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Soil respiration is a very important factor influencing carbon deposition in peat and reflecting the intensity of soil organic matter decomposition, root respiration, and the ease of transporting gases to the surface. Carbon dioxide release from three different peat soil profiles (0-80 cm) of the Polesie Lubelskie Region (Eastern Poland) was analyzed under laboratory conditions. Peat samples were incubated at 5, 10, and 20°C in aerobic and anaerobic environments, and their CO2-evolution was analyzed up to 14 days. The respiration activity was found to be in the range of 0.013-0.497 g CO2 kg-1 DW d-1. The respiratory quotient was estimated to be in the range of 0.51-1.51, and the difference in respiration rates over 10°C ranged between 4.15 and 8.72 in aerobic and from 1.15 to 6.53 in anaerobic conditions. A strong influence of temperature, depth, the degree of peat decomposition, pH, and nitrate content on respiration activity was found. Lack of oxygen at low temperature caused higher respiration activity than under aerobic conditions. These results should be taken into account when the management of Polish peatlands is considered in the context of climate and carbon storage, and physicochemical properties of soil in relation to soil respiration activity are considered.
Properties of peat reflect the peat-forming environment, peat development processes and the types of peat-forming plant. They also enable peat classification and quality evalution. Investigation of the physicochemical properties of organic matter is the key to understanding the history, evolution and geology of bogs. The purpose of this study was to determine some physicochemical properties, such as pH, Eh, electrolytic conductivity, carbon forms in water extracts and dry peat samples (TOC, IC, TC), degree of decomposition, macrofossil plant analysis and ash content, in a whole stratigraphic profile of bog sediment located near Lake Moszne. The research comprised a 17.5 ha lake, which was described in the 1990s as a dystrophic one, and the adjacent mires. The open water surface of the lake is surrounded by a 30–150 m wide belt of floating mat, composed of peatmosses and sedges with the dominant Sphagno-Caricetum rostratae association, all representing vegetation typical for transitional mires. These communities are most often found in the Polesie Lubelskie Region, in old lakes, and usually on their floating mat. The research material was collected from such a site. The analysis demonstrated acidic pH (4.17 in profile I and 4.08 in profile II, respectively) in the layer of 0-0.65 m, whilst from the 1.50 m depth to the mineral bottom the pH increased to nearly neutral (pH = 6.62 ± 0.18 in profile I and pH = 6.45 ± 0.12 in profile II). Redox potential in the surface layer corresponds to good oxygenation of mineral soils: 577 mV and 490 mV for profile I and II, respectively. A nearly linear decrease of Eh was observed to about 118 mV at the depth of 2.50 m. Lower than that, down to the depth of 3.50 m, the Eh value was stabilized. The graphical presentation of the Eh-pH relationship shows that in both cases (profiles I and II) aerobiosis prevails to the depth of 0.45-0.65 m, confirming that oxygen continues to be the final electron acceptor.
The aim of our study was to analyze the impact of such soil physical parameters as water potential (pF), microdiffusion of oxygen (ODR), redox potential (Eh), and air porosity (Eg) on respiration activity (RA), defined as CO₂ evolution after a 10-day soil incubation at 20℃. Moisture content was determined for a range of pF values (0, 1.5, 2.2, 2.7, and 3.2) that corresponded to water availability for usability by microorganisms and plant roots. Selected soil samples were extracted from the following soils layers: surface (0-30 cm), subsurface (30-60 cm), and subsoil (60-100 cm), and were classified (FAO) as Orthic Podzol, Eutric Histosol, and Haplic Phaeozem. ODR, Eh, and Eg increased with higher soil water tension, but generally a high variability of a examined factors was observed. Respiration processes in the surface layers were the most intensive (71.5-91.2 mg CO₂ kg⁻¹d⁻¹), whereas those in the subsurface and the subsoil samples were reduced by 65-98% to the level 1.6-19.2 mg CO₂ kg⁻¹d⁻¹. Our results revealed significant (p<0.001) relationships between soil RA and pF, ODR, and Eh as Eg level. However, correlation coefficients (r) varied as they were indirectly dependent on soil type and depth.
The potential of methanotrophic activity (MTA) has been investigated under labo-ratory conditions in three types of peatland profiles: high (H), transition (T) and low (L) originating from Polesie Lubelskie Region. Selected peat samples differed in respect of pH, TOC, von Post index and moisture. The experiment was conducted at natural moisture (198-719 %w/w) with dif-ferent ranges of both, temperature (5, 10 and 20°C) and CH4 enrichment (1 and 5%v/v). The highest MTA (19.69-155.79 mg CH4kg D.W.-1 d-1) was observed at 20°C. Regardless of temperature, MTA was lower (1.38-51.16 mg CH4 kg D.W.-1 d-1) when peat samples were incubated in atmosphere enriched in 1% than in 5% CH4 v/v (4.75-191.26 mg CH4kg D.W.-1 d-1). Strong influence of tem-perature and sampling sites on MTA was also noted. Total DNA was isolated from the most active (20°C, 5% CH4 v/v) peat samples from each site and the PCR (polimerase chain reaction) amplify-ing of genes pmoA (primers A189f/mb661r) and sequence 16S rRNA (primers Type If /Type Ir and Type IIf/Type IIr) specific for methanotrophic bacteria were carried out. Positive results of PCR with primers of pmoA gene after sequencing confirmed that methanotrophs from L point belong to family Methylococcaceae, while 16S rRNA gene sequences from microorganisms inhabiting H peat demonstrated the highest similarity to genus Methylocystis and Methylosinus.
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