution (p < 0.05). The pollution of birds in Khuzestan province with toxic elements was considerable and in all ten elements investigated, this province is among the first 5 provinces in terms of pollution. In the case of most of the investigated elements, namely Pb, Cd, Cr, Zn, As, and Ni, the highest concentration was related to the habitat of open grasslands (2.10, 0.04, 0.98, 64.66, 0.15, and 1.26 mg/kg, respectively). Regarding most of the studied elements, adult birds had the highest concentration, but elements such as Ni and As showed a reverse trend so that nestling birds had higher concentrations of Ni and As in their feathers. As a conclusion, tawny owl, spotted little owl, and pallid scops owl can be introduced among the important group of raptor birds as distinct indicators of environmental pollution.

Modulatory effects of inorganic mercury (Hg (II)) and lead (Pb (II)) on immune responses of Pekin ducklings (Anas platyrhynchos domesticus) upon a viral-like immune challenge

Trace metal contamination is ubiquitous around the world and may affect the health of wildlife. Divalent trace metals, including ions of mercury (Hg) and lead (Pb), have been shown to be immunotoxic to avian species. However, little is known about the immunomodulatory effects of trace metal exposure on viral infections, especially in young birds, who may be more sensitive. Therefore, the objective of the current study is to provide more insights in the causality between trace metal exposure and the effects of exposure on the immune responses in young waterfowls. Pekin duckling was used as an animal model to investigate the effects of inorganic divalent Hg (II) and Pb (II) on avian immune responses upon a viral-like challenge with double-stranded RNA. Our results indicate that Hg (II) altered the immune gene expression 24 h post-challenge, as reflected by induction of pro-inflammatory genes IL-8, iNOS, TLR3 and TLR7, and a significant decrease of microRNA-155. Ducklings exposed to Pb (II) showed lower levels of natural antibodies, reduced white blood cell counts and lower heterophil proportions 24 h post-challenge. Although inorganic divalent Hg (II) and Pb (II) showed specific differential effects on the immune response of Pekin ducklings, the overall adverse immunomodulatory outcomes in both cases point to inflammation, impaired B-cell function, and weaker immunocompetence.

Factors affecting the concentration of metals and metalloids in the kidneys of a top predator, the Eurasian Buzzard (Buteo buteo) wintering in farmland in Poland

During late autumn and winter, raptors in the western Palearctic face challenges due to food scarcity and dropping temperatures. That time they can be exposed to various elements including toxic ones ingested with food. Kidney samples from 22 females and 19 males of a medium-sized raptor, the Common Buzzard Buteo buteo found dead in farmland of Eastern Poland in winter were analyzed for a concentration of 21 elements. Elemental concentrations were analyzed regarding the age and sex of birds. Results revealed that only 4.9% of individuals had kidney lead levels exceeding 8.0 mg, while 9.8% showed cadmium levels above 8.0 mg/kg, indicating potential poisoning. The study also highlighted the limited entry of arsenic into agricultural ecosystems exploited by Common Buzzards. Sex differences were noted, with females accumulating more lead and vanadium than males which can be associated with foraging niche partitioning between sexes driven by body size dimorphism. Sulfur showed complex interactions with cadmium, mercury, and zinc, with a positive correlation between sulfur and zinc levels in the kidneys, emphasizing dietary needs during food scarcity. A positive correlation was found between zinc and lead concentrations, indicating zinc's role in mitigating lead's impact. The study also revealed positive correlations between selenium and highly toxic elements like mercury (Spearman correlation, rs = 0.41) and cadmium (rs = 0.51), suggesting a mitigating effect of selenium on exposure to heavy metals. This study enhances understanding of year-round environmental contamination exposure for raptors and sheds light on bioaccumulation in a top predator.

Elevated Heavy Metal(loid) Blood and Feather Concentrations in Wetland Birds from Different Trophic Levels Indicate Exposure to Environmental Pollutants

The research assessed the exposure to total mercury (THg), lead (Pb), and arsenic (As) in Colombian wetland species of different trophic levels Platalea ajaja, Dendrocygna autumnalis and Nannopterum brasilianus. The results show high THg blood levels in P. ajaja (811.00 ± 349.60 µg L-1) and N. brasilianus (209.50 ± 27.92 µg L-1) with P. ajaja possibly exhibiting adverse effects. Blood Pb concentration was high in D. autumnalis (212.00 ± 208.10 µg L-1) and above the threshold for adverse effects, suggesting subclinical poisoning. Levels of blood As were below the assumed threshold for detrimental effect (20 μg L-1). The mean concentration of feather THg was below the assumed natural background levels (5 µg g-1) for all three species. Feather Pb levels exceeded the levels for assumed threshold effects in all sampled N. brasilianus (7.40 ± 0.51 µg g-1). Results for feather As concentration were below the threshold for adverse impacts in all species, although a positive correlation between As and THg concentrations was detected in P. ajaja feathers. The overall results could help understand how metal(loid)s biomagnify through trophic levels and how wetland species may serve as environmental indicators. By exploring the interactions of metal(loid)s within different matrices and body, this study offers insights into the dynamics of contaminant accumulation and distribution in the environment. This concept can be applied to wetlands worldwide, where bird species can serve as indicators of ecosystem health and the presence of contaminants such as heavy metals and metalloids.

Regulated Inductively Coupled Plasma–Optical Emission Spectrometry Detectible Elements in Utah Lake: Characterization and Discussion

During the 2021 (n = 15) and 2022 (n = 13) summers, we measured the total and dissolved (<0.45 μm) concentration of 25 elements in Utah Lake using Inductively Coupled Plasma–Optical Emission Spectrometry (ICP-OES) with detection limits in the order of a few parts-per-billion (ppb). This resulted in 1400 measurements, which is a unique dataset in terms of sensitivity and temporal resolution. Regulated elements are not commonly measured at the ppb-level; thus, these data provide insight into both the behavior and existence of these elements in an aquatic environment and have implications for both the management and regulation of the lake. Utah regulates twelve of these elements. While ICP-OES has ppb-level sensitivity, it is not the approved regulatory analysis method for these elements. All regulations are for dissolved concentrations, except aluminum (Al) and phosphorus (P), which are for total recovery. We found total Al above the allowable concentration, but dissolved concentrations were well below allowable concentrations. We attribute high total concentrations to suspended clays. This suggests that regulatory methods should be reviewed for lakes with a high suspended-solid content. Dissolved copper (Cu) concentrations were below regulatory levels in 2021, but some samples were above regulatory levels in 2022. This could be related to the use of Cu-based algaecide treatments, or from other sources. Lead (Pb) data were inconclusive; dissolved Pb concentrations were well below the acute (1 h average) limit, but the chronic concentration limit (4 h average) was below the ICP-OES minimal detection limit. Arsenic (As) concentrations exhibited a seasonal trend that we attribute to groundwater inflows—they were below regulatory levels for aquatic environments but around the levels for drinking water. This ppb-level study with high temporal resolution provides insight into regulated elements in Utah Lake previously not available due to the high sensitivity of the method and measurements of both total and dissolved concentrations.

Mercury and rare earth elements (REEs) show different spatial trends in feathers of Kentish plover (Charadrius alexandrinus) breeding along the Adriatic Sea coast, Italy

Feather analysis is an ethical and effective method for assessing the exposure of wild birds to environmental contamination due to trace elements and organic pollutants. We used feather to monitor the exposure to three toxic and non-essential metals (Hg, Cd, and Pb) and rare earth elements (REEs) of Kentish plover (Charadrius alexandrinus) breeding in different coastal areas (Veneto, Emilia-Romagna, Marche, Abruzzo, and Apulia) along the Italian coast of the Adriatic Sea. Feathers (n = 113) were collected from April to June. Feather concentrations evidenced a significant exposure to Hg (13.05 ± 1.71 mg kg-1 dw) and REEs (447.3 ± 52.8 ng g-1 dw) in the Kentish plover breeding in Veneto (n = 21) compared to the other coastal areas, with several individuals showing Hg concentrations above the adverse effect (5 mg kg-1 dw) and high-risk (9.14 mg kg-1 dw) thresholds reported for birds. Higher REE concentrations compared to Marche (n = 29), Abruzzo (n = 11) and Apulia (n = 13) were also reported for birds breeding in Emilia-Romagna (474.9 ± 41.9 ng g-1 dw; n = 29). The exposure to Cd and Pb was low in all the coastal areas, and only a few samples (n = 6 and n = 4 for Cd and Pb, respectively) exceeded the adverse effect thresholds (0.1 and 4 mg kg-1 for Cd and Pb, respectively). A significant sex-related difference was observed for REE-concentrations, with females showing higher concentration than males. These data highlight the need to monitor the exposure of the Kentish plover to Hg and REEs, especially in the northern basin of the Adriatic Sea, since these elements might negatively affect species' reproductive success and threaten its conservation.

Trace element levels in the muscles of three tern species (Aves: Laridae) from the western Arabian Gulf: environmental assessment and implications for conservation

In the Arabian Gulf (called also Persian Gulf; hereafter 'the Gulf'), Jana and Karan Islands are recognized as one of the most Important Bird Areas in the region. Many migratory breeding seabirds, like the Greater Crested Tern Thalasseus bergii, White-cheeked Tern Sterna repressa and Bridled Tern Onychoprion anaethetus, depend on these islands during the breeding season. However, these aquatic wildlife species are suffering from intensified urban and industrial coastal development and various contamination events including wars and related oil spills. In this study, we used these three piscivorous top predator birds to analyse the levels of 19 trace elements (TEs; i.e. Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sr, V and Zn) in 15 muscular tissue samples from Jana and Karan Islands. PERMANOVA analysis showed no difference in contamination profile between sites nor between species probably due to their spatial and ecological proximity and therefore similar levels of exposure to TEs. Comparing these levels with existing literature, our results showed no particular concern for all elements, except for Al (maximum values recorded = 116.5 µg g-1 d.w.) and, in two samples, Ba (33.67 µg g-1 d.w.) and Pb (5.6 µg g-1 d.w.). The results can be considered as an initial step for supplementary evaluations with a larger number of samples and specified time intervals for the collection of specimens. This study provided baseline information on the pollution status of these two ecologically important sites which require a continuous biomonitoring programme.

The non-selective Antarctic filter feeder Salpa thompsoni as a bioindicator of mercury origin

Hg is considered as the most toxic metal in the environment. Sources of Hg in the environment include burning fossil fuels, burning waste, and forest fires. The long residence time of the gaseous form in the atmosphere allows mercury to be transported over long distances. The pelagic tunicate Salpa thompsoni is an important component of the Antarctic environment. Over the past few decades an expansion of this species to the higher latitudes has been noted, mainly due to the ongoing climate change. The study material consisted of samples of S. thompsoni individuals, collected in the waters surrounding Elephant Island (Western Antarctic). Total mercury and five of its fractions were determined. Whole organisms were analyzed as well as internal organs: stomachs, muscle strips, and tunics. Obtained results showed that the highest concentrations of mercury in salps were observed in stomachs. With the Hg fraction results, it can be concluded that the main route of exposure of S. thompsoni to Hg is presumably absorption from the food-filtered organic and non-organic particles. Moreover, the process of transformation of simple soluble forms into organic forms of Hg in stomachs and intestines and its distribution to other tissues was observed.

Content of Lead and Cadmium in the Tissues and Organs of the Wild Mallard Duck (Anas platyrhynchos L.) Depending on the Region of Poland Where It Is Harvested

A property common to heavy metals is that even in small concentrations they can exert toxic effects on living organisms, including humans. The aim of this study was to analyze the quality of the tissues and organs of wild mallard ducks (Anas platyrhynchos L.) by estimating the potential hygiene and toxicological hazard associated with the concentrations of lead and cadmium in these tissues and organs, as well as the influence of the birds' sex and place of origin on these parameters. A significantly higher average lead content was noted in the breast muscles and the livers of the mallards harvested in the Leszno hunting district compared to the birds from the Siedlce hunting district. A higher average cadmium concentration was recorded in the breast and leg muscles of the mallards harvested in the Leszno hunting district than the Siedlce hunting district. The concentration of cadmium in the tissues and organs of the mallards harvested in the Siedlce or the Leszno hunting district did not exceed the acceptable limits for the muscles and livers of slaughtered animals. This study found no significant effect of the sex of the wild crossbreeds on the content of lead and cadmium in tissues and organs. This study showed that the mallard has a measurable response to environmental pollution with lead and cadmium, and therefore it is a species that could to some extent be used as a bioindicator of the level of contamination of the environment with these xenobiotics. The ban on the use of lead pellets as ammunition in Poland may largely limit the degree of lead contamination of the tissues and organs of mallards.

Tissue distribution and correlations of heavy metals in wild birds from Southern Turkey: an ecologically important region on the west Palearctic migration route

Even if some are essential for biological functions, the accumulation of heavy metals above tolerable physiological limits is potentially toxic to also wild animals. The present study aimed to investigate concentrations of environmentally relevant heavy metals (As, Cd, Cu, Fe, Hg, Mn, Pb, and Zn) in feathers, muscle, heart, kidney, and liver tissues of wild birds (golden eagle [Aquila chrysaetos], sparrowhawk [Accipiter nisus], and white stork [Ciconia ciconia]) from Hatay province, southern Turkey. The metal concentrations of tissues were determined by a validated ICP-OES analysis method after microwave digestion. The concentration differences of metals in species/tissues and the correlations between essential/non-essential metals were determined by statistical analysis. According to the results, Fe (326.87±3.60 mg kg^-1) had the highest, and Hg (0.09±0.00 mg kg^-1) had the lowest mean concentration in all tissues. Compared to the literature; Cu, Hg, Pb, and Zn concentrations were lower; Cd, Fe, and Mn concentrations were higher. The correlations between As and all essentials; Cd and Cu, Fe; Hg and Cu, Fe, Zn; Pb and all essentials were significantly positive. In the conclusion, while essential Cu, Fe, and Zn are below the threshold value and do not pose a risk, Mn is close to the threshold value. Therefore, periodically monitoring the pollutant concentrations in bioindicators is a key necessity for the early determination of biomagnification trends and prevention of potential toxic stress on wildlife ecology.

Heavy Metals in the Liver, Kidney, Brain, and Muscle: Health Risk Assessment for the Consumption of Edible Parts of Birds from the Chahnimeh Reservoirs Sistan (Iran)

The concentrations of four heavy metals, zinc (Zn), lead (Pb), nickel (Ni), and cadmium (Cd), were determined in the liver, kidney, muscle, and brain of nine species of birds from the Chahnimeh Sistan from Iran to assess the metal levels and the potential risk to birds and to the people who eat them. Significantly higher levels of all metals were found in the brain than in the other tissues of other birds. There were no significant gender differences in heavy metals in all tissue. The levels of Pb, Cd, Ni, and Zn in the liver and kidney varied as a function of feeding habitats; the median levels were significantly higher in invertebrate predators than they were for fish predators and omnivorous species. Short-distance migrant birds had significantly higher median levels of heavy metals in the liver and kidney than long-distance migrant birds. Ni levels in the liver and kidney tissues in 56% of birds were higher than the critical threshold levels for effects in birds. Our data indicate that environmental exposures to metals were higher in the wintering populations of birds in the Chahnimeh of Sistan from Iran than elsewhere. Concentrations of Zn, Pb, and Cd in a small percentage of birds were above toxicity levels. However, 56% of liver and kidney samples for nickel were above toxicity levels. Determining the exposure frequency and daily intake of birds, the hazard quotient for edible tissues (kidney, liver, and muscle) of these birds showed that their consumption may provide health risk to people consuming them.

Use of Feathers from Birds that Collided with Vehicles to Monitor Heavy Metal Contamination in Western Khorasan Razavi, Iran

In the present study, lead, zinc and copper concentrations in the feathers of Common kestrel (Falco tinnunculus), Eurasian magpie (Pica pica), Common buzzard (Buteo buteo), Crested lark (Galerida cristata), Eurasian hoopoe (Upupa epops), Little owl (Athene noctua), Long-eared owl (Asio otus), Eurasian eagle-owl (Bubo bubo) and Long-legged buzzard (Buteo rufinus) from Sabzevar and Neghab, Khorasan Razavi of Iran were measured. Almost all of the specimens were obtained from birds that had collided with vehicles or were unable to fly. There were no significant differences in metal concentrations between adult and juvenile, diurnal and nocturnal raptors and species with different diets. Elemental concentrations were lower than toxicity threshold values, so exposure to these elements does not appear to pose a health risk to the studied species. It should be noted that this study was the first study of metals in Galerida cristata, Asio otus and Buteo rufinus.

A multi-tissue biomonitoring investigation of toxic trace elements and their trophic transfer potential in a semi aquatic bird species, the Cattle Egret (Bubulcus ibis)

The constant exposure of toxic trace elements can elicit adverse health effects particularly in birds and species residing higher at the food web. The current study is designed to evaluate the tendency of toxic trace elements viz. Cd, Cr, Pb, Cu, As and Hg to bioaccumulate in liver, kidney, blood, pelvic and pectoral muscles of cattle egret (Bubulcus ibis) collected from premises of a metropolitan city, Lahore, Pakistan. Further, the Trophic Transfer Potential of these elements was also estimated using prey/food samples of cattle egret. All of the selected toxic trace elements except Hg and As were detected with varying concentrations in different tissues of cattle egret. In general, toxic trace elements followed the pattern as Cu > Pb > Cd > Cr in tissues of cattle egret. The maximum mean (Min-max) concentrations (μg/g) of Cu 0.58 (0.11-0.93) and Pb 0.46 (0.40-0.54) in blood and Cd at 0.46 (0.40-0.54) were observed in liver. Similarly, the highest mean (min-max) concentration (μg/g) of Cr 0.17 (0.09-0.25) was recorded in pectoral muscle. In general, blood and liver were found as the most contaminated tissues followed by kidney, pectoral and pelvic muscles. Differences of trace elements were found non-significant (all P > 0.05) among tissues of cattle egret reflecting their homogenous distribution in body. Principal Component Analysis (PCA) corroborated lack of strong association between any of the trace elements and tissues. All the toxic trace elements except Cr showed higher tendency of trophic transfer potential through food chain in all the tissues of Cattle Egret (TTF >1). Although the current study revealed decreasing trends of toxic trace elements, yet their still presence in the local environment and greater likelihood of trophic transfer can undoubtedly cause some severe health effects to the already declining bird populations.

The Impact of Pb from Ammunition on the Vegetation of a Bird Shooting Range

Hunting with lead ammunition represents a source of heavy metal pollution to the environment that can be potentially high at the local scale. Intensive hunting of small game species can concentrate high levels of ammunition discharging in small areas. This type of hunting is a relevant economic resource for private landowners in some regions of Spain, and current legislation allows the use of lead ammunition in these scenarios. It becomes, therefore, highly relevant to study whether this activity may pose concerns to the conservation of the environment in the areas where it takes place. Using a red-legged partridge (Alectoris rufa) shooting range as a study area, we examined the effect of intensive hunting on this species on the vegetation present. We found significantly higher lead levels in the sprouts of plants of shooting areas related to control sites of the same property where partridge shooting does not occur. We found differences in the presence of lead between sprouts of different plant species. In addition, old sprouts of existing vegetation in shooting areas also showed higher lead levels than newly emerged sprouts of the same plants. These results demonstrate the impact of lead ammunition on vegetation in terms of persistence over time and differences between species. Further analyses using chemical and ecotoxicological data are necessary to evaluate the extent of environmental pollution risks. Our results provide new support in favor of the use of alternative ammunition, with particular emphasis on scenarios where hunting activity is intensive.

Heavy metals in liver, kidney, brain, and muscle slender-billed gull (Chroicocephalus genei) from south-eastern Iran

The concentrations of four heavy metals nickel (Ni), cadmium (Cd), lead (Pb), and zinc (Zn) were determined in liver, kidney, muscle, and brain tissues of 40 slender-billed gulls (Chroicocephalus genei) from the Chahnimeh water reservoirs of Sistan and the Oman Sea coast of Iran. There were significant differences between Ni, Cd, Pb, and Zn concentrations observed in the liver and brains of birds from the Oman Sea coast than in the liver and brains of gulls from the Chahnimeh water reservoirs (P < 0.05). Higher levels of Pb, Cd, and Zn were found in the brain and liver of gulls than in the kidney and muscles tissues. There were significant gender differences in heavy metals in liver and brain tissue. In gulls from the coast of Oman Sea, all four elements (Cd, Pb, Ni, and Zn) were positively correlated with levels in all organs, and except for muscle, the elements were positively correlated with the other elements in the other tissues (except Ni in the brain). Thus, the pathways and sources of entry for the elements are similar, and the pathways for accumulation of these elements, and the reactions of different organs of the body to these elements, are very similar. Also, 40% of gulls in Oman Sea coast had levels of lead in the brain (>5 μg g^{-1 -1} d.w) that were above the adverse effect levels, Ni concentrations in the liver of slender-billed gull in Oman Sea coast (100 %) and Chahnimeh water reservoirs (90 %) were above toxic levels (> 3 μg g^-1 d.w), and 80% of Ni concentration in kidneys in gulls from the Oman Sea coast and Chahnimeh water reservoirs were higher than the toxicity levels (> 10 μg g^-1 d.w).

Sex-related and spatial variation in trace elements in feathers of the Kentish plover (Charadrius alexandrinus) from different coastal areas of the Iberian Peninsula

This study investigated the sex-related and spatial variation in trace elements concentrations in feathers of the Kentish plover (Charadrius alexandrinus) inhabiting different coastal locations in the Iberian Peninsula. Feathers were sampled in a total of 50 breeding birds from 7 different locations: 3 on the Mediterranean coast (n=18), 1 on the Atlantic coast of Andalusia (n=9) and 3 on the NW Atlantic coast (n=23). The feathers were analyzed to determine the concentrations of Al, Cr, Mn, Cu, Zn, As, Se, Cd, Hg and Pb. All of the trace elements were present at detectable concentrations, and the mean concentrations of Al, Zn and Cu were highest of those considered. The coastal section had a significant effect on 5 elements (Mn, Cu, As, Cd and Pb). The mean concentrations of almost all of the trace elements were highest in the birds from Andalusia, intermediate in the birds from the Mediterranean area and, in general, lowest in the birds from the NW Atlantic coast. Females showed significant higher Mn concentrations and high levels of exogenous elements (Al and As) in contrast with males. Less preening activity during the day of female birds, when they are occupied in incubating eggs, could favour higher concentrations of exogenous trace elements. The high levels of several trace elements observed in the samples from Mediterranean and Atlantic coast of Andalusia may pose a serious threat to these populations.

Preferential Liver Accumulation of Mercury Explains Low Concentrations in Muscle of Caiman yacare (Alligatoridae) in Upper Amazon

Caiman yacare is considered one of the top predators in the Amazon basin, and understanding pollutant distribution within its tissues may help its sustainable management. As a top predator, C. yacare should have the highest mercury concentrations, but has lower Hg concentrations than carnivorous fish (Rivera et al. 2016), which are part of their diet. We compared total Hg among liver, kidney, fat, and muscle of C. yacare, and whether trends in the distribution of Hg among tissues were like other crocodilians, aquatic birds, omnivorous, and carnivorous fish. Fat had the lowest concentrations (0.025 ± 0.03 mg kg^-1) followed by muscle (0.15 ± 0.06 mg kg^-1), kidney (0.57 ± 0.30 mg kg^-1) and liver (1.81 ± 0.80 mg kg^-1). Such preferential accumulation makes C. yacare meat a safer alternative for human consumption than carnivorous fish. The relation between Hg accumulation in liver and muscle is highest in crocodilians, which has evolutive and environmental implications.

Antarctic Adélie penguin feathers as bio-indicators of geographic and temporal variations in heavy metal concentrations in their habitats

Seabird feathers are effective indicators of heavy metal contamination. To propose a biological detection method suitable for the long-term monitoring of heavy metals in the Antarctic environment, eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in Adélie penguin feathers from different body parts, years, and molting grounds in the Antarctic were investigated in this study. It is found that the concentrations of heavy metals in the feathers showed differences among the body part of origin. The levels of the eight elements in the abdomen and back feathers were approximately the same, but some elements of them were significantly higher than those in the tail feathers. The Hg and Cd concentrations in the abdomen and back feathers increased from root to tip, regardless of the sampling year or molting ground. Based on a structural analysis of the feathers, Hg and Cd were mainly distributed in the feather vane rather than the shaft. The methylmercury content accounted for 83%-97% of the total mercury content in all feather samples, regardless of location, year, or body part, thereby supporting the assumption that mercury entering the feather was predominantly methylated and indicating that a relatively toxic form of Hg is excreted through the feathers. The heavy metals in feathers from the same molting ground showed significant differences over the sampling years. The average concentrations of As, Cr, Cu, Ni, and Zn increased significantly from 2015 to 2019, whereas those of Cd, Hg, and Pb tended to decrease. The concentrations of the eight elements in Adélie feathers from three molting grounds varied greatly, possibly in relation to their living areas and dietary structures. Feathers from the Ross Sea site had the highest Cd, Cu, Hg, Ni, and Zn concentrations, the highest As and Cr concentrations were detected in feathers from the Zhongshan site, and feathers from the Great Wall site showed higher Pb concentrations than those from the other two sites. This study established a long-term, nondestructive, and efficient method for monitoring heavy metal contamination in the polar environment in the future.

Trace elements' reference levels in blood of breeding black-browed albatrosses Thalassarche melanophris from the Falkland Islands

Trace elements' concentration in the ocean is fast growing and is a source of major concern. Being charismatic and at the top of food chains, seabirds are often used as biological monitors of contaminants. We studied the concentration of trace elements in blood of black-browed albatross from the Falklands Islands, which we here show, by tracking with geolocators, forage over most of the Patagonian Shelf. Levels of trace elements were measured in males and females from two different islands. Blood concentrations of trace elements were not significantly different between islands, which is consistent with observations from foraging behavior revealing that birds from both islands foraged in broadly the same areas in the months before sampling. Arsenic and selenium concentrations in females were higher than in males. Sex-related differences in the concentration of these elements may be related to unknown slight differences in diet or to differences in assimilation between sexes. These results provide reference values for monitoring elemental contamination in the Patagonian Shelf Large Marine Ecosystem using black-browed albatrosses, one of the most abundant top predators and a suitable sentinel for the region's environmental health.

Impact of heavy metals on Ciconia boyciana feathers and Larus saundersi egg shells in the Yellow River delta estuary

In this study, the Ciconia boyciana and Larus saundersi, typical wetland birds in the Yellow River estuary, were selected as research objects. The feathers and egg shells of Ciconia boyciana and Larus saundersi were collected to determine the contents of heavy metals Cd, Cr, Cu, Zn, Mn, Ni and Pb in the samples. Correlation analysis (CA), principal component analysis (PCA), principal factor analysis (PFA) and potential ecological risk index (RI) were used to analyse and treat the measured heavy metal content data to determine the heavy metal pollution status, source and potential ecological risk in the Yellow River estuary. The results of CA, PCA and PFA showed that the content of Cd in the Yellow River estuary was much higher than the background value and its pollution was the most serious. Cr pollution was second and Mn pollution was the lowest. Heavy metal pollution mainly came from human activities such as oil exploitation, industrial production, use of pesticides and fertilizers, and the pollution caused by natural sources was relatively low. Based on the RI value of heavy metals in the study area, heavy metal Cd had an extremely high ecological risk status, and other heavy metals were all low. The results of this study can provide some reference and theoretical support for bird protection, heavy metal pollution control and ecological restoration in the Yellow River delta.

In this study, the Ciconia boyciana and Larus saundersi, typical wetland birds in the Yellow River estuary, were selected as research objects.

Quantitative assessment of metal contamination and associated pollution risk in sediments from the Mara River in Tanzania

For most rivers in sub-Saharan Africa, information about pollution indices related to sediments is sparse. Sedimentological research of rivers that empty into Lake Victoria is highly patchy and wide apart. The present study determined the levels and associated risk of As, Cd, Cr, Hg, and Pb in sediments collected from four different sites along the Mara River that empties into Lake Victoria in Tanzania. Samples were collected in the dry and rainy months in 2019. Pollution indices, namely geo-accumulation index (I_geo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (E_rⁱ), and potential ecological risk index (RI) were used to evaluate the influence of heavy metal contamination in sediments. Dry month mean concentrations, in milligram per kilogram, of heavy metals were as follows: As (11.04 ± 0.13), Cr (1.02 ± 0.29), Cd (0.43 ± 0.05), and Hg (0.01) in the dry month. Respective sediment heavy metal concentrations for the rainy month were 22.22 ± 0.05 mg As/kg, 3.84 ± 0.34 mg Pb/kg, 1.53 ± 0.15 mg Cd/kg, 1.43 mg Cr/kg, and 0.03 mg Hg/kg. Generally, the risk indices showed high values in the rainy month and low values in the dry month, especially for As and Cd-an indication of anthropogenic influence. Correlation coefficient analysis for Pb and Cd showed a strong positive correlation (r = 0.99, p < 0.01)-this may suggest a similar source or similar transport behavior. Special attention needs to be paid with regard to rainy season As and Cd enrichment in the study area.

Assessing the association and predictability of heavy metals in avian organs, feathers, and bones using crowdsourced samples

Birds are bioindicators for research on the relationship between environmental heavy metal concentration levels and accumulation levels in bird tissues. We use roadkill samples, collected by citizen science participants, to investigate the accumulation levels and associations of seven heavy metals in internal organs (heart, liver, and kidney), feathers (primary and breast), and bones (sternum and femur) of two focal species, Amaurornis phoenicurus and Gallinula chloropus. We found that heavy metal accumulation varied by target tissue, and that variables are associated with bird species and heavy metal type. Although Zn and Cu were highest by concentration among both species, Cu was mostly accumulated in internal organs, As in feathers, and Pb in bones. Concentrations of As, Ni, and Pb in feathers of both focal species were lower than those reported in literature, whereas Cd and Cr were above toxic levels. The results also showed that spatial correlation for heavy metal concentration among bird tissues were weaker than non-spatial correlation, suggesting low spatial autocorrelations and variability. In addition, multiple regression analysis revealed significant correlation for Cr, As, and Pb estimations in A. phoenicurus heart, sternum, and kidney, respectively; and potentially Cr in G. chloropus femur by using feathers. These results support the feasibility of using feathers as indicators of As, Cr, and Pb heavy metal contamination to enhance our understanding of heavy metal accumulation in birds, although caution is required for feather-based estimations of Cd, Cu, and Ni concentration.

Trace Element Bioaccumulation in Stone Curlew (Burhinus oedicnemus, Linnaeus, 1758): A Case Study from Sicily (Italy)

: The study aimed to highlight the degree of trace element contamination along three sites of Sicily: the Magnisi peninsula (MP), located in proximity to the Augusta-Priolo-Melilli petrochemical plant; the Ragusa agro-ecosystem (RA), characterized by a rural landscape; and the Gela plain (GP), characterized by intensive agriculture and a disused petrochemical plant. We collected biological samples (abraded back feathers and blood) of the Stone Curlew (Burhinus oedicnemus Linnaeus, 1758) as well as soil samples to determine the trace elements concentrations of As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Se and V using ICP-MS analysis. The results found for the three sites show different trends of accumulation, which depend on the different management and geological characteristics of the areas. The Gela plain and Magnisi peninsula showed a higher degree of contamination (As, Co, Cu, Mn and Se for the Gela plain; Pb and Hg for the Magnisi peninsula). Nevertheless, no critical values were found for either the environment-if the results are compared with the legal limits fixed by the Legislative Decree No. 152/2006, approving the Code on the Environment-or for living organisms-if the results are compared with the toxicological thresholds for birds, especially if the short-term exposure results from the blood values are considered. Only the Se levels in animal blood from the RA and GP were found slightly higher than the minimum level required in bird diets. The positive scenario can be attributed on the one hand to the interruptions of emissions of the Gela refinery around 5 years ago, and on the other hand to the more intense and strict controls that are implemented in the area surrounding the petrochemical pole of Augusta-Priolo-Melilli.

Little egret (Egretta garzetta) as a bioindicator of heavy metal contamination from three different localities in Egypt

This work aimed at using Little Egrets (Egretta garzetta), for the first time in Egypt, as a bioindicator of heavy metal contamination from three different Egyptian land use types (Qillin within Kafr El-Sheikh (S1, agricultural), Toukh within Qalyubia (S2, semi-rural area), and Abu Rawash within Giza (S3, urban)). Concentrations of aluminum (Al), barium (Ba), cobalt (Co), cadmium (Cd), chromium (Cr), copper (Cu), manganese (Mn), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn) were analyzed in liver and kidney samples of twenty-six adult Little Egrets collected from the three localities during winter 2018. Moreover, the study calculated the Metal Pollution Index (MPI) to highlight the health of the surrounding environment using birds' internal organs as a mirror. Results revealed that, throughout the three sampling sites, the total metal concentrations in liver samples exceeded that of the kidney, indicating that the liver is the target organ of metal accumulation. The Little Egret's liver was found to be the best-recommended organ to use in future biomonitoring of Cu, Zn, Fe, Mn, and Ni, whereas Al, Co, Cr, Ba, Pb, and Cd can be monitored in the kidney. Cu and Pb were higher in the Little Egret's tissues collected from the agricultural site (S1), whereas Ba, Ni, and Fe were higher in the semi-rural site (S2), followed finally by Cd in the urbanized site (S3). The concentrations of trace elements reported in Little Egrets were within the known background level for water birds. However, alarming concentrations were found for Ni levels in liver (from Qillin and Toukh), as well as Pb and Cr levels in kidney samples (from the three localities). MPI of the eleven studied metals in both liver and kidney of the studied species decreased in the order Qillin (24.36) > Abu Rawash (17.98) > Toukh (3.90). In the three investigated localities, the overall calculated MPI values were higher than one, indicating that the ecosystem is polluted. The study suggested using Little Egrets as a bioindicator of metal contamination.

Dietary proxies (δ15N, δ13C) as signature of metals and arsenic exposure in birds from aquatic and terrestrial food chains

In this study, exposure to arsenic (As), lead (Pb), cadmium (Cd), copper (Cu) and zinc (Zn) was investigated in the blood, pectoral muscles and tail feathers of two terrestrial (spotted owlet; Athena brama and bank myna; Acridotheres ginginianus) and two aquatic (cattle egret; Bubulcus ibis and pond heron; Ardeola grayii) bird species inhabiting Pakistan. Food chain specimens, as well as the dietary proxies δ¹⁵N and δ¹³C, were also analyzed to validate potential trophic and dietary transfers of metals and As in birds. Zn was found to be the most prevalent metal in the tissues of birds followed by Pb, As, Cu, and Cd. The bioaccumulation of metals and As was higher in tail feathers reflecting the combined effect of both endogenous and exogenous contamination. Pectoral muscle and blood harbored lower levels of As and metals, indicating less recent exposure through diet. Aquatic birds feeding at higher trophic levels accumulated significantly higher concentrations of metals and As in their tissues (P < 0.05) and, therefore, may be at a greater risk of metal and As toxicity than terrestrial birds. Linear regression model depicts δ¹⁵N as a strong predictor of metals and As levels in the tissues of both aquatic and terrestrial birds, followed by the δ¹³C dietary proxy. All metals in aquatic species, except for Cd, as well as terrestrial species, except for Cu, exhibit bioaccumulative potential through the food chain (Trophic transfer factor: TTFs > 1) indicating potential harmful consequences for birds. Elevated concentrations of metals and As in tissues may cause harmful effects in birds potentially leading to declines in their populations.

Oxidative stress risk assessment through heavy metal and arsenic exposure in terrestrial and aquatic bird species of Pakistan

In this study, we investigated metal- and metalloid-induced oxidative stress response in two aquatic (cattle egret (Bubulcus ibis) (n = 10), pond heron (Ardeola grayii) (n = 10)), as well as two terrestrial (spotted owlet (Athene brama) (n = 6) and bank myna (Acridotheres ginginianus) (n = 16)) bird species collected from the outskirts of Lahore city, Pakistan. For this purpose, glutathione (tGSH) and lipid peroxidation (thiobarbituric acid-reactive substances (TBARS)) levels and activities of antioxidant enzymes (superoxide dismutase (SOD); catalase (CAT)) were analyzed as biomarkers of oxidative stress against metal (Pb, Cd, Cu, Zn) and metalloid (As) concentrations in kidney liver and blood of birds. Our results depicted significant correlation for Pb, Cd, and As with oxidative stress biomarkers in birds. The levels of heavy metals and As and their corresponding effects on oxidative stress biomarkers were comparably higher in aquatic species (p ≤ 0.01) except for Pb and Zn. In comparison of species, SOD and tGSH activities were higher in bank myna and cattle egret, while CAT activity and TBARS concentrations were higher in pond heron and cattle egret, respectively. We deduced that tissues with higher accumulation of metal(loid)s such as liver and kidney were under a great risk to oxidative damage. The overall order of metal accumulation and subsequent oxidative damage among families followed the pattern as Strigidae ≥Ardieda ≥ Sturnidae with their respective trophic levels. Globally, metal- and As-induced oxidative stress is least emphasized in multiple tissues of birds that is needed to be addressed with focus on case-control studies using dose-response approach. Graphical abstract .

Subcellular partitioning of cadmium and lead in Eisenia fetida and their effects to sperm count, morphology and apoptosis

Earthworms and their biomarkers are considered good indicators for assessing the effects of toxic chemicals. Therefore, in this study, we exposed Eisenia fetida to lethal and sub-lethal concentrations of Cd and Pb nitrate in artificial soil for 14 and 28 days to evaluate the impact on subcellular partitioning, lethal toxicity (LC₅₀), growth, sperm count, morphology and apoptosis (using TUNEL assay). The soluble internal pools of both metals were good predictors of the responses of biomarkers. We found sperm deformation, TUNEL positive sperms and weight loss positively and sperm count negatively correlated with the concentrations of Cd and Pb in the total internal and cytosolic fraction (p < 0.01) and to a lesser extent with Pb concentrations in the granular fraction (p < 0.05). Fourteen days LC₅₀ for Cd and Pb were 2169 ± 322 and 6387 ± 904 μg/g, respectively. Cadmium and Pb caused a significant depression in sperm count after 14 (Cd: up to 46.9%; Pb: up to 36.24%) and 28 (Cd: up to 72.47%; Pb: up to 43.12%) days of exposure relative to the control (p < 0.05). Cadmium induced higher abnormality in sperm heads than Pb. For both metals, TUNEL positive sperms significantly increased after 14 (Cd: up to 14.17%; Pb: up to 16.33%) and 28 (Cd: up to 16.33%; Pb: up to 11.67%) days of exposure compared with the control (p < 0.05). The findings of this study, illustrate the importance of considering sperm parameters as a rapid, easy and sensitive biomarker for the evaluation of metal toxicity.

Storm petrels as indicators of pelagic seabird exposure to chemical elements in the Antarctic marine ecosystem

Data on trace element bioavailability in the south-polar marine ecosystem is still scarce, compared to that relating to temperate zones. Seabirds can be used as indicators of ecosystem health and sentinels of environmental pollution, constituting a link between marine and terrestrial environments. Here, we analysed the concentration of 17 elements (with special emphasis on mercury, Hg) in feathers of adults and chicks of two pelagic seabirds - the Wilson's storm petrel Oceanites oceanicus and the black-bellied storm petrel Fregetta tropica - breeding sympatrically in the maritime Antarctic. Since adult feathers are formed during the non-breeding period away from the breeding grounds, but down and body feathers of chicks grow at the breeding sites, we were able to evaluate the birds' exposure to contaminants at various stages of their annual life cycle and in various marine zones. We found that of the two studied species, adult black-bellied storm petrels had significantly higher mercury, selenium and copper levels (5.47 ± 1.61; 5.19 ± 1.18; 8.20 ± 0.56 μg g^-1 dw, respectively) than Wilson's storm petrels (2.38 ± 1.47; 1.81 ± 0.98; 2.52 ± 2.35 μg g^-1 dw, respectively). We found that Wilson's storm petrel chicks had a significantly different contaminant profile than adults. Arsenic, bismuth and antimony were detected exclusively in the chick feathers, and the Se:Hg molar ratio was higher in chicks than in adults. Our study also suggests considerable maternal transfer of Hg (to down feathers) in both species. As global contaminant emissions are expected to increase, birds inhabiting remote areas with sparse anthropogenic pollution can indicate the temporal trends in global contamination.

Lead and Other Trace Elements in Danish Birds of Prey

Lead is a widely used and toxic heavy metal that poses a serious hazard to wildlife species and their ecosystems. Lead is used for production of hunting ammunition. Via gunshot or rifle projectiles, it spreads in ecosystems and may end up in predators and scavengers feeding on wounded or dead animals shot with lead-based ammunition. To assess to what degree Danish raptors are subject to lead contamination, we measured the content of lead in liver tissue from Danish birds of prey (n = 137). Additionally, the study included values for 54 other trace elements. In our analysis, emphasis was put on interpretation of lead levels. Levels of cadmium, mercury and selenium were also discussed, while data for the remaining elements were provided for reference purposes. Bismuth was included to assess if lead originated from bismuth gunshot used as an alternative to lead shot. Concentrations of lead, cadmium, mercury and selenium were generally below the levels in similar studies of birds of prey in other northern European countries and none exceeded known and generally accepted threshold values for adverse health effects. As for lead, this is possibly related to the phase out of lead shot for hunting since 1986. The study confirms results from other studies showing that bismuth shot contains traces of lead that is deposited with bismuth in the target animal.

Temporal Changes in Concentrations of Lead and Other Trace Metals in Free-Ranging Eurasian Eagle Owls Bubo bubo in Sweden

Patterns of lead and other trace metals were examined in 122 Eurasian eagle owls Bubo bubo found dead in Sweden in the period 1978-2013. Environmental lead (Pb) has decreased over recent decades from reduced anthropogenic emissions but mortality by Pb poisoning is still frequently reported for avian raptors and scavengers exposed to Pb ammunition. One objective here was to determine if Pb concentrations in a nocturnal non-scavenging raptor follow the general decline observed in other biota. Pb concentration in owl liver was significantly correlated with body weight, sex, latitude, longitude and season. Pb showed a significant decreasing trend towards north and west. Starved birds had significantly higher concentrations. Total Pb concentrations in liver averaged 0.179 μg g^-1 dry weight (median 0.103) and decreased by 5.6% per year 1978-2013, or 5.3% after adjustment for confounding factors, similar to trends in other species. Among 14 other trace elements only antimony and arsenic showed decreasing trends. Lead isotope ratios ²⁰⁶Pb/²⁰⁷Pb and ²⁰⁸Pb/²⁰⁷Pb increased from 1.138 and 2.408 in 1978-1985 to 1.170 and 2.435 in 2010-2013, respectively, demonstrating that the decreasing Pb concentration in eagle owl is related to the phase-out of leaded gasoline in Europe, where Pb additives had much lower isotope ratios than natural lead in Swedish soils. Only one incidence of suspected Pb poisoning (40.7 μg g^-1 in liver) was observed indicating that poisoning from ingestion of metallic lead is rare (< 1%) in eagle owl in Sweden, in contrast to what has been reported for eagles.

Accumulation of trace elements in feathers of the Kentish plover Charadrius alexandrinus

A non-invasive study of trace element accumulation in tail feathers of the Kentish plover (Charadrius alexandrinus) was performed along the coastline of the northern littoral strip of the Venice Lagoon, with the aim to verify whether contamination may be a factor affecting conservation status of Kentish plover populations. Body burdens in feathers of 11 trace elements including toxic metals/metalloids and essential elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, V, Zn) were quantified by ICP-MS, then concentrations were normalized to feather's age calculated using ptilochronology in order to obtain daily deposition rates. Mercury emerged as a major threat to the conservation of the species, since average feather concentration was clearly above the adverse-effect threshold associated with impairment in the reproductive success in a number of bird species. Also Cd and Se occurred at levels that may impact on the conservation status of the studied species at local scale, even if to a lesser extent than Hg. Gender-related differences in trace element accumulation emerged only for As, although for this element the risks associated to environmental exposure seem to be negligible.

Feathers of Humboldt penguin are suitable bioindicators of Rare Earth Elements

Rare earth elements (REEs), also called lanthanides, are emerging contaminants worldwide, due to their unique physical and chemical characteristics that make them essential in a variety of industrial applications. However, there is still a gap in the knowledge of occurrence and accumulation of REEs in biota, and no investigations have yet been performed in penguin feathers, which have already been widely utilized as a non-invasive tool for the biomonitoring of trace elements. The concentrations of 16 REEs were investigated in a colony of Humboldt penguins (Spheniscus humboldti) housed at the Acquario di Cattolica (Italy). Multielement determination of REEs was performed by an Inductively Coupled Plasma-Mass Spectrometer after a microwave digestion of feathers. As this colony lives indoors in a controlled environment, it was the ideal choice for studying lanthanide occurrence in penguin feathers. Since there is a strict link between metal levels in feathers and the diet of penguins, their food (capelin) was also tested for REEs. Chondrite normalized values revealed the same pattern for REEs in feathers and fish, but REE concentrations were an order of magnitude higher in penguin feathers, demonstrating the suitability of this tissue as a bioindicator of REEs.

Metal content in the liver, kidney, and feathers of Northern gannets, Morus bassanus, sampled on the Spanish coast

The value of birds as bioindicators for monitoring the environmental inorganic elements has been globally recognized. In this context, due to its well-known ecology and population stability, the Northern gannet (Morus bassanus) could be particularly useful. Dead Northern gannets (n = 30) were collected and samples from the liver, kidney, and feathers were taken, dried, mineralized, and finally analyzed via ICP-MS. Metals and metalloids, namely As, Cd, Hg, Pb, and Zn, associated with environmental pollution and toxicity on living organisms, were evaluated. The mean highest concentrations of As, Hg, and Zn were found in the liver (0.916, 7.026, and 89.81 mg/kg dry weight, respectively). For Cd, the kidney showed the highest mean concentration (17.51 mg/kg dry weight), whereas for Pb, this value corresponded to the feathers (0.399 mg/kg dry weight). Significant differences were found between the age classes in terms of contaminant concentrations, with the adults exhibiting higher metal levels. This difference was significantly relevant for Pb and Hg, where the effect of age was observed for all the considered tissues. When considering the effect of gender, no significant differences were observed, in agreement with similar studies performed in other geographical regions. Finally, positive correlations between the concentrations of Hg and Pb in the feathers and in the liver (r = 0.688, p < 0.001 and r = 0.566, p < 0.001, respectively) were observed, as well as between the feather and kidney concentrations (r = 0.685, p < 0.001) indicating the possibility to use feathers, a non-invasive biomonitoring tissue, for better understanding Hg and Pb exposure in seabirds.

Lead (Pb) in the tissues of Anatidae, Ardeidae, Sternidae and Laridae of the Northern Hemisphere: a review of environmental studies

Due to the ability of birds to travel long distances in the air, the potential feeding area of each individual is much larger than that of typical terrestrial animals. This makes birds a convenient indicator of environmental lead (Pb) pollution over large areas, in particular areas of inland and coastal waters. The aim of this study was to assess the concentrations of Pb in various organs of water birds from a variety of locations. The focus was on ducks, geese and swans (Anatidae); herons and egrets (Ardeidae); terns (Sternidae); and gulls (Laridae). This article describes the level of lead in the most commonly studied tissue types: feathers, bones and the liver. The study also presents data concerning the concentration of lead in the eggs of water birds. The highest levels of lead pollution can be observed in China and Korea, related to their high level of industrialization. In Iran too, environmental lead pollution is high, likely due to the developed petrochemical industry. Lead pollution in Japan, as well as in Western European countries (Spain, France, Italy), seems to be much lower than in China, India or Iran. Nevertheless, the level of pollution in Europe is higher than satisfactory, despite the introduction of a number of bans related to, for example, the use of leaded petrol or lead-containing paints. Finally, the USA and Canada appear to be the areas with the lowest lead pollution, possibly due to their low population densities.

Humboldt penguins' feathers as bioindicators of metal exposure

Avian feathers have the potential to accumulate trace elements originating from contaminated food and polluted environments. In fact, in feathers, metals bind to keratin, a sulphur-containing protein for which several metals have a strong affinity. Here, the concentrations of 18 essential and non-essential elements were investigated in a Humboldt penguin (Spheniscus humboldti) colony housed at the Acquario di Cattolica (Italy). This species is listed as vulnerable in the Red List of the International Union for Conservation of Nature. According to the literature, there is usually a link between metal levels in the diet of birds and levels detected in their feathers. Thus, metals were also determined in the penguins' food (capelin, Mallotus villosus). We hypothesize that the controlled conditions in which birds are kept in captivity, and the homogeneous diet that they follow could allow a better understanding of metal bioaccumulation (such as mercury) or bio-dilution (such as arsenic) in the marine food chain, indicated by penguins' feathers. Moreover, comparisons with our previous investigations performed on an ex-situ African penguin (Spheniscus demersus) colony suggest that penguins living indoors have lower body burden of metals than those living outdoors. Indeed, environmental contaminants usually found in areas subjected to anthropogenic impact, where zoos and aquaria are often located, are not accumulated to levels of concern.

Inter-species and inter-colony differences in elemental concentrations in eggshells of sympatrically nesting great cormorants Phalacrocorax carbo and grey herons Ardea cinerea

We compared the concentrations of 17 heavy metals and essential elements in post-hatching eggshells of two waterbirds, the obligate piscivorous great cormorant Phalacrocorax carbo (GCM) and the more omnivorous grey heron Ardea cinerea (GHR), breeding sympatrically in eight mixed colonies in Poland. We found significant inter-species and inter-colony differences in the levels of most of the elements. GHR had significantly higher concentrations of Al, which can be explained by its very low stomach pH: an acidic environment favours the release of Al compounds. Differences in Mn, Ni, Cu, Se and Hg concentrations can be attributed to the various contributions of fish and other aquatic organisms to the diet, and to the exploration of different habitats (GCM exclusively aquatic, GHR a wider range) and microhabitats (GCM, in contrast to wading GHR, dive for food, exploring the whole depth range of water bodies), differently exposed to contamination by those elements from sediments. Inter-colony differences were related to the level of industrialisation. We recorded higher levels of some elements in the eggshells (Fe, Mn in both species and Cr, Ni and Zn in GCM) collected in industrialised areas, which may be associated with the negative environmental impact of industrial areas.

Mercury (Hg), Lead (Pb), Cadmium (Cd), Selenium (Se), and Arsenic (As) in Liver, Kidney, and Feathers of Gulls: A Review

Mercury (Hg), lead (Pb), cadmium (Cd), selenium (Se), and arsenic (As) are metals or metalloids of high concern because of their effects on the environment and, specially, their potential toxicity on the animals inhabiting there. Due to their relevance, these elements have been object of several biomonitoring studies in different animal species around the world. Birds are widespread and, as species, are able to supply specific and relevant information about the regions where they live, being useful as bioindicators, as long as they are not birds with a strong migratory character. The main goal of this review is to summarize data collected from different studies using seabirds, paying special attention to gulls, in order to be helpful for coming studies and regulatory affairs.Several tissues have been used to evaluate Hg, Cd, Pb, Se, and As concentrations in seabirds, being focused the present review in those analyzing the liver, kidneys, and feathers. The most frequently analyzed tissue for Hg was the liver, followed by feathers, and finally kidney. For Cd levels, most of the studies were carried out in the liver, followed by feathers and kidneys. Pb, Se, and As levels were determined to a lesser extent. Feathers should be taken carefully as indicator of accumulation of pollutants, since procedure during analysis may lead to controversial results.Some authors reported that interspecific differences in the exposure of elements are determined by multiple factors, including properties of the contaminant, species, feeding habits, migratory status, sex, and age.The present review provides a comprehensive overview of the analyzed elements' occurrence in different species of seabirds, including gulls. Therefore, it can be a useful database providing for Hg, Pb, Cd, Se, and As levels in different tissues of seabirds.

Cadmium-mediated miR-30a-GRP78 leads to JNK-dependent autophagy in chicken kidney

Cadmium-mediated microRNAs have become a heavily researched topic. Few studies mention the regulation of autophagy by cadmium through microRNAs, especially regarding poultry. The kidney is one of the organs most severely affected by cadmium, as it is involved in the accumulation of metal ions; causing such types of damage as apoptosis, necrosis and autophagy to the body. However, the relationship between miR-30a and GRP78 in the chicken kidney during ER stress and autophagy via JNK has not been thoroughly elucidated to date. In our research, we randomly assigned 128 Hy-Line Brown laying chickens to four groups with different diet treatments. The four groups consisted of the control group (0.2 mg Se kg-1), the Se group (2 mg kg-1 of Na₂SeO₃), the Se + Cd group (150 mg kg-1 of CdCl₂ and 2 mg kg-1 of Na₂SeO₃) and the Cd group (150 mg kg-1 of CdCl₂). On the 90th day, we detected the expression of miR-30a, GRP78, ER stress-related genes, IRE-1-JNK and autophagy-related genes. Compared with the control group, the mRNA levels of IRE-1-JNK, ER stress-related genes, autophagy-related genes and GRP78 were significantly increased (P < 0.05), while the expression of miR-30a was significantly decreased (p < 0.05) in the Cd group. However, those changes were clearly alleviated in the Se + Cd group (p < 0.05). In summary, we demonstrated that Cd triggered an miR-30a-GRP78 signaling axis disorder, increasing ER stress and activating the IRE-1-JNK pathway, thereby promoting autophagy in the chicken kidney. Moreover, Se could antagonize the negative impact of Cd.

Evidence for exposure to selenium by breeding interior snowy plovers (Charadrius nivosus) in saline systems of the Southern Great Plains

Interior snowy plover (Charadrius nivosus) population declines and deteriorating conditions throughout the Southern Great Plains (SGP) of Texas, New Mexico, and Oklahoma may be linked to environmental contaminants. Concentrations of V, As, Cd, Pb, and Se were quantified in breeding snowy plover blood, feathers (5th primary; P5), and potential prey (tiger beetles [Cicindela circumpicta and C. togata]). Se was (a) most commonly detected relative to other quantified elements and (b) frequently quantified at levels exceeding background or toxicity thresholds. Of samples greater than instrumentation detection limits, 98% of snowy plover blood and 22% of feather samples were greater than Se toxicity thresholds of 1 ppm ww for blood and 5 ppm dw for feathers (blood quantifiable range: 0.83-15.12 ppm; feathers quantifiable range: 1.90-27.47 ppm). Almost all tiger beetle Se concentrations were below reported invertebrate thresholds of 30 ppm dw (quantifiable range: 0.54-45.84 ppm). Snowy plover blood Se concentrations were related to sex, individual body condition, and local tiger beetle Se concentrations, while plover P5 Se concentrations were related to state, sex, and presence of body molt. Tiger beetle Se concentrations were related to individual study sites in Texas. These results provide some of the first evidence of Se exposure risk for interior snowy plovers nesting in saline lake and alkali flat environments of the SGP. Future efforts should focus upon specific Se uptake pathways during breeding and nonbreeding seasons, as snowy plovers breeding in the SGP appear to be exposed to Se throughout their annual cycle.

Metals in Feathers of African Penguins (Spheniscus demersus): Considerations for the Welfare and Management of Seabirds Under Human Care

Bird feathers have been proven to be reliable indicators of metal exposure originating from contaminated food and polluted environments. The concentrations of 15 essential and non-essential metals were investigated in African penguins (Spheniscus demersus) feathers from a Northwestern Italian zoological facility. These birds are exclusively fed with herring from the northeast Atlantic Ocean. Certain elements, such as Hg and Cd, reflected the bioaccumulation phenomena that occur through the marine food chain. The levels of Cr, Mn, and Ni were comparable to those registered in feathers of birds living in polluted areas. These results are important for comparative studies regarding the health, nutrition and welfare of endangered seabirds kept under human care.

A Global Overview of Exposure Levels and Biological Effects of Trace Elements in Penguins

Trace elements are chemical contaminants that can be present almost anywhere on the planet. The study of trace elements in biotic matrices is a topic of great relevance for the implications that it can have on wildlife and human health. Penguins are very useful, since they live exclusively in the Southern Hemisphere and represent about 90% of the biomass of birds of the Southern Ocean. The levels of trace elements (dry weight) in different biotic matrices of penguins were reviewed here. Maps of trace element records in penguins were included. Data on exposure and effects of trace elements in penguins were collected from the literature. The most reported trace elements in penguins are aluminum, arsenic, cadmium, lead, mercury, copper, zinc, and manganese. Trace elements have been measured in 11 of the 18 species of penguins. The most studied biotic matrices are feathers and excreta. Most of the studies have been performed in Antarctica and subantarctic Islands. Little is known about the interaction among metals, which could provide better knowledge about certain mechanisms of detoxification in penguins. Future studies of trace elements in penguins must incorporate other metals such as vanadium, cobalt, nickel, and chromium. Data of metals in the species such as Eudyptes pachyrhynchus, Eudyptes moseleyi, Eudyptes sclateri, Eudyptes robustus, Eudyptes schlegeli, Spheniscus demersus, Spheniscus mendiculus, and Megadyptes antipodes are urged. It is important to correlate levels of metals in different biotic matrices with the effects on different species and in different geographic locations.

Concentration of 12 Metals and Metalloids in the Blood of White Stork (Ciconia ciconia): Basal Values and Influence of Age and Gender

The white stork (Ciconia ciconia) is being increasingly used in biomonitoring programmes of environmental contaminants due to its growing population in Europe; however, studies on inorganic elements are scarce. The blood of 70 white storks was collected and analysed by inductively coupled plasma mass spectroscopy (ICP-MS) to determine the presence of the following elements: lead (Pb), mercury (Hg), arsenic (As), nickel (Ni), iron (Fe), zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), chromium (Cr), cobalt (Co), and cadmium (Cd). Our main goals were to determine the mean concentrations of these elements in the blood and to study its association with age and gender. Mean concentrations were highest for Fe, followed by Zn, and lowest for Co and Cd. The metal levels were similar to the values referred in the literature for the same species from different locations. No statistically significant differences were found between males and females. Regarding age, statistically significant differences were observed for Ni, Cu, Se, Hg, and Pb between young and adult animals (except for Pb, values in adults were higher than in fledglings). Many element concentrations were correlated, with the strongest correlations between the pairs Hg-Se, Hg-As, and Fe-Zn, mainly in adults. This study provides the baseline data for a monitoring program based on white stork blood as a nondestructive sample.

Polycyclic aromatic hydrocarbons and heavy metals in the Cispata Bay, Colombia: A marine tropical ecosystem

The concentrations of polycyclic aromatic hydrocarbons and heavy metals were evaluated in shallow sediments, water, fish and seabird samples from the Cispata Bay, Colombia. The heavy metals concentrations in the sediment was in the following order: Cu>Pb>Hg>Cd. The heavy metal concentration was different (p<0.05) in juvenile and adult birds. High concentrations of mercury were registered in the seabird (10.19±4.99mgkg^-1) and fish (0.67μgg^-1) samples. The total concentration of polycyclic aromatic hydrocarbons ranged from 7.0-41ngg^-1 in sediment, 0.03-0.34ngmL^-1 in water samples, 53.24ngg^-1 in fish, and 66ngg^-1 in seabirds. The high concentrations of heavy metals in seabirds may be explained by their feeding habits. The presence of polycyclic aromatic hydrocarbons in the Cispata Bay may be due to hydrocarbon spills during oil transport at the nearby oil port.

Metal Levels in Shorebird Feathers and Blood During Migration Through Delaware Bay

We investigated levels of arsenic mercury, lead, cadmium, and chromium in Red Knot (Calidris canutus), Semipalmated Sandpipers (Calidris pusilla), and Sanderling (Calidris alba) migrating through Delaware Bay, New Jersey to determine if contaminant levels are likely to be causing negative effects on the populations of these shorebirds, to compare among species, and to explore differences among individuals collected early and late during their migration stopover. We analyzed blood and feathers, both nonlethal ways of exploring contaminants in birds. Blood contaminant analysis provides a direct measure of recent dietary exposure, whereas feathers reflect body burden at the time of feather molt. We found some differences among species and between early and late samples. Levels of Hg and Pb were higher in Sanderling blood collected early (36.52 ± 8.45 and 145.00 ± 12.56 ng/g ww respectively) compared with later (16.21 ± 6.03 and 33.60 ± 4.05 ng/g ww respectively) during the migration stopover. Blood Pb levels of Sanderling in the early period were higher than those of the other two species (75.38 ± 15.52 ng/g ww in Red Knot and 42.39 ± 8.42 ng/g ww in Semipalmated Sandpipers). Semipalmated Sandpipers had lower blood As levels than the other two species (254.33 ± 40.15 and 512.00 ± 66.79 ng/g ww early and late respectively) but higher feather levels (914.01 ± 167.29 and 770.00 ± 116.21 ng/g dw early and late respectively), and their blood As was higher in the later sampling period compared with the early sampling period. Arsenic levels in shorebird tissues were relatively high and may reflect levels in horseshoe crab eggs, their primary diet item in Delaware Bay. In Red Knot, blood Cr levels were elevated in the later samples (572.17 ± 62.82 ng/g ww) compared to the early samples (382.81 ± 95.35 ng/g ww) and to the other species. The mean values of the metals analyzed were mostly below effect levels-the level that has a measurable negative impact-although relatively high As levels in Semipalmated Sandpiper feathers and some high levels of Pb need to be further explored.

Vitamin profiles in two free-living passerine birds under a metal pollution gradient - A calcium supplementation experiment

Vitamin and carotenoid deficiency may impair development in free-living vertebrates, because of the importance of these micronutrients to growth, antioxidant defense and calcium regulation. Micronutrient and calcium insufficiency can be intensified by metal pollution which can interfere with nutrient homeostasis or indirectly reduce food availability. Furthermore, absorption of dietary heavy metals is dependent on food calcium and vitamin levels. We investigated the effect of calcium on plasma vitamin and carotenoid profiles and how these affected growth and survival in two passerine birds with different calcium turnover living along a metal pollution gradient. Vitamins (A, D₃ and E) and carotenoids were quantified from blood plasma of great tit (Parus major) and pied flycatcher (Ficedula hypoleuca) nestlings. Metal concentrations in soil and in feces from the same nestlings were used to assess the exposure to air pollution. Additionally, we examined the vitamin level variation between developmental stages (eggs and nestlings within the same brood). Our results showed that generally higher concentrations of vitamins and carotenoids circulate in blood of great tits than in pied flycatchers. In general, birds inhabiting the polluted zone presented lower concentrations of the studied micronutrients. Calcium supplementation and metal pollution decreased vitamin A concentration in pied flycatcher, but not in great tit, while vitamin A affected growth and survival in great tit and pied flycatcher respectively. Our results suggest that populations under exposure to metal pollution may experience increased vitamin A deficiency, and that the two passerine species, while obtaining similar micronutrients in food, respond differently to environmental disturbance of nutrients.