Essential and nonessential elements in nestling rooks Corvus frugilegus from eastern Poland with a special emphasis on their high cadmium contamination

Trace Metal Bioaccumulation in Feral Pigeons (Columba livia f. domestica) and Rooks (Corvus frugilegus) Residing in the Urban Environment of Iasi City, Romania

Nowadays, trace metal contamination within urban atmospheres is a significant and concerning global issue. In the present study, two synanthropic bird species, namely, the feral pigeon (Columba livia f. domestica) and the rook (Corvus frugilegus), were employed as bioindicators to assess the atmospheric trace metal pollution in Iasi City, Romania. The concentrations of Ni, Pb, Cd, Co, Cr, and Cu were determined through high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF-AAS) of various tissues, including the liver, kidney, lung, heart, muscle, and bone, of feral pigeons and rooks collected in Iasi City. The order of trace metal concentrations in the tissues of feral pigeons and rooks in Iasi City was similar: Cu > Pb > Ni > Cd > Cr > Co. However, trace element values in most tissues were higher in the rook samples than in feral pigeon ones, except for Co, which had elevated levels in feral pigeon renal and cardiac tissues, and Cu, which registered the highest concentrations in feral pigeon liver and kidney tissues. While not statistically significant, Pb concentration values in the PM10 fraction of atmospheric particles positively correlated with Pb concentrations in rook kidney samples (p = 0.05). The concentration levels of Cd, Pb, and Ni in the PM10 fraction of air particles showed a positive correlation with Cd levels in the samples of pigeon heart and rook liver, kidney, and heart, Pb levels in the samples of pigeon kidney, heart, and muscle and rook liver and bone, and Ni levels in the samples of pigeon liver, kidney, and bone and rook liver, muscle, and bone, respectively.

Antioxidant defence barrier of great tit Parus major nestlings in response to trace elements

Metals can have direct and indirect effects on the generation of reactive oxygen species in wild birds. The aim of this work has been to examine the effect of exposure to trace metals (copper Cu, iron Fe, cobalt Co, manganese Mn) on oxidative stress biomarkers such as lipoperoxidation TBARS and level of superoxide dismutase SOD, catalase CAT, and reduced glutathione GSH in the livers and kidneys of great tit Parus major nestlings (n = 165, 63 broods) living in polluted environments associated with soda plants and agricultural activities (Kujawy region) and from a reference site (Tuchola Forest), both in the north of Poland. As we predicted, the level of TBARS in both organs of chicks from polluted areas was higher than in those from reference site. This could be connected with Fe concentrations, particularly in areas adjacent to soda plants (livers R_s = 0.49, p < 0.002; kidneys R_s = 0.69, p < 0.001). We also showed differences in the level of antioxidants depending on the environment. CAT activity was higher in nestlings from Kujawy than in those from Tuchola. Meanwhile SOD activity (both organs) and GSH levels (kidneys) were lower in the polluted area compared to the reference site. Concentrations of Cu, Fe, Co, and Mn may play a role in regulating the antioxidant system components' activity.

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.

Effect of spatial resolution of soil data on predictions of eggshell trace element levels in the Rook Corvus frugilegus

Although a considerable research effort has gone into studying the dietary pathways of metals to the bodies of laying female birds and their eggs in recent years, no detailed investigations have yet been carried out relating the properties of the biogeochemical environment at large spatial scales to eggshell trace element levels in typical soil-invertebrate feeding birds under natural conditions. We used data from a large-scale nationwide monitoring survey of soil quality in Poland (3724 sampling points from the 43 792 available) to predict levels of five trace elements (copper [Cu], cadmium [Cd], nickel [Ni], zinc [Zn] and lead [Pb]) in Rook Corvus frugilegus eggshells from 42 breeding colonies. Our major aim was to test whether differences exist in the explanatory power of soil data (acidity, content of elements and organic matter, and particle size) used as a correlate of concentrations of eggshell trace elements among four different distances (5, 10, 15 and 20 km) around rookeries. Over all four distances around the rookeries only the concentrations of Cu and Cd in eggshells were positively correlated with those in soil, while eggshell Pb was correlated with the soil Pb level at the two longest distances (15 and 20 km) around the rookeries. The physical properties of soil (primarily the increase in pH) adversely affected eggshell Cd and Pb concentrations. The patterns and factors governing metal bioaccumulation in soil invertebrates and eggshells appear to be coincident, which strongly suggests a general similarity in the biochemical pathways of elements at different levels of the food web. The increasing acidification of arable soil as a result of excessive fertilisation and over-nitrification can enhance the bioavailability of toxic elements to laying females and their eggs.

Lead in the Red-Crowned Cranes (Grus japonensis) in Zhalong Wetland, Northeastern China: A Report

The dietary uptake of Cd and Pb may contribute to the decline of migratory red-crowned cranes (Grus japonensis) on the Asian mainland. To uncover the relevance of this hypothesis, we determined the concentrations of Pb and Cd as well as further macro and trace elements (Ca, Mg, Cu, Zn, Hg and As) in the gastric contents, gastric wall, intestinal wall, liver, kidney, muscle, and feathers of two individuals found dead in Zhalong Wetland in Northeastern China. Indeed, the Pb concentrations in the liver and kidney tissues was with 31.4 and 60.3 mg kg(-1) dry weight (dw), respectively, above concentrations considered as potentially toxic level in common birds (i.e. 30 mg kg(-1)). These Pb concentration may have possibly been associated with lethal toxicosis in this endangered species suggesting Pb as major threat for G. japonensis populations. Thus, the inputs of Pb into Zhalong Wetland should be reduced to maintain and reestablish environmental conditions supporting the population development of these migratory red-crowned cranes in the Zhalong Wetland, a critical crane habitat for the long-term sustainability of this species.

Variable contribution of functional prey groups in diets reveals inter- and intraspecific differences in faecal concentrations of essential and non-essential elements in three sympatric avian aerial insectivores: a re-assessment of usefulness of bird faeces in metal biomonitoring

Aerial insectivores through their insect diet can contribute to biotransfer of elements across habitats. We investigate the relationship between dietary composition as expressed by the contributions of six functional invertebrate prey groups (primarily of agriculturally subsidised invertebrates characteristic of agricultural areas in temperate regions of Europe) and concentrations of essential (Na, K, Ca, Mg, Fe, Cu, Zn, Mn, Co) and non-essential (As, Cd, Pb) elements of environmental concern in the faeces of nestlings of three species of avian aerial insectivores - Common Swift Apus apus, Barn Swallow Hirundo rustica and House Martin Delichon urbicum - which breed sympatrically and use apparently similar resources of flying insect prey. There were significant differences between the species for 7 of the 12 elements (Ca, Zn, Cu, Co, As, Pb, Cd); these differences were attributable to the variable dietary composition, even though the concentrations of the elements varied enormously between the faecal samples from the individual species. Partial correlation analysis between the biomass (expressed in mg dry weight) of the six functional prey groups and faecal concentrations of elements showed the highest number of significant relationships for toxic metals (As, Pb and Cd). The results of the General Regression Model explaining faecal element concentrations revealed the different explanatory power of the effects of PCA (of six functional prey groups) dietary scores. A significant fit of GRM was obtained for 7 elements (Na, Mg, Fe, Mn, As, Pb, Cd) for Barn Swallows, 2 elements (Cu, As) for House Martins and 1 element (Mn) for Common Swifts. Overall, the results confirmed our predictions that the biomass of consumed coprophilous taxa and insects from crop habitats was positively correlated with the faecal concentrations of toxic elements. Unexpectedly, however, the faecal samples (primarily those of Common Swifts) that contained many oil-seed rape insect pests had lower Ca, Pb and Cd levels and a higher As level. Our study implies that the cross-boundary transfer of contaminants, primarily non-essential elements, by aerially foraging birds through the considerable accumulation of their faeces has potential consequences for the local biogeochemical cycle and environmental quality.

Trace element contamination in nestling black-tailed gulls (Larus crassirostris) in Korea

At Hongdo Island, Gyeongsangnam-do, Korea, a breeding site of black-tailed gull (Larus crassirostris), we collected nestlings from two locations: a "reference" site (n = 10) with no known source of lead contamination and "lighthouse" site (n = 10) with suspected lead contamination from leaded paint. Iron concentrations in the kidney and bone, manganese in the muscle, copper in the bone, lead in the muscle and bone, and cadmium in the liver, muscle, and bone at the reference site were significantly higher than at the lighthouse. Manganese concentrations in the liver and kidney, and lead in the kidney were significantly greater at the lighthouse than at the reference site. Iron, zinc, manganese, copper, lead and cadmium concentrations had tissue-specific accumulation at both sites. Lead concentrations in 10 % of livers and in 80 % of kidneys at the lighthouse, and in 20 % of livers from the reference were within a range considered toxic (>6.00 μg/g dw in the liver and kidney). Lead concentrations in 50 % of black-tailed gull nestlings at the reference and 80 % nestlings at the lighthouse were greater in livers than in bones, which is suggestive of acute lead exposure. For cadmium, all liver and kidney concentrations from two sites were at a level considered background in birds. Cadmium concentrations of every sample were higher in kidneys than in livers, suggestive of chronic cadmium exposure. Lead concentrations in gull nestlings in the present study were relatively higher than other gull species worldwide, but cadmium concentrations were relatively lower.

Tissue distribution of heavy metals in heron and egret chicks from Pyeongtaek, Korea

Iron, zinc, manganese, lead and cadmium were measured in the liver, kidney and bone of Grey Heron (Ardea cinerea), Intermediate Egret (Egretta intermedia), Little Egret (Egretta garzetta) and Black-crowned Night Herons (Nycticorax nycticorax) from Korea. Iron, zinc, manganese, lead and cadmium concentrations had species- and tissue- specific accumulation. Lead concentrations in all tissues of Black-crowned Night Heron and cadmium in kidneys of Intermediate Egret chicks were relatively higher than in other species. Iron and manganese in the liver, zinc in the bone, and lead and cadmium in the kidney were relatively higher than other tissues and these results have been reported in other birds. Lead concentrations in all species were at a level associated with acute lead poisoning and cadmium concentrations except for Grey Heron chicks were at a level associated with chronic cadmium exposure. Lead concentrations in livers and bones of heron and egret chicks were within a range considered background level (<6.00 μg/g dw). But, lead concentrations in kidneys of 12 of 37 heron and egret chicks were at concentrations associated with lethal lead poisoning (6.00-18 μg/g dw) and 7 of 37 chicks were compatible with death (>18.0 μg/g dw). For cadmium, all liver and kidney concentrations were at a level considered background for birds (<3.00 μg/g dw). Essential elements such as iron, zinc and manganese concentrations were within the range observed in other birds.

Trace-element interactions in Rook Corvus frugilegus eggshells along an urbanisation gradient

Concentrations of seven trace elements [arsenic (As), chromium (Cr), nickel (Ni), lead (Pb), copper (Cu), zinc (Zn), and cadmium (Cd)] in the eggshells of Rooks Corvus frugilegus, a focal bird species of Eurasian agricultural environments, are increased above background levels and exceed levels of toxicological concern. The concentrations of Cr, Ni, Pb, Cu, and Zn are greater in eggshells from urban rookeries (large cities) compared with rural areas (small towns and villages) suggesting an urbanisation gradient effect among eggs laid by females. In the present study, the investigators assessed whether the pattern of relationships among the seven trace elements in eggshells change along an urbanisation/pollution gradient. Surprisingly, we found that eggshells with the greatest contaminant burden, i.e., from urban rookeries, showed far fewer significant relationships (n = 4) than eggshells from villages (n = 10), small towns (n = 6), or rural areas (n = 8). In most cases, the relationships were positive. As was an exception: Its concentration was negatively correlated with Ni and Cd levels in eggshells from small town rookeries (where As levels were the highest), whereas eggshells from villages (with a lower As level) showed positive relationships between As and Cd. Our findings suggest that at low to intermediate levels, interactions between the trace elements in Rook eggshells are of a synergistic character and appear to operate as parallel coaccumulation. A habitat-specific excess of some elements (primarily Cr, Ni, Cu, As) suggests their more competitively selective sequestration.

Residues of chromium, nickel, cadmium and lead in Rook Corvus frugilegus eggshells from urban and rural areas of Poland

We examined the concentrations of chromium (Cr), nickel (Ni), cadmium (Cd) and lead (Pb) in Rook Corvus frugilegus eggshells from 43 rookeries situated in rural and urban areas of western (=intensive agriculture) and eastern (=extensive agriculture) Poland. We found small ranges in the overall level of Cr (the difference between the extreme values was 1.8-fold; range of concentrations=5.21-9.40 Cr ppm), Ni (3.5-fold; 1.15-4.07 Ni ppm), and Cd (2.6-fold; 0.34-0.91 Cd ppm), whereas concentrations of Pb varied markedly, i.e. 6.7-fold between extreme values (1.71-11.53 Pb ppm). Eggshell levels of these four elements did not differ between rural rookeries from western and eastern Poland, but eggshells from rookeries in large/industrial cities had significantly higher concentrations of Cr, Ni and Pb than those from small towns and villages. Our study suggests that female Rooks exhibited an apparent variation in the intensity of trace metal bioaccumulation in their eggshells, that rapid site-dependent bioaccumulation of Cu, Cr, Ni and Pb occurs as a result of the pollution gradient (rural<urban), and that Cd levels are probably regulated physiologically, even though these were relatively high, which could be treated as an overall proxy of a heavy Cd load in the soil environment.