This work aimed to study the effect of long-term polymetallic contamination on the state and parameters of soil bacterial communities, including the abundance of different groups of culturable bacteria and the activity of nitrification.
Materials and methodsMonitoring plots were located in the dry lake and surrounding area, which had been formerly used for the discharge of industrial waste. The soils in the 16 plots were characterized by extremely high levels of heavy metal pollution. This study evaluated the main soil physicochemical properties by various methods, total metal contents by X-ray analysis, mobile metal content by atomic absorption spectrophotometry, the abundance of chosen groups of culturable bacteria by inoculation on solid media, and nitrification activity from ammonium and nitrite oxidation rates.
Results and discussionHigh adaptation capacity of microbial communities to long-term pollution was revealed through marked lack of decrease in the abundance of some of the bacterial groups in soils with high contamination levels. Among the bacteria determined by the colony count method, copiotrophic and spore-forming bacteria were the least sensitive to contamination, and actinomycetes were the most sensitive. The high levels of soil pollution with heavy metals had pronounced adverse effects on nitrification activity. The decrease in activity was strongly correlated with pollutant concentrations. The oxidation of nitrite was shown to be more affected by pollution that the oxidation of ammonium.
ConclusionsSome groups and parameters of culturable microorganisms can be used for soil status estimation under pollution conditions even though they are only a small fraction of the microbial community. The most sensitive parameter was the nitrification rate, while the number of actinomycetes was found to be most promising parameter among the groups of bacteria determined by plate counts. The use of sensitive groups of culturable microorganisms for bioindication purposes is a method, which may provide a cheap and sufficiently reliable tool for large-scale soil monitoring studies.
相似文献Purpose
Nanoparticles (NPs) have received increased attention in recent past due to their unique distinct properties. Metal-based NPs are widely used in chemical and allied sector. Most of the research is directed to study the efficiency of NPs in medicine and agriculture. The aim of this review is to explore the possible threats posed by toxicity of various NPs on plants and microbial diversity.Materials and methods
First, major sources of NPs to the environment were analyzed. The effects of metal-based NPs on the microbiota and plants are presented in this review. The results obtained by the authors during last 12 years of research are used.Results and discussion
The exposure of soil to nanoparticles causes a decrease in soil microbial biomass and enzymatic activity, which impacts microbial community composition including yeasts, bacteria, fungi, and biological diversity. The effects of NPs on plants result in various types of abnormalities. Nanoparticles can also pose risks to human health.Conclusions
Increased applications of NPs pose a threat to beneficial microbial communities as well as crops and soils. Thus, it is important to explore whether NPs could compromise crop yield, soil properties, soil organisms, and functional activities of soil.Accounting for ionic strength and ion association, the degree of calculated supersaturation with CaCO3 of gleyic solonetz and molic solonetz soil solution is high. The purpose of the research was to reveal the effect of the water-dissolved organic matter (DOM) on the calcium carbonate equilibrium (CCE) in soil solution, to create a thermodynamic model of carbonate association and complexation with DOM and heavy metals (HMs), and to correct the principal of soil management.
Materials and methodsObject of research—Kastanozem complex of the dry steppe, Rostov Oblast, Russia. The water extraction of soluble salts was made at the water-to soil-ratio 5:1 and analyzed using standard methods. DOM content was determined by Strosser (J Agrobiol 27:49–60, 2010). The soil solution macro-ion equilibrium composition was calculated using ION-2 program (Endovitsky et al. 2009). DOM role in soil solution supersaturation with СаСО3 was assessed, comparing C content in real solution and in identical artificial solution prepared without organic matter. Taking into account the ion association, the molar fractions of free and bound HM ion were calculated using microelement association coefficient, kas(ME). The soil liquid-phase saturation with CaCO3 was characterized by the ratio of the real solubility product (S) to the thermodynamic solubility product (S0): К?=?S/S0.
Results and discussionThe soil solution supersaturation with CaCO3 was characterized by the product of analytical concentrations (S), equilibrium concentrations [accounting ion activity (SI), ion association (SII), ion association and complexation (SIII)], and the thermodynamic solubility product (S0). To evaluate the role of DOM in soil solution supersaturation with CaCO3, the initial pure Ca (HCO3)2 solution series was prepared. The humic and fulvic acids from the illuvial horizon of gleyic solonetz with concentrations of 20 mg C L?1 and 120 mg C L?1 decreased the CaCO3 precipitation compared with initial soil solution. The release of CaCO3 from soil water extracts containing water-soluble organic matter was 1.2–1.9 times less compared with identical artificial solution not containing organic matter. The HM binding by carbonates is proportional to the DOM content.
ConclusionsIn molic solonetz and gleyic solonetz, the neutralization of the soda should be assessed by the soil solution supersaturation with CaCO3. To calculate the degree of HM passivation in soil solution containing DOM, the coefficient of soil solution oversaturation with CaCO3 is proposed. For reducing soil organic matter and DOM mobility and loss from soil, as well as for Pb passivation, intra-soil mechanical processing, intra-soil waste management, and intra-soil watering are proposed.
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