Peat Soil Profiles Research Articles

Comparison of the transformation of organic matter flux through a raised bog and a blanket bog

AbstractThis study has proposed that organic matter transfer and transformation into and through a peatland is dominated by preferential loss of carbohydrates and the retention of lignin-like molecules. Here we used elemental analysis and thermogravimetric analysis to analyse the biomass, litter, peat soil profile, particulate organic matter, and dissolved organic matter fluxes sampled from a continental raised bog in comparison a maritime blanket bog. The macromolecular composition and thermodynamic analysis showed that in the raised bog there had been little or no transformation of the organic matter and the accumulation was rapid with comparatively little transformation with only 13% loss of cellulose by 1 m depth compared to 92% removal of cellulosic material in the blanket bog. The lack of transformation is reflected in a difference in long term carbon accumulation rates between raised and blanket bog sites. We propose that raised bogs, with their lack of a stream outfall, have high stable water tables that mean the pore water become thermodynamically closed and reactions cease higher in the peat profile than in a blanket bog where sloping sites mean a frequent flushing of pore water and discharge of water leading to fluctuating water tables, flushing of reaction products and pore spaces remaining open.

Variations in the water storage capacity of a mountain peatland with complex stratigraphy

Peatlands in mountain regions commonly occur in valley bottoms and tend to have a complex soil profile due to the geomorphically dynamic environment. Characterization of the specific yield for mountain peatlands is rare despite that it is a parameter that is critical for modelling water table position, determining the water release rate and simulating carbon storage dynamics. The specific yield of a fen peatland in the Canadian Rocky Mountains, Alberta, Canada, was studied along with the factors affecting it. Specific yield was estimated using the water table fluctuation method for 82 rainfall events at a series of shallow well sites, totaling 225 event-well combinations. Specific yield showed strong depth dependency declining logarithmically with depth, but only within the upper 50 cm. Below 50 cm depth, the variability of specific yield increased. Specific yield at depth was controlled by spatial variations in peat-sediment stratigraphy. The bootstrapped, depth-integrated median specific yield [lower, upper 95 % confidence intervals] was 0.21 [0.17, 0.25] for the peat-mineral-gravel soil profile, 0.11 [0.07, 0.16] for the peat-mineral-peat soil profile, and 0.16 [0.12, 0.22] for the Carex-Sphagnum peat soil profile. The analysis also shows a strong effect of year, with lower specific yield occurring in drier years. The study has implications for the modelling of hydrologic and carbon dynamics of mountain fens, and for supporting low flows under climate change.

Geochemical Distribution of Heavy Metals in Peat Soil Profile and Estimation of Water Table Patterns in Peatland at Klias Peninsular, Sabah.

The geochemical distribution of heavy metals in peat soil profile and estimation of water table patterns of peatland in oil palm plantation were carried out in the Klias Peninsular West Coast of Sabah. The geological setting of the Klias Peninsular mainly consists of the Crocker Formation and Quaternary Alluvium which in mainly composed of peat soil. The peat soil from 10 sites were collected for the geochemical analysis. The geophysical surveys were performed to measure the water table, which influenced the concentration of trace metals. The geochemical analysis of the peat soil at 0-6m depth shows an acidic pH value (3.0-4.0), moisture content (90%-1000%) and organic matter content (30-99) %. The texture of the peat soil profile varies from peat at the top of profile to silty clay at the bottom of the peat profile. The result of geochemical analysis shows that the element of Fe has the highest concentration (37.54-2049.18)mg/kg and followed by Zn(5.13-270.06)mg/kg, Mn(0.1-253.56)mg/kg, Pb(0.71-157.46)mg/kg, Cr(0.05-152.62)mg/kg, Ni(0.1-64.48) mg/kg and Cu(1.81-61.39)mg/kg. The water table ranging from (0.25m-0.3m) induced the oxidation of Fe. The concentration of Fe2+ tends to absorb other elements such as Zn and Mn. Whereas, the organic matter at pH value (5-5.5) enhanced the absorption of elements Pb, Cr, Ni and Cu in the peat soil profile.

Variations in peat soil properties at the west coast of Sumatra Island

Peat in coastal areas has different characteristics compared to peat in inland areas because coastal peat usually has high DHL, pyrite, marine sandy substratum, and maturity which is generally classified as hemic to sapric. These variants in soil characteristics drive peculiarity in its management. For this reason, a more detailed information about the characteristics is needed to allow sustainable management and utilization. A total of 78 peat soil samples from 20 peat soil profiles taken over west coast of Sumatra was studied and analyzed for their physical and chemical properties. Field observations were made using a peat auger to determine thickness and maturity, substratum, presence of pyrite, and others. Results showed that peat thickness varied from shallow (50-100 cm), medium (100-200 cm), to very deep (>700 cm); peat situated closer to the coast generally has shallow peat depth. Peat soil in coastal areas contained a mineral soil substrate with a sand content of >70%. It was found that soil had a hemic maturity level and a very acidic to acidic pH value (pH 2.5-5.4). The P2O5 content extracted by 25% HCl varied from low to moderate, while K2O content of 25% HCl extraction was very low. Cations K, Na, and Ca were very low to very high, while Mg spanned from very low to high. Based on its thickness, 25% of peatland were not suitable (Nrc) for general agriculture uses because of >300 cm thickness. Therefore, it is necessary to improve soil fertility and water management in several places.

Distribution of cesium-137 in peat soil of a high-bog depending on the microrelief

Spatial heterogeneity of the distribution of cesium-137 in the upper part of the peat soil profile of the high-bog Sodrinskoe (Mshinskoe swamp nature preserve, Leningrad region, RF) has been established. The horizontal distribution of cesium-137 is significantly influenced by the surface microrelief. Concentration of radionuclide depends on whether the sample was taken in a hollow or from a nearby bump.

Heat Capacity of Drained Peat Soils

Soil-specific heat capacity (cp) and volumetric heat capacity (Cv) are recognized as a fundamental soil property essential for the accurate prediction of soil temperature and heat flow. This study presents the analysis of these thermal properties for drained peat soils in Poland. The objectives of this study were to (i) measure and develop a method for determining cp, (ii) analyze the (Cv) data for undisturbed soil samples from surface layers, and (iii) test the applicability of the cp value for calculating Cv of drained peat soils using the mixing model concept. The cp value was measured under laboratory conditions using a modulated differential scanning calorimetry (MDSC) for 18 soil layers sampled in six degraded peat soil profiles. The Cv was estimated for undisturbed triplicate soil samples from the 22 depths (66 samples) by using a dual-needle probe. The cp data for the organic soils were linearly temperature-dependent (MDSC) for the temperature range considered (−20–30 °C). The overall average cp value was equal to 1.202 J g−1 K−1 at a temperature of 0 °C. An increment in temperature of 1 °C corresponded to an increase in cp of 0.0043 J g−1 K−1 on average. Nevertheless, the lowest cp value was obtained for moss samples whereas the highest value represents alder peats. The Cv data measured using the heat thermal probe (HTP) method changed linearly with changes in the soil moisture content (θv) of the moorsh soils. The volumetric heat capacity calculated using the mixing model was comparable to the mean of measured values obtained on the triplicate samples.

Bacterial Number and Genetic Diversity in a Permafrost Peatland (Western Siberia): Testing a Link with Organic Matter Quality and Elementary Composition of a Peat Soil Profile

Permafrost peatlands, containing a sizable amount of soil organic carbon (OC), play a pivotal role in soil (peat) OC transformation into soluble and volatile forms and greatly contribute to overall natural CO2 and CH4 emissions to the atmosphere under ongoing permafrost thaw and soil OC degradation. Peat microorganisms are largely responsible for the processing of this OC, yet coupled studies of chemical and bacterial parameters in permafrost peatlands are rather limited and geographically biased. Towards testing the possible impact of peat and peat pore water chemical composition on microbial population and diversity, here we present results of a preliminary study of the western Siberia permafrost peatland discontinuous permafrost zone. The quantitative evaluation of microorganisms and determination of microbial diversity along a 100 cm thick peat soil column, which included thawed and frozen peat and bottom mineral horizon, was performed by RT-PCR and 16S rRNA gene-based metagenomic analysis, respectively. Bacteria (mainly Proteobacteria, Acidobacteria, Actinobacteria) strongly dominated the microbial diversity (99% sequences), with a negligible proportion of archaea (0.3–0.5%). There was a systematic evolution of main taxa according to depth, with a maximum of 65% (Acidobacteria) encountered in the active layer, or permafrost boundary (50–60 cm). We also measured C, N, nutrients and ~50 major and trace elements in peat (19 samples) as well as its pore water and dispersed ice (10 samples), sampled over the same core, and we analyzed organic matter quality in six organic and one mineral horizon of this core. Using multiparametric statistics (PCA), we tested the links between the total microbial number and 16S rRNA diversity and chemical composition of both the solid and fluid phase harboring the microorganisms. Under climate warming and permafrost thaw, one can expect a downward movement of the layer of maximal genetic diversity following the active layer thickening. Given a one to two orders of magnitude higher microbial number in the upper (thawed) layers compared to bottom (frozen) layers, an additional 50 cm of peat thawing in western Siberia may sizably increase the total microbial population and biodiversity of active cells.

Organic carbon and nitrogen dynamics during a peatland storm event: How dissolved combined amino acids reveal the spatial and temporal separation of organic molecules

The export of fixed carbon from peatlands is likely important in driving freshwater ecosystem productivity in head water streams. Here we studied the stream composition from three peatlands, and the sub-catchment containing these peatlands, in response to a natural storm event. We investigated the dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) mobilised by this event as well as the dissolved combined amino acids (DCAAs; proteins, peptides and free AAs) component of the DOC/DON. The storm pulse was characterised by a strong DOC/DON/DCAA pulse reflecting the mobilisation of materials from the peat profile. Through the storm cycle a transient increase in the C:N ratio of the DOC was observed (ranging over 20 – 50 across the four sites), likely reflecting the mobilisation of less decomposed material from higher in the peat soil profile. By comparing the DCAA and DON dynamics we show that a DCAA-rich component (fast-DCAA) is mobilised earlier in the storm cycle, likely reflecting a higher mobility in the peat soil. Similarly, comparison of the DCAA and DOC dynamics suggests that at least part of the DOC is mobilised more rapidly than fast-DCAA (fast-DOC). While we may not expect the composition of a storm pulse to be uniform through the cycle, this study shows that within the DOC and DON pools there is spatial and temporal separation of molecular groups. Proteins (in principal) represent both highly bioavailable N-sources as well as potential biological trigger molecules, so our work shows that these compounds are more dominant in the early part (rising limb) of the storm pulse. This understanding of the changing composition of DOC through a storm peak also provides greater insight into the concentration-discharge (C-Q) response of peatlands; our work shows that the activation of water paths higher in the peat profile at high flows leads to the mobilisation of different pools of DOC such that the molecular characteristics of DOC change through the storm cycle.

Holocene development of the Vistula Spit (Baltic Sea coast) based on multidisciplinary investigations

Coastal barriers are the first line of defense for the mainlands against the impacts of severe storms, therefore the need for better understanding how barriers evolve is arising. Spits (barriers) are the dominant landform type of the southern and south-eastern Baltic Sea coast. The aim of this paper is to gain present a better insight into problems of the Vistula Spit origin in general, and especially on the age of formation of the dune ridges. The Vistula Spit is one of the largest barriers on the southern Baltic coast. The analysis comprised: OSL dating of dune sands, radiocarbon dating of peat and palynological studies of peat and fossil soil profiles. Results shows that the onset of the oldest dunes formation begun ca. 7000–6000 years ago and the highest ridge were formed ca. 4000–2000 years ago. The youngest dunes, located closest to the modern shore, formed in the past 2000 years. Aeolian processes were also activated locally and periodically as a result of forest wildfires and human activities. Vistula Spit emergence and development is connected to two global events; beginning of the oldest dunes formation is related to slowing down in the sea level rise around 7000–6000 years ago, whereas the onset of the highest dunes building can be clearly connected with the climate cooling and aridification around 4200 years ago.

Horizontal and Vertical Emissions of Carbon Dioxide and Methane from a Tropical Peat Soil Cultivated with Pineapple (Ananas comosus (L.) Merr.)

Peat soils have been developed for large scale plantations such as oil palm due to their positive contribution to Malaysia’s economic growth in agriculture sector. However, these developments contribute to the emissions of greenhouse gases (GHGs) mainly carbon (CO2) and methane (CH4). To date, there were limited information of GHGs emissions from pineapple cultivation and also inadequate data on horizontally and vertically soil GHGs emissions in peat soil profile. Thus, this study was carried out to determine carbon CO2 and CH4 emissions horizontally and vertically from a drained tropical peat soils from a drained tropical peat soils cultivated with pineapple (Ananas comosus (L.) Merr. Horizontal and vertical movements of CO2 and CH4 were measured from a drained tropical peatland with Ananas comosus (L.) Merr. Tropical peat soils cultivated with Ananas comosus (L.) Merr. contributed to 79.7 % of CO2, and 0.2 % of CH4 based on the yearly basis regardless of the differences in diurnal transportation; horizontal and vertical emission. Soil CO2 and CH4 were emitted the most through horizontal transportation with 70.84 % CO2, and 0.19 % CH4 compared to 8.85 % CO2, and 0.02 % CH4 in vertical transportation. The emission of CO2 was influenced by depth of water table and temperature. It is generally believed that lowering of peats water table leads to emission of higher CO2 emission because this process leads to exposure of peat soils to oxidation. Seasonal variation in CH4 flux was higher in the wet seasons due to rainfall; this might have increased the water table of the peat soil. The results suggest that CO2 and CH4 emissions occur both horizontally and vertically regardless of season. Therefore in order not to underestimate CO2 and CH4 emissions from peat soil, it is important to measure the emissions of this greenhouse gas which has been implicated in environmental pollution horizontally and vertically.

Groundwater dynamics at the hillslope–riparian interface in a year with extreme winter rainfall

Water movement in hillslopes is determined by the subsurface characteristics that control flow paths connecting precipitation to stream flow. The hydrological response of hillslopes is notoriously non-linear and non-stationary; with the relative importance of vertical and lateral flow paths also depending on event characteristics and antecedent conditions. In northern boreal regions, climate change projections indicate that wetter and warmer winter conditions are likely to generate more extreme flood events. Here, we report a study from an upland catchment in northern Scotland where a monitoring year provided an opportunity to contextualise observations during the hillslope response to a winter rainfall event that locally caused the most extreme flooding for over 200 years. Monitoring the hillslope water table, soil moisture and isotopes in precipitation, groundwater and stream flow provided invaluable insight into hillslope–riparian coupling. Groundwater with a shallow water table (<0.05 m deep) in poorly drained valley bottom drift deposits maintained almost fully saturated and stream-connected peat soil profiles in riparian areas. In the wettest periods, the groundwater beneath the peat was artesian. On steeper hillslopes, soils were drier and the water table was generally deeper (0.5–1 m below ground level), though the profile could fully saturate and groundwater levels reach the surface during the wettest period. Groundwater in deeper wells typically showed an anti-clockwise hysteresis compared to stream flow, and peak levels typically lagged behind the stream by a few hours in the valley bottom and >1 day in the upper hillslope. In contrast, shallower wells in the soil profiles in the riparian area showed a more responsive perched groundwater system with transmissivity feedback in the upper soil layers resulting in much more rapid responses which generally peaked before the stream and exhibited clockwise hysteresis. Analysis of stable isotopes in precipitation, groundwater and streamflow, indicated that groundwater was remarkably well mixed with limited fractionation effects, inferring precipitation on the upper, unconfined hillslopes was the dominant source of recharge - particularly during the winter. The study shows that groundwater plays two roles in generating stream flow: a constant baseflow supply to the stream and time varying-exfiltration into the edge of the riparian zone, which contributes to surface runoff during storm events.

A Molecular Budget for a Peatland Based Upon 13C Solid‐State Nuclear Magnetic Resonance

AbstractPeatlands can accumulate organic matter into long‐term carbon (C) storage within the soil profile. This study used solid‐state 13C nuclear magnetic resonance (13C‐NMR) to investigate the transit of organic C through a peatland ecosystem to understand the molecular budget that accompanies the long‐term accumulation of C. Samples of biomass, litter, peat soil profile, particulate organic matter, and dissolved organic matter (DOM) were taken from the Moor House National Nature Reserve, a peat‐covered catchment in northern England where both the dry matter and C budget for the ecosystem were known. The results showed that: The interpretation of the 13C‐NMR spectra shows that polysaccharides are preferentially removed through the ecosystem, while lignin components are preferentially retained and come to dominate the organic matter accumulated at depth in the profile. The DOM is derived from the oxidation of both biomass and the degradation of lignin, while the particulate organic matter is derived from erosion of the peat profile. The DOM is differentiated by its proportion of oxidized functional groups and not by its aromatic content. The changes in functionality leading to DOM production suggest side chain oxidation resulting in C‐C cleavage/depolymerisation of lignin, a common reaction within white rot fungi. The 13C‐NMR budget shows that O‐alkyl functional groups are disproportionately lost between primary production and accumulation in the deep peat, while C‐alkyl functional groups are disproportionately preserved. The carbon lost as gases (CO2 and CH4) was estimated to be composed of 93% polysaccharide‐derived carbon and 7% lignin‐derived carbon.

The flux of organic matter through a peatland ecosystem: The role of cellulose, lignin, and their control of the ecosystem oxidation state

This study used thermogravimetric analysis (TGA) to study the transit of organic C through a peatland ecosystem. The biomass, litter, peat soil profile, particulate organic matter (POM), and dissolved organic matter (DOM) fluxes were sampled from the Moor House National Nature Reserve, a peat-covered catchment in northern England where both the dry matter and carbon budget for the catchment were known. The study showed that although TGA traces showed distinct differences between organic matter reservoirs and fluxes, the traces could not readily be associated with particular functionalities or elemental properties. The TGA trace shows that polysaccharides are preferentially removed by humification and degradation with residual peat being dominated by lignin compositions. The DOM is derived from the degradation of lignin while the POM is derived from erosion of the peat profile. The carbon lost as gases (CO2 and CH4) was estimated to be composed of 92 to 95% polysaccharide carbon. The composition of the organic matter lost from the peat ecosystem means that the oxidative ratio (OR) of the ecosystem experienced by the atmosphere was between 0.96 and 0.99: currently, the Intergovernmental Panel on Climate Change uses an OR value of 1.1 for all ecosystems.

Impact of land use change on profile distributions of organic carbon fractions in peat and mineral soils in Northeast China

The impact of land use on the content of labile soil organic carbon (SOC) has been studied well. However, limited information is known about its effect on the recalcitrant SOC pool, which is a key proxy for long-term carbon sequestration. We investigated the impact of land use change on the distribution of labile and recalcitrant SOC fractions in soil profiles (0–30cm) in the Jinchuan peatland, Northeast China, where native peatland (with peat soil) and forest (with mineral soil) are converted to paddy and cropland, respectively. Peat and mineral soil profile samples were collected from 10 sites in native and cultivated land. Total organic carbon (TOC) and KMnO4-oxidizable carbon (KOC) defined as the labile SOC fraction were measured in both peat and mineral soils. Fibre and lignin were also determined in peat samples. The mineral-associated organic carbon (MOC) and black carbon were examined as two recalcitrant SOC fractions. In peat soil profiles, the TOC and KOC contents increased with the increasing depth across all land uses. The conversion of peatland to paddy field can affect TOC content at each peat soil depth. The KOC content was lower in cultivated soils, indicating that cultivation decreased KOC. The KOC decrease was smaller than the TOC decrease, indicating that some recalcitrant SOC fractions were decomposed because of land use change. Unlike peat soil profiles, the TOC and KOC contents decreased with depth in mineral soil profiles across all land uses. The TOC and KOC contents in surface soil decreased remarkably after cultivation to cropland but were not affected in deep soil. Interestingly, recalcitrant SOC fractions, such as MOC, increased in mineral soil profile after cultivation but showed no change in peat soil profile. This study suggests that conversion of peatland to paddy can release the recalcitrant SOC fraction. In addition, conversion of cultivated forest to cropland decreased the TOC content but prolonged the long-term storage of some recalcitrant SOC fractions, such as MOC.

Physical and Chemical Properties of Cultivated Peat Soils in Four Trial Sites of ICCTF in Kalimantan and Sumatra, Indonesia

The large distribution of peat soils in Indonesia have important role in carbon stock and greenhouse gas emission which contribute to global warming issue. The objective of this study was to characterize physical and chemical properties of cultivated peat soils in four trial sites of Indonesia Climate Change Trust Fund (ICCTF) in Central Kalimantan, South Kalimantan, Riau and Jambi Provinces to provide a baseline data by a greenhouse gas emission study. Detailed soil observations were conducted using grid system with spacing of 25 × 50 m. A total of 16 representative peat soil profiles consisting of 74 soil samples of horizons were selected for laboratory analyses. The results showed that peat maturity varied from hemic to sapric in the surface layers and hemic in the subsurface layers, except in Site-2 that was fibric. The peat thickness ranged respectively from 5.4 to 7.0 m in Site-1 and Site-3, and from 0.5 to 2.5 m in site-2 and site-4, and all overlying fine-textured mineral soil (substratum). Depth of water table varied from 10 to 30 cm in Site-2 and Site-4, and from 30 to 70 cm in Site-1 and Site-3. Fiber content ranged from 13 to 57% and increased with depth indicating the peat was less decomposed. The bulk density was very low (0.07-0.24 g cm-3) and negatively correlated to fiber content (r = 0.74 for Kalimantan and r = 0.66 for Sumatra). The ash content was low (0.1-8.5%) and negatively correlated to organic carbon content (r = 0.89 for Kalimantan and r = 0.65 for Sumatra). Soil CEC was high and positively correlated to organic carbon content (r = 0.86 for Kalimantan and r = 0.93 for Sumatra). These soils showed very acid reaction (pH 3.3-4.7), low content of exchangeable bases and total P2O5 and K2O (HCl 25%). Based on these properties, the peat soils were grouped as oligotrophic ombrogenous peat. The estimated carbon stock for all the trial sites with total extent of 22.58 ha was 57,282 Mg C. The variation of thickness, maturity, and water table depth will imply to the magnitude of carbon reserves and greenhouse gas emissions. [How to Cite: Hikmatullah and Sukarman. 2014. Physical and Chemical Properties of Cultivated Peat Soils in Four Trial Sites of ICCTF in Kalimantan and Sumatra, Indonesia. J Trop Soils 19: 131-141. Doi: 10.5400/jts.2014.19.3.131]

Mitigating greenhouse gas fluxes from cultivated organic soils with raised water table

Cultivated organic soils are a remarkable source of greenhouse gases (GHG) in many countries. Keeping the ground water table as high as possible could lower the mineralization rate of the peat and thus the emissions of carbon dioxide (CO2) and nitrous oxide (N2O) from these soils. We studied the effect of raised water table on the emissions of N2O, CO2 and methane (CH4) from undisturbed peat soil profiles of six different Finnish cultivated organic soils during a 5-week outdoor mesocosm experiment. The aim was to determine an optimum water table that would enable grass cultivation but lower the net gas balance of the soil. Raised water table decreased the GHG emissions from each peat type ranging from weakly decomposed Sphagnum peat to highly humified Carex peat. Based on the results, the optimum water table would be 30 cm below the soil surface. The average reduction of the total net emissions with a raise of water table from a typical drainage depth of 70 to 30 cm was 42 % in the outdoors mesocosm experiment and 23 % at a constant temperature (+6 °C). The emissions of both CO2 and N2O declined and the net consumption of CH4 changed to net production as the water table rose. The results were confirmed by long-term measurements at one of the sampled sites. As a conclusion, we see that promoting drainage systems enabling raising of the ground water table and cultivation of crops capable of producing good yields also in wet conditions would be beneficial for the GHG mitigation in agriculture.

Aerobic and Anaerobic Respiration in Profiles of Polesie Lubelskie Peatlands

Abstract 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.

Metagenomic Insights into Anaerobic Metabolism along an Arctic Peat Soil Profile

A metagenomic analysis was performed on a soil profile from a wet tundra site in northern Alaska. The goal was to link existing biogeochemical knowledge of the system with the organisms and genes responsible for the relevant metabolic pathways. We specifically investigated how the importance of iron (Fe) oxides and humic substances (HS) as terminal electron acceptors in this ecosystem is expressed genetically, and how respiratory and fermentative processes varied with soil depth into the active layer and into the upper permafrost. Overall, the metagenomes reflected a microbial community enriched in a diverse range of anaerobic pathways, with a preponderance of known Fe reducing species at all depths in the profile. The abundance of sequences associated with anaerobic metabolic processes generally increased with depth, while aerobic cytochrome c oxidases decreased. Methanogenesis genes and methanogen genomes followed the pattern of CH4 fluxes : they increased steeply with depth into the active layer, but declined somewhat over the transition zone between the lower active layer and the upper permafrost. The latter was relatively enriched in fermentative and anaerobic respiratory pathways. A survey of decaheme cytochromes (MtrA, MtrC and their homologs) revealed that this is a promising approach to identifying potential reducers of Fe(III) or HS, and indicated a possible role for Acidobacteria as Fe reducers in these soils. Methanogens appear to coexist in the same layers, though in lower abundance, with Fe reducing bacteria and other potential competitors, including acetogens. These observations provide a rich set of hypotheses for further targeted study.

The soil fungi communities of peat soils in the Narew National Park

The study was conducted in the years 2003-2004 on four low peatland peat soil profiles located in the Narew National Park. All studied soils were sedge peat soils sampled from various habitats. The recognition of the soil fungi communities and their stratification in the studied profiles were the aim of the study. The 214 isolates were made, which were represented by 45 species. The reason for little differentiation of quantitative-qualitative structures of soil fungi communities in peat soils is their high moisture. The distinct differentiation among the soil fungi communities was observed. These results suggest that not only the soil-forming process affects the soil fungi communities development but also the soil properties, which were under influence in the past and have been still affected by the habitat conditions, are very important to the development process of soil fungi communities.

137Cs in a raised bog in central Sweden

The vertical distribution of 137Cs activity in peat soil profiles and 137Cs activity concentration in plants of various species was studied in samples collected at two sites on a raised bog in central Sweden. One site (open bog) was in an area with no trees and only a few sparsely growing plant species, while the other (low pine) was less than 100 m from the open bog site and had slowly growing Scots pine, a field layer dominated by some ericaceous plants and ground well-covered by plants. The plant samples were collected in 2004–2007 and were compared with samples collected in 1989 from the same open bog and low pine sites. Ground deposition of 137Cs in 2005 was similar at both sites, 23 000 Bq m −2. In the open bog peat profile it seems to be an upward transport of caesium since a clear peak of 137Cs activity was found in the uppermost 1–4 cm of Sphagnum layers, whereas at the low pine site 137Cs was mainly found in deeper (10–12 cm) layers. The migration rate was 0.57 cm yr −1 at the open bog site and the migration centre of 137Cs was at a depth of 10.7, while the rate at the low pine site was 0.78 cm yr −1 and the migration centre was at 14.9 cm. Heather ( Calluna vulgaris) was the plant species with the highest 137Cs activity concentrations at both sites, 43.5 k Bq −1 DM in 1989 decreasing to 20.4 in 2004–2007 on open bog and 22.3 k Bq kg −1 DM in 1989 decreasing to 11.2 k Bq −1 DM by the period 2004–2007 on the low pine site. 137Cs transfer factors in plants varied between 0.88 and 1.35 on the open bog and between 0.48 and 0.69 m 2 kg −1 DM at the low pine site.