Ecotoxicological assessment of soil using the Bacillus pumilus contact test

We estimated the toxicity of soils artificially contaminated with metals and a pesticide using the Bacillus pumilus dehydrogenase activity (DHase) inhibition test. We found a masking effect of organic matter while testing the toxicity of soil samples with low content of toxicants. To avoid this effect, uncontaminated soil should be used as a control; in its absence, we recommend using a " substitute" control. We developed a method to estimate the " substitute" control by multiplying the quotient (So), which depends on organic matter content (Corg) of the soil sample, by the activity of the test culture determined in the presence of water (Arelw). This method does not require uncontaminated soil controls and can be extended to use with other test organisms that are sensitive to Corg. © 2010

The effectiveness of co-digestion of sewage sludge and phytogenic waste

The authors explore the effect of the composition of mixtures of sewage sludge and phytogenic waste, their preliminary inoculation with a methanogenic community and the length of the process on biogas release in anaerobic co-digestion in thermophilic conditions. The study determines the effect of co-digestion products on the soil microbial community, as well as biometric parameters of the oat plants (Avena sativa L.). The authors demonstrate the principal possibility of co-digestion of the wastes. In terms of biogas release, the most preferable is the mixture of sewage sludge and maize silage. This mixture's co-digestion products possess fertilizing qualities. © IDOSI Publications, 2014

Effects of leakage of compounds from radioactive oily waste on soil microbial community

The study deals with the effects of disposal of oily waste containing natural radionuclides on chemical and biological properties of different soil layers. Two wastes were used in a laboratory experiment: raw oily waste H (TPH - 575±121 g kg-1,226Ra - 4403±312,232Th - 2848±211, 40K - 1276±133 Bq kg-1) from a production yard, and treated waste R obtained by eluting oily components from waste H. The wastes were disposed on soil columns (H-and R-columns), at the amount equalized by the concentration of radionuclides. C-columns without waste disposed were used as a control. After 30 days of irrigation, soil properties of layers 0-20,20-40 and 40-60cm were estimated. TPH content in all the layers of H-columns was significantly higher than in C- and R-columns. Activity concentrations of 226Ra and 232Th in R0-20 samples were 3.5 times higher than in control samples. Soil microbial biomass decreased from the upper to the lower layer in all the columns. Significant reduction of microbial biomass in the upper layer of column H was observed in comparison with columns C and R (12, 26 and 22 mg Cmic kg-1 correspondingly). Respiration activity in samples H0-20 was 2.4 and 1.5 times higher in comparison to C0-20 and Rn.20 samples. Hydrocarbon oxidizing bacterial counts was significantly higher in all the samples of H-column, whereas there were no differences in total bacteria counts. On the basis of cluster analysis of the data obtained, it was concluded that namely the oily compounds cause the alteration in microbial communities, especially in the upper layer of soil. The effect of radionuclides on soil microbiota was not observed

Biological and agrochemical properties of soils on uncultivated slopes

Agrochemical (organic carbon and total nitrogen content) and biological (microbial biomass, respiration, urease, dehydrogenase and cellulose activities) parameters of soil samples from five uncultivated slopes with an incline of 10-15° were estimated. The sampling points were located in the watershed area, at the foot of the slope and in between, along transect. The organic carbon content in samples taken on watershed ranged between 3.1 and 5.6%. Only for one of the slopes was a decrease of Corg content along the slope transect observed. The content of total nitrogen in samples taken on watershed ranged between 0.17 and 0.29%. Microbial respiration in watershed ranged from 27.6 to 164.2 CO2-C g-124h-1. In the same samples, the level of microbial biomass ranged between 93.2 and 413.6 μg kg-1, and dehydrogenase activity was approximately equal in all the samples (4.8-7.1 mg l-1 sodium resazourine salt 24 h-1); levels of urease activity ranged from 0.7 to 7.6 g NH4+ kg-1, and cellulase activity from 0.8 to 8.1 g C6H12O6 kg-1. Values of agrochemical and biological parameters in the soils sampled along transects fluctuated significantly, but no trends were observed. To analyze the contradictory data obtained, cluster analysis was used. It was shown that differences in the characteristics of samples from different slopes are more significant than differences in the characteristics inside the same slope. The agrochemical parameters and biological activity of soils located on slopes have the same values as those of similar types of soils located on a flat terrain and do not depend on the location or on slope profile

Responses of wheat and cucumber plants on the treatment with newly developed humic substances containing fertilizer

© SGEM 2018. Humates are substances possessing high physiological activity, contributing to the photosynthetic yield in plants and having no carcinogenicity or mutagenicity. It is the combination of these unique properties that makes humates promising plant growth and development stimulators. Within the framework of the present investigation the efficiency of application of two humate products has been assessed, and a comparative analysis of their influence on the growth and development of agricultural crops has been carried out. Commercial peat based products EDAGUM®SМ and HUMAT K have been chosen as the subjects of research. To study their influence on the growth and development of plants, laboratory-induced germination, germination, plant survival and morphometric parameters were determined in the course of the experiments. To evaluate the photosynthetic rate, total plant leaf chlorophyll (a and b) content has been determined. EDAGUM®SМ has shown greater positive influence on the survival of both plants, compared to HUMAT K. The use of neither of the preparations influenced the germination, morphometric parameters or biomass of the plants. EDAGUM®SМ influenced positively on total chlorophyll content in wheat leaves

Influence of cadmium and glucose on soil microbial communities

© 2015 Aliya Gilmullina, Polina Galitskaya and Svetlana Selivanovskaya. A laboratory-based simulation of exposure of the soil community in a gray forest soil to cadmium and glucose has been conducted. It was established that while growing in a fertile medium microbial communities isolated from a soil sample contaminated with cadmium have a substantially increased phase of growth delay and there is a reduction in total growth. While analyzing communities by Biolog Ecoplate method, it was found that, as compared to the community isolated from a soil rich in glucose, the community in a soil with cadmium is characterized by significantly lower AWCD, R and H indices, in which the differences increase with time of incubation. Also differences in the pattern and rate of recyclable substrates have been revealed. The resulting data suggest changes in the functional activity of the microbial community in the soil under the influence of cadmium

Restoration of soil quality after oil pollution

© 2014, SGEM. All Rights Reserved. In this study, the self-restoration and remediation of oily polluted soil was investigated, Microbial parameters were used as indicators of the processes. The amount of oil that was used for artificial contamination of soil was 20 g kg-1. We analyzed total petroleum hydrocarbon (TPH) content and dynamics of microbial activities in polluted soil, polluted dugged-up soil, control soil in the layers 0-20, 20-40, 40-60 cm after 3 and 36 months after pollution. It was shown that oil mainly remains in the upper layer and does not migrate significantly along soil profile. The digging-up permitted the intensify the natural process of oil destruction (up to 42%). Changes in TPH content influenced the concentrations of organic carbon in the soil - they increased in 3.3-3.9 times in the upper layer of soil after 3 months since contamination in comparison to control. The level of microbial biomass in the control samples ranged from 172 to 201 mg Cmic g-1in the upper soil layers, and decreased with depth. The maximum level of this parameter (807 mg Cmic g-1) was observed in the upper layer of non-digged polluted soil after 3 months of contamination. Soil respiration activity values ranged from 94 to 100 mg CO2-C g-124h-1. The positive correlation (R=0.86) between basal respiration and microbial biomass was found in control samples but not in polluted samples. Oil pollution did not influence significantly the cellulase activity of the soil which was more determined by depth but not TPH concentration or presence/absence of pollution. In opposite, urease activity was highly dependent on oil pollution - in all polluted samples it was 3-383 times lower than in the corresponding control

Changes in the ecological properties of organic wastes during their biological treatment

© 2016 Elsevier LtdOrganic wastes, such as the organic fractions of municipal solid waste (OFMSW) or sewage sludge (SS), have become a serious environmental problem in Russia as well as in other countries. The use of these wastes as soil amendments allows their negative impact on the environment to be minimized. However, before these wastes can be used, they need to be treated appropriately in order to decrease their level of hazard. In this study, composting of raw SS, OFMSW, a mixture of these two wastes (OFMSW + SS) at a ratio 1:2 as well as the anaerobically digested variants of these wastes (SSd, OFMSWd and OFMSWd + SSd) mixed with oiled sawdust was performed. Composting was conducted in the containers containing 20 kg of the wastes. The results of three elutriate bioassays (with water flea Daphnia magna, infusoria Paramecium caudatum and radish plant, Raphanus sativus) and one contact bioassay (with oat plant Avena sativa) were used to indirectly estimate changes in the hazardous properties of the biological treatments. Besides, Corg, Ntot content and pH were analyzed in the process of composting. Within the study stability tests to determine maturation process completion were not carried out. It was revealed, that in the process of anaerobic pretreatment for 15 days, the toxicity increased by a mean of 1.3-, 1.9- and 1.1-fold for OFMSW, SS and OFMSW + SS, respectively. During composting, the toxicity level of these pretreated samples decreased more rapidly as compared with those which were not pretreated. As a result, the toxicity levels of the elutriates from the final composts made of pretreated wastes OFMSW, SS and OFMSW + SS were three-, two- and 17-fold lower for D. magna and 15-, 21- and 12-fold lower for P. caudatum. As follows from phytotoxicity estimations, composts from digested substrates became mature on the 60th day and had a stimulation effect on the plants after the 90th day of incubation. For the composts prepared from raw substrates, a significantly longer period was needed for maturation. On the basis of ecotoxicity changes of the wastes treated, it can be concluded that anaerobic pretreatment of the municipal solid wastes is an effective acceleration tool for further composting and that waste mixtures can be treated more efficient as compared with raw wastes

Eco-toxicity of oily wastes containing TENORM

Oily wastes are considered as one of the most hazardous waste types. Additionally to petroleum components, they can contain radioactive elements. This study aimed to estimate the toxicity of four raw and two treated waste samples obtained from petroleum production yard. Eight elutriate bioassays using plants (Raphanus sativus and algae Scenedesmus quadricauda), crustacean (Daphnia magna and Thamnocephalus platyurus), rotifer (Brachionus calyciflorus), protozoa (Paramecium caudatum) and bacteria (Bacillus pumilus and luminescent commercial strain) were used. Two contact bioassays based on R. sativus and B. pumilus were applied. Total petroleum hydrocarbons (TPH) content and activity concentrations of radium, thorium and potassium were determined. Copyright © 2014 Inderscience Enterprises Ltd

Bioremediation of oil waste under field experiment

The remediation process of oily waste, selected in the tank battery, was conducted under field experiment. Compost (5 and 50%), prepared from the organic fraction of municipal solid waste, sewage sludge and sawdust, as well as two strains of soil bacteria Bacillus thuringiensis RG2 and Bacillus pumilus RG1 were used for remediation process. The lowest amount of petroleum hydrocarbons was detected when mixing waste with soil and compost at the amount of 50%. In the first case noted effect was achieved by increasing the number of hydrocarbon oxidizing bacteria, whereas in the second case it was attained by increasing the total microbial biomass and metabolic activity of the mixtures. Adding microorganisms-destructors did not have a significant effect on the hydrocarbon decomposition process. Taking into account the relevancy for soil resources preservation, the use of compost for bioremediation seems to be the most promising technique. © IDOSI Publications, 2014