18,328 research outputs found
The Inorganic Geochemistry Of Peats And The Physical Chemistry Of Waters From Some Sphagnum Bogs (volumes I And Ii)
Carbon dioxide {dollar}(10\sp{lcub}-1.5{rcub}{dollar} atm), acetic acid (0.5 mg {dollar}\ell\sp{lcub}-1{rcub}),{dollar} and oxalic acid (0.1-0.4 mg {dollar}\ell\sp{lcub}-1{rcub}){dollar} contribute to the low pH (approximately 4) of bog surface waters. Calculations using pH, {dollar}{lcub}\rm SO{rcub}\sb{lcub}4{rcub}\sp{lcub}2-{rcub},{dollar} and total dissolved sulphide show that log {dollar}{lcub}\rm P\sb{lcub}O\sb{lcub}2{rcub}{rcub}{rcub} = -70{dollar} atm. Oxalic and other low molecular weight organic acids are important ligands for Al, Cu, Fe, Pb, and U in these waters.;The concentrations of Na and Mg in the maritime peats exceed their concentrations in the continental bog by more than 3 times, reflecting inputs from sea spray. The Ca contents of Luther bog peats exceed their concentrations in Barrington bog peats by more than 2 times, reflecting the composition of the underlying till (40% calcite). The Al contents of the peats at the two bogs also reflect differences in till lithology (limestone- versus granite-derived).;The vertical distributions of Cr, Ni, and V generally follow ash, and relative to typical crustal abundance, these metals are neither enriched nor depleted in the peats studied here. In acidic, anaerobic peats, Fe and Mn are relatively depleted. On average, the peats studied here are depleted in Fe and Mn by 2 times, relative to typical crustal abundance. In contrast, Cu is enriched in the peats by a factor of 2 times, and U 4 times, relative to typical crustal abundance, and these enrichments reflect their diminished solubility under anaerobic conditions. Zinc and Pb are enriched in the peats too, by factors of 2 times and 9 times, respectively, due to anthropogenic contributions. The following order of relative inorganic association is proposed for trace metals in peats: {dollar}{lcub}\rm Ni - V \u3e Cr \u3e Fe \u3e Mn \u3e Cu = U \u3e Zn \u3e Pb{rcub}{dollar};The literature on the geochemistry of peats and peatlands is critically reviewed
Effect of cement on compressibility and microstructure of tropical peat
Peats are geotechnically problematic soil due to their high compressibility and low shear strength. Cement is widely used for the stabilization of peat by deep mixing method (DMM). This paper presents the results of the model study of compressibility property of peats stabilized with cement columns formed by DMM. The results of consolidation test, scanning electron micrographs (SEM) and energy dispersive x-ray spectrometer (EDX) showed that the compressibility of peats can be improved significantly by the installation of cement stabilized columns. The amount of cement used to form the column was observed to influence the engineering behaviour of treated tropical peats and it had more influence on sapric peat than on hemic and fibrous peats
Сравнительная характеристика торфов Томской области и республики Алтай
В данной работе была проведена сравнительная характеристика торфов Томской области и республики Алтай. Для этих торфов были определены технический и групповой составы.
В результате исследований выявлено, что торфа с месторождений Томской области и республики Алтай отличаются по степени разложения и зольности. В торфах республики Алтай получили большее содержание гуминовых кислот и лигнина по сравнению с торфами Томской области .
Кроме этого, в торфах республики Алтай выявлено низкое содержание битумов и углеводного комплекса и повышенное содержание гуминовых кислот и лигнина. Установлено, что на базе месторождений республики Алтай возможна организация производства гуминовых кислот и битумов в ограниченных размерах.In this work the comparative characteristic of peats of the Tomsk region and Altai Republic has been carried out. For these peats, the technical and group compositions were determined.
As a result of the researches it is revealed that peats from deposits of the Tomsk region and Altai Republic differ on extent of decomposition and an ash-content. In peats of Altai Republic have received the bigger content of humic acids and a lignin in comparison with peats of the Tomsk region.
Besides, in peats of Altai Republic the low content of bitumens and a carbohydrate complex and the increased content of humic acids and a lignin is revealed. It is established that on the basis of fields of Altai Republic the organization of production of humic acids and bitumens in limited sizes is possible
Sediment and particulate carbon removal by pipe erosion increase over time in blanket peatlands as a consequence of land drainage
Land drainage is common in peatlands. Artificially drained blanket peat catchments
have been shown to have a significantly greater soil pipe density than intact catchments.
This paper investigates the role of surface land drains in the enhancement of soil
piping in blanket peats. The density of piping was found to significantly increase in a
linear fashion with the age of the drainage. Thirty-five years after drains were cut, slopes
would be expected to have twice the density of soil piping than would an undrained
blanket peat catchment. The rate of pipe erosion increases exponentially over time, so that
particulate carbon loss from subsurface pipes is greatest where drains are oldest
Erodibility of hill peat
peer-reviewedThe project was funded by the European Union Structural Funds EAGGF distributed under the Department of Agriculture and Food Stimulus Fund.The energy necessary to entrain soil in water depends on the soil strength. Once entrained, the settling velocity of the eroded soil in water is of fundamental importance to the processes of sediment transport and deposition. In this paper, stream power theory and transport concepts coupled with the equation of continuity were used to derive a transport-limited peat concentration. The ratio of the log of the actual sediment concentration in surface run-off to the log of the transport-limited sediment concentration was the index of erosion used. The value of this index is a measure of the sensitivity of peat to erosion by sheet flow. Four peats were subjected to a range of overland flow rates under two slopes in a laboratory flume. The peats represented peat farmed in a sustainable manner (Leenane), overgrazed peat (Maam), peat undergoing erosion (Newport) and peat which had undergone weathering following exposure by a landslip (Croagh Patrick). Both in situ and surface damaged slabs were studied. The results indicate that shearing and remoulding of a wet peat surface (e.g., by animal treading) and weathering of exposed drained peat surfaces predispose peat to erosion. Defoliation by overgrazing is considered to be of secondary importance.Department of Agriculture, Food and the MarineEuropean Union Structural Funds EAGG
Сравнительная характеристика торфов Томской области и республики Алтай
В данной работе была проведена сравнительная характеристика торфов Томской области и республики Алтай. Для этих торфов были определены технический и групповой составы.
В результате исследований выявлено, что торфа с месторождений Томской области и республики Алтай отличаются по степени разложения и зольности. В торфах республики Алтай получили большее содержание гуминовых кислот и лигнина по сравнению с торфами Томской области .
Кроме этого, в торфах республики Алтай выявлено низкое содержание битумов и углеводного комплекса и повышенное содержание гуминовых кислот и лигнина. Установлено, что на базе месторождений республики Алтай возможна организация производства гуминовых кислот и битумов в ограниченных размерах.In this work the comparative characteristic of peats of the Tomsk region and Altai Republic has been carried out. For these peats, the technical and group compositions were determined.
As a result of the researches it is revealed that peats from deposits of the Tomsk region and Altai Republic differ on extent of decomposition and an ash-content. In peats of Altai Republic have received the bigger content of humic acids and a lignin in comparison with peats of the Tomsk region.
Besides, in peats of Altai Republic the low content of bitumens and a carbohydrate complex and the increased content of humic acids and a lignin is revealed. It is established that on the basis of fields of Altai Republic the organization of production of humic acids and bitumens in limited sizes is possible
Piping and woody plants in peatlands: Cause or effect?
This paper presents, for the first time, evidence to show that Calluna species are one
causative factor of piping in blanket peat catchments. Ground-penetrating radar survey on
960 plots illustrated that piping was prevalent throughout blanket peats. However, soil
pipe occurrence was significantly higher where bare peat (149 pipes/km) or Calluna
(87 pipes/km) were present compared to other species (67 pipes/km). A case study
catchment where there was an altitudinal limit to Calluna provided some control over
potential factors that may lead to an association between piping and Calluna. Under the
controlled conditions of topographic index, peat depth, and water table, piping was greater
under the Calluna-covered peat than under other vegetation covers. Laboratory
experiments demonstrated that 10 years worth of rainfall was enough to almost double the
proportion of macropore flow occurring in recently colonized Calluna peatlands. This
suggests that given enough water and time, the woody Calluna plants result in water being
preferentially channeled through the upper peat. Improvements are therefore required in
our understanding of the relationships between peatland plant nutrient and water supply
and the feedbacks between ecosystem functioning and landform development. These
results are also important given the propensity to encourage Calluna growth for game bird
enhancement in many northern peatlands
Artificial drainage of peatlands: hydrological and hydrochemical process and wetland restoration
Peatlands have been subject to artificial drainage for centuries. This drainage has been in response to agricultural demand, forestry, horticultural and energy properties of peat and alleviation of flood risk. However, the are several environmental problems associated with drainage of peatlands. This paper describes the nature of these problems and examines the evidence for changes in hydrological and hydrochemical processes associated with these changes. Traditional black-box water balance approaches demonstrate little about wetland dynamics and therefore the science of catchment response to peat drainage is poorly understood. It is crucial that a more process-based approach be adopted within peatland ecosystems. The environmental problems associated with peat drainage have led, in part, to a recent reversal in attitudes to peatlands and we have seen a move towards wetland restoration. However, a detailed understanding of hydrological, hydrochemical and ecological process-interactions will be fundamental if we are to adequately restore degraded peatlands, preserve those that are still intact and understand the impacts of such management actions at the catchment scale
Gaseous, PM2.5 Mass, and Speciated Emission Factors from Laboratory Chamber Peat Combustion
Peat fuels representing four biomes of boreal (western Russia and Siberia), temperate (northern Alaska, USA), subtropical (northern and southern Florida, USA), and tropical (Borneo, Malaysia) regions were burned in a laboratory chamber to determine gas and particle emission factors (EFs). Tests with 25 % fuel moisture were conducted with predominant smoldering combustion conditions (average modified combustion efficiency (MCE) =0.82+/-0.08). Average fuel-based EFCO2 (carbon dioxide) are highest (1400 +/- 38 g kg(-1)) and lowest (1073 +/- 63 g kg(-1)) for the Alaskan and Russian peats, respectively. EFCO (carbon monoxide) and EFCH4 (methane) are similar to 12 %15 % and similar to 0.3 %0.9 % of EFCO2, in the range of 157171 and 310 g kg(-1), respectively. EFs for nitrogen species are at the same magnitude as EFCH4, with an average of 5.6 +/- 4.8 and 4.7 +/- 3.1 g kg(-1) for EFNH3 (ammonia) and EFHCN (hydrogen cyanide); 1.9+/-1.1 g kg(-1) for EFNOx (nitrogen oxides); and 2.4+/-1.4 and 2.0 +/- 0.7 g kg(-1) for EFNOy (total reactive nitrogen) and EFN2O (nitrous oxide). An oxidation flow reactor (OFR) was used to simulate atmospheric aging times of similar to 2 and similar to 7 d to compare fresh (upstream) and aged (downstream) emissions. Filter-based EFPM2.5 varied by \u3e 4-fold (1461 g kg(-1)) without appreciable changes between fresh and aged emissions. The majority of EFPM2.5 consists of EFOC (organic carbon), with EFOC / EFPM2.5 ratios in the range of 52 %98 % for fresh emissions and similar to 14 %23 % degradation after aging. Reductions of EFOC (similar to 79 g kg(-1)) after aging are most apparent for boreal peats, with the largest degradation in low-temperature OC1 that evolves at \u3c 140 degrees C, indicating the loss of high-vapor-pressure semivolatile organic compounds upon aging. The highest EFLevoglucosan is found for Russian peat (similar to 16 g kg(-1)), with similar to 35 %50 % degradation after aging. EFs for water-soluble OC (EFWSOC) account for similar to 20 %62 % of fresh EFOC. The majority (\u3e 95 %) of the total emitted carbon is in the gas phase, with 54 %75 % CO2, followed by 8 %30 % CO. Nitrogen in the measured species explains 24 %52 % of the consumed fuel nitrogen, with an average of 35 +/- 11 %, consistent with past studies that report similar to 1/3 to 2/3 of the fuel nitrogen measured in biomass smoke. The majority (\u3e 99 %) of the total emitted nitrogen is in the gas phase, with an average of 16.7 % as NH3 and 9.5 % as HCN center dot N2O and NOy constituted 5.7 % and 2.9 % of consumed fuel nitrogen. EFs from this study can be used to refine current emission inventories
Effect of aggressive pH media on peat treated by cement and sodium silicate grout
The effects of aggressive peat nature (pH) on the strength of peat treated by cement and cement-sodium silicate grout were investigated by evaluating the changes in unconfined compressive strength, moisture content, and scanning electron microscopy (SEM) of samples with time in different pH media. The results indicate that peats treated by cement-silicate have higher strength than peats treated by cement, due to an increase in pH value of the media. Furthermore, cement and cement-silicate are highly effective in reducing the moisture content and void ratio of the treated peats. The microstructures of treated peats support the laboratory test results
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