Changes in soil microbiota under the effect of acrylonitrile in a model experiment

A laboratory experiment was performed to evaluate the effect of acrylonitrile (20, 200, and 2000 mg/kg soil) on the abundance and structure of soil microbial community. The results of direct inoculation showed that acrylonitrile at 200 mg/kg stimulated the development of nitrile-utilizing prokaryotes, whereas at 2000 mg/kg it inhibited all test groups of microorganisms, including nitrile- and amide-utilizing bacteria. According to real-time PCR data, representatives of α- and ß-Proteobacteria were the most labile members of the soil microbial community, while Bacteroidetes and Fungi proved to be highly resistant to the effect of the pollutant.     

Long-term seasonal polymorphism of the Krasnodar greenbug population for virulence to sorghum varieties carrying different resistance genes

The genetic structure of the Krasnodar population of the greenbug (Schizaphis graminum Rondani) was analyzed in 2002 to 2010. A high level of general and seasonal polymorphism for the insect virulence to different sorghum accessions was revealed. Abiotic factors were shown to play an important role in the seasonal variation of the frequencies of virulence phenotypes: they can alter the relative competitiveness of greenbug clones, and, therefore, changes in environmental conditions lead to differential selection in the S. graminum population.     

Biological diversity of nitrile-metabolizing bacteria in soils of the Perm region affected by human activities

The diversity of bacteria metabolizing nitriles of carbonic acids was studied in soils of the Perm region affected by human activities. Effective methods for selective isolation of cultures possessing the nitrile hydratase and nitrilase activities were developed. Most microorganisms capable of utilizing nitriles were Grampositive Nocardia-like bacteria of the genus Rhodococcus. Isolates with a detectable nitrilase activity were also represented by Gram-negative forms (Gram-negative aerobic/microaerophilic bacilli and cocci of the genera Pseudomonas, Azomonas, Azotobacter, and Acidovorax). Two enzyme systems for nitrile hydrolysis were found in 27% of cultures. The nitrile hydratase and nitrilase activities of the studied strains exceeded these enzymatic activities in bacteria isolated from native soils, which indicates that natural selection of saprophytic microflora occurs in chemically altered soils.     

A comparison of the growth of Scots pine (Pinus sylvestris L.) in a reclaimed oil shale post-mining area and in a Calluna site in Estonia

The growth of Scots pine and its suitability for afforestation of post-mining landscapes in Northeast Estonia were assessed in comparative analytical studies by using morphological parameters and mineral nutrition characteristics. The growth and nutrient uptake of Scots pine growing on post-mining substrate were compared with the characteristics of pines of the same age (22–23 years) in a Calluna forest site type predominant in North Estonia in similar climatic zone. Results of the analyses of soil upper layers showed that the concentration of N and P in soil did not differ between the opencast spoil and Calluna site, but significantly higher pH of soil and concentrations of K, Ca, and Mg were found in mine spoil. The concentrations of K and Mg in needles were significantly higher in the post-mining area, but the concentrations of N, P, and Ca did not differ significantly. Comparison of the needle nutrient concentration with the standard for optimum concentrations revealed P deficit in the post-mining area and P and K deficit in the Calluna site. Scots pine formed longer and thinner needles and shoots in the post-mining substrate than in the Calluna site. It was assumed that in the post-mining area the growth of pines is predominantly dependent on K and Ca concentrations in their tissues as the biomass of needles was strongly correlated with the K/Ca ratio, whereas the biomass in the Calluna site was correlated with the N/P ratio. The height and diameter of trees were significantly larger in the post-mining area.     

Seasonal and Interannual Dynamics of Active Part of Bacterioplankton in Overgrowing Littoral Zone of Rybinsk Reservoir: Influence of Gull Colonies

This article analyzes the seasonal and interannual dynamics of active and viable bacteria in coastal waters of a large plain reservoir (Rybinsk Reservoir, Volga River) due to the activity of birds of the families Laridae and Sternidae. An increase in the number and proportion of dividing cells and cells with undisturbed nucleoids in bacterioplankton at the beginning of the nesting period of the birds (late May to early June) and their decrease by mid- July have been recorded. A decrease in the proportion of active bacteria near the gull colony has been recorded.     

Effect of climatic conditions on the expression of self-fertility in Scots pine

The results of 12-year experiment on monitoring the types of Scots pine seed reproduction systems in Voronezh oblast are generalized. Sample structure with respect to self-fertility in optimal years is characterized and its transformations in years with weather anomalies (cold, warm, moderately and severely droughty) are described. It is shown that the contribution of self-fertilization to annual seed production increases proportionally to the severity of weather stress affecting the population.     

Soil-dwelling Collembola in coniferous forests along the gradient of pollution with emissions from the Middle Ural Copper Smelter

The results of three-year studies on Collembola communities in spruce-fir forests along the gradient of pollution with emissions from the Middle Ural Copper Smelter (Revda, Sverdlovsk oblast) are presented. They show that the species and ecological structure of these communities change abruptly in the impact zone (1 km from the source of emissions), compared to the background zone (30 km from the source), which involves a decrease in the abundance and diversity of Collembola. Their total abundance and species richness in the zone of intermediate disturbance (7 and 4 km) are considerably higher than in the background zone, and the species structure of communities is characterized by superdominance. Four species groups differing in sensitivity to pollution are distinguished. Preference for zones with different pollution levels in closely related species is regarded as a case of ecological vicariation.     

On the Classification of Aquatic Communities: An Example of Zooplanktonic Cenoses of Karst Lakes in the North of European Russia

Nine lakes in the Arkhangelsk oblast were analyzed with respect to their morphometry, hydrology, and hydrochemistry, and their zooplankton was studied for three years. The data on zooplankton abundance, biomass, the ratio of filter-feeders and predators, the Shannon index of species diversity, and average individual weight of zooplankters were obtained. Differences in the structure of zooplanktonic cenoses were revealed in lakes differing in morphometric parameters, prevailing ions (HCO₃ ^–, SO₄ ^2–), and their concentration.     

Remediation of chloroform in fine-textured soil using zero-valent iron

Chloroform, a probable human carcinogen, is mainly produced anthropogenically for industrial use and may be released to the environment from a large number of sources related to its manufacture and use, including pulp and paper mills, hazardous waste sites, and sanitary landfills. Remediation of chloroform through conventional technologies has been met with limited success due to the conditions required and the formation of hazardous substances such as dichloromethane. The objective of this study was to investigate chloroform reduction in multicontaminated fine-textured soil using zero-valent iron (Fe⁰) in anaerobic microcosms. Four amended matrices were tested: simple matrix control (glass beads), soil matrix control (glass beads + soil), Fe⁰ in a simple matrix (glass beads + Fe⁰), and Fe⁰ in a soil matrix (soil + Fe⁰). Headspace chloroform and its transformation products dichloromethane, chloromethane, and methane were measured over 230 days and during short intervals in the initial 3 days. Chloroform (~0.3 mM initial mass) persisted in both control microcosms but was completely transformed in microcosms containing soil + Fe⁰ by 12 h and glass beads + Fe⁰ by 48 h. Reductive dechlorination of chloroform occurred with simultaneous production of dichloromethane (~0.11 to 0.14 mM mass) and chloromethane (~0.02 to 0.13 mM mass). Little methane (~0.07 to 0.26 μM mass) production as an end product of chloroform reduction was observed in microcosms amended with Fe⁰. Produced dichloromethane and chloroform almost disappeared by 230 days. The results showed a complete chloroform transformation pathway that has good potential for the remediation of chlorinated compounds in fine-textured soil. The role of soil clay minerals in redox reactions can be further investigated to improve the reductive dechlorination of chlorinated compounds in contaminated environments.