The response of the microbial community (microbial biomass carbon (Cmic), basal respiration (BR), and functional diversity (FD)) of agrosoddy-podzolic soil (Albic Glossic Retisols (Loamic, Aric Cutanic, Ochric)) to pollution by heavy metals (HMs: Cu 660, Zn 1100, Pb 650 mg/kg) and carbon-containing preparations (5% of biochar and 0.25% of lignohumate) was studied in model experiment (30 days). Soils with different organic carbon contents (Corg 3.86 and 1.30%) were sampled at two sites (Chashnikovo, Moscow oblast). We determined Cmic by the substrate-induced respiration method and FD by multisubstrate testing (47 substrates). It was found that HMs application reduced Cmic on average by 49–57%, BR by 23–52%, and FD by 45%, but, on the contrary, increased the microbial metabolic quotient (qCO2 = BR/Cmic) by 9–46%. The changes of these properties were most significant in the soil with low Corg content (1.30%). Carbon-containing preparations did not contribute to variations in Cmic, BR, and qCO2 in both soils with HMs, but increased their FD. It is concluded that the studied microbiological parameters may be used as indicators for optimal assessment of soil quality: FD and Cmic are the more sensitive to HMs than BR and qCO2.

Two approaches were considered in searching for an efficient procedure for preparing magnetic nanocomposites based on activated carbon and magnetite nanoparticles by chemical precipitation: preliminary synthesis of magnetite nanoparticles by chemical precipitation from solutions of bi- and trivalent iron salts, followed by introduction of the nanoparticles into the activated carbon matrix, and synthesis of magnetite nanoparticles in the activated carbon matrix. A comparative analysis of the content of magnetite nanoparticles and functional characteristics (textural parameters, sorption capacity, saturation magnetization, and coercive force of the nanocomposites) was made. The ex situ synthesis proved to be the best procedure for preparing nanocomposite sorbents based on activated carbon and magnetite nanoparticles by chemical precipitation, as judged from the yield and functional characteristics of the target product. In biological testing, the maximal harmless (inactive) concentration of the magnetic nanocomposite in the test system with microalgae appeared to be higher by an order of magnitude than that in the test system with ciliates.

The influence of iron-based magnetic nanomaterials on living systems — photosynthetic plants – have been studied in standardized test systems. The effects of magnetite and maghemite nanoparticles after stabilization of their surface with humic acids by the reactions of microalgae Scenedesmus quadricauda (Turp.) Breb. and sprouts of seeds of higher plants - white mustard Sinapis alba L. – have been compared. The dynamics of growth test functions have been evaluated by changing the fluorescence of chlorophyll in a suspension of microalgae and by changing the length of the roots of seed seedlings during incubation with the studied drugs relative to the control variants (without drugs). It has been found that the treatment with humic acids sufficient for the stability of iron nanoparticles in terms of the phase state does not reduce the toxicity of maghemite in both test systems. Possible mechanisms for changing the ecotoxicity of synthesized magnetic iron nanopreparations in interaction with living systems in their growth environment are discussed.

Abstract—The influence of two lead salts on the soil enzymatic activity dynamics (urease, dehydrogenase, the total hydrolase activity, acidic phosphatase, and peroxidase), with lead ion concentrations of 10, 100, 300, 500, and 1000 mg/kg, was assessed in a 21-day-long model experiment. A reliable inhibitory effect of lead nitrate applied at doses of 500 and 1 000 mg (Pb2+)/kg on the total activity of hydrolases, dehydrogenase, and peroxidase has been identified, while lead acetate mostly caused a stimulating effect. Based on the data obtained, the diagnostic indicators have been ranked by the reduction of their sensitivity to lead nitrate pollution in the following order: total activity of hydrolases > peroxidase > dehydrogenase > urease ~ acidic phosphatase.

The use of bioassays for environment contamination assessment, in particular for aquatic ecosystems, has gained topicality and found extensive applications over the past decades. The methodologies are well established, but the standardization of bioassay conditions needs to be better defined in order to assure applicability as an efficient analytic tool and that results are ecologically relevant. This paper addresses the analysis of the current international situation and the specifics of Russian practice in culturing and use of test organisms for freshwater bioassays. Standardization of bioassays calls for the utilisation of pertinent sources of test cultures and the provision of appropriate cultivation conditions. The paper discusses and reviews recommendations for the selection of test species and their culturing in the context of established ecotoxicological targets and the assessment of sensitivity to various reference toxicants. The significance of the quality of water utilized for test cultures and sample dilution is highlighted. Strict water quality requirements and synthetic media options are analyzed and due consideration is given to temperature and illumination conditions. Toxkit microbiotests are discussed as an alternative to toxicity bioassays alleviating the need for continuous stock test culturing and maintenance.

The influence of two lead salts on the enzymatic activity dynamics (urease, dehydrogenase, the total activity of hydrolases, acid phosphatase, and peroxidase) at lead ion concentrations of 10, 100, 300, 500 and 1,000 mg/kg in a model 21-day experiment was estimated. A significant inhibitory effect of lead nitrate on the total activity of hydrolases, dehydrogenase and peroxidase at doses of 500 and 1,000 mg (Pb2+)/kg was observed, while lead acetate was characterized by predominantly stimulating effect. On the basis of the data obtained the authors have arranged the diagnostic indicators by the reduction of the sensitivity to lead nitrate pollution as follows: the total activity of hydrolases > peroxidase > dehydrogenase > urease ~ acidic phosphatase.