Vera Terekhova

Spectral Characterization of Fungal Metabolites in Aqueous Medium with Humus Substances

The work is targeted to confirm participation of microscopic fungi in transformation of humus substances in aquatic environments. The research is focused on the spectroscopic study of the collection of fungal strains with different pigmentation of mycelium. Spectral properties of fungal metabolites were measured and compared to that of natural aquatic nonliving organic matter and commercial humus substances in aqueous solutions. The experiments revealed that the effect of microscopic fungi growing in the culture medium with added humate appeared as changes in the humic-type fluorescence: its characteristics became more similar to that of nonliving organic matter in natural waters than to original humate preparation. The experiments demonstrated degradation of coal-originated humate due to microbial activity into compounds of smaller molecular size and increased heterogeneity. We resume that transformation of humus substances by fungal cultures can be monitored and characterized using spectral measurements.

Engineered Nanomaterials’ Effects on Soil Properties: Problems and Advances in Investigation

In this work, the sources of entry and migration pathways of engineered nanomaterials (NMs) in soil were described. NMs effect on soil ecotoxicity and some physical and chemical characteristics were studied in laboratory experiments. The influence of carbon- and metal-containing NMs with different sizes of nanoparticles (NPs) on living organisms in bioassay tests was analyzed. In standard biotests, organisms from different trophic levels were used. It was shown that the organic matter (humic substances) highly modified the toxic effects of NMs in soils, in particular, nanomagnetite. We suppose that these effects appear not only due to various specific surfaces of the nanoparticles used but also due to change of rheological characteristics of soil particles caused by interaction between soil particles and engineered nanoparticles in the presence of humate.

Triad Method for Assessing the Remediation Effect of Humic Preparations on Urbanozems

The data on the pollutant content, ecological toxicity, and structural and functional specifics of soil microbial communities in urbanozem sampled in the city of Kirov were used to describe the remediation effect of humic substances (lignohumate and nanomagnetitohumate). The integral index of environmental risk on contaminated and background soil sites was calculated using the triad method. Based on varying Chemical Risk Index, Ecotoxicological Risk Index, and Ecological Risk Index, this method proved that humic substances are able to reduce ecological toxicity and transform the ecophysiological indices of biota in urban soils. The most vivid effect of humic products has been revealed on introduction of 0.0025 and 0.01% mass. The biological activity of nanomagnetitohumate and lignohumate, rather than their ability to bind toxicants, is apparently the principal factor controlling their remediating effect.

Influence of Commercial Humic Products on Living Organisms and Their Detoxification Ability in Cu-Polluted Soil in Model Experiment

To estimate the influence of a number of commercial humic products (HPs) on living organisms and their detoxification ability in Cu-polluted soil, a model experiment was carried out. Model soil mixture was incubated with five commercially available humates, manufactured from different organic source materials (coal, peat and lignosulphonate) applied at the rate of 0.1 g kg−1 during 21 days. In parallel soil was incubated with 660 g kg−1 Cu as copper nitrate and the same humates were applied. After incubation, the soil content of Cu was determined. Community-level physiological profiling (CLPP) and bioassays using plants (barley and mustard) and algae (Scenedesmus quadricauda) as test cultures were carried out. Results showed that most of HPs tested increased soil biological activity and demonstrated certain detoxification ability, depending on HPs’ nature and sensitivity of the test cultures.

Improvement of laboratory phytotest for the ecological evaluation of soils

Analysis of methodological documents, Russian and foreign standards, and scientific publications has been performed to reveal best global practices and current trends in the improvement of laboratory phytotesting. It is proposed to increase the number of simultaneously used test cultures and the range of simultaneously controlled test functions at the first (screening) stage of phytotest to increase the information value of laboratory phytotests. Attention is focused on the assurance of the statistical reliability of test results. The advisability of creating universal regulations of Russian Federation for phytotesting methods to unify approaches to the ecological evaluation of soils.