Chemical stabilization--the mixing of additives like cement, lime, or fly-ash with soil to improve its mechanical properties-- conventionally relies on hydration reactions to generate a binder. Accelerated soil carbonation is a nascent alternative method, whereby carbon dioxide is intentionally introduced in soil mixed with alkali additives to generate a carbonate binder and sequester carbon dioxide. Non-plastic sand and silt specimens mixed with hydrated lime were carbonated for varying amounts of time at different water contents and densities to evaluate the index properties influencing the rate of carbonation and degree of mechanical improvement. It was demonstrated that volumetric air and water contents primarily govern the rate of binder formation and that mechanical properties are influenced by the carbonate binder content and density. Under optimum conditions, soil specimens could be fully carbonated within 3-24 h and unconfined compressive strengths as great as 3-4 MPa were achieved. The degree of strength improvement is comparable to cement-stabilized materials and has a similar dependence on soil type, density, and binder content. If techniques are developed that enable carbonation at scale, the sequestration of carbon dioxide would offset emissions associated with production of chemical additives used for chemical stabilization.

Generally, nanotechnology plays an very important role in various applied scientific fields. Iron and magnesium nanoparticles (NPs) can cause positive or negative changes in soil physical and mechanical properties, especially in long periods. The aim of this study was to investigate the multi-year effects of NPs on soil water retention and aggregate tensile strength. A wheat farm loamy soil was amended with 1%, 3%, and 5% (weight/weight) of magnesium oxide (MgO) and iron oxide (Fe3O4) NPs in three replications and incubated for three years. Water contents were measured at different matric suctions of 0, 10, 20, 40, 60, 100, 300, 1 000, and 15 000 cm. The van Genuchten model was fitted to the moisture data. Tensile strength was measured on the 2-4 mm aggregates at matric suctions of 300 (i.e., field capacity) and 15 000 (i.e., permanent wilting point) cm. The results showed that the levels of 1% and 3% Fe3O4 NPs significantly increased water retention, compared to the no NP application control and 5% MgO NPs, which is probably due to the increase of adsorption surfaces in the treated soils. Water contents at field capacity and permanent wilting point in the 5% MgO NP treatment decreased compared to those of the other treatments, due to the increased soil vulnerability and reduced soil fine pores. The application of Fe3O4 NPs did not have any significant effect on soil tensile strength. Based on the results of this study, soil physical and mechanical properties could be affected by NP application.

Wet fen meadows under traditional land use are nowadays mainly preserved through nature conservation measures. Recent discussions suggest that this land use may also be regarded as a form of paludiculture - that is, use of wet peatland with preservation of the peat body. However, the climate effect of this land use type is largely unknown. This study presents full two-year greenhouse gas (GHG) balances for two previously unexplored, long-term rewetted fens under a nature conservation management regime. Closed-chamber GHG fluxes were measured biweekly at two north-east German sites with acute sedge (Carex acuta) and at one site with creeping bentgrass (Agrostis stolonifera). Including harvest and dissolved carbon export, the CO2-eq emissions of the three sites were between 10.4 and 16.3 t ha(-1) yr(-1), with mean annual water levels between -10 and -19 cm relative to ground level. Emissions consisted mainly of CO(2 )uptake and release and were influenced by the timing and frequency of harvests as well as by periods of surface flooding during the growing season. CH4 emissions also contributed to the net GHG balances at two of the sites due to inundation in late summer 2014. N2O emissions were of minor importance at all three sites. This study shows that, with proper water management, the climate effect of fen meadows under management for nature conservation can be similar to that of other fen paludicultures, with a CO2-eq GHG mitigation potential of 15-20 t ha(-1) yr(-1) compared to drainage-based grassland use of fens. Therefore, for GHG reporting purposes, it may be justifiable to treat existing wet fen meadows under nature conservation management as paludicultures.

The main purpose of this article is to evaluate the influence of sand-gravel quarrying from the river bed on the bed deformation and the environment. Sand and gravel reserves are the second largest produced and traded resource after water. Every year, the demand for these materials in the world is 40-50 billion m3. Large-scale quarrying of sand and gravel from sea coasts and river beds leads to serious problems. Thus, the sand and gravel quarried from the sea shores cause flooding of the coastal zones, and the quarrying from the river beds leads to strong deformations. The sand resources produced from the seashores in Azerbaijan do not meet the current growing demand in the ever-expanding construction sector, and at the same time, they do not meet the quality standards. Therefore, the quarrying of sand and gravel from river beds has become an increasingly important process. Production of sand and gravel from river beds seriously impacts not only bed deformation but also the environment, flora, and fauna. The expansion of the river bed has led to the destruction of the forest areas, and the deepening has led to the depletion and disappearance of fish resources. Excavation works in the river bed also affect the infrastructure. Thus, the soil-cement road passing near the area where the excavation works were carried out, the bridge, and the electric columns have undergone influence. Therefore, as a result of the impact of anthropogenic factors in the Valvalachay River, the damage it caused to the environment was studied. Many parameters were measured in the Valvelachay River, and water consumption entering and leaving the holt was compared. For observation of changes along the river, a longitudinal profile in the study area was compiled based on the DEM (Digital Elevation Model) and topographic measurements in the ArcGIS program. Based on topographical and bathymetric measurements, it was determined that the depth in the part where the bed is deepened (the place where cobble gravel is mined) varies between 1.5-2 meters.