The article presents the results of research on the bioproductivity of ecologically clean waste generated during excavation work on subway construction sites and other underground construction. It is ...proposed to use waste as one of the components of soil mixture preparation. In the course of the work, soil mixtures varied in relation to the waste/peat soil. A number of laboratory experiments on the germination of a lawn grass mixture, widely used in the improvement of cities, was set up. Based on the results of the work, recommendations were proposed for compiling a methodology for studying artificial soil mixtures.
Soil organic matter (SOM) in arctic and boreal soils is the largest terrestrial reservoir of carbon. Increased SOM mineralisation under increased temperature has the potential to induce a massive ...release of CO2. Precise parameterisation of the response of arctic soils to increased temperatures is therefore crucial for correctly simulating our future climate. Here, we investigated the temperature response of SOM mineralisation in eight arctic soil profiles of Norway, Svalbard and Russia. Samples were collected at two depths from both mineral and organic soils, which were affected or not by permafrost and were incubated for 91 days at 4, 8, 12, and 16 °C. Temperature response was investigated through two parameters derived from a simple exponential model: the intensity of mineralisation, α, and the temperature sensitivity, Q10. For each sample, SOM quality was investigated by 13C-NMR, whereas bacterial and fungal community structure was characterised by T-RFLP and ARISA fingerprints, respectively. When estimated from the whole incubation period, α proved to be higher in deep permafrost samples than in shallow active layer ones due to the presence transient flushes of mineralisation in deep permafrost affected soils. At the end of the incubation period, after mineralization flushes had passed, neither α nor Q10 (averaging 1.28 ± 0.07) seemed to be affected by soil type (organic vs mineral soil), site, depth or permafrost. SOM composition and microbial community structure on the contrary where affected by site and soil type. Our results suggest that deep samples of permafrost affected soil contain a small pool of fast cycling carbon, which is quickly depleted after thawing. Once the mineralization flush had passed, the temperature response of permafrost affected soil proved to be relatively homogenous among sample types, suggesting that the use of a single temperature sensitivity parameter in land surface models for SOM decomposition in permafrost-affected soils is justified.
•Temperature response of SOM mineralization studied in profiles for 3 Arctic sites.•Initial mineralization intensity higher in permafrost than active layers.•Uniform Q10 among samples (1.21–1.43).•OM composition and microbial community structure site specific, not depth related.•OM and microbes not directly linked to mineralization intensity and Q10.
•Growth synchrony patterns of Siberian Scots pine populations are driven by climate.•Growth synchrony in sites with mineral soil has increased but decreased in peats.•High fire occurrence reduced ...synchrony in frequently burned sites since mid-1980s.•Growth suppressions allow reconstructing past fire occurrence.•Post-fire legacies last from 1-5 years depending on soil type, fire and tree features.
Wildfires are the main disturbance of boreal ecosystems, one of the largest reservoirs of terrestrial carbon. Two-thirds of boreal forests are in Siberia, where peatlands commonly appear mixed with mineral soils. Siberian forests are currently facing a dual shift in environmental conditions regarding climate change and increased fire activity. Therefore, assessing growth patterns of trees subjected to different disturbance regimes is essential to understand the impact of ongoing environmental changes on forest functioning. Following a dendroecological approach, we aimed at analyzing spatial synchrony (âC) patterns of trees subjected to different ecohydrological and fire disturbance conditions in forests of Pinus sylvestris of south-western Siberia. Furthermore, we assessed growth suppression as a proxy for fire occurrence based on tree-ring width chronologies after removing climate signals. Our results endorsed climate as the main driver of âC, which showed different trends depending on substrate type. A release of temperature constraints in the more temperature-limited peat soils led to decreasing âC from mid-1960s onwards, while the opposite pattern was found in mineral soils where stronger reliance on summer precipitation progressively increased âC. However, frequently burned stands suffered a sharp reduction in âC since 1980s likely due to the decoupling of growth from climate as a result of an increase in fire activity. Strong replication of growth suppressions supported by historical and palaeoecological records pointed to 1915, 1952, 1977, 1983, 2003 and 2012 as potential fire years. Post-fire legacies on tree growth after such fire events lasted from one to five years, although differences were modulated by soil type, fire event, growth rate prior fire and tree age. This study highlights the usefulness of addressing spatial synchrony in tree growth and past growth suppressions to disentangle the impacts of climate change and increased fire occurrence on boreal forests.
•First pore-scale simulation in peat and 3D characterization of peat pore space.•Good match between pore network model and direct numerical simulation results.•Calculated hydraulic conductivity (K) ...and dispersivity matched measured values.•K and effective diffusion coefficient decrease with depth in peat soil.•K is locally isotropic, but becomes anisotropic after upscaling to field-scale.
Micro-scale properties of peat pore space and their influence on hydraulic and transport properties of peat soils have been given little attention so far. Characterizing the variation of these properties in a peat profile can increase our knowledge on the processes controlling contaminant transport through peatlands. As opposed to the common macro-scale (or bulk) representation of groundwater flow and transport processes, a pore network model (PNM) simulates flow and transport processes within individual pores. Here, a pore network modeling code capable of simulating advective and diffusive transport processes through a 3D unstructured pore network was developed; its predictive performance was evaluated by comparing its results to empirical values and to the results of computational fluid dynamics (CFD) simulations. This is the first time that peat pore networks have been extracted from X-ray micro-computed tomography (µCT) images of peat deposits and peat pore characteristics evaluated in a 3D approach. Water flow and solute transport were modeled in the unstructured pore networks mapped directly from µCT images. The modeling results were processed to determine the bulk properties of peat deposits. Results portray the commonly observed decrease in hydraulic conductivity with depth, which was attributed to the reduction of pore radius and increase in pore tortuosity. The increase in pore tortuosity with depth was associated with more decomposed peat soil and decreasing pore coordination number with depth, which extended the flow path of fluid particles. Results also revealed that hydraulic conductivity is isotropic locally, but becomes anisotropic after upscaling to core-scale; this suggests the anisotropy of peat hydraulic conductivity observed in core-scale and field-scale is due to the strong heterogeneity in the vertical dimension that is imposed by the layered structure of peat soils. Transport simulations revealed that for a given solute, the effective diffusion coefficient decreases with depth due to the corresponding increase of diffusional tortuosity. Longitudinal dispersivity of peat also was computed by analyzing advective-dominant transport simulations that showed peat dispersivity is similar to the empirical values reported in the same peat soil; it is not sensitive to soil depth and does not vary much along the soil profile.
Global demand for milk is increasing, however, the dairy sector has considerable environmental impact and cattle are large contributors to greenhouse gas (GHG) emissions that lead to global warming. ...In a circular food system, the role of animals should be to convert biomass that humans cannot or do not want to eat into nutrient-dense products. In this system, dairy cows are only fed with grass from marginal lands and by-products from harvesting and food industries. One example of marginal land are peat areas, since these soils are mainly too wet for arable crop production. However, drainage caused peat to oxidize and emit CO2 and N2O.
The objective of this study was to evaluate global warming potential (GWP) and economic performance of Dutch dairy farms on peat compared to sandy soil. Also, two scenarios that might reduce GHG emissions of a dairy farm on peat soil were considered: 1) increased groundwater tables and 2) an adjusted dairy cow diet consisting of grass and by-products only.
A whole-farm linear programming (LP) model used for dairy farms on sandy soil was updated and adjusted to simulate structure, management and labour income of a dairy farm on peat soil. The basic LP model is a static year model that includes all relevant activities and constraints that are common to a Dutch dairy farm and the solution generates feeding management, manure application and land use. The objective function maximized labour income. In addition, the linear model was combined with a Life-Cycle Assessment to determine the GWP of the produced milk, economically allocated between milk and meat.
The results of this study showed that dairy farms on peat soil have lower labour income and considerably higher GWP compared to dairy farms on sandy soil. When the groundwater table on peat soil was increased, labour income decreased even more, however GHG emissions were somewhat reduced. Feeding a dairy cow diet with only grass and by-products resulted in higher labour income, but equal GWP compared to a regular dairy farm on peat soil. A sensitivity analysis was performed to explore the effect of grass yield on the economic and environmental performance of dairy farms on peat soil.
Dairy farms on peat soils have lower labour income and considerably higher GWP compared to sandy soils. Improvement of GWP is possible and can lead to increased labour income.
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•Peat soils are mainly too wet for arable crop production, however, drainage of the soil causes peat to oxidize and emit CO2 and N2O.•The objective of this study was to evaluate global warming potential and economic performance of Dutch dairy farms on peat compared to sandy soil.•Dairy farms on peat soil have lower labour income and considerably higher global warming potential compared to sandy soil.•Higher groundwater table on peat soil decreased greenhouse gas emissions and feeding cattle only grass and by-products increased labour income.•Improvement of global warming potential of dairy farms on peat soil is possible and can lead to increased labour income.
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•Peat soil and lignite were added in UASB to study phenolic wastewater treatment.•Peat soil improved phenols degradation but lignite showed poor removal performance.•Peat soil ...enhanced the secretion of EPS and F420 following higher phenols removal.•Peat soil facilitated the growth of syntrophic fermentation bacteria and methanogens.
Two humic-rich natural materials namely peat soil and lignite were supplemented in up-flow anaerobic sludge blanket (UASB) bioreactors for the treatment of phenolic wastewater. Peat soil improved phenol degradation and resistance to shock load; ultimately, contributing to higher COD removal efficiency (83.3%), methane production (4532 mL d-1), and better reactor’s stability. Accordingly, the amount of extracellular polymeric substances (EPS) and coenzyme F420 in sludge were increased to 1.3-fold and 2.5-fold, respectively, as compared to the control treatment. The addition of lignite however displayed poor phenol degradation and no effects on the secretion of EPS and F420. The peat soil significantly influenced the microbial community structures, whereas the effect of lignite was inconspicuous. In the presence of peat soil, the abundance of syntrophic fermentation bacteria and methanogens was significantly increased. This study illustrates the potential use of peat soil in UASB for the treatment of phenolic wastewaters.
Drained peatlands are a global concern due to alterations of the water and carbon cycle, loss of habitat, and increased fire frequency. However, methods for restoring drained sloping peatlands are ...limited and poorly tested. Therefore, we measured water table dynamics, CO₂ fluxes, and soil properties at four sloping fens that were restored (1–20 years post‐restoration) with the installation of small check dams in ditches that had drained the sites for a century. Restoration had a positive effect on water tables, increasing from approximately 45 cm below the surface to approximately 15 cm below the surface during the summers. Restoration also benefited CO₂ fluxes, as the mean net ecosystem exchange was greatest in the restored areas (−2.19 g CO₂ m⁻² hour‐¹) compared to the unrestored drained areas (−1.28 g CO₂ m⁻² hour⁻¹), while in reference areas it was −1.74 g CO₂ m⁻² hour⁻¹. Drainage also caused significant changes to the peat soil including: 25% reduction in soil organic matter (lost between 1.4 to 3.6 kg/m²), increased bulk density, decreased porosity, and reduced saturated hydraulic conductivity. Restoration did not affect these parameters, even 20 years after restoration. This study suggests that although natural water table levels have been reestablished and the process of carbon sequestration improved, the physical properties of the most disturbed, near surface peat soils do not mimic reference conditions 20 years post‐restoration.
Rewetted peatlands are reestablished hot spots for CH4 emissions, which are subject to increased drought events in the course of climate change. However, the dynamics of soil methane-cycling ...microbiomes in rewetted peatlands during summer drought are still poorly characterized. Using a quantitative metatranscriptomic approach, we investigated the changes in the transcript abundances of methanogen and methanotroph rRNA, as well as mcrA and pmoA mRNA before, during, and after the 2018 summer drought in a coastal and a percolation fen in northern Germany. Drought changed the community structure of methane-cycling microbiomes and decreased the CH4 fluxes as well as the rRNA and mRNA transcript abundances of methanogens and methanotrophs, but they showed no recovery or increase after the drought ended. The rRNA transcript abundance of methanogens was not correlated with CH4 fluxes in both fens. In the percolation fen, however, the mcrA transcript abundance showed a positive and significant correlation with CH4 fluxes. Importantly, when integrating pmoA abundance, a stronger correlation was observed between CH4 fluxes and mcrA/pmoA, suggesting that relationships between methanogens and methanotrophs are the key determinant of CH4 turnover. Our study provides a comprehensive understanding of the methane-cycling microbiome feedbacks to drought events in rewetted peatlands.
Oil palm (Elaeis guineensis Jacq.) production in Indonesia and Malaysia is currently the focus of concern due to its potential impact on the environment via greenhouse gas emissions. Oil palm ...plantations have been reported to release large quantities of nitrous oxide (N ₂O) into the atmosphere, which is most likely linked to nitrogen (N) fertilizer use. However, there are still limited studies comparing effects of the type of soil and N fertilizer on N ₂O and carbon dioxide (CO ₂) emissions. This study aimed to evaluate the effects of soil types and N fertilizer on N ₂O and CO ₂ emissions in oil palm plantations. N ₂O and CO ₂ emissions were measured for 15–16 months from 2010–2012 in Tunggal sandy loam soil, Indonesia, and in Simunjan sandy soil and Tatau peat soil, Malaysia. Within each site, treatments with coated fertilizer and conventional fertilizer, and unfertilized with and without tillage, were established. N ₂O and CO ₂ fluxes showed high variabilities with seasons, types of soil and fertilizer treatments. The mean of the N ₂O fluxes from each treatment in the Simunjan sandy soil was the lowest among the three soils, ranging from 0.80 to 3.81 and 1.63 to 5.34 μg N m ⁻² h ⁻¹ in the wet and dry seasons, respectively. The mean of the N ₂O fluxes from each treatment in the Tunggal sandy loam soil ranged from 27.4 to 89.7 and 6.27 to 19.1 μg N m ⁻² h ⁻¹ in the wet and dry seasons, respectively. The mean of the N ₂O fluxes was found to be the highest among the three soils in each treatment of the Tatau peat soil, ranging from 131 to 523 and 66.1 to 606 μg N m ⁻² h ⁻¹ in the wet and dry seasons, respectively. The N application rate of coated fertilizer was about half that of conventional fertilizer and was applied as deep placement. In the Tungal soil, coated fertilizer reduced N ₂O emissions by 31 and 48% in wet and dry seasons, respectively, compared to the conventional fertilizer, and was similar to unfertilized treatment. However, N ₂O emissions increased in Simunjan and Tatau soils during dry seasons. There was no significant difference between treatments. These results show that N ₂O and CO ₂ fluxes in the tropical oil palm plantations were significantly affected by the type of soil, but not always by fertilizer treatments.
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