Water In Peat Research Articles

Organic petrology and geochemistry of Triassic and Jurassic coals of the Tabas Basin, Northeastern/Central Iran

Jurassic and Triassic coals and organic matter-rich shales of the Tabas Basin, Iran, were investigated with respect to their thermal maturation and petrographic composition. The Triassic coals of the Parvadeh coal field range in vitrinite reflectance between 1.17% and 1.37% and the Jurassic coals of the Mazino coal field between 2.08% and 2.29% VRr. Maceral analysis revealed a predominance of vitrinite in all samples, with slightly higher percentages of inertinite in the Jurassic samples. Rock–Eval analyses confirm the presence of type III kerogen in the Triassic coals, while the Jurassic coals contain strongly carbonized residual kerogen. The range of sulfur contents for coals from the Parvadeh coal field (0.37% to 4.64%) and Mazino coal field (0.45% to 2.92%) is related to the effect of marine water in peat. The studied samples are characterized by the predominance of short- over long-chained n-alkanes. The relatively high Pr/Ph ratios indicate predominance of terrestrial organic matter whereas Pr/n-C17 and Ph/n-C18 ratios prove oxic conditions during deposition. In addition, the DBT/Phen ratio shows that these coals formed in fluvial/deltaic environments. Molecular geochemical parameters such as carbon preference index (CPI, 0.99–1.04), methyl phenanthrene index (MPI, 1.20–1.60), methyl naphthalene ratio (MNR, 1.61–3.45), and ethyl naphthalene ratio (ENR, 4–6.78) confirm the high maturity of the samples. Burial and thermal history reconstruction indicates necessity of an erosional thickness of about 4000 m in the Parvadeh area. Towards the Mazino area, a higher basal heat flow up to 80 mW m−2 is assumed for the Paleogene leading to higher maturities.

Transport of chloride and deuterated water in peat: The role of anion exclusion, diffusion, and anion adsorption in a dual porosity organic media

The dual-porosity structure of peat and the extremely high organic matter content give rise to a complex medium that typically generates prolonged tailing and early 50% concentration breakthrough in the breakthrough curves (BTCs) of chloride (Cl−) and other anions. Untangling whether these observations are due to rate-limited (physical) diffusion into inactive pores, (chemical) adsorption or anion exclusion remains a critical question in peat hydrogeochemistry. This study aimed to elucidate whether Cl− is truly conservative in peat, as usually assumed, and whether the prolonged tailing and early 50% concentration breakthrough of Cl− observed is due to diffusion, adsorption, anion exclusion or a combination of all three. The mobile-immobile (MiM) dual-porosity model was fit to BTCs of Cl− and deuterated water measured on undisturbed cores of the same peat soils, and equilibrium Cl− adsorption batch experiments were conducted. Adsorption of Cl− to undecomposed and decomposed peat samples in batch experiments followed Freundlich isotherms but did not exhibit any trends with the degree of peat decomposition and sorption became negligible below aqueous Cl− concentrations of ~310 mg L−1. The dispersivity determined by fitting the Cl− BTCs whether assuming adsorption or no adsorption were significantly different than determined by the deuterated water (p < .0001). However, no statistical differences in dispersivity (p = .27) or immobile water content (p = .97) was observed between deuterated water and Cl− when accounting for anion exclusion. A higher degree of decomposition significantly increased anion exclusion (p < .0001) but did not influence the diffusion of either tracer into the immobile porosity. Contrary to previous assumptions, Cl− is not truly conservative in peat due to anion exclusion, and adsorption at higher aqueous concentrations, but the overall effect of anion exclusion on transport is likely minimal.

Effect of Hydro-Physical Properties of Peat on Regulation of Peatland Drainage Systems

The paper analyzes changes in the hydro-physical properties of peat micro- and macrosystems in the process of drainage. Maximum moisture-holding capacity of peat is used as the main characteristic. With a full drying cycle and subsequent moistening of peat, there are three stages associated with the coagulative structure formation in the system. The boundary of the transition from the state «peat in water» to the state «water in peat» is moisture content equal to one. It divides the period of structure formation into two periods, due to the predominating action of van der Waals interactions or hydrogen bonds. In the state «water in pear» the peat system loses the ability to recover its original hydro-physical properties. Scaling up the research results on peat deposits (marshes) makes it possible to classify them according to the degree of drainage of the deposit. A new approach to the use of the term «surface water body» for peat deposits is proposed.

Electrical Conductivity Breakthrough Experiment and Immobile Water Estimation in Organic Substrates: Is R = 1 a Realistic Assumption?

Core Ideas Breakthrough of NaCl in peat shows that R may differ from 1. Immobile water in peat is difficult to estimate because of NaCl sorption. Solute sorption in peat varies because of uncoiling of organic components. Measuring electrical conductivity (EC) in outflow breakthrough curves (BTCs) is an approach commonly used to define transport parameters because it is rapid, inexpensive, and reliable. Earlier work has raised questions regarding the assumption that the retardation factor may be set at R = 1 when using EC as a tracer in organic soils. This study investigates the breakthrough of a NaCl tracer in a peat–sawdust mixture leached with distilled water. The results show that in such system, R may significantly differ from 1 because of sorption of Na+ and Cl− by peat with the R value estimated by batch experiments to reach 1.9 for Na+ and 1.5 for Cl−. The sorption properties may vary during solute transport because of uncoiling of humic and fulvic components with decreasing ionic strength of the solution.

Moving the Field into the Lab: Simulation of Water and Heat Transport in Subarctic Peat

ABSTRACTLarge climate chambers are suitable to simulate, at or close to field scale, the annual freezing and thawing of layered peat in subarctic active layers above permafrost. An experiment in a climate chamber at the University of Western Ontario was designed to freeze and thaw four peat cores 60 cm in diameter. This paper describes the climate chamber and experimental setup, and evaluates their ability to maintain one‐dimensional change in soil moisture and temperature profiles. Preliminary results on soil water content (liquid and total) indicate that active‐layer freezing resulted in an upward movement of water towards a freezing front that propagated downward. The physical simulations will contribute towards improving conceptual and mathematical hydrological models for permafrost regions. Copyright © 2012 John Wiley &amp; Sons, Ltd.

A LABORATORY METHOD FOR MEASURING PHYSICAL PROPERTIES OF GROWING MEDIA AND THEIR EVOLUTION DURING DRYING/WETTING CYCLES: PRELIMINARY RESULTS

A new apparatus was developed for simultaneously and continuously measuring the water retention and shrink/swell properties of growing media during several drying/wetting cycles. Initial results obtained on peats show that water retention and shrink/swell properties are mainly affected by the first drying and rewetting cycle and remain quasi-constant thereafter, regardless of the intensity and the number of drying/wetting cycles. Hysteresis phenomena in water retention are always observed. The use of a wetting agent (as compared with water) in peat leads to the reinforcement of the physical stability of growing media and to the limitation of hysteresis phenomena in water retention for the highest suction values.

The hydrology of northern peatlands as affected by biogenic gas: current developments and research needs

AbstractRecent research indicates that accumulation and release of biogenic gas from northern peatlands may substantially affect future climate. Sudden release of free‐phase gas bubbles into the atmosphere may preclude the conversion of methane to carbon dioxide in the uppermost oxic layer of the peat, resulting in greater contribution of methane to the atmosphere than is currently estimated. The hydrology of these peatlands also affects and is affected by this process, especially when gas is released suddenly and episodically. Indirect hydrological evidence indicates that ebullitive gas releases are relatively frequent in some peatlands and time‐averaged rates may be significantly greater than diffusive releases. Estimates of free‐phase gas contained in peat have ranged from 0 to nearly 20% of the peat volume. Abrupt changes in the volume of gas may alter hydraulic gradients and movement of water and solutes in peat, which in turn could alter composition and fluxes of the gas. Peat surfaces also move vertically and horizontally in response to accumulation and release of free‐phase gas. Future research should address the distribution, temporal variability, and relative significance of ebullition in peatlands and the consequent hydrological responses to these gas‐emission events. Copyright © 2006 John Wiley &amp; Sons, Ltd.

The micromorphology of selected Irish milled peats

The movement of water in milled peat is of importance to the peat industry particularly in terms of rewetting. Considering the importance of structure with regard to water flow, micromorphology was used to obtain information regarding the nature of milled peat as a porous medium in a manner not available by other means. Peat was sampled from the undisturbed surface of two bogs (raised and fen origin) and from milled peat stockpiles. Thin sections were prepared to describe the nature of the two peat materials (milled and unmilled) in terms of the particle / pore properties and composition. Image analysis and point counting techniques were used to quantify results wherever possible. Although overall macro-porosity was similar for the two stockpiles, particle and pore size distributions varied considerably. Variations arose from the nature of the peat type and its interaction with milling operations with results suggesting that smaller pore sizes relate to a greater propensity to rewet.

Light hydrocarbons of interstitial water in peat from Tateyama, Midagahara

Light hydrocarbons of interstitial water in peat from Tateyama, Midagahara

The Characterization of Water in Peat

AbstractThe functionality and ultimate use of peat are intimately bound up with the way in which absorbed water behaves in the host matrix. Control of the amount of absorbed water, the dynamics of water loss in drying, and the gain of water in rewatering are important determinants in its commercial exploitation. We examined the nature and behavior of water in a range of different Irish peat samples by exploiting the combined capabilities of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and proton nuclear magnetic resonance (NMR). Up to four different forms of water were detected in heavily hydrated peat: absorbed or tightly bound water, which is non‐freezable and behaves like a glass at low temperatures; two forms of loosely bound water; and bulk water. Increasing temperature across the subambient regime revealed the sequential onset of mobility of the different forms of water. The transitions are well‐defined in terms of both water concentration and the temperature at which motion sets in. Unlike hydrated polymers, NMR estimates of the maximum amounts of bound water at low temperatures depend on overall water content, reflecting the extent to which the peat matrix can restructure and swell when hydrated. The TGA, which maps out the loss of water under controlled conditions of temperature and atmosphere, offers additional evidence on the mechanism of dehydration, indicating that drying on a small scale under laboratory conditions is not grossly impeded by internal barriers. The gratifying consistency between the data from the three experimental techniques used, along with pertinent data in the literature, give additional insights into the role of water in peat.

Modeling solute segregation during freezing of peatland waters

Freezing of the shallow water in a peatland causes the downward movement of solutes. Field and laboratory data demonstrate that a considerable portion of the solutes are driven into the top soil from the overlying water by freezing. Such solute redistribution phenomena in peatlands are of interest for establishing the geochronology of deposits and determining the nature of pollutant burial. A mathematical model has been developed to describe the solute segregation processes at the freezing front in both overlying water and interstitial water in the porous peat and solute transport in the unfrozen water. An algorithm has been developed to solve this nonlinear moving interface problem. The solute concentrations in ice and water phases are reproduced by the model. Computer simulation results provide good predictions of independent experimental data.

Peat beneficiation by wet carbonization

Peat, as it exists in nature, contains about 90% water and has a heating value of about 19.8 MJ/kg (dry basis). The water in peat is very difficult to remove by mechaninal means. The current technology can dewater peat to a moisture content of only about 67 wt.%. Wet carbonization is a process whereby carbonaceous materials are heated under pressure for a period of time to produce a beneficiated product. In the case of peat, a low-sulfur solid fuel with enhanced heating value, improved dewaterability, and better handling characteristics is produced. A comprehensive study on the effects of operating conditions on the wet-carbonization characteristics of Minnesota peat was conducted. This study was jointly sponsored by the U.S. Department of Energy/Pittsburgh Energy Technology Center and Minnesota Power and Light Company. Tests were conducted in a 360-kg/h continuous process research unit. The operating conditions studied were temperatures ranging from 175 to 260°C; residence times of 1–60 min; atmosphere, steam and air; product filtrate recycle; and slurry concentration, 6.1–9.5 wt.%. The effluent process water was treated by IGT's two-phase anaerobic digestion process for energyrecovery. This process maximizes the production of methane and minimizes hydraulic retention times in the digesters. An integrated wet-carbonization process to produce a solid peat fuel with energy and by-product recoveries from the liquid effluent streams has been developed. This paper discusses the work accomplished in this study.

Determination of water content and calorific value of peat by near i.r. spectroscopy

Near infrared reflectance (n.i.r.) spectroscopy is used for the determination of water and calorific value in peat. Partial least squares modelling in latent variables (PLS) has been used to correlate n.i.r. spectra to water content and calorific value. Separate calibrations for water and calorific value have been compared with the simultaneous calibration for both properties. The result of the simultaneous calibration for water is better than the result obtained in the separate calibration. This indicates that the inclusion of an extra meaningful variable will stabilize the calibration.

THE IMPREGNATION OF WET PEAT FOR THE PRODUCTION OF THIN SECTIONS

SummaryA technique is described to replace the water in peat by acetone prior to impregnation with resin. The peat is exposed to the vapour of aqueous acetone of increasing concentration up to 100 per cent acetone. After impregnation with resin, high quality thin sections can be obtained.

A Thermal-Electric Method for Measuring Lateral Movement of Water in Peat

SUMMARY A flowmeter, based on a modified form of the Poppendiek thermal-electric anemometer, for measuring lateral flow of water in peat at rates less than a few cm s - 1is described. It consists essentially of a probe made up of pairs of thermocouples and a heating unit, coupled to a heating circuit and an output circuit. Calibration proved satisfactory for flow rates of 0-2-30 cm sec', within the range of field temperatures. Water temperature had negligible influence in the relatively cold environment under consideration. Field data are given for two mire sites, in Sweden and in England. The probe offers the possibility of measurements of water seepage within peat deposits.

The Changing Pattern of Norwegian Hydroelectric Development

I T seems surprising that Norway should see fit to construct a power station harnessing nuclear energy when it has the world's largest production of hydroelectricity per capita of population, and a utilization of its water power resources amounting to only 37.5 per cent of the total-4.3 million kw. out of 12.3 million (although 16 million has been given as the total).' It is, of course, a far-sighted project, for the time will come when Norway's requirement of electricity will outstrip the possible production within reach of the more heavily populated and industrialized areas. Research work and experience in nuclear power station operation are required as much in Norway as they are anywhere else. At the same time, the utilization of the available resources of hydroelectricity is increasing in momentum. During the 1930-1940 period development was at a rate of 40,000 kw. per year. The war years saw an increase to 60,000 kw. per year, but this is small compared to the post-war rates of 140,000 kw. per year in the 1945-1950 period2 and 258,000 kw. per year in the 1950-1955 period. The cause is the increasing industrial activity and the expansion of the electrification of the railway system, but most Qf all the greater use of electricity and electric appliances in Norwegian homes, some 96 per cent of which now have an electricity supply.3 The effect has been a change in the type of producer of hydroelectricity, in the method of supplying the power to the consumer, in fact, in the whole geography of power in Norway. Because the nation depends on hydroelectricity for its industrial power, and so for much of its wealth, it is of value to note this change while it is actually in progress and to visualize the eventual results. An account must, however, be primarily qualitative because the change is still in progress. The quantities concerned are subject to frequent alterations which make general statistics speedily out-of-date. The larger part of this article is, therefore, concerned with showing the shape of the change through the use of detailed examples, made possible by a temporary diminution of the processes of change in a limited region. The southern part of Norway forms an area which is well-nigh unsurpassable as the perfect field for hydroelectric power production. It consists mainly of a plateau at a height of 3000 to 4000 feet above sea level. This has an undulating surface which is ideal for the storage of water in lakes and peat 1 Industries of Norway, 0. J. Adamsom, edit., Oslo, 1952. 2 From Industries of Norway. I Norges Vassdragsog Elektrisitetsvesen, Arsberetning, 1954-1955, p. 7.