Exposure of insects and insectivorous birds to metals and other elements from abandoned mine tailings in three Summit County drainages, Colorado

Review: Abandoned mines as a resource or liability for wildlife

Abandoned Mine Lands (AMLs) are areas where previous mineral extraction or processing has occurred. Hundreds of thousands of AMLs exist within the United States. Contaminated runoff from AMLs can negatively affect the physiology and ecology of surrounding terrestrial and aquatic habitats and species and can be detrimental to human health. As a response, several U.S. federal and state agencies have launched programs to assess health risks associated with AMLs. In some cases, however, AMLs may be beneficial to specific wildlife taxa. There is a relative paucity of studies investigating the physiological and ecological impacts of AMLs on wildlife. We conducted a systematic review examining published scientific articles that assessed the negative and positive impacts of AMLs across invertebrate and vertebrate taxa. We also offer suggestions on evaluating AMLs to develop effective mitigation strategies that reduce their negative tole on human and wildlife communities. Peer-reviewed publications were screened across WebofScience, PubMed and Google Scholar databases. Abandoned mine lands were generally detrimental to wildlife, with adverse effects ranging from bioaccumulation of heavy metals to decreased ecological fitness. Conversely, AMLs were an overall benefit to imperiled bat populations and could serve as tools for conservation. Studies were unevenly distributed across different wildlife taxa groups, echoing the necessity for additional taxonomically diverse research. We suggest that standardized wildlife survey methods be used to assess how different species utilize AMLs. Federal and state agencies can use these surveys to establish effective remediation plans for individual AML sites and minimize the risks to both wildlife and humans.

Ecological Harm and Economic Damages of Chemical Contamination to Linked Aquatic-Terrestrial Food Webs: A Study-Design Tool for Practitioners

Contamination of aquatic ecosystems can have cascading effects on terrestrial consumers by altering the availability and quality of aquatic insect prey. Comprehensive assessment of these indirect food-web effects of contaminants on natural resources and their associated services necessitates using both ecological and economic tools. In the present study we present an aquatic-terrestrial assessment tool (AT2), including ecological and economic decision trees, to aid practitioners and researchers in designing contaminant effect studies for linked aquatic-terrestrial insect-based food webs. The tool is tailored to address the development of legal claims by the US Department of the Interior's Natural Resource Damage Assessment and Restoration Program, which aims to restore natural resources injured by oil spills and hazardous substance releases into the environment. Such cases require establishing, through scientific inquiry, the existence of natural resource injury as well as the determination of the monetary or in-kind project-based damages required to restore this injury. However, this tool is also useful to researchers interested in questions involving the effects of contaminants on linked aquatic-terrestrial food webs. Stylized cases exemplify how application of AT2 can help practitioners and researchers design studies when the contaminants present at a site are likely to lead to injury of terrestrial aerial insectivores through loss of aquatic insect prey and/or dietary contaminant exposure. Designing such studies with ecological endpoints and economic modeling inputs in mind will increase the relevance and cost-effectiveness of studies, which can in turn improve the outcomes of cases and studies involving the ecological effects of contaminants on food webs. Environ Toxicol Chem 2023;42:2029-2039. Published 2023. This article is a U.S. Government work and is in the public domain in the USA. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Lead exposure is correlated with reduced nesting success of an urban songbird

Lead exposure is a concern in urban ecosystems, with physiological and behavioral effects well documented in humans. Wildlife inhabiting urban ecosystems are also exposed to lead, yet little work has documented the sublethal effects of lead exposure in urban wildlife. We studied northern mockingbirds (Mimus polyglottos) in three neighborhoods of New Orleans, Louisiana, two with high soil lead and one with low soil lead, to better understand how lead exposure may influence mockingbirds' reproductive biology. We monitored nesting attempts, measured lead concentrations in blood and feathers of nestling mockingbirds, documented egg hatching and nesting success, and assessed rates of sexual promiscuity in relation to neighborhood soil lead levels. We found that nestling mockingbirds' blood and feather lead levels reflected the soil lead levels of their neighborhoods and nestling blood lead levels were similar to those of adult mockingbirds in the same neighborhoods. Nest success, as evaluated by daily nest survival rates, was higher in the lower lead neighborhood. Clutch sizes varied substantially across neighborhoods, but rates of unhatched eggs did not covary with neighborhood lead levels, suggesting that other drivers are influencing variation in clutch sizes and hatching success in urban habitats. At least one-third of nestling mockingbirds were sired by an extra-pair male, and there was no relationship between extra-pair paternity rates and neighborhood lead levels. This study provides insight on how lead contamination may influence reproduction in urban-dwelling wildlife and suggests that nestling birds could serve as useful bioindicators of lead levels in urban neighborhoods.

Mercury entomotoxicology

Mercury is an industrial pollutant of global concern. Currently entomofauna is disappearing and chemical pollution is one cause, however, it is unknown whether mercury is an additional threat. Therefore, it is necessary to know the entomotoxicology of mercury. The aim of the present work was to perform a comprehensive literature review on the entomotoxicology of mercury. The toxicokinetics and toxicity of mercury in insects, the participation of insects in the mercury cycle and the fact that this element is a threat to entomofauna are characterized. Insects can be exposed to mercury through ingestion, tracheal respiration, and gill respiration. Organic forms of mercury are better absorbed, bioaccumulated and distributed than inorganic forms. In addition, insects can biotransform mercury, for example, by methylating it. Metal elimination occurs through feces, eggs and exuvia. Toxicity molecular mechanisms include oxidative stress, enzymatic disruptions, alterations in the metabolism of neurotransmitters and proteins, genotoxicity, cell death and unbalances in the energetic state. Moreover, mercury affects lipid, germ, and gut cells, causes deformations, disturbs development, reproduction, behavior, and locomotion, besides to alters insect populations and communities. In terrestrial ecosystems, entomofauna participate in the mercury cycle by bioaccumulating mercury from soil and air, predating, being predated and decomposing organic matter. In aquatic ecosystems insects participate by accumulating mercury from water and sediment, predating, being predated and transporting it to terrestrial ecosystems when they emerge as winged adults. There are still information gaps that need to be addressed.

Enhanced Rare Earth Element Mobilization in a Mountain Watershed of the Colorado Mineral Belt with Concomitant Detection in Aquatic Biota: Increasing Climate Change-Driven Degradation to Water Quality

In the western USA, one legacy of historic mining is drainage of acidic, metal-rich water generated by exposure to oxygen of sulfide minerals in mine workings, referred to as acid mine drainage (AMD). Streams receiving AMD and natural acid rock drainage (ARD) have a low pH, high dissolved metal concentrations, and extensive streambed oxide deposits. Recently, enhanced ARD generation in the Snake River watershed in the Rocky Mountains has been shown to be associated with warmer summer air temperatures, which has been attributed to expanding weathering fronts that promote oxidation due to earlier drying of shallow soils. In mountain watersheds where complex orogeny disseminated minerals throughout the landscape, weathering processes may also mobilize rare earth elements (REEs). We report that in the Snake River REEs are currently distributed in streams at concentrations ranging from 1 to 100 μg/L. Further, analysis of archived sample indicates that REE increases over time are also associated with increased summer air temperatures. In downstream reaches where the Snake River discharges into a water supply reservoir, colloidal and particulate metal oxides are abundant and sorptive processes may influence REE speciation. We also show that REEs accumulate in benthic invertebrates at concentrations comparable to toxic metals associated with ARD.

Variation in metal concentrations across a large contamination gradient is reflected in stream but not linked riparian food webs

Aquatic insects link food web dynamics across freshwater-terrestrial boundaries and subsidize terrestrial consumer populations. Contaminants that accumulate in larval aquatic insects and are retained across metamorphosis can increase dietary exposure for riparian insectivores. To better understand potential exposure of terrestrial insectivores to aquatically-derived trace metals, metal concentrations in water and tissues were analyzed from different components of streams and riparian food webs across a large (2-3 orders of magnitude) metal gradient (e.g., Zn, Cu, Cd, Pb) in the Rocky Mountains (USA). Our research indicates that the trace metal concentration gradient present among streams was lost during metamorphosis of aquatic larval insects into terrestrially flying adults, decoupling terrestrial exposures from aquatic concentrations. This pattern was caused by declines in 1) among-stream variation in trace metal concentrations, 2) relationships between metal concentrations in paired water and food web components, and 3) mean metal concentrations within aquatic food webs and across the aquatic-terrestrial boundary. Specifically, among-stream variation in trace metal concentrations was highest for water and aquatic vegetation, intermediate for aquatic insect larvae (~30% lower than water) and lowest for adult aquatic insects and riparian spiders (~65% lower). Metal concentrations in paired water and food web components ranged from highly related across the stream-metal gradient (slopes ~1) for water and aquatic vegetation, to less related (slopes closer to 0) for aquatic vegetation and aquatic insect larvae, to unrelated (slopes ~0) for aquatic larval and adult insects. Finally, mean metal concentrations were highest in aquatic vegetation and lowest in adult aquatic insects emerging from streams (~50% lower than aquatic vegetation). Our results indicate less efficient trophic transfer and higher metamorphic loss of trace metals from high metal streams (i.e., exposure-dependent transfer). For many trace metals, aquatic-terrestrial dietary transfer is unlikely to be an important source of exposure for terrestrial insectivores of adult aquatic insects.

Metalliferous Mining Pollution and Its Impact on Terrestrial and Semi-terrestrial Vertebrates: A Review

Metalliferous mining, a major source of metals and metalloids, has severe potential environmental impacts. However, the number of papers published in international peer-reviewed journals seems to be low regarding its effects in terrestrial wildlife. To the best of our knowledge, our review is the first on this topic. We used 186 studies published in scientific journals concerning metalliferous mining or mining spill pollution and their effects on terrestrial and semi-terrestrial vertebrates. We identified the working status of the mine complexes studied, the different biomarkers of exposure and effect used, and the studied taxa. Most studies (128) were developed in former mine sites and 46 in active mining areas. Additionally, although several mining accidents have occurred throughout the world, all papers about effects on terrestrial vertebrates from mining spillages were from Aznalcóllar (Spain). We also observed a lack of studies in some countries with a prominent mining industry. Despite >50% of the studies used some biomarker of effect, 42% of them only assessed exposure by measuring metal content in internal tissues or by non-invasive sampling, without considering the effect in their populations. Most studied species were birds and small mammals, with a negligible representation of reptiles and amphibians. The information gathered in this review could be helpful for future studies and protocols on the topic and it facilitates a database with valuable information on risk assessment of metalliferous mining pollution.

Bird Feces as Indicators of Metal Pollution: Pitfalls and Solutions

Bird feces are commonly used as a proxy for measuring dietary metal exposure levels in wild populations. Our study aims to improve the reliability and repeatability of fecal metal measurements and gives some recommendations for sampling. First, we studied levels of variation in metallic element (arsenic, calcium, cadmium, cobalt, copper, nickel, lead) concentrations: temporal variation within an individual, among siblings in a brood and among-brood/spatial variation. Second, we explored the variation caused by dual composition (urate vs. feces) of bird droppings. Two sets of fresh fecal samples were collected from pied flycatcher (Ficedula hypoleuca) nestlings living in a metal polluted area in summers 2017 (dataset 1) and 2018 (dataset 2). We found a great deal of temporal intra-individual variation in metal levels, suggesting that dietary exposure varied markedly in a short time scale (within a day). A sample from only one nestling per brood did not well describe the brood mean value, and we recommend that at least four siblings should be sampled. Brood level samples give relatively good temporal repeatability for most metals. For all the metals, the levels in the fecal portion were more than double to those in the urate portion. Since the mass proportion of urate in the bird droppings varied a great deal among samples, standardizing sampling, e.g., by collecting only the fecal part, would markedly reduce the variation due to composition. Alternatively, urate portion could be used for biomonitoring of internally circulated bioavailable metal.

Sustainable resolutions for environmental threat of the acid mine drainage

Acid Mine Drainage (AMD) caused by abandoned mines is an enormous source of negative impact on the environment and the species that inhabit it. The low levels of pH and high concentration of metals and metalloids (copper, gadolinium, lithium, etc.) in mining pits with standing water lead to changing the balance of surrounding organisms and ecosystems. The scale of the issue and the quantity of AMD sites throughout the globe are factors that make AMD a critical environmental threat. Many AMD treatments have been implemented to reduce the negative impact of AMD, with many solutions being very costly and only suited for particular project situations. Policymakers have strong leverage in correcting AMD problems by developing regulations and laws. This study proposes three more sustainable solutions for reducing and eventually eliminating the impact of AMD with less capital investment while also resolving the landfill problem as well. Also, some governmental strategies are suggested for forming collaborative relationships between industry professionals from different perspectives with the goal to resolve the AMD issue through innovative ideas. Implementation of previous strategies and suggested ones, as well as the further involvement of more communities, can enhance the sustainability of life exposed to AMD.

Element Concentrations in Tree Swallows (Tachycineta bicolor) from the U.S. and Binational Great Lakes Areas of Concern

Selected elements were targeted in state Remedial Action Plans as one group of chemicals affecting the Beneficial Use Impairments of Great Lakes Areas of Concern (AOCs). Livers of nestling tree swallows, Tachycineta bicolor, were harvested from 76 sites in the Great Lakes, which included multiple sites at 27 AOCs and 12 reference sites from 2010 to 2015, and were analyzed for 21 elements. Mercury concentrations were at background levels at all sites. Elevated cadmium (Cd) concentrations were associated with industry. The highest Cd values were from the Black River, OH AOC and were associated with historic coke production but were not at toxic levels. Lead (Pb) concentrations were highest on the Rouge River, MI AOC-the oldest and most heavily populated and industrialized area in southeast Michigan. Individual Pb concentrations were elevated to a level associated with delta-aminolaevulinic acid dehydratase inhibition but not to a level considered toxic. In contrast, livers harvested from sites on the southwest shore of Lake Michigan had selenium (Se) concentrations elevated to levels associated with reduced avian reproduction. One likely source of the high Se concentrations was pollution from a local coal-fired power plant. Concentrations of the remaining elements were at background levels.

Mercury Bioaccumulation in Two Species of Insectivorous Bats from Urban China: Influence of Species, Age, and Land Use Type

Mercury (Hg) is a widespread, toxic pollutant, and China is the world's largest emitter. We investigated Hg concentrations of fur in Japanese pipistrelles (Pipistrellus abramus) and Chinese noctules (Nyctalus plancyi) from Chengdu, Sichuan Province, in relation to degree of urbanization. Bats were mist-netted in June and July 2013, and the fur was analyzed via atomic absorption. Statistical comparisons were made between ages, species, and site types with unpaired t tests and between Hg concentration and body condition with Spearman's rank correlations. Across sites, adult pipistrelles (n = 10) had significantly greater concentrations than adult noctules (n = 16). Adult N. plancyi (n = 16) had significantly greater concentrations than juvenile N. plancyi (n = 14). Contrary to our predictions, there was no significant difference in Hg values between urban (n = 3) and peri-urban (n = 6) locations for P. abramus. While small sample sizes precluded additional comparisons, the highest value (33 mg/kg) came from an adult female P. abramus in the agricultural area. The relationship between body condition and Hg concentration was insignificant. However, most pipistrelles (7/13) and no noctules (0/31) had concentrations > 10 mg/kg, a threshold associated with disruption of homeostatic control and mobility. All bats had concentrations > 0.2 mg/kg, which is associated with compromised immunity. These are the first published records of contaminant concentrations from bats in China. For future studies, we recommend P. abramus as a regional bioindicator, longer term assessments of pre- and post-exposure effects, and simultaneous assessment of blood and fur Hg concentrations.

The Impact of Environmental Mn Exposure on Insect Biology

Manganese (Mn) is an essential trace element that acts as a metal co-factor in diverse biochemical and cellular functions. However, chronic environmental exposure to high levels of Mn is a well-established risk factor for the etiology of severe, atypical parkinsonian syndrome (manganism) via its accumulation in the basal ganglia, pallidum, and striatum brain regions, which is often associated with abnormal dopamine, GABA, and glutamate neural signaling. Recent studies have indicated that chronic Mn exposure at levels that are below the risk for manganism can still cause behavioral, cognitive, and motor dysfunctions via poorly understood mechanisms at the molecular and cellular levels. Furthermore, in spite of significant advances in understanding Mn-induced behavioral and neuronal pathologies, available data are primarily for human and rodents. In contrast, the possible impact of environmental Mn exposure on brain functions and behavior of other animal species, especially insects and other invertebrates, remains mostly unknown both in the laboratory and natural habitats. Yet, the effects of environmental exposure to metals such as Mn on insect development, physiology, and behavior could also have major indirect impacts on human health via the long-term disruptions of food webs, as well as direct impact on the economy because of the important role insects play in crop pollination. Indeed, laboratory and field studies indicate that chronic exposures to metals such as Mn, even at levels that are below what is currently considered toxic, affect the dopaminergic signaling pathway in the insect brain, and have a major impact on the behavior of insects, including foraging activity of important pollinators such as the honey bee. Together, these studies highlight the need for a better understanding of the neuronal, molecular, and genetic processes that underlie the toxicity of Mn and other metal pollutants in diverse animal species, including insects.

Evaluating blood and excrement as bioindicators for metal accumulation in birds

Birds are widely used to assess metal contamination in the environment and there are different approaches to determine the exposure level in individuals, some being destructive (collection of soft tissues) and some non-destructive (blood, feathers and excrement). The use of blood to detect internal concentrations of metals is an acknowledged method, but to what extent blood can predict the concentrations in soft tissues has been less well evaluated in wild terrestrial birds. The same is true for excrements. This study compares the non-destructive methods using blood and excrement with liver sampling, with respect to exposure and accumulation of the elements arsenic, cadmium, copper, lead and zinc in nestling pied flycatchers (Ficedula hypoleuca). Blood, liver and excrement reflected the environmental exposure of non-essential elements and were independent of nestling sex. There were asymptotic relationships between the concentration of arsenic, cadmium and lead in liver and blood, excrement and liver, and excrement and blood, but none for copper or zinc. Those relationships were generally stronger between liver and blood than between excrements and internal concentrations. Lead had the strongest associations for all matrixes. The conclusion is that blood is an appropriate tool to assess accumulation of arsenic, cadmium and especially lead, but that blood can underestimate the accumulation at highly contaminated sites. Excrement can also give an indication of metal accumulation, but may overestimate internal concentrations at high exposure, and individual variability makes direct comparisons between these matrices less appropriate.

Metal Concentrations in Eurasian Eagle Owl Pellets as a Function of Reproductive Variables in Korea

Eight metals were analyzed in the pellet of Eurasian eagle owls (Bubo bubo) breeding in Korea: Paju, Ganghwa, Gimpo, and Sihwa, Gyeonggi-do (N = 15, respectively). Except for cadmium (Cd), concentrations of all metals differed among sites (ANOVA, p < 0.001); Sihwa had relatively higher metal concentrations compared with other sites. Clutch size did not differ among the four sites. However, Sihwa had the greatest nesting success and number of fledglings (per hatchlings and laid egg) and highest mean weight of diet. Lead concentrations in the pellets were generally lower than the excrements of various birds worldwide. We suggest that all metal concentrations in pellets do not negatively affect the reproduction of Eurasian eagle owls, and food supply at Sihwa seems likely more important to breeding success than metal contamination.

Concentrations of Trace Elements in Adult and Nestling Black-Tailed Gulls (Larus crassirostris)

Trace element concentrations (Cd, Pb, Cr, Al, Cu, Mn, Zn and Fe) were measured in the liver of black-tailed gull (Larus crassirostris) adults (n = 10) and nestlings (n = 10) collected at Chilsando Island, Jellanam-do, Korea, in June 2011. Adults gulls, when compared to nestlings, accumulated higher concentrations of all trace elements; Cd, 0.53 and 0.04 µg/g dry weight (dw), respectively, Pb, 0.47 and 0.21 µg/g dw, Cr, 0.08 and 0.05 µg/g dw, Al, 6.56 and 3.94 µg/g dw, Cu, 5.57 and 3.88 µg/g dw, Mn, 3.71 and 1.99 µg/g dw, Zn, 34.1 and 22.9 µg/g dw and Fe, 279 and 171 µg/g dw. No individuals of either adults or nestlings exceeded the threshold level for toxic effects for Cd (>3.0 µg/g dw), Pb (>6.0 µg/g dw) and Cr (>4.0 µg/g dw). Cd, Pb and Cr concentrations were comparable or lower than reported in other gull studies worldwide. None of the other elements present in the liver of black-tailed gull adults and nestlings were at toxic levels.

Effect of embedded shot on trace element concentrations in livers of Anseriformes species

Trace elements were analyzed in the liver of white-fronted geese (Anser albifrons, n=15), mallards (Anas platyrhynchos, n=4) and spot-billed ducks (Anas poecilorhyncha, n=13) found dead in Gimpo, Korea. All mallards and eight spot-billed ducks had embedded lead shot. Embedded shot could be affected elevated trace element concentrations on geese and ducks. Element concentrations of cadmium (Cd), lead (Pb), chromium (Cr), aluminum (Al), copper (Cr), manganese (Mn) and zinc (Zn) differed among species and white-fronted geese without embedded shot had the lowest concentrations for all elements (geomean 0.36, 0.43, 0.07, 1.46, 7.60, 2.61 and 13.5µg/g dw, respectively). Cadmium in four (3.27-7.77µg/g dw) of 32 individuals and Pb in eight (5.07-9.72µg/g dw) of 32 individuals exceeded a tentative threshold effect level of Cd (>3.0µg/g dw) and Pb (>5.0µg/g dw) for birds; all geese and ducks for Cr (0.07-0.43µg/g dw) were within the background level (<4.0µg/g dw). All trace element concentrations were much greater in waterfowl species with embedded shot than without shot. Essential trace elements such as Cr, Al (geomean 1.46-37.3µg/g dw), Cu (7.60-57.1µg/g dw), Mn (2.61-27.6µg/g dw) and Zn (13.5-176µg/g dw) were within the normal range and were probably maintained by normal homeostatic mechanisms.

Metals and metalloids in nestling tree swallows and their dietary items near oilsands mine operations in Northern Alberta

Tree swallows (Tachycineta bicolor) nesting near oilsands development in northern Alberta are potentially exposed to elevated levels of metals. The objective of this study was to determine whether levels of metals and metalloid elements in dietary items and tissues of nestling tree swallows inhabiting areas near oilsands mine operations were higher compared to those of reference sites. We hypothesized that if there was increased, industry-related exposure to metals, it would be via the diet. We identified the invertebrate prey in the stomach contents of nestlings. We also collected invertebrates using Malaise traps near nest boxes, and analyzed those taxa found in the nestling diet to understand potential variability in metal exposure. For most elements, we found no significant differences in concentrations in the liver, kidney, or stomach contents between sites near to and far from oilsands operations. Concentrations of five elements were positively correlated among tissues and stomach contents. For invertebrates collected from Malaise traps, location differences occurred in some absolute elemental concentrations, which were most often highest at reference sites away from mining operations. We found no evidence that nestling tree swallows accumulated metals approaching toxic levels. Tree swallows consumed relatively high quantities of terrestrial insects, possibly limiting exposure to water borne, food-web-related contaminants. We suggest that annual variability associated with elemental exposure and dietary levels of elements be considered when interpreting concentrations in bird tissues.

Lesser White-fronted (Anser erythropus) and Greater White-fronted (A. albifrons) Geese wintering in Greek wetlands are not threatened by Pb through shot ingestion

Fecal lead (Pb) levels were investigated in the threatened European population of the Lesser White-fronted Goose (LWfG, Anser erythropus) and of the non-threatened Greater White-fronted Goose (GWfG, Anser albifrons) wintering in two wetland areas in northern Greece in order to assess the potential risk from Pb exposure. Fecal, soil and food plant samples were analyzed. Levels of Pb were normalized using Al concentrations in order to separate the effect of possible ingestion of Pb shot from that of soil or sediment accidentally ingested with food. All concentrations are expressed on a dry weight basis. Geometric means of Pb content in the feces of LWfG were 6.24 mg/kg at Evros Delta and 7.34 mg/kg at Lake Kerkini (maximum values of 28.61 mg/kg and 36.68 mg/kg, respectively); for fecal samples of GWfG geometric means were 2.39 mg/kg at Evros Delta and 6.90 mg/kg at Kerkini (corresponding maximum values of 25.09 mg/kg and 42.26 mg/kg). Soil Pb was in the range of 5.2-60.2mg/kg (geometric mean = 22.6 mg/kg) for the Evros Delta and between 13.4 and 64.9 mg/kg (geometric mean=28.1mg/kg) for Kerkini. A general linear model fitted to the data showed that Pb levels were very closely dependent on Al levels in the feces from both species and at both sites indicating soil or sediment were the only significant source of Pb; species and site, as well as their interaction, were not statistically significant factors. For both species and at both sites exposure to Pb was evidently very mild and the observed levels of Pb were well below the proposed thresholds for lethal or sublethal effects of Pb poisoning. Soil ingestion appeared to gradually increase from October to December for LWfG at Kerkini, corresponding to a gradual depletion of their food source.

Relationship between heavy metals concentrations in egret species, their environment and food chain differences from two Headworks of Pakistan

Concentration of ten metals (Cd, Cr, Co, Cu, Fe, Li, Mn, Ni, Pb and Zn) were analyzed in the egg contents, prey and soil samples of little egret (Egretta garzetta) and cattle egret (Bubulcus ibis) from two Headworks to determine habitat and species-specific differences; to assess the importance of prey and habitat contamination as an exposure source for heavy metals. Concentration of Cu, Mn, Cr and Pb in egg contents, Fe, Co, Cu, Mn, Zn in prey and Fe, Co, Cu, Ni, Li in surface soils were significantly different (P<0.05). Mean metal concentrations of Cr, Pb and Cd were relatively higher in little egret whereas Cu and Mn were higher in the egg contents of cattle egret. The mean concentrations of Cu, Mn and Zn were higher in prey samples of cattle egrets and Cr, Cd and Pb in prey samples of little egrets. In soil samples collected from little egret heronries metal concentrations were higher except Cu and Ni. Correlation Analysis and Hierarchical Agglomerative Cluster Analysis (HACA) identified relatively similar associations of metals and their source identification. Metals such as Fe, Cu, Mn, and Li were related with geochemical origin from parent rock material as well as anthropogenic input whereas Cr, Cd, Pb, Ni, Co and Zn were associated mostly with anthropogenic activities. The study suggested that eggs are useful bio-monitor of local heavy metal contamination.

Trace metal concentrations in tissues of two tinamou species in mining areas of Bolivia and their potential as environmental sentinels

Mining has a long history in the Bolivian Andes and has left many tailing piles, from which trace metals may reach surface waters, soils, and biota. The potential of tinamous (Birds: Tinamidae) as sentinels has never been tested before, although their biological and ecological characteristics mean they could well be appropriate bioindicators. We captured 13 and nine individuals of the Ornate Tinamou (Nothoprocta ornata) from two polluted sites (P1 and P2) and 10 and five from control unpolluted sites (NP1 and NP2) and used, for comparative purposes, four specimens bred in captivity. We also captured six specimens of Darwin's Nothura (Nothura darwinii) from the polluted site, P2. We determined the concentration of As, Cd, Pb, and Sb in feathers, liver, and kidney and conducted histological analyses of liver and kidney. For the Ornate Tinamou, a site effect was found for all trace metals in all tissues, with the highest concentrations at polluted sites. At the P2 site, no differences between the two tinamou species were detected except in some cases where Darwin's Nothura shows near-double concentrations. In some cases, mean and/or individual values of trace metal concentrations reached toxicity levels at the polluted sites. Thesaurismosis in proximal convoluted renal tubules, probably related to Cd exposure, was observed in 30% of the samples from the P1 site. Significant correlations were observed between all tissues for all trace metals and also for all trace metals in each tissue. Because the species studied are ubiquitous and relatively abundant, we recommend monitoring programs based on feather analysis.