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<p>Ombrotrophic bogs are rainwater-fed, water-logged, anoxic, and carbon-rich ecosystems with low concentrations of dissolved inorganic terminal electron acceptors (TEAs), such as nitrate and sulfate. Consequently, methanogenesis is expected to dominate carbon turnover in many of these systems and to result in an approximatively equimolar formation of CO<sub>2</sub> and CH<sub>4</sub>. Yet, numerous studies have reported elevated molar CO<sub>2</sub>:CH<sub>4</sub> formation ratios in peat bog soil incubations, indicating that anaerobic respiration prevails over methanogenesis despite the apparent scarcity of inorganic TEAs. To explain anaerobic respiration, particulate organic matter (POM) was proposed to act as previously unrecognized TEA. Here, we present results from combined <em>in situ</em> field studies and laboratory peat soil incubations to assess electron transfer to oxidized POM (POM<sub>ox</sub>) and its effects on CO<sub>2</sub> and CH<sub>4</sub> formation. <em>In situ</em> studies consisted of deploying litter mesh bags containing POM<sub>ox</sub> in the anoxic, water saturated subsurface of three ombrotrophic bogs – Lungsmossen (LM), Storhultsmossen (SM), and Björsmossen (BM) – for one year. The electron accepting capacity (EAC) of the retrieved POM decreased by 0.16±0.02 mmol e<sup>-</sup>/g dry POM in LM, 0.15±0.02 in SM, and by 0.17±0.01 mmol e<sup>-</sup>/g dry POM in BM, as compared with the buried POM<sub>ox</sub>, demonstrating extensive electron transfer to the buried POM over the course of one year. Extents of POM<sub>ox</sub> reduction were similar for different depths, as tested in BM bog. Exposure of the reduced POM to air (i.e. O<sub>2</sub>)<sub> </sub>resulted in an increase in its EAC, supporting that POM acts as a reversible TEA at the oxic-anoxic interface of peat soils. We complemented these <em>in situ</em> field studies with laboratory incubations of reduced POM collected from the same three bogs. Methanogenic conditions were observed in BM peat soil incubations, which were used for further studies. Amending BM soils with POM<sub>ox </sub>and glucose resulted in increases in CO<sub>2</sub>:CH<sub>4</sub> formation ratios of several orders of magnitude. These findings pointed towards anaerobic respiration using POM<sub>ox</sub> as TEA, thereby suppressing methanogenesis. Taken together, our work provides evidence for POM<sub>ox</sub> reduction <em>in situ</em> and substantiates the important role of POM as TEA in controlling CH<sub>4</sub> formation in ombrotrophic bogs.</p>

The assessment of potential effects of the application of fly ash in road construction was based on the results of tests of fly ash from two thermal power plants in Serbia and three characteristic soil types: the medium plasticity clay, silty-sandy clay and high plasticity clay. The physical and mechanical characteristics of the stabilization of the above three types of soils with different percentages of fly ash and stabilizers (cement/lime) were determined in the study, and pavement designs for three traffic levels, from 1,000 to 10,000 vehicles/day were developed. The savings that can be achieved by using fly ash are going up to 16.8% depending on the type of material in the subgrade and the level of traffic. The potential savings are higher if the subsoil has lower bearing capacity, and if the traffic level is higher.

Short review of provisions of Eurocode 7 for determination of pile axial bearing capacity is given in this paper. Design guidelines and recommendations for determination of bearing capacity of jacked-in MEGA piles, according to pile installation technology and chosen design approach in National Annex for Eurocode 7 (Part 1) in Serbia are presented. A validation of proposed guidelines through comparison with previous concept of allowable pile force is presented on the example of the rehabilitation of the foundations of a residential building in Zemun, Serbia. Obtained results confirm the adequacy of chosen design approach and proposed guidelines for determination of bearing capacity of MEGA piles.