Stable isotope discrimination during soil denitrification: Production and consumption of nitrous oxide

Measuring the stable isotope composition of nitrous oxide ( N(2)O) evolved from soil could improve our understanding of the relative contributions of the main microbial processes ( nitrification and denitrification) responsible for N(2)O formation in soil. However, interpretation of the isotopic data in N(2)O is complicated by the lack of knowledge of fractionation parameters by different microbial processes responsible for N(2)O production and consumption. Here we report isotopic enrichment for both nitrogen and oxygen isotopes in two stages of denitrification, N(2)O production and N(2)O reduction. We found that during both N(2)O production and reduction, enrichments were higher for oxygen than nitrogen. For both elements, enrichments were larger for N(2)O production stage than for N(2)O reduction. During gross N(2)O production, the ratio of delta(18)O- to-delta(15)N differed between soils, ranging from 1.6 to 2.7. By contrast, during N(2)O reduction, we observed a constant ratio of delta(18)O- to-delta(15)N with a value near 2.5. If general, this ratio could be used to estimate the proportion of N(2)O being reduced in the soil before escaping into the atmosphere. Because N(2)O- reductase enriches N(2)O in both isotopes, the global reduction of N(2)O consumption by soil may contribute to the globally observed isotopic depletion of atmospheric N(2)O

Tree species and moisture effects on soil sources of N2O: Quantifying contributions from nitrification and denitrification with O-18 isotopes

Nitrous oxide (N2O) is an important greenhouse gas and participates in the destruction of stratospheric ozone. Soil bacteria produce N2O through denitrification and nitrification, but these processes differ radically in substrate requirements and responses to the environment. Understanding the controls over N2O efflux from soils, and how N2O emissions may change with climate warming and altered precipitation, require quantifying the relative contributions from these groups of soil bacteria to the total N2O flux. Here we used ammonium nitrate (NH4NO3, including substrates for both processes) in which the nitrate has been enriched in the stable isotope of oxygen, O-18, to partition microbial sources of N2O, arguing that a molecule of N2O carrying the O-18 labeled will have been produced by denitrification. We compared the influences of six common tree species on the relative contributions of nitrification and denitrification to N2O flux from soils, using soils from the Siberian afforestation experiment. We also altered soil water content, to test whether denitrification becomes a dominant source of N2O when soil water content increases. Tree species altered the proportion of nitrifier and denitrifier-derived N2O. Wetter soils produced more N2O from denitrification, though the magnitude of this effect varied among tree species. This indicates that the roles of denitrification and nitrification vary with tree species, and, that tree species influence soil responses to increased water content

Single tree-effects on denitrification and soil microbial biomass in agroforestry systems and natural forests of the Amazon region.

The aim of the present study was to find the effect of tree species used in agroforestry system in Amazonian region and natural forests on the total biomass of heterotrophic microorganisms (BH), which is mainly responsible for CO2 emission, and on the biomass of denitrifiers (BD), which control N2O emission

Using Fuzzy Modeling for Diagnostics of the Technical Condition of a Loom

Определены методы, определяющие срок проведения ремонта ткацкого станка с помощью нечеткого моделирования в программном пакете «MATLAB». Разработано программное обеспечение, оценивающее степень износа механизмов ткацкого станка и сроки проведения следующего ремонта по рассчитанным параметрам среднеквадратичного отклонения информационного сигнала с трех осевого акселерометра системы диагностирования ткацкого станка.The methods that determine the period for the repair of a loom using fuzzy modeling in the software package «MATLAB» are defined. Software has been developed that estimates the degree of wear of the loom mechanisms and the timing of the next repair according to the calculated parameters of the information signal standard deviation of the from the three-axis accelerometer of the loom diagnosing system

Wildfire effects on BVOC emissions from boreal forest floor on permafrost soil in Siberia

One of the effects of climate change on boreal forest will be more frequent forest wildfires and permafrost thawing. These will increase the availability of soil organic matter (SOM) for microorganisms, change the ground vegetation composition and ultimately affect the emissions of biogenic volatile organic compounds (BVOCs), which impact atmospheric chemistry and climate. BVOC emissions from boreal forest floor have been little characterized in southern boreal region, and even less so in permafrost soil, which underlies most of the northern boreal region. Here, we report the long-term effects of wildfire on forest floor BVOC emission rates along a wildfire chronosequence in a Larix gmelinii forest in central Siberia. We determined forest floor BVOC emissions from forests exposed to wildfire 1, 23 and > 100 years ago. We studied how forest wildfires and the subsequent succession of ground vegetation, as well as changes in the availability of SOM along with the deepened and recovered active layer, influence BVOC emission rates. The forest floor acted as source of a large number of BVOCs in all forest age classes. Monoterpenes were the most abundant BVOC group in all age classes. The total BVOC emission rates measured from the 23- and >100-year-old areas were ca. 2.6 times higher than the emissions from the 1-year-old area. Lower emissions were related to a decrease in plant coverage and microbial decomposition of SOM after wildfire. Our results showed that forest wildfires play an important indirect role in regulating the amount and composition of BVOC emissions from post-fire originated boreal forest floor. This could have a substantial effect on BVOC emissions if the frequency of forest wildfires increases in the future as a result of climate warming. (C) 2019 Elsevier B.V. All rights reserved.Peer reviewe

Pleiotropic immunomodulating effects of peptide Arginyl-alpha-Aspartyl-Lysyl-Valyl-Tyrosyl-Arginine on various subsets of neutrophilic granulocytes and their phenotype in patients with COVID-19 <i>in vitro</i>

The key role of neutrophilic granulocytes (NG) in the pathogenesis of COVID-19 makes them new targets for therapeutic approaches and of influencing the course and outcome of the disease, restoring changes in the phenotype and functions of NG. Synthetic peptides or polypeptide complexes of action are the most promising in the treatment of COVID-19. Aim: to reveal the effects of the influence of the hexapeptide (HP) – Arginyl-alpha-Aspartyl-Lysyl-Valyl-Tyrosyl-Arginine on the phenotype of functionally significant NG subsets in moderate COVID-19.The study examined patients 61 (57-71) years old (n = 45) in the acute period of COVID-19 – study group1 (SG1). In vitro, samples SG1 were incubated with HP (106 g/L, 60 min, 37 °C) – study group2 (SG2). The number of NG subsets was evaluated: CD16+IFNα/βR1+CD119+, CD16+IFNα/βR1+CD119- , CD16+IFNα/βR1+CD119+, CD64- CD16+CD32+CD11b+, CD64+CD16+CD32+CD11b+ and phenotype by membrane receptor expression density (MFI) (FC 500, Beckman Coulter, USA); NG phagocytic activity was tested before and after incubation with HP. The comparison group (GS) – of 22 volunteers examined in the pre-COVID period.It was revealed that unidirectional effects of HP in vitro contributing to the restoration of the phenotype of subsets CD16+IFNα/βR1- CD119+, CD16+IFNα/βR1+CD119- to CG indicators. There was a decrease in MFI CD16 (p &lt; 0.05) in both subsets; MFI CD119 (p &lt; 0.05) in the CD16+IFNα/βR1- CD119+NG subset, MFI IFNa/βR1 in the CD16+IFNα/βR1+CD119- NG subset. The effects of HP on the phenotype of CD16+IFNα/βR1+CD119+NG subsets in 76% of cases were manifested by a decrease in MFI CD16 (p&lt;0.05), an increase in MFI IFNα/βR1 and CD119 (p1, 2&lt;0.05), and in 24% of cases a decrease in MFI IFNα/βR1 (p&lt;0.05). HP in vitro remodeling of the phenotypes subsets CD64- CD16+CD32+CD11b+ and CD64+CD16+CD32+CD11b+ were established, providing the usefulness of effector functions from hyperactivated to normal. In the CD64- CD16+CD32+CD11b+ subset, there was a decrease in MFI CD16 and CD11b to the indicators CG (p1, 2 &lt; 0.05). Recovery of the NG phenotype under the influence of HP led to the restoration of the phagocytic function of NG.Positive effects of HP in vitro on the phenotypes of subsets actively and NGfunctions in COVID-19 open up prospects for the creation of new methods of immunotherapy to restore NG dysfunctions

Environmental and microbial factors influencing methane and nitrous oxide fluxes in Mediterranean cork oak woodlands: trees make a difference

Original Researchinfo:eu-repo/semantics/publishedVersio

Improved isotopic model based on 15N tracing and Rayleightype isotope fractionation for simulating differential sources of N2O emissions in a clay grassland soil

Isotopic signatures of N2O can help distinguish between two sources (fertiliser N or endogenous soil N) of N2O emissions. The contribution of each source to N2O emissions after N‐application is difficult to determine. Here, isotopologue signatures of emitted N2O are used in an improved isotopic model based on Rayleigh‐type equations. The spatial dispersal of N and C significantly affected the quantity, but not the timing, of gas fluxes. Cumulative emissions are larger for treatment 3c than treatment 1c. The 15N‐enrichment analysis shows that initially ~70% of the emitted N2O derived from the applied amendment followed by a constant decrease. The decrease in contribution of the fertiliser N‐pool after an initial increase is sooner and larger for treatment 1c. The Rayleigh‐type model applied to N2O isotopocules data (δ15Nbulk‐N2O values) shows poor agreement with the measurements for the original one‐pool model for treatment 1c; the two‐pool models gives better results when using a third‐order polynomial equation. In contrast, in treatment 3c little difference is observed between the two modelling approaches. The importance of N2O emissions from different N‐pools in soil for the interpretation of N2O isotopocules data was demonstrated using a Rayleigh‐type model. Earlier statements concerning exponential increase in native soil nitrate pool activity highlighted in previous studies should be replaced with a polynomial increase with dependency on both N‐pool sizes.This study was funded by BBSRC project BB/K001051/1. D

The contribution of trees to ecosystem methane emissions in a temperate forested wetland

Wetland-adapted trees are known to transport soil-produced methane (CH4), an important greenhouse gas to the atmosphere, yet seasonal variations and controls on the magnitude of tree-mediated CH4 emissions remain unknown for mature forests. We examined the spatial and temporal variability in stem CH4 emissions in situ and their controls in two wetland-adapted tree species (Alnus glutinosa and Betula pubescens) located in a temperate forested wetland. Soil and herbaceous plant-mediated CH4 emissions from hollows and hummocks also were measured, thus enabling an estimate of contributions from each pathway to total ecosystem flux. Stem CH4 emissions varied significantly between the two tree species, with Alnus glutinosa displaying minimal seasonal variations, while substantial seasonal variations were observed in Betula pubescens. Trees from each species emitted similar quantities of CH4 from their stems regardless of whether they were situated in hollows or hummocks. Soil temperature and pore-water CH4 concentrations best explained annual variability in stem emissions, while wood-specific density and pore-water CH4 concentrations best accounted for between-species variations in stem CH4 emission. Our study demonstrates that tree-mediated CH4 emissions contribute up to 27% of seasonal ecosystem CH4 flux in temperate forested wetland, with the largest relative contributions occurring in spring and winter. Tree-mediated CH4 emissions currently are not included in trace gas budgets of forested wetland. Further work is required to quantify and integrate this transport pathway into CH4 inventories and process-based models

Effects of Mowing on Methane Uptake in a Semiarid Grassland in Northern China

Background: Mowing is a widely adopted management practice for the semiarid steppe in China and affects CH4 exchange. However, the magnitude and the underlying mechanisms for CH 4 uptake in response to mowing remain uncertain. Methodology/Principal Findings: In two consecutive growing seasons, we measured the effect of mowing on CH 4 uptake in a steppe community. Vegetation was mowed to 2 cm (M2), 5 cm (M5), 10 cm (M10), 15 cm (M15) above soil surface, respectively, and control was set as non-mowing (NM). Compared with control, CH4 uptake was substantially enhanced at almost all the mowing treatments except for M15 plots of 2009. CH4 uptake was significantly correlated with soil microbial biomass carbon, microbial biomass nitrogen, and soil moisture. Mowing affects CH 4 uptake primarily through its effect on some biotic factors, such as net primary productivity, soil microbial C\N supply and soil microbial activities, while soil temperature and moisture were less important. Conclusions/Significance: This study found that mowing affects the fluxes of CH4 in the semiarid temperate steppe of north China