Arsenic contamination in wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) on abandoned mine sites in southwest Britain

Arsenic can be highly toxic to mammals but there is relatively little information on its transfer to and uptake by free-living small mammals. The aim of this study was to determine whether intake and accumulation of arsenic by wild rodents living in arsenic-contaminated habitats reflected environmental levels of contamination and varied between species, sexes and age classes. Arsenic concentrations were measured in soil, litter, wood mice (Apodemus sylvaticus) and bank voles (Clethrionomys glareolus) from six sites which varied in the extent to which they were contaminated. Arsenic residues on the most contaminated sites were three and two orders of magnitude above background in soil and litter, respectively. Arsenic concentrations in the stomach contents, liver, kidney and whole body of small mammals reflected inter-site differences in environmental contamination. Wood mice and bank voles on the same sites had similar concentrations of arsenic in their stomach contents and accumulated comparable residues in the liver, kidney and whole body. Female bank voles, but not wood mice, had significantly higher stomach content and liver arsenic concentrations than males. Arsenic concentration in the stomach contents and body tissues did not vary with age class. The bioaccumulation factor (ratio of arsenic concentration in whole body to that in the diet) in wood mice was not significantly different to that in bank voles and was 0.69 for the two species combined, indicating that arsenic was not bioconcentrated in these rodents. Overall, this study has demonstrated that adult and juvenile wood mice and bank voles are exposed to and accumulate similar amounts of arsenic on arsenic-contaminated mine sites and that the extent of accumulation depends upon the level of habitat contamination.     

Responses of wild small mammals to a pollution gradient: Host factors influence metal and metallothionein levels

We investigated how host factors (species, age, gender) modulated Cd, Pb, Zn, and Cu concentrations, metallothionein levels (MTs) and their relationships in 7 sympatric small mammal species along a pollution gradient. Cd concentrations in liver and kidneys increased with age in all species. Age effect on other metals and MTs differs among species. Gender did not influence metal and MT levels except in the bank vole. Three patterns linking internal metal concentrations and MTs were observed along the gradient: a low metal accumulation with a (i) high (wood mouse) or (ii) low (bank vole) level of MTs accompanied by a slight or no increase of MTs with Cd accumulation; (iii) an elevated metal accumulation with a sharp increase of MTs (common and pygmy shrews). In risk assessment and biomonitoring perspectives, we conclude that measurements of MTs and metals might be associated because they cannot be interpreted properly when considered separately.     

Concentrations of metals in mink and other mammals from Washington and Idaho

From 1981 to 1983, concentrations of metals were determined in mink Mustela vison, muskrats Ondatra zibethica, and small mammals at one contaminated site in Idaho and at two less contaminated sites in Idaho and Washington. The highest concentrations of Pb and Cd occurred in samples from the Coeur d'Alene River system near or downstream from an extensive mining-smelting complex in northern Idaho. Maximum concentrations of Pb in the liver of a mink (22 microg g(-1)) and in pooled liver samples of both voles (Microtus spp., 5.8 microg g(-1)) and deer mice (Peromyscus maniculatus, 10.5 microg g(-1)) were higher than those inducing serious problems, including mortality, in experimental mammals on Pb-contaminated diets. Concentrations of Cd, Cu, Hg, and Zn were generally low. Declines in certain mammal populations have probably occurred in northern Idaho as a result of direct toxicity of metals and associated secondary effects on cover and food supply.     

Bioaccumulation of metals and effects of a landfill in small mammals. Part II. The wood mouse, Apodemus sylvaticus

We assess the bioaccumulation of metals (Pb, Hg, Cd, Fe, Mg, Zn, Cu, Mn, Mo, Cr) and effects of landfill leachates on morphological (RI, relative weights), plasma (GPT, GOT, creatinine), and genotoxic (MNT) parameters in wood mice, Apodemus sylvaticus, inhabiting close the Garraf landfill site (NE Spain). Due to the high age- and sex-dependent variation in wild populations, we also studied the effect of these biotic factors on the parameters studied. Wood mice from the landfill site, sited in a partially protected area, showed more Cd, Fe, Zn, Cu, Mn, Mo, and Cr than specimens from the reference site. Moreover, mice near the landfill registered low RI and high relative renal weight, GPT, and MN frequency, which indicate that the landfill affects the health of wild mice. In contrast to sympatric shrews from a previous study, wood mice showed lower bioaccumulation of metals and lower variation caused by biotic factors. Moreover, the morphological and physiological alterations demonstrated that they were also more sensitive at environmental pollution. Given the contribution of small mammals to ecosystem function and the scarce ecotoxicological data on the effects of landfill pollution on wild terrestrial mammals, we consider that our study can be used to improve the management of this protected area.     

Partitioning of Cd and Pb in the blood of European blackbirds (Turdus merula) from a smelter contaminated site and use for biomonitoring

Blood composition is commonly measured to assess exposure to and effects of metals on birds. In most of passerine species, only small volumes of blood may be sampled safely (<500 μL), which limit the measure of several markers of health status and chemical residues. Here, we documented the partitioning of Cd and Pb in the blood of European Blackbirds Turdus merula in order to propose usable relationships between whole blood concentrations (for which toxicological benchmarks exist) and those measured in the erythrocytes. Sixty-two blackbirds were trapped along a pollution gradient (smelter of Metaleurop Nord, Northern France). Blood was sampled and Cd and Pb concentrations were measured both in whole blood and in the erythrocytes only. Birds coming from the most contaminated sites exhibited high residues for both Cd and Pb. We assessed that 73% and 99% of Cd and Pb, respectively, were associated to erythrocytes. Strong linear relationships, that were not influenced by neither the age nor the sex, were established between whole blood residues and those of erythrocytes for Cd and Pb (adj-R² = 0.78 and 0.93, respectively). Present findings are promising to optimize the use of small blood samples in order to investigate several responses relative to wildlife health status.     

Accumulation of heavy metals in the mole in Finland

Metal concentrations (Cu, Ni, Zn, Cd, Cr, Hg, Pb and Mo) were analysed from the liver and kidneys of moles, Talpa europaea L. (Insectivora), trapped in southern Finland on both contaminated and rural areas. In rural areas the concentrations of Cd, Cu, Zn, Pb and Mo were lower in juveniles (individuals in their first summer), except for Zn in the liver, which was lower in adults. When the animals were divided into annual classes (0-6 years), Cd and Mo concentrations in the liver increased significantly with age, while concentrations of Cu, Zn and Cr tended to decrease. Female moles had higher Pb concentrations than males, especially adult females, which also had lower levels of Cu in the liver than adult males. Moles in the metropolitan area of Helsinki clearly differed from those in rural areas in that the concentrations of heavy metals in these moles were higher (especially for the most toxic metals: Cd, Pb and Hg), and their body weight was lower. The renal concentrations of Cd in most of the moles in Helsinki exceeded the threshold that has been shown to have a nephrotoxic effect in mammals. In one subsample from Helsinki, Pb and Zn concentrations in the mole liver decreased as the distance from the highway increased. Concentrations of Pb in earthworms and several heavy metals in soil also decreased similarly in the same area. Our data indicate that Pb accumulates in moles through their diet of earthworms.     

Glutathione levels and enzyme activity in the tissues of bank vole Clethrionomys glareolus chronically exposed to a mixture of metal contaminants

The biochemical response to chronic heavy metal exposure was studied in tissues of bank voles Clethrionomys glareolus. Animals were collected from three sites located 4, 8 and 30km from a zinc-lead smelter, the area's main source of metal contamination. Concentrations of Cd, Pb, Zn and Fe were measured in the liver, kidneys and gonads to assess the level of metal intoxication. In response to intoxication, organisms activate detoxification mechanisms which can protect animals from metals' toxicity. Glutathione plays an important role in toxic substance detoxification. Total glutathione (tGSH) and glutathione disulfide (GSSG) were measured in the tissues. Also, the activity of glutathione reductase (GR), glutathione peroxidase (GPX), and glutathione-S-transferase (GST) was measured in the studied tissues. Results indicate that levels of all studied parameters were tissue and site-dependent. Evidence indicates that the most sensitive parameter of metal toxicity for animals living in a chronically contaminated environment is the GSH/GSSG ratio. In our study, the GSH/GSSG ratio was decreased in the liver of animals with high Cd levels. However, the relationship between Pb and the GSH/GSSG ratio was positive in the gonads. Cadmium and lead negatively influenced GPX activity in the liver; this was probably connected with inhibition of the Se-dependent fraction. The relationship between iron and GR activity in the kidney was also negative, but other correlations for iron both in liver and kidney were not significant. Positive correlations between Zn levels and GST and GR activity were found in the gonads of bank voles.     

Tissue, sex and age specific accumulation of heavy metals (Zn, Cu, Pb, Cd) by populations of the mole (Talpa europaea L.) in a central urban area

Heavy metal accumulation was studied in urban populations of moles, Talpa europaea L. (Insectivora) at three sites along the "Donaukanal" in Vienna. Kidneys, liver, lung, gonads, spleen, pancreas, femur, stomach + content, heart and skin were analysed for Zn, Cu, Pb and Cd contents. Female moles showed higher Zn concentrations in spleen, gonads and skin, higher Cd concentrations in femur and stomach and lower Cu content in kidneys compared to males. Age classes were determined using teeth section. A significant increase in Cd concentration with age was found in kidneys, liver, heart, lung, skin and femur, with the highest increase for kidney samples. Pb accumulated in bone tissue (femur) with increasing age. Although significant site differences in heavy metal concentrations of soil and vegetation samples existed, these differences were only partly reflected by tissue contents.     

The relationships between heavy metal (Cd,Cr, Cu,Fe, Pb,Zn) levels and the size of six Mediterranean fish species

Heavy metal (Cd, Cr, Cu, Fe, Pb, Zn) concentrations in the muscle, gill and liver of six fish species (Sparus auratus, Atherina hepsetus, Mugil cephalus, Trigla cuculus, Sardina pilchardus and Scomberesox saurus) from the northeast Mediterranean Sea were measured and the relationships between fish size (length and weight) and metal concentrations in the tissues were investigated by linear regression analysis. Metal concentrations (as microg/g d.w.) were highest in the liver, except for iron in the gill of Scomberesox sauris and lowest in the muscle of all the fish species. Highest concentrations of Cd (4.50), Cr (17.1) and Pb (41.2) were measured in liver tissues of T. cuculus, Sardina pilchardus and A. hepsetus, respectively. The liver of M. cephalus showed strikingly high Cu concentrations (202.8). The gill of Scomberesox saurus was the only tissue that showed highest (885.5) iron concentrations. Results of linear regression analysis showed that, except in a few cases, significant relationships between metal concentrations and fish size were negative. Highly significant (P<0.001) negative relationships were found between fish length and Cr concentrations in the liver of A. hepsetus and M. cephalus, and Cr concentrations in the gill of T. cuculus. Cr and Pb concentrations in the liver and Cu concentrations in all the tissues of Scomberesox saurus also showed very significant (P<0.001) negative relationships. Negative relationships found here were discussed.     

Uptake of 207Pb and 111Cd through bark of mature sugar maple,white ash and white pine: a field experiment

A field study was undertaken to determine whether 207Pb and 111Cd, applied to the exterior bark of sugar maple (Acer saccharum Marsh.), white ash (Fraxinus americana L.) and white pine (Pinus strobus L.), could enter xylem tissue. Stable isotope tracers (3 microg Pb ml(-1); 2 microg Cd ml(-1)) were applied separately to bark in simulated rainfall, acidified to pH 4.5, in multiple doses over a 4 month (July-October) period. Tree cores were extracted from the region of application in the following March, and Pb and Cd isotopes were measured in bark and the outer tree rings using inductively coupled plasma mass spectrometry. The majority of the applied stable isotope tracer recovered (over 94%) was present in bark tissue, although a small amount of each metal tracer entered the outer (1-3) tree rings in all trees. Despite high concentrations of excess 207Pb in bark (up to 50 microg g(-1)), the maximum concentration of excess 207Pb measured in tree rings was only around 50 ng g(-1), which represents less than 30% of the background Pb concentration in wood at the study site. High excess 111Cd concentrations in bark (up to 35 microg g(-1)) also resulted in small increases in 111Cd in wood (up to 50 ng g(-1)), but due to lower background Cd concentrations in wood, such increases more than doubled the amount of Cd in wood compared with background levels. However, at sites where such high bark Cd concentrations are found, uptake from Cd-contaminated soil would probably be much greater than found at our study site. It appears that Cd and Pb applied to bark can enter woody tissue, but that this route of uptake is likely to be a minor contributor to the metal burden in wood.     

Effects of soil properties on food web accumulation of heavy metals to the wood mouse (Apodemus sylvaticus)

Effects of soil properties on the accumulation of metals to wood mice (Apodemus sylvaticus) were evaluated at two sites with different pH and organic matter content of the soil. pH and organic matter content significantly affected accumulation of Cd, Cu, Pb and Zn in earthworms and vegetation. For Cd, Cu and Zn these effects propagated through the food web to the wood mouse. Soil-to-kidney ratios differed between sites: Cd: 0.15 versus 3.52, Cu: 0.37 versus 1.30 and Zn: 0.33-0.83. This was confirmed in model calculations for Cd and Zn. Results indicate that total soil concentrations may be unsuitable indicators for risks that metals pose to wildlife. Furthermore, environmental managers may, unintentionally, change soil properties while taking specific environmental measures. In this way they may affect risks of metals to wildlife, even without changes in total soil concentrations.     

Cadmium accumulation in deer tongue grass (Panicum clandestinum L.) and potential for trophic transfer to microtine rodents

Site 36 at the Crab Orchard National Wildlife Refuge includes a Cd-contaminated soil dominated by deer tongue grass (Panicum clandestinum L.). Analysis of deer tongue grass from this site indicated that biomass and leaf surface area were reduced and that there was a linear relationship between both plant bioavailable soil Cd and total soil Zn and tissue Cd concentration. The Cd concentrations in stems and leaves were also used to estimate the dietary Cd exposures that might be experienced by prairie voles (Microtus ochrogaster) and pine voles (M. pinetorum) consuming deer tongue grass. Renal and hepatic Cd burdens predicted from exclusive consumption of deer tongue grass would be comparable to those that have resulted in chronic toxicity in rodents. The results suggest that for the contaminated soil at Site 36, conditions could allow for the accumulation of Cd in deer tongue grass to concentrations that may pose an ecological risk.     

Earthworms as biological monitors of cadmium, copper, lead and zinc in metalliferous soils

Earthworms (Lumbricus rebellus and Dendrodrilus rubidus) were sampled from one uncontaminated and fifteen metal-contaminated sites. Significant positive correlations were found between the earthworm and 'total' (conc. nitric acid-extractable) soil Cd, Cu, Pb and Zn concentrations (data log1) transformed). The relationships were linear, and the accumulation patterns for both species were similar when a single metal was considered, even though there were species difference in mean metal concentrations. Generally, the earthworm Cd concentration exceeded that of the soil; by contrast, the worm Pb concentration was lower than the soil Pb concentration in all but one (acidic, low soil Ca) site. Our observations suggest that Cu and Zn accumulation may be physiologically regulated by both species. Total-soil Cd explained 82-86% of the variability (V2) in earthworm Cd concentration; 52-58% of worm Pb and worm Zn concentrations were explained by the total-soil concentrations of the respective metals. Total-soil Cu explained only 11-32% of the worm Cu concentration. The effect of soil pH, total Ca concentration, cation-exchange capacity (CEC) and organic carbon on metal accumulation by L. rubellus and D. rubidus was investigated by multiple regression analysis. Soil pH (coupled with CEC) and soil Ca had a major influence on Pb accumulation (V2 of worm Pb increased to 77-83%), and there was some evidence that Cd accumulation may be suppressed in extremely organic soils. The edaphic factors investigated had no effect on Cu or Zn accumulation by earthworms. In the context of biomonitoring, it is proposed that earthworms have a potential in a dual role: (1) as 'quantitative' monitors of total-soil metal concentrations (as shown for Cd); and (2) as estimators of 'ecologically significant' soil metal, integrating the effects of edaphic factors (as shown for Pb).     

Accumulation of mercury and its effect on antioxidant enzymes in brain,liver, and kidneys of mice

Abstract

The effect of mercuric chloride (HgCl₂) on the activities of catalase, Superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and its effect on glutathione (GSH) content were evaluated in different organs (liver, kidneys, and brain) of mice after administration at 0, 0.25, 0.5 and 1.0 mg/kg/day for 14 days. The uptake of mercury shows that the kidneys accumulated the highest levels of mercury compare to brain and liver. The enzyme levels varied in mercury treated organs compare to control. A dose dependent increase of antioxidant enzymes occurred in the liver and kidneys. The increase in enzyme activities correlated with highest mercury accumulation in the kidneys and liver. Mercury is known to generate reactive oxygen species (ROS) in vivo and in vitro, therefore, it is likely that enzyme activities increased to scavenge ROS levels produced as a result of mercury accumulation. Glutathione content increased in liver and kidneys of mercury treated mice compare to control. The results showed that the highest oral dose of mercury significantly increased antioxidant enzymes in kidneys and liver. The increased antioxidant enzymes enhance the antioxidant potential of the organs to reduce oxidative stress.     

Metal accumulation by wood-decaying fungi

Metal concentrations (Na, K, Rb, Mg, Ca, Sr, Mn, Fe, Cu, Zn, Cd, Al, and Pb) in the sporophores of ten wood-decaying macromycete species were related to concentrations in the wood substrates. Manganese, Sr, Ca, and Pb were usually excluded by the fungi, K, Rb, and, to a lower degree, Cd, Fe, Zn, Cu, Mg and Na, were accumulated. Accumulation ratios are compared with similar ratios for soil and litter inhabiting species previously studied.     

Influence of parasitism on the use of small terrestrial rodents in environmental pollution monitoring

Bioaccumulation of cadmium, chromium, copper, manganese, nickel, lead and zinc in small terrestrial rodents – voles and their cestode parasite Paranoplocephala dentata was studied. Contents of Pb, Mn, Ni and Zn in the parasite were found to be higher than in the kidney and liver of the parasitized animals. Lead level in the cestode was 37 fold higher than in the liver of the infected rodents. Bioaccumulation factors of zinc, nickel and manganese in the cestode are mostly in the range from 2 to 4.5. Considering the different contents of manganese and zinc in livers of non-parasitized and parasitized rodents, kidney tissue was found to be more reliable than liver as an indicator of environmental pollution by manganese and zinc; the kidneys of parasitized animals showed no significant change in the concentrations of those elements that are accumulated in the cestode.     

Accumulation of mercury and its effect on antioxidant enzymes in brain, liver, and kidneys of mice.

The effect of mercuric chloride (HgCl2) on the activities of catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione reductase (GR) and its effect on glutathione (GSH) content were evaluated in different organs (liver, kidneys, and brain) of mice after administration at 0, 0.25, 0.5 and 1.0 mg/kg/day for 14 days. The uptake of mercury shows that the kidneys accumulated the highest levels of mercury compare to brain and liver. The enzyme levels varied in mercury treated organs compare to control. A dose dependent increase of antioxidant enzymes occurred in the liver and kidneys. The increase in enzyme activities correlated with highest mercury accumulation in the kidneys and liver. Mercury is known to generate reactive oxygen species (ROS) in vivo and in vitro, therefore, it is likely that enzyme activities increased to scavenge ROS levels produced as a result of mercury accumulation. Glutathione content increased in liver and kidneys of mercury treated mice compare to control. The results showed that the highest oral dose of mercury significantly increased antioxidant enzymes in kidneys and liver. The increased antioxidant enzymes enhance the antioxidant potential of the organs to reduce oxidative stress.     

Bioaccumulation of metals and effects of landfill pollution in small mammals. Part I. The greater white-toothed shrew, Crocidura russula

Here we quantified the bioaccumulation of metals (lead, mercury, cadmium, iron, magnesium, zinc, copper, manganese, molybdenum, and chromium) and assessed several morphological (RI, relative weights) and genotoxic parameters as biomarkers of pollution from the landfill of Garraf (Barcelona, NE Spain). Specimens of Crocidura russula (Insectivora, Mammalia) from the landfill site showed increased Pb, Cd, Mg, Zn, Cu, and Cr concentrations in their tissues. Levels of mercury were below detection limits. Concentrations of Cd, Pb, and Cr varied significantly with age and no differences were found between males and females. While no differences were found in morphological parameters between shrews from the two sites, those from the polluted one showed more micronuclei in blood than those from reference site (1.786+/-0.272 vs. 0.088+/-0.045 per thousand; U=46.000, p<0.001). The considerable amounts of potentially toxic metals (Pb till 59.71 and Cd till 56.57microgg(-1) DW in kidneys) and the genotoxic effects indicate the harmful effect on biota. We consider necessary biomonitoring this landfill sited in a partially protected area.     

Bank voles as monitors of environmental contamination by heavy metals. A remote wilderness area in Poland imperiled

Concentrations of heavy metals (Cd, Pb, Cu, Zn, Fe) were determined in the tissues of bank voles collected in polluted forest sites in southern Poland and in Bia?owieza National Park. The highest cadmium concentrations were found in livers (0.9-12.8 microg g(-1)) and kidneys (3.2-29.6 microg g(-1)), whereas the lowest were in bones (0.2-0.9 microg g(-1)). The lead concentrations found in kidneys and bones ranged from 9.5 to 40.0 microg g(-1). The ranges of zinc, iron and copper concentrations in the tissues of animals were: 137-343 microg g(-1), 206-1017 microg(-1) and 12.0-73.8 microg(-1), respectively. Some of the differences between the levels found in various sites were statistically significant.