Toxicity of copper in sewage sludge

Sewage sludge is a source of organic matter and nutrients, but a major obstacle for its recycling is that the municipal wastewater sludge has low but significant levels of contaminants. This investigation, on the acute toxicity of copper in sewage sludge, was conducted with three organisms, Daphnia magna, Lemna minor and Raphanus sativus (seeds). The toxicity of the leakage water from sewage sludge spiked with CuSO(4) was studied for 64 days. The toxicity increased during the first 8-16 days and then started to decrease. The first increase in toxicity was due to ammonia, but after 32 days, a dose-related effect of copper was found. After 64 days, L. minor had an EC50 of 3800 mg Cu/kg dw for 7 days growth inhibition, a LOEC of 3200 mg Cu/kg dw and a NOEC of 1600 mg Cu/kg dw. D. magna had an EC50 of 18100 mg Cu/kg dw (24-h immobility) and a NOEC of 12800 mg Cu/kg dw. Root elongation of R. sativus was reduced at 25600 mg Cu/kg dw. Both for Daphnia and Lemna, the pH of the leakage water had an effect of the toxicity. This means that chemical speciation and bioavailability is very important for the hazard assessment of copper in sludge and soil.     

Speciation and hydrological transport of metals in non-acidic river systems of the Lake Baikal basin: Field data and model predictions

The speciation of metals in aqueous systems is central to understanding their mobility, bioavailability, toxicity and fate. Although several geochemical speciation models exist for metals, the equilibrium conditions assumed by many of them may not prevail in field-scale hydrological systems with flowing water. Furthermore, the dominant processes and/or process rates in non-acidic systems might differ from well-studied acidic systems. We here aim to increase knowledge on geochemical processes controlling speciation and transport of metals under non-acidic river conditions. Specifically, we evaluate the predictive capacity of a speciation model to novel measurements of multiple metals and their partitioning, under high-pH conditions in mining zones within the Lake Baikal basin. The mining zones are potential hotspots for increasing metal loads to downstream river systems. Metals released from such upstream regions may be transported all the way to Lake Baikal, where increasing metal contamination of sediments and biota has been reported. Our results show clear agreement between speciation predictions and field measurements of Fe, V, Pb and Zn, suggesting that the partitioning of these metals mainly was governed by equilibrium geochemistry under the studied conditions. Systematic over-predictions of dissolved Cr, Cu and Mo by the model were observed, which might be corrected by improving the adsorption database for hydroxyapatite because that mineral likely controls the solubility of these metals. Additionally, metal complexation by dissolved organic matter is a key parameter that needs continued monitoring in the Lake Baikal basin because dependable predictions could not be made without considering its variability. Finally, our investigation indicates that further model development is needed for accurate As speciation predictions under non-acidic conditions, which is crucial for improved health risk assessments on this contaminant.

     

The Phenomenon of Pseudoviviparity in Alpine and Arctomontane Grasses (DeschampsiaBeauv., FestucaL., and PoaL.)

It is known that pseudoviviparous plant taxa are most numerous in the Arctic and high mountain regions, where they sometimes account for a noticeable part of the local flora and play an important phytocenotic role. The complex of pseudoviviparous taxa is an interesting model for investigating the processes of hybridogenic speciation, as various mechanisms stabilizing the hybrid genetic systems proved to be effective in them. In particular, this concerns vast and taxonomically complex groups such as the genera Deschampsia, Festuca, and Poa.In this paper, published data on the taxonomy, chromosome numbers, and distribution of pseudoviviparous grasses in the Arctic regions and subarctic mountain systems are reviewed.     

Physiological effects of nanoparticles on fish: a comparison of nanometals versus metal ions

The use of nanoscale materials is growing exponentially, but there are also concerns about the environmental hazard to aquatic biota. Metal-containing engineered nanoparticles (NPs) are an important group of these new materials, and are often made of one metal (e.g., Cu-NPs and Ag-NPs), metal oxides (e.g., ZnO and TiO(2) NPs), or composite of several metals. The physiological effects and toxicity of trace metals in the traditional dissolved form are relatively well known and the overall aim of this review was to use our existing conceptual framework of metal toxicity in fish to compare and contrast the effects of nanometals. Conceptually, there are some fundamental differences that relate to bioavailability and uptake. The chemistry and behaviour of nanometals involves dynamic aspects of aggregation theory, rather than the equilibrium models traditionally used for free metal ions. Some NPs, such as Cu-NPs, may also release free metal ions from the surface of the particle. Biological uptake of NPs is not likely via ion transporters, but endocytosis is a possible uptake mechanism. The body distribution, metabolism, and excretion of nanometals is poorly understood and hampered by a lack of methods for measuring NPs in tissues. Although data sets are still limited, emerging studies on the acute toxicity of nanometals have so far shown that these materials can be lethal to fish in the mg-μgl(-1) range, depending on the type of material. Evidence suggests that some nanometals can be more acutely toxic to some fish than dissolved forms. For example, juvenile zebrafish have a 48-h LC(50) of about 0.71 and 1.78mgl(-1) for nano- and dissolved forms of Cu respectively. The acute toxicity of metal NPs is not always explained, or only partly explained, by the presence of free metal ions; suggesting that other novel mechanisms may be involved in bioavailability. Evidence suggests that nanometals can cause a range of sublethal effects in fish including respiratory toxicity, disturbances to trace elements in tissues, inhibition of Na(+)K(+)-ATPase, and oxidative stress. Organ pathologies from nanometals can be found in a range of organs including the gill, liver, intestine, and brain. These sublethal effects suggest some common features in the sublethal responses to nanometals compared to metal salts. Effects on early life stages of fish are also emerging, with reports of nanometals crossing the chorion (e.g., Ag-NPs), and suggestions that the nano-forms of some metals (Cu-NPs and ZnO NPs) may be more toxic to embryos or juveniles, than the equivalent metal salt. It remains possible that nanometals could interfere with, and/or stimulate stress responses in fish; but data has yet to be collected on this aspect. We conclude that nanometals do have adverse physiological effects on fish, and the hazard for some metal NPs will be different to the traditional dissolved forms of metals.     

210Pb as a tool for establishing sediment chronologies: examples of potentials and limitations of conventional dating models

For aquatic sediments, the use of ²¹⁰Pb originating from the decay of atmospheric ²²²Rn is a well-established methodology to estimate sediment ages and sedimentation rates. Traditionally, the measurement of ²¹⁰Pb in soils and sediments involved laborious and time-consuming radiochemical separation procedures. Due to the recent development of advanced planar (‘n-type’) semi-conductors with high efficiencies in the low-energy range which enable the gamma-spectrometric analysis of the 46.5 keV decay line of ²¹⁰Pb, sediment dating using this radionuclide has gained renewed interest.In this contribution, potentials and limitations of the ²¹⁰Pb methodology and of the models used for estimating sediment ages and sedimentation rates are discussed and illustrated by examples of freshwater and marine sediments. Comparison with the use of ¹³⁷Cs shows that the information which may be gained by these two tracers is complementary. As a consequence, both radionuclides should be used in combination for dating of recent sediments. It is shown that for various sedimentation regimes additional information from other sources (e.g. sediment lithology) may be needed to establish a reliable chronology. A strategy for sediment dating using ²¹⁰Pb is recommended.     

Development of a Test System for Assessing the Toxicity of Multicomponent Wastes Stored in the Natural Environment

A biological test system is proposed for assessing the toxicity of multicomponent wastes stored in the natural environment, with sewage sludge being used as an example. The principles of creating a test system and ranking the samples of multicomponent masses with respect to environmental hazard are discussed.     

The effect of complex formation on the adsorption characteristics of heavy metals

In most aqueous environmental systems, inorganic and organic metal complexes represent a significant contribution to the total soluble metal. Metal adsorption is often a highly pH-dependent phenomena. Such behavior can generally be attributed to changes in metal speciation with solution acidity as well as variation in the extent of surface protonation. Thus, because adsorbability may vary drastically between different metal species, (e.g. Cu²⁺ (aq) compared to CuOH⁺) a knowledge of metal species distribution is essential to understanding and interpreting metal adsorption behavior.Organic complexation has been reported to enhance, suppress and have no perceptible effect on trace metal adsorption. Such differences arise because adsorption depends on factors such as the ligand/metal ratio, adsorbability of the free ligand, and various solution parameters (e.g. pH). Most important in determining the effect of complexation on adsorption is the adsorbability of the resulting complexes. Thus, it is difficult to make generalizations about the influence of organic complexation on metal adsorption.Adsorption of metal complexes is frequently reported to be predominantly coulombic in nature; that is, binding of an anionic or cationic complex to an oppositely charged colloidal particle. However, electrostatic forces can often represent an insignificant contribution to the total free energy of adsorption and can be overshadowed by chemical reactions with the surface, hydrogen bonding, and hydrophobic effects.     

Fractionation of radionuclide species in the environment

Naturally occurring and artificially produced radionuclides in the environment may be present in different physico-chemical forms (i.e., radionuclide species) varying in size (nominal molecular mass), charge properties and valence, oxidation state, structure and morphology, density, degree of complexation, etc. Low molecular mass (LMM) species are believed to be mobile and potentially bioavailable, while high molecular mass (HMM) species such as colloids, polymers, pseudocolloids and particles are considered inert. Due to time-dependent transformation processes such as mobilisation of radionuclide species from solid phases or interactions of mobile and reactive radionuclide species with components in soils and sediments, the original distribution of radionuclides deposited in ecosystems will change over time. To assess the environmental impact from radionuclide contamination, information on radionuclide species deposited, interactions within affected ecosystems and the time-dependent distribution of radionuclide species influencing mobility and biological uptake is essential. The development of speciation techniques to characterize radionuclide species in waters, soils and sediments should therefore be essential for improving the prediction power of impact and risk assessment models. The present paper reviews available fractionation techniques which can be utilised for radionuclide speciation purposes.     

Environmental fate and ecotoxicity of lanthanides: Are they a uniform group beyond chemistry?

Lanthanides are a chemically uniform group of metals (La–Lu) that, together with yttrium (Y) and scandium (Sc), form the group of rare earth elements (REEs). Because of their many applications (e.g., agriculture, medicine, motor industry), their global production has increased exponentially in the last decades and their biogeochemical cycles are being disrupted by human uses (e.g., gadolinium anomalies in freshwater and tap water, REEs enrichment of soils as a consequence of agricultural practices). However, ecotoxicological effects and mechanism of action of these elements are still poorly understood. In particular, there is no consensus as to lanthanides showing a coherent and predictable pattern of (eco)toxicity in the same way as their atomic properties. For aquatic organisms, contradictory conclusions on this issue can be found in the bibliography. This review shows that the variable composition of culture media used in ecotoxicology, and the associated differences in lanthanide's speciation, are the most likely cause for such discrepancies. In particular, the formation of insoluble species in some highly complexing media likely leads to changes in the soluble concentration of lanthanide during some tests; with the potential for a generalized underestimation of their toxicity at the present state of knowledge. For terrestrial organisms, suitable studies to establish trends in lanthanides' toxicity are practically nonexistent; with most research focusing on the effects of REE mixtures. Molecular level studies to elucidate the mechanisms of action of lanthanides are essentially limited to La, pointing to the need for further research to identify common mechanisms of action or modes of action across lanthanides. Overall, agreement on the correct procedures to follow to obtain reliable and comparable data for individual lanthanide is the first action to take in order to arrive at a reliable risk assessment for this group of elements in both aquatic and terrestrial systems.     

Metal and metallothionein level in the heat-treated cytosol of gills of transplanted mussels Mytilus galloprovincialis Lmk

A stock of mussels Mytilus galloprovincialis was transplanted over 1 year to four sites in a semi-enclosed bay in Croatia which is under the influence of various sources of pollution. The positive correlation of metal (Cd, Zn, Cu, Mn, Fe) and metallothionein (MT) tissue contents based on the analysis of heat-treated cytosol of gills with shell mass, as an indicator of mussel age, indicated to accumulation of metals, as well as the increase of MTs with mussel age. The principal component analysis (PCA) revealed that 74% of total variance of obtained results could be explained through two principal components. The first principal component was highly correlated with MT, Cd and Zn indices (metal or MT content/shell mass), and the second one with Cu, Mn, and Fe indices, as well as the gill index. High correlation of MTs with Zn and Cd is consistent with their affinity for binding to MTs.     

Effects of cadmium and zinc on larval growth and survival in the ground beetle,Pterostichus oblongopunctatus

Carabid beetles, like Pterostichus oblongopunctatus, living in metal contaminated areas may be exposed to elevated levels of metals within their diets. However, when compared to other second order consumers, they have one of the lowest observed levels of metals, indicating methods of detoxification to deal with such toxicants. In this study, we investigated if chronic, multigenerational exposure to metals leads to resistance to toxic metal concentrations, and if so, what are the costs associated with them. Adult organisms were collected from two sites, a polluted and a reference site near Olkusz, in southern Poland. These adults were immediately mated, and eggs were collected twice weekly to assess the effects in the larvae of the F(1) generation. Larvae were randomly exposed to one of four artificial mediums: control, 50 mg kg(-1) Cd, 500 mg kg(-1) Zn, and a combined treatment of 50 mg kg(-1) Cd and 500 mg kg(-1) Zn to investigate possible interactions. Individuals were sacrificed at 10, 30, and 40 days. Although metals were not accumulated in larvae (p>0.05), larvae fed the Cd or the Zn treatment grew significantly slower, and had the lowest survival rate (p<0.05) in respect to control. Out of metal treated animals, those on the combined treatment of CdZn grew the quickest and had the highest observed survival (p<0.05). Although previous studies have demonstrated changes in adult population parameters under chronic, multigeneration exposure to toxic metal concentrations, our study did not reveal any changes in the larval stage.     

Challenges in radioecology

Today, radioecology covers a broad scientific field; from the source to long term environmental impact from ionizing radiation. To summarize key challenges within radioecology, the present paper focuses upon knowledge gaps related to processes, mechanisms and variables contributing most to the overall uncertainties in environmental impact assessments. A series of sources related to the nuclear weapon cycle and the civil nuclear cycle has contributed, is still contributing or can potentially contribute to release of radionuclides to the environment in the future. The speciation of most radionuclides depends on the source and release conditions, and will influence ecosystem transport, biological uptake, doses and effects in flora and fauna. Radionuclides may also co-occur in contaminant mixtures (e.g., metals, organics), which potentially could lead to synergisms or antagonisms. Thus, challenges associated with the links between the source or release term – radionuclide speciation – ecosystem transfer – exposure – response relationships are highlighted.     

Machine learning for toxicity characterization of organic chemical emissions using USEtox database: Learning the structure of the input space

Toxicity characterization of chemical emissions in Life Cycle Assessment (LCA) is a complex task which usually proceeds via multimedia (fate, exposure and effect) models attached to models of dose–response relationships to assess the effects on target. Different models and approaches do exist, but all require a vast amount of data on the properties of the chemical compounds being assessed, which are hard to collect or hardly publicly available (especially for thousands of less common or newly developed chemicals), therefore hampering in practice the assessment in LCA. An example is USEtox, a consensual model for the characterization of human toxicity and freshwater ecotoxicity. This paper places itself in a line of research aiming at providing a methodology to reduce the number of input parameters necessary to run multimedia fate models, focusing in particular to the application of the USEtox toxicity model. By focusing on USEtox, in this paper two main goals are pursued: 1) performing an extensive exploratory analysis (using dimensionality reduction techniques) of the input space constituted by the substance-specific properties at the aim of detecting particular patterns in the data manifold and estimating the dimension of the subspace in which the data manifold actually lies; and 2) exploring the application of a set of linear models, based on partial least squares (PLS) regression, as well as a nonlinear model (general regression neural network — GRNN) in the seek for an automatic selection strategy of the most informative variables according to the modelled output (USEtox factor). After extensive analysis, the intrinsic dimension of the input manifold has been identified between three and four. The variables selected as most informative may vary according to the output modelled and the model used, but for the toxicity factors modelled in this paper the input variables selected as most informative are coherent with prior expectations based on scientific knowledge of toxicity factors modelling. Thus the outcomes of the analysis are promising for the future application of the approach to other portions of the model, affected by important data gaps, e.g., to the calculation of human health effect factors.     

Toxicities and tolerances of Cd, Cu, Pb and Zn in a primary producer (Isochrysis galbana) and in a primary consumer (Perna viridis)

Studies on toxicities and tolerances of cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) in the brown alga Isochrysis galbana and in the green-lipped mussel Perna viridis were conducted by short-term bioassays using endpoints growth production and mortality, respectively. The 5-day EC(50) and 24-h LC(50) of these heavy metals were determined in the brown alga and mussel, respectively. The EC(50) values calculated for the alga were 0.74 mg/l for Cd, 0.91 mg/l for Cu, 1.40 mg/l for Pb and 0.60 mg/l for Zn. The LC(50) values for the mussels were 1.53 mg/l for Cd, 0.25 mg/l for Cu, 4.12 mg/l for Pb and 3.20 mg/l for Zn. These LC(50) values were within the concentration ranges as reported by other authors who used P. viridis as the test organism. Based on these EC(50) and LC(50) values, the alga was most sensitive to Zn, followed by Cd, Cu and Pb while the mussel was most sensitive to Cu, followed by Cd, Zn and Pb. Differences in the trophic levels, metal handling strategies, biology and ecology of the primary producer (brown alga) and the primary consumer (mussel) are believed to be the plausible causes for the different toxicities and tolerances of the metals studied.     

Distribution Of Cadmium And Nickel Among Various Forms In Natural And Contaminated Soils Amended With Edta

Because of its strong chelating capacity, application of ethylenediaminetetraacetic acid (EDTA) to soils may change the amount and distribution of heavy metals among their various chemical forms. Therefore, a greenhouse experiment was conducted using two cultivars of Brassica species (Brassica juncea and Brassica carinata) as hyper accumulator test crops on natural and artificially Cd and Ni contaminated soils. Both natural and metal amended soils were treated with disodium salt of EDTA at 0 and 1 g kg^–1 soil. After harvest of crops, soil samples were fractionated into water soluble plus exchangeable (WE), carbonate (CARB), organic matter (OM), Mn oxide (MnOX), amorphous Fe oxide (AFeOX), crystalline Fe oxide (CFeOX) and residual (RES) fractions. In metal amended soils, Cd and Ni were found predominantly in the AFeOX fraction in the absence of EDTA application and in the WE fraction in EDTA treated soil. Application of EDTA resulted in the redistribution of Cd among different forms and increased significantly Cd in the WE fraction with a concomitant significant decrease in the OM fraction. In natural soils, more than 40% of the total Cd was present in the RES fraction while in contaminated soil it was only 5%. Nickel in the WE fraction increased significantly while it considerably decreased in the CARB, OM, MnOX, AFeOX and CFeOX fractions with EDTA addition. This indicated that applied EDTA is capable to move Cd and Ni from the less soluble or more stable forms (CARB, OM, MnOX, AFeOX and CFeOX) to the most soluble form (WE). N natural soils, Ni in the RES fraction was found upto 49%, whereas only 10% of the total Ni was observed in contaminated soil, irrespective of EDTA treatment. In general, the amount of Cd recovered after harvest of both the Brassica cultivars did not differ significantly in any fraction except the WE fraction. The amount of Ni recovered in the AFeOX fraction was significantly higher after harvest of B. juncea as compared to B. carinata.Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Toxicological availability of nickel to the benthic oligochaete Lumbriculus variegatus

It is generally accepted that the bioavailability of metals in sediments is influenced by the presence of acid volatile sulfides (AVS). The pore water hypothesis predicts that, if the molar concentration of simultaneously extracted metals (SEM) in a sediment is smaller than the molar concentration of AVS, the free metal ion activity in the pore water is very small and that consequently no metal toxicity in short-term toxicity tests is observed. In this study we examined (1) if this concept can be extended to predict the absence of chronic Ni toxicity to the oligochaete deposit-feeding worm Lumbriculus variegatus and (2) if the organic carbon normalized excess SEM; i.e. [SEM-AVS]/f(OC) predicts the magnitude of Ni toxicity to L. variegatus. A 28-day toxicity experiment was performed in which biomass production of L. variegatus was determined in two natural sediments with different [AVS] and f(OC), spiked at different Ni concentrations. The absence of toxicity is predicted correctly by the [SEM-AVS]<0 criterion when only the 0-1 cm surface layer of the sediment is considered, but not when the whole bulk sediment is considered (0-3 cm). In both sediments, the same [SEM-AVS]/f(OC) at the surface corresponds with a similar decrease in L. variegatus biomass. Thus, [SEM-AVS]/f(OC) in the surface layer accurately predicts the magnitude of toxicity. This measure is therefore a good estimator of toxicologically available Ni. On the other hand, the free Ni(2+) ion activity in the overlying water appeared to be an equally good predictor of the magnitude of toxicity. Consequently, it was not possible to determine the relative importance of the overlying water and pore water exposure route with the semi-static laboratory experiments.     

Effects of the Bacterial Component on the Viability of the Paramecium bursariaSymbiotic Complex (Infusorian–Zoochlorella)

A hypothesis is considered that the establishment and maintenance of mass exchange processes in the Paramecium bursariasymbiotic complex (infusorian–alga) depends on the presence of the third component—bacteria—whose role is underestimated but essential for completing the exchange cycle. The role of this component in the symbiotic cycle of Paramecium bursariais possible to reveal using special bactericidal preparations specifically inhibiting the bacteria involved in the metabolic cycle but having no effect on the functions of the host cell and the zoochlorella population. Experiments with various preparations of this type were performed, and the response to treatment was estimated from growth rates of the symbiotic complex and its components. This allowed identification of an antibiotic (rifampicin) that had no adverse influence on free-living zoochlorella and chlorella-free paramecia (the basic components of the symbiotic cycle) but drastically inhibited the growth of the P. bursariasymbiotic complex, which could be interpreted as evidence in favor of the hypothesis concerning the existence of the third symbiotic component.     

Using nematodes in soil ecotoxicology

Nematodes represent a very abundant group of soil organisms and non-parasitic species are important for soil quality and in the soil food web. In recent years, it has been shown that nematodes are appropriate bioindicators of soil condition and they are also suitable organisms for laboratory toxicity testing. The aims of this paper are to overview and critically assess methods and approaches for researching soil nematode ecotoxicology. In natural ecosystems, nematode abundance and community structure analyses were proved to be sensitive indicators of stress caused by soil pollutants and ecological disturbance. Community structure analyses may be approached from a functional or ecological point of view; species are divided into groups according to their feeding habits or alternatively the maturity index is calculated according to their ecological strategy. Many environmental factors have the potential to affect nematode community, which consequently results in high space and time variability. This variance is major handicap in field ecotoxicological studies because pollutant-nematode relationships are obscured. For prospective risk assessment of chemicals, several toxicity tests with nematodes were developed and are increasingly used. Sensitivity of these tests is comparable to tests with other soil species (e.g. enchytraeids, earthworms and springtails) while tests are less demanding to space and time. Most studies have focused on metal toxicity but organic compounds are almost overlooked. Endpoints used in tests were often mortality, reproduction or movement, but more sublethal endpoints such as feeding or biomarkers have been used recently too. Although there is an increasing amount of knowledge in soil nematode ecotoxicology, there is still a lot of various issues in this topic to research.     

Climate change driven plant–metal–microbe interactions

Various biotic and abiotic stress factors affect the growth and productivity of crop plants. Particularly, the climatic and/or heavy metal stress influence various processes including growth, physiology, biochemistry, and yield of crops. Climatic changes particularly the elevated atmospheric CO₂ enhance the biomass production and metal accumulation in plants and help plants to support greater microbial populations and/or protect the microorganisms against the impacts of heavy metals. Besides, the indirect effects of climatic change (e.g., changes in the function and structure of plant roots and diversity and activity of rhizosphere microbes) would lead to altered metal bioavailability in soils and concomitantly affect plant growth. However, the effects of warming, drought or combined climatic stress on plant growth and metal accumulation vary substantially across physico–chemico–biological properties of the environment (e.g., soil pH, heavy metal type and its bio-available concentrations, microbial diversity, and interactive effects of climatic factors) and plant used. Overall, direct and/or indirect effects of climate change on heavy metal mobility in soils may further hinder the ability of plants to adapt and make them more susceptible to stress. Here, we review and discuss how the climatic parameters including atmospheric CO₂, temperature and drought influence the plant–metal interaction in polluted soils. Other aspects including the effects of climate change and heavy metals on plant–microbe interaction, heavy metal phytoremediation and safety of food and feed are also discussed. This review shows that predicting how plant–metal interaction responds to altering climatic change is critical to select suitable crop plants that would be able to produce more yields and tolerate multi-stress conditions without accumulating toxic heavy metals for future food security.     

Abnormal Cranial Variation in the Sable (Martes zibellinaL.) and the State of Environment

An abnormal cranial variation in the sable (Martes zibellinaL.) from the extreme Russian Northeast was studied. In the populations formed as a result of reacclimation, the proportion of animals with morphological cranial anomalies proved to be significantly higher than in the parental populations (from which the animals for reintroduction were taken). Probable factors responsible for this effect are discussed.