Heavy metal and selenium levels in birds at Agassiz National Wildlife Refuge,Minnesota: Food chain differences

The levels of heavy metals and selenium in the eggs and in breast feathers of adult doublecrested cormorant (Phalacrocorax auritus), black-crowned night heron (Nycticorax nycticorax), and franklin's gull (Larus pipixcan) nesting at Agassiz National Wildlife Refuge in Marshall County, northwestern Minnesota were examined. Also examined were metal levels in the feathers of fledgling night herons and gulls, in the feathers of adult and fledgling American bittern (Botaurus lentiginosus), in eggs of American coot (Fulica americana) and eared grebe (Podiceps caspicus), and in feathers of adult Canada geese (Branta canadensis). These species represent different levels on the food chain from primarily vegetation-eating species (geese, coot) to species that eat primarily fish (cormorant). A clear, positive relationship between level on the food chain and levels of heavy metals occurred only for mercury in feathers and eggs. Otherwise, eared grebes had the highest levels of all other metals in their eggs compared to the other species. No clear food chain pattern existed for feathers for the other metals. For eggs at Agassiz: 1) lead, selenium, and manganese levels were similar to those reported in the literature, 2) mercury levels were slightly higher for cormorants and night herons, 3) all species had higher chromium and cadmium levels than generally reported, and 4) eared grebes had significantly higher levels of cadmium than reported for any species from elsewhere. For adult feathers: 1) gulls had higher levels of lead than the other species, 2) cadmium levels were elevated in gulls and adult herons and cormorants, 3) mercury levels showed an increase with position on the food chain, 4) selenium and chromium levels of all birds at Agassiz were generally low and 5) manganese levels in adults were generally higher than in the literature for other species. Adults had significantly higher mercury levels than fledgling gulls, night herons, and bitterns.     

Heavy metal and selenium levels in feathers of herring gulls (Larus argentatus): Differences due to year,gender, and age at Captree,Long Island

The concentrations of heavy metals (mercury, lead, cadmium, chromium, manganese) and selenium in the feathers of herring gulls (Larus argentatus) from a nesting colony at Captree, Long Island, New York were examined from 1989 to 1993 to determine if there were differences from year to year, and between males and females, adult and young, and dead versus live gulls. Variation in metal levels in regression models was explained by age (all metals), year (all except manganese), and whether the feathers were from live or dead birds (all except lead and chromium). The feathers of adults had significantly higher levels of mercury, lead and manganese than those of young, but lower levels of selenium and cadmium than those of young. Levels in down and fledgling feathers were similar for lead, cadmium and selenium, but fledgling feathers had higher levels for mercury, chromium, and manganese. There were no gender differences in metal levels for adult feathers except for lead (females had higher levels). Levels of mercury and manganese were higher in feathers of live adults whereas levels of cadmium and selenium were higher in the feathers of dead adults.     

Strontium-90 in Canada goose eggshells and reed canary grass from the Columbia River,Washington

Strontium-90 (⁹⁰SR) released to the ground near the N Reactor at the U.S. Department of Energy's Hanford Site enters the Columbia River through shoreline seeps. The ⁹⁰Sr is then potentially available for uptake by plants and animals. The life history and foraging behavior of nesting Canada geese is such that female geese could ingest ⁹⁰Sr while foraging on shoreline plants. Radichemical analyses showed that goose eggshells taken from an island, downstream from the N Reactor, contained more ⁹⁰Sr than did eggshells collected from other downstream islands. Reed canary grass samples taken from shoreline areas immediately downstream from the N Reactor contained higher concentrations of ⁹⁰Sr than samples from other downstream areas. All goose eggshells did not contain enhanced levels of ⁹⁰Sr, and all reed canary grass samples did not contain enhanced levels of ⁹⁰Sr, but a relationship exists between the releases of ⁹⁰Sr to the Columbia River and the enhanced levels of ⁹⁰Sr in some of the environmental samples analyzed.Pacific Northwest Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under contract DE-ACO6-76RLO 1830.     

Mercury and other metals in eggs and feathers of glaucous-winged gulls (Larus glaucescens) in the Aleutians

Levels of mercury and other contaminants should be lower in birds nesting on isolated oceanic islands and at high latitudes without any local or regional sources of contamination, compared to more urban and industrialized temperate regions. We examined concentrations of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in the eggs, and the feathers of fledgling and adult glaucous-winged gulls (Larus glaucescens) nesting in breeding colonies on Adak, Amchitka, and Kiska Islands in the Aleutian Chain of Alaska in the Bering Sea/North Pacific. We tested the following null hypotheses: 1) There were no differences in metal levels among eggs and feathers of adult and fledgling glaucous-winged gulls, 2) There were no differences in metal levels among gulls nesting near the three underground nuclear test sites (Long Shot 1965, Milrow 1969, Cannikin 1971) on Amchitka, 3) There were no differences in metal levels among the three islands, and 4) There were no gender-related differences in metal levels. All four null hypotheses were rejected at the 0.05 level, although there were few differences among the three test sites on Amchitka. Eggs had the lowest levels of cadmium, lead, and mercury, and the feathers of adults had the lowest levels of selenium. Comparing only adults and fledglings, adults had higher levels of cadmium, chromium, lead and mercury, and fledglings had higher levels of arsenic, manganese and selenium. There were few consistent interisland differences, although levels were generally lower for eggs and feathers from gulls on Amchitka compared to the other islands. Arsenic was higher in both adult feathers and eggs from Amchitka compared to Adak, and chromium and lead were higher in adult feathers and eggs from Adak compared to Amchitka. Mercury and arsenic, and chromium and manganese levels were significantly correlated in the feathers of both adult and fledgling gulls. The feathers of males had significantly higher levels of chromium and manganese than did females. The levels of most metals in feathers are below those known to be associated with adverse effects in the gulls or their predators. However, levels of mercury in some gull eggs are within a range suggesting that several eggs should not be eaten in one day by sensitive humans.     

Interspecific and Locational Differences in Heavy Metal Levels in Four Species of Birds Near Sydney, Australia

We examined the levels of cadmium, chromium, lead, manganese, mercury, and selenium in four species of birds near Sydney, New South Wales, Australia in January, 1996. Molted contour feathers were collected from silver gull, Larus novaehollandiae (Royal National Park and downtown Sydney), sulphur-crested cockatoo, Cacatua sulphurea (Blue Mountains, Royal National Park, and Sydney), Australian white ibis, Threskiornis molucca (Sydney), and rock dove Columba livia (Royal National Park and Sydney). We tested the null hypothesis that there were no species or locational differences in metal levels. There were significant species differences in all metals, with rock doves having the highest levels of cadmium, chromium, lead, and manganese, and silver gulls having the highest levels of mercury and selenium. Metal levels were generally low in cockatoos, and were lowest in those from the Royal National Park. For silver gulls, cadmium, lead, and chromium levels were highest at Sydney, and there were no locational differences in manganese, mercury, and selenium levels. For rock doves, cadmium, chromium and manganese were higher in Sydney, and there were no locational differences in lead, mercury, and selenium. Overall, cadmium and chromium levels were significantly higher in Sydney than in the Royal National Park for all species, and there were no locational differences in mercury levels. Although the levels of most metals in feathers from these Australian birds were within the ranges reported worldwide, lead levels in ibises and rock doves were among the highest reported worldwide, suggesting a cause for concern.     

Lead and cadmium contaminations in feathers of heron and egret chicks

In birds, concentrations of heavy metal contaminants were associated with their diet and environmental quality. This study presents concentrations of lead and cadmium in feathers and the relationship between concentrations in the feather and stomach content of three species of heron and egret chicks. Cadmium concentrations were higher in the Little Egret (geomean 0.75 μg/g dry weight) and Black-crowned Night Heron (geomean 0.88 μg/g dry weight) chicks than in Grey Heron chicks (geomean 0.48 μg/g dry weight). Lead and cadmium concentrations had significant correlations between feathers and stomach contents of heron and egret chicks. The mean lead and cadmium concentrations in feathers were within the background levels for wild birds. Heron and egret species forage around breeding colony (4–7 km). Lead and cadmium concentrations in heron and egret chicks were moderately associated with those of prey concentrations. These results suggest that contaminant concentrations such as lead and cadmium in feathers of heron and egret chicks can reflect local heavy metal contaminations and serve as a great biological indicator for monitoring heavy metal contamination. In addition, the feathers can be a routine monitoring tool over time and space without harming the wild birds.     

Prioritizing R&D for the U.S. Department of Energy's Weapons Complex Clean-Up

Prioritizing the U.S. Department of Energy's (DOE's) targeted R&D program supporting weapons-complex clean-up has been problematic. Considering issues common to all R&D evaluation, linking R&D prioritization to clean-up project prioritization, the latter aligned with institutional goals, offers a pragmatic solution. This method is illustrated with results of a clean-up prioritization model of DOE's Oak Ridge National Laboratory site.     

Environmental Bioindication Studies by Bayesian Network with Use of Grey Heron as Model Species

The article presents a procedure for assessing the quality of the environment, using eggshells of birds as a biomarker implemented into a Bayesian network. An environmental quality index (EQI) was proposed and calculated on the basis of local quality indicators. Experimental data on concentrations of toxic elements in grey heron (Ardea cinerea) eggshells (biomarker of river valleys) were used to determine the empirical variables (nodes) and the probability distributions on the set of these variables. A probabilistic graphical model represents a multitude of relationships between variables in a system that enables the prediction of EQI. The model presented is a useful tool for environmental quality management.     

The consequences of alternative environmental management goals: A non-linear programming analysis of nuclear weapons legacy clean-up at Oak Ridge National Laboratory

Prioritization of projects within the U.S. Department of Energy's (DOE) Weapons Complex Clean-up Program, exemplified with data from the Oak Ridge National Laboratory, is quite sensitive to overall goals. Non-linear programming analysis of three alternative goals - mortgage reduction, terminal-period risk minimization, and current-period risk minimization - shows substantial differences in waste treated, risk reduced, and cost over a ten-year period. This revised version was published online in July 2006 with corrections to the Cover Date.     

Dermal Insecticide Residues from Birds Inhabiting an Orchard

The US Environmental Protection Agency conducts risk assessments of insecticide applications to wild birds using a model that is limited to the dietary route of exposure. However, free-flying birds are also exposed to insecticides via the inhalation and dermal routes. We measured azinphos-methyl residues on the skin plus feathers and the feet of brown-headed cowbirds (Molothrus ater) in order to quantify dermal exposure to songbirds that entered and inhabited an apple (Malus x domestica) orchard following an insecticide application. Exposure to azinphos-methyl was measured by sampling birds from an aviary that was built around an apple tree. Birds sampled at 36 h and 7-day post-application were placed in the aviary within 1 h after the application whereas birds exposed for 3 days were released into the aviary 4-day post-application. Residues on vegetation and soil were also measured. Azinphos-methyl residues were detected from the skin plus feathers and the feet from all exposure periods. Our results underscore the importance of incorporating dermal exposure into avian pesticide risk assessments.     

Metals in feathers of brown noddy (Anous stolidus): Evidence for bioaccumulation or exposure levels?

Levels of environmental pollution are generally assumed to be greater in nearshore and estuarine habitats compared to the open ocean. This difference presumably derives from high inputs from industrial and agricultural sources entering estuaries and bays from rivers and as direct runoff. This suggests that levels of heavy metals should be higher in birds that obtain their food resources from nearshore habitats rather than the open ocean far from land. I compared the levels of lead, cadmium, mercury and selenium in feathers of young and adult brown noddies (Anous stolidus) along the coast of Oahu, Hawaii. Prior to fledging, young noddies obtain all their food resources from their parents that bring back fish and squid from a few km offshore, whereas adults spend much of the year outside the breeding season on the open ocean, where they obtain most of the metals that accumulate in their feathers. For all metals, the young noddies had lower levels than adults. These data do not support the hypothesis that heavy metal pollution is greater nearshore than on the open ocean, but further investigation is needed to distinguish simple biaccumulation with age from differential exposure by habitat, and contamination from the birds own secretions during preening and from the outside.     

Assessing heavy metal pollution using Great Tits (Parus major): feathers and excrements from nestlings and adults

Passerine species have been increasingly used as bioindicators of metal bioaccumulation especially by taking benefit of non-invasive procedures, such as collecting feathers and excrements. In 2009, metal (As, Cd, Cu, Hg, Ni, Pb, Se and Zn) concentrations were determined in feathers and excrements of nestling and adult female great tits (Parus major) in industrial (a paper mill) and rural sites in maritime pine forests on the west coast of Portugal. The aim of this study was to compare the levels of metals between the areas but also between sampling methods (feather vs. excrement) and age classes (nestling vs. adult). Although excrements and feathers of nestling great tits showed different concentrations, similar patterns of accumulation were detected in both study areas. There was a significantly higher concentration of mercury in the industrial area and significantly higher concentrations of arsenic in the rural area in both sample types. Metal levels in adult females had quite different results when compared to nestlings, and only nickel presented significantly higher levels near the paper mill. Since metal levels showed a consistent pattern in feathers and excrements of nestling great tits, we conclude that both represent good and non-invasive methods for the evaluation of these elements in polluted areas.     

Monitoring of heavy metal contaminants using feathers of shorebirds, Korea

This study presents concentrations of iron, zinc, copper, lead and cadmium in the feathers of 3 shorebird species (n = 29) from Okgu Mudflat, Korea in the East Asian-Australian Migration Flyways. Lead concentrations (ANOVA, p < 0.001) in Red-necked Stints (geomean = 9.61 μg g(-1) dry weight) were higher than in Terek Sandpipers (geomean = 5.56 μg g(-1) dry weight) which in turn were higher than in Great Knots (geomean = 2.78 μg g(-1) wet weight). Cadmium concentrations (ANOVA, p < 0.001) were higher in Great Knots (geomean = 2.97 μg g(-1) wet weight) and in Red-necked Stints (geomean = 2.70 μg g(-1) dry weight) than in Terek Sandpipers (geomean = 0.33 μg g(-1) dry weight). Lead (r = 0.574, p < 0.01) and cadmium (r = 0.380, p < 0.05) concentrations between feathers and livers of shorebirds were significantly correlated. Lead concentrations in 65.5% (19 individuals) of shorebirds exceeded a toxicity threshold for feathers (4 μg g(-1) dry weight). Iron, zinc, copper, lead and cadmium concentrations in feathers were within the range of earlier studies for wild birds, but lead concentrations in Red-necked Stints were higher than those reported in other studies. Because lead concentrations in feathers and livers of Red-necked Stints were markedly higher than in other shorebirds, we suggest that Red-necked Stints were exposed to higher lead concentrations than the other shorebirds on their breeding or wintering grounds.     

Comparison of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers in bald eagle (Haliaeetus leucocephalus), and comparison with common eider (Somateria mollissima), glaucous-winged gull (Larus glaucescens), pigeon guillemot (Cepphus columba), and tufted puffin (Fratercula cirrhata) from the Aleutian Chain of Alaska

There is an abundance of field data for levels of metals from a range of places, but relatively few from the North Pacific Ocean and Bering Sea. In this paper we examine the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in feathers from common eiders (Somateria mollissima), glaucous-winged gulls (Larus glaucescens), pigeon guillemots (Cepphus columba), tufted puffins (Fratercula cirrhata) and bald eagles (Haliaeetus leucocephalus) from the Aleutian Chain of Alaska. Our primary objective was to test the hypothesis that there are no trophic levels relationships for arsenic, cadmium, chromium, lead, manganese, mercury and selenium among these five species of birds breeding in the marine environment of the Aleutians. There were significant interspecific differences in all metal levels. As predicted bald eagles had the highest levels of arsenic, chromium, lead, and manganese, but puffins had the highest levels of selenium, and pigeon guillemot had higher levels of mercury than eagles (although the differences were not significant). Common eiders, at the lowest trophic level had the lowest levels of some metals (chromium, mercury and selenium). However, eiders had higher levels than all other species (except eagles) for arsenic, cadmium, lead, and manganese. Levels of lead were higher in breast than in wing feathers of bald eagles. Except for lead, there were no significant differences in metal levels in feathers of bald eagles nesting on Adak and Amchitka Island; lead was higher on Adak than Amchitka. Eagle chicks tended to have lower levels of manganese than older eagles.     

Bird skins in museum collections: are they suitable as indicators of environmental metal load after conservation procedures?

To find out whether modern conservation treatments alter thelevel of metals in feathers, we analysed the content of 10metals in feathers before and after skins were washed withdetergent and treated with Eulan U-33 (a commonly usedpreservative at museums). Feathers of 31 birds of Goshawk Accipiter gentilis, Eagle Owl Bubo bubo, Feral PigeonColumba livia domest. and Common Eider Somateriamollissima were analysed. We found that in most cases metalswere partly washed out of the feathers, but the effects wererelated to species and type of feather. The value of bird skinsas indicators of environmental metal load is therefore affectedby this treatment. It is recommended that the conservationtechniques used at museums should be reconsidered if skins areintended for specimen banking for future reference inenvironmental monitoring schemes and research.     

Relationship between Pb and Cd accumulations in house crow,their habitat,and food content from Klang area,Peninsular Malaysia

Heavy metal pollution has become a global concern due to accumulation in tissue and transferable effects to humans via the food chain. This study focused on monitoring the accumulation of cadmium (Cd) and lead (Pb) in surface soil and body content: bone, heart, brain, liver, lung, muscle, kidney, feathers, feces, and gizzard contents of house crow Corvus splendens in the Klang region, Malaysia. The results revealed the occurrence of Pb and Cd in all biological samples from house crows, food contents, and surface soil samples. Heart and kidney accrued high amounts of Cd, while high amounts of Pb were found to accumulate in bones and feathers. Major discrepancies were also discovered in the concentrations of metals between juvenile and adults, as well as female and male bird samples. Concentrations of Pb and Cd in house crow internal tissues correlated significantly with that of bird feathers, but none could be established with that of surface soil. In addition, a significant correlation was observed between Pb concentration in the internal tissues to that of the feces, but the same was not the case when compared with the surface soil concentration. Metal accrual in the house crows feathers and feces may be through a long-term transmission via the food chain, which are eliminated from feathers via molting. This may suggest the utility of molted breast feathers of house crow in the bio-monitoring of Cd and Pb contamination, whereas feces of house crow appear only to be suitable for the bio-monitoring of Pb contamination.     

The importance of exogenous contamination on heavy metal levels in bird feathers. A field experiment with free-living great tits, Parus major

Feathers have been used extensively as non-destructive biomonitors for heavy metal pollution. Birds excrete heavy metals into growing feathers during moult. After feather formation, the feathers become isolated from the rest of the body, suggesting that the feathers contain information of circulating heavy metal concentrations in the blood at the time of their development. However, heavy metal levels may change due to exogenous contamination, resulting in higher concentrations in feathers that are exposed most to exogenous conditions. We studied the effect of exogenous contamination in free-living adult great tits (Parus major) by measuring--within the same individual--the concentrations of twelve heavy metals (Ag, Al, As, Cd, Co, Cu, Fe, Hg, Mn, Pb, Tl and Zn) in three outermost tail feathers that were exposed to exogenous contamination for different periods of time. In particular, for each individual heavy metal levels in the removed left outermost tail feather were compared with levels in the regrown left and the right outermost tail feather, that were both removed 40 days after removal of the original left feather. This study revealed that, with the exception of mercury, the concentration of all heavy metals was significantly different among the three outermost tail feathers. Our results suggest that concentrations of most heavy metals build up with increasing age of the feather, indicating that exogenous contamination may be an important source of heavy metals in feathers. However, we found no significant differences in Hg concentrations and we found only small differences in Zn concentrations among tail feathers. Consequently, the concentrations of zinc and mercury in feathers are probably primarily due to endogenous deposition.     

Use of Central Stonerollers (Cyprinidae: Campostoma anomalum) from Tennessee as a Bioindicator of Metal Contamination

We compared the levels of arsenic, cadmium, chromium, lead, manganese, mercury and selenium in a small species of fish (Central stonerollers, Campostoma anomalum) collected from East Fork Poplar Creek (EFPC) and a reference site in eastern Tennessee. Stonerollers are minnows in the Cyprinidae family that serve as prey for many carnivores in aquatic systems. Fish were collected from East Fork Poplar Creek within the U.S. Department of Energy's Y-12 National Security Complex, part of the Oak Ridge Reservation, and from a reference stretch of the Little River in East Tennessee. Whole fish were homogenized for analysis. Concentrations of all metals (except arsenic) were significantly higher in stonerollers from EFPC compared to the reference site. Mercury levels in minnows from EFPC averaged 0.4 ppm (μg/g), four times higher than the average for fish in the U.S. in general. This was higher than levels in fish from the nearby Clinch River and higher than fillets of white bass (Morone chrysops) from the same creek. Most metal levels were inversely related to size and weight of the stonerollers, perhaps due to growth dilution.     

Heavy metal concentrations in feathers of common loons (Gavia immer) in the Northeastern United States and age differences in mercury levels

Feathers serve as a useful, non-destructive approach for biomonitoring some aspects of environmental quality. Birds can eliminate over 90% of their body burden of mercury by sequestration in growing feathers, and they molt their feathers at least annually. Thus mercury concentrations should not vary in avian feathers as a function of age. We tested the null hypothesis that there are no age differences in the concentrations of mercury, lead, cadmium, selenium, copper, chromium and manganese in the feathers of immature and adult common loons Gavia immer from the Northeastern United States where the species is declining. Adults had significantly higher mean levels of mercury (20245 ppb) than immature loons (9677 ppb), but there were no age-related differences for other elements. Even with the small number of immatures, females had significantly higher levels of mercury than males, although the gender difference was not significant for adults.     

Little Egrets (Egretta Garzetta) and Trace-Metal Contamination in Wetlands of China

The rapidly developing Asian countries may face threatening environmental contamination, that however remains largely unassessed. We studied persistent trace elements in three wetlands, Poyang Lake, relatively unpolluted, and Tai Lake, and Pearl River Delta, selected as hotspots of pollution in Central China. We adopted as indicator the Little Egret, a widespread colonial waterbird, and during 1999 and 2000 we collected and analysed the same samples as for a parallel study we conducted in Pakistan, e.g. eggs, body feathers of chicks, prey spontaneously regurgitated by the chicks, and sediments at the areas most used by foraging egrets. The levels of trace-metals at our three study areas were similar, or within the range, of those found in the few other studies for East Asia, with few exceptions. The concentrations of the various elements were below the threshold that may affect the survival or reproduction of the birds, and even the highest concentrations relative to background, i.e. Se in eggs, and Hg in feathers at Pearl Delta, do not pose toxic hazards. In sediments, the levels of trace elements were lower than the critical levels assumed for contaminated soil, except for alarming high levels of As at Poyang. These results do not confirm our expectation, that Poyang was relatively uncontaminated, while Tai and Pearl were polluted. Although trace metal concentration differed significantly among the three study areas, these differences were minor and were not consistent among elements and samples. The bioaccumulation ratios from sediments through prey, feather and egg, were consistent with our previous findings for Pakistan. Only Hg exhibited high bioaccumulation, while Se and Zn had low accumulation, and the other elements no accumulation. This reasserts that feathers of predators such as egrets, may be more sensitive indicators of environmental contamination for the elements subject to bioaccumulation, whereas the sediments or the organisms low in the food chain are better indicators for the other elements.