Waterlogged Peat Research Articles

Below the disappearing marshes of an urban estuary: historic nitrogen trends and soil structure.

Marshes in the urban Jamaica Bay Estuary, New York, USA are disappearing at an average rate of 13 ha/yr, and multiple stressors (e.g., wastewater inputs, dredging activities, groundwater removal, and global warming) may be contributing to marsh losses. Among these stressors, wastewater nutrients are suspected to be an important contributing cause of marsh deterioration. We used census data, radiometric dating, stable nitrogen isotopes, and soil surveys to examine the temporal relationships between human population growth and soil nitrogen; and we evaluated soil structure with computer-aided tomography, surface elevation and sediment accretion trends, carbon dioxide emissions, and soil shear strength to examine differences among disappearing (Black Bank and Big Egg) and stable marshes (JoCo). Radiometric dating and nitrogen isotope analyses suggested a rapid increase in human wastewater nutrients beginning in the late 1840s, and a tapering off beginning in the 1930s when wastewater treatment plants (WWTPs) were first installed. Current WWTPs nutrient loads to Jamaica Bay are approximately 13 995 kg N/d and 2767 kg P/d. At Black Bank, the biomass and abundance of roots and rhizomes and percentage of organic matter on soil were significantly lower, rhizomes larger in diameter, carbon dioxide emission rates and peat particle density significantly greater, and soil strength significantly lower compared to the stable JoCo Marsh, suggesting Black Bank has elevated decomposition rates, more decomposed peat, and highly waterlogged peat. Despite these differences, the rates of accretion and surface elevation change were similar for both marshes, and the rates of elevation change approximated the long-term relative rate of sea level rise estimated from tide gauge data at nearby Sandy Hook, New Jersey. We hypothesize that Black Bank marsh kept pace with sea level rise by the accretion of material on the marsh surface, and the maintenance of soil volume through production of larger diameter rhizomes and swelling (dilation) of waterlogged peat. JoCo Marsh kept pace with sea-level rise through surface accretion and soil organic matter accumulation. Understanding the effects of multiple stressors, including nutrient enrichment, on soil structure, organic matter accumulation, and elevation change will better inform management decisions aimed at maintaining and restoring coastal marshes.

The Ecology, Distribution and Invasiveness of <i>Gunnera</i> L. Species in Connemara, Western Ireland

The huge herbaceous Gunnera tinctoria (Giant rhubarb), long naturalised in coastal Connemara, has recently spread rapidly and moved inland causing considerable concern. Its native habitat in South America comprises disturbed areas on volcanic soils. In Connemara it has colonised quarries and roadsides, spreading out from these, though rarely onto bog. Gravel spread from infested quarries has been an important dispersal factor. It is mostly associated with plant communities of damp and disturbed habitats, with other invasive aliens. In a growth experiment, it grew poorly in waterlogged peat or gravel and best in a drained mixture of both substrates. Gunnera manicata (Brazilian giant rhubarb) is here confirmed for Connemara and both species are mapped. G. manicata appears to occur through accidental transfer of rhizome parts, while G. tinctoria can also spread by its abundant seed. The exceptionally severe winter of 2009/2010 checked the growth of G. tinctoria away from the coast, but not G. manicata. It is likely that the previous long run of milder winters facilitated the recent rapid spread of G. tinctoria. Climate change hypotheses predict increased milder oceanic conditions for Western Europe, which could result in both species becoming more widely invasive.

THE ECOLOGY, DISTRIBUTION AND INVASIVENESS OF GUNNERA L. SPECIES IN CONNEMARA, WESTERN IRELAND

The huge herbaceous Gunnera tinctoria (Giant rhubarb), long naturalised in coastal Connemara, has recently spread rapidly and moved inland causing considerable concern. Its native habitat in South America comprises disturbed areas on volcanic soils. In Connemara it has colonised quarries and roadsides, spreading out from these, though rarely onto bog. Gravel spread from infested quarries has been an important dispersal factor. It is mostly associated with plant communities of damp and disturbed habitats, with other invasive aliens. In a growth experiment, it grew poorly in waterlogged peat or gravel and best in a drained mixture of both substrates. Gunnera manicata (Brazilian giant rhubarb) is here confirmed for Connemara and both species are mapped. G. manicata appears to occur through accidental transfer of rhizome parts, while G. tinctoria can also spread by its abundant seed. The exceptionally severe winter of 2009/2010 checked the growth of G. tinctoria away from the coast, but not G. manicata. It is likely that the previous long run of milder winters facilitated the recent rapid spread of G. tinctoria. Climate change hypotheses predict increased milder oceanic conditions for Western Europe, which could result in both species becoming more widely invasive.

Aromatase inhibitor as neoadjuvant hormone therapy for breast cancer

Methane (CH4) flux into the atmosphere during spring thaw was investigated in a small ombrotrophic peatland (141°48′E, 43°19′N, Japan) using the conventional chamber method. More than 50 chamber deployments on top of the snow cover were carried out and continued for more than 165 h until the surface snow and underlying ice cover on top of the peat layer had thawed completely. Methane emissions were almost absent in the presence of snow cover. At the very moment the surface ice cover thawed, a large CH4 flush (>10 mg CH4 m−2 h−1) was recorded, which was on the same order of magnitude as episodic ebullition previously observed in the high-summer. Gas bubbles trapped in the ice layer on top of the waterlogged peat were preliminarily analyzed for the volumetric percentage in the total ice volume and their gas species compositions. Results showed that the bubbles occupied about 3.2% volume and that the mixing ratio of CH4 in the bubbles was about 20%. The abundance of the bubble-form CH4 was sufficient to explain the observed episodic CH4 release during the thaw. Results of this study show that CH4 emissions during the thaw season have great temporal variability; emission occurs as an episodic release of bubble-form CH4 stored in the frozen layer. The results also imply the possibility that gas-phase CH4 plays an important role, not only during the growing season but also in cold-season CH4 dynamics in northern peatlands.

Episodic release of methane bubbles from peatland during spring thaw

Methane (CH 4) flux into the atmosphere during spring thaw was investigated in a small ombrotrophic peatland (141°48′E, 43°19′N, Japan) using the conventional chamber method. More than 50 chamber deployments on top of the snow cover were carried out and continued for more than 165 h until the surface snow and underlying ice cover on top of the peat layer had thawed completely. Methane emissions were almost absent in the presence of snow cover. At the very moment the surface ice cover thawed, a large CH 4 flush (>10 mg CH 4 m −2 h −1) was recorded, which was on the same order of magnitude as episodic ebullition previously observed in the high-summer. Gas bubbles trapped in the ice layer on top of the waterlogged peat were preliminarily analyzed for the volumetric percentage in the total ice volume and their gas species compositions. Results showed that the bubbles occupied about 3.2% volume and that the mixing ratio of CH 4 in the bubbles was about 20%. The abundance of the bubble-form CH 4 was sufficient to explain the observed episodic CH 4 release during the thaw. Results of this study show that CH 4 emissions during the thaw season have great temporal variability; emission occurs as an episodic release of bubble-form CH 4 stored in the frozen layer. The results also imply the possibility that gas-phase CH 4 plays an important role, not only during the growing season but also in cold-season CH 4 dynamics in northern peatlands.

Sulfur mobility in peat

Lead-210 chronologies, vertical S concentration gradients and δ 34S values are presented for 5 Sphagnum-dominated peat bogs located in Central Europe (Rybarenska slat and Ocean Bog; Czech Republic) and the British Isles (Thorne Moors, England; Connemara, Ireland; and Mull, Scotland). Sulfur concentrations were measured in three 40-cm deep peat cores per site, sectioned into 2-cm segments. The coefficient of variation in S concentrations was low across all depths and sites (mean of 16%), indicating a high degree of within-site homogeneity in vertical S patterns. Similar S concentration trends and similar δ 34S trends were found at all study sites. With an increasing peat depth, S concentrations first increased and then decreased. S concentrations peaked in layers which were deposited in ca. 1959, 1907, 1945, 1899 and 1799 at Rybarenska slat, Ocean, Thorne Moors, Connemara and Mull, respectively. Atmospheric S deposition peaked in 1972 in the UK and in 1987 in the Czech Republic. Due to downward S mobility in peat, S concentration maxima were found in layers 59 (±19) a older that the year of the actual peak in S input. With an increasing depth, the maturating peat substrate at all sites exhibited first a negative δ 34S shift, resulting from dissimilatory bacterial SO 4 reduction, and then a positive δ 34S shift, which may be related to advancing S mineralization. Minimum δ 34S values were detected in layers which were deposited in ca. 1988, 1982, 1945, 1940 and 1978. A comparison of historical δ 34S signatures of atmospheric S in England, measured on archived grain from the Broadbalk experiment (1845–1994), with δ 34S values of Thorne Moors peat (1830–1994) also indicated mobility of S in peat. Sulfur mobility in water-logged peat is of concern during the present period of easing industrial pollution because SO 4 released from peatlands may increase the acidity of the output.

Approaches and Methods for Commissioned Archaeology in Wetlands: Experience from the E4 Project in Skane, Southern Sweden

In this article I discuss problems and possibilities connected with commissioned archaeology in wetlands. The cultural heritage of wetlands is threatened by large-scale infrastructure projects, and there is a need within commissioned archaeology to develop approaches and techniques for systematic surveying in wetlands. With examples from an on-going project in southern Sweden, different surveying techniques are presented together with some results and interpretations. Attempts to grasp the complexity of the wetlands right from the beginning of the project proved to be fruitful, in that the palaeoenvironmental interpretations were decisive for the selection of sites for trial excavations. Interpretation of peatland expansion through time was important for the reading of the landscape and the search for settlement sites. Some techniques for trial excavations in waterlogged peat are also presented.

Siderite as a Corrosion Product on Archaeological Iron from a Waterlogged Environment

This paper discusses the occurrence of siderite (FeCO3) on iron artifacts excavated from the waterlogged peat and gyttja sediment of the Danish Iron Age site Nydam Mose. Siderite was identified by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy with energy-dispersive spectrometry (SEMEDS), which showed only minor contents of other minerals in the corrosion scales. The implications of the formation of siderite as a corrosion product are discussed in terms of its possible passivating properties and thermodynamic stability in situ. A Pourbaix diagram adjusted to the actual conditions in Nydam is presented and discussed. Different mechanisms for the formation of siderite in this environment are proposed, based on the results of environmental monitoring in the area.

Approaches and Methods for Commissioned Archaeology in Wetlands: Experience from the E4 Project in Skåne, Southern Sweden

In this article I discuss problems and possibilities connected with commissioned archaeology in wetlands. The cultural heritage of wetlands is threatened by large-scale infrastructure projects, and there is a need within commissioned archaeology to develop approaches and techniques for systematic surveying in wetlands. With examples from an on-going project in southern Sweden, different surveying techniques are presented together with some results and interpretations. Attempts to grasp the complexity of the wetlands right from the beginning of the project proved to be fruitful, in that the palaeoenvironmental interpretations were decisive for the selection of sites for trial excavations. Interpretation of peatland expansion through time was important for the reading of the landscape and the search for settlement sites. Some techniques for trial excavations in waterlogged peat are also presented.

MACROPOROSITY AFFECTS WATER MOVEMENT AND PORE WATER SAMPLING IN PEAT SOILS

The measurement of chemical concentration profiles in pore water is a starting point for the analysis of biogeochemical processes in waterlogged peat soils. Concentration patterns may be obscured when macroporosity causes preferential flow in column experiments and when pore water is retrieved from the peat by suction. To investigate the magnitude of such effects, we used LiBr as a tracer in peat columns at outflow rates of 0, 2–3, and 8 mm d−1. The results were compared with modeled advective-diffusive migration rates. Twenty to fifty percent of the tracer was recovered from depths at which the tracer would have been absent if preferential flow had not occurred. At the high flow rate, the preferential flow was stronger, and the retrieved pore-water was probably in disequilibrium with the matrix. When pore water was retrieved by suction, linear concentration gradients decreased by about 30% through the recovery of water from different depths, and the quality of fitted linear gradients decreased from R2 = 0.99 to R2 = 0.82. When flow rates are low (<3 mm d−1) and pore water concentration values from samplers are aggregated or regressed, the obtained concentration profiles seem to represent the vertical distribution of chemical species reasonably well. The use and interpretation of pore water profiles in peat soils is problematic if flow rates are higher and if vertical gradients are based on individual or few data points that have been obtained by suction samplers.

Surface water acidification in the South Pennines I. Current status and spatial variability

The South Pennines, an area of acid-sensitive geology at the centre of a major industrial region, have undergone perhaps the most severe historic exposure to sulphur and nitrogen deposition in the UK. This study addresses a lack of existing research on the region by presenting the findings of a survey of 62 surface waters sampled during a 1-week period in April 1998. Results indicate that acidification in the region is acute; 27 of the sampled surface waters had a negative acid neutralising capacity (ANC) and 28 had a pH below 5.0. Minimum recorded pH values were below 4.0. Non-marine sulphate levels were extremely high (median 222 μeq/1), and widespread high nitrate concentrations (median 41 μeq/1) suggest that soils in the region as a whole may be at an advanced stage of nitrogen saturation. A consistent relationship was identified between site acidity and the balance between the major weathering-derived cations, calcium and magnesium, and sulphate. This could in turn be linked to catchment soil type and land use, with the most acidic conditions occurring in peat-dominated catchments, where weathering is minimal and the influence of atmospheric deposition most pronounced. Percentage of peat in each catchment was the single best predictor of surface water acidity. Nitrate concentrations, although not a dominant control on acidity, varied significantly according to land use. Elevated concentrations were observed in catchments containing forestry, due to enhanced deposition inputs, and in catchments containing improved land, linked to fertiliser use. Ammonium concentrations, although low at most catchments, were a significant component of the inorganic nitrogen total in a number of surface waters draining waterlogged peat catchments.

Greenhouse gas emissions from farmed organic soils: a review

Abstract. The large boreal peatland ecosystems sequester carbon and nitrogen from the atmosphere due to a low oxygen pressure in waterlogged peat. Consequently they are sinks for CO2 and strong emitters of CH4. Drainage and cultivation of peatlands allows oxygen to enter the soil, which initiates decomposition of the stored organic material, and in turn CO2 and N2O emissions increase while CH4 emissions decrease. Compared to undrained peat, draining of organic soils for agricultural purposes increases the emissions of greenhouse gases (CO2, CH4, and N2O) by roughly 1t CO2 equivalents/ha per year. Although farmed organic soils in most European countries represent a minor part of the total agricultural area, these soils contribute significantly to national greenhouse gas budgets. Consequently, farmed organic soils are potential targets for policy makers in search of socially acceptable and economically cost‐efficient measures to mitigate climate gas emissions from agriculture. Despite a scarcity of knowledge about greenhouse gas emissions from these soils, this paper addresses the emissions and possible control of the three greenhouse gases by different managements of organic soils. More precise information is needed regarding the present trace gas fluxes from these soils, as well as predictions of future emissions under alternative management regimes, before any definite policies can be devised.

Role of wetland plants in the diurnal control of CH 4 and CO 2 fluxes in peat

We demonstrate that a major portion of the microbial activities in peat monoliths are driven by photosynthetic processes and that effluxes of CH 4 and CO 2 are regulated by the surface vegetation. CH 4 and CO 2 monitored continuously at a depth of 15 cm and in the headspace above the peat showed oscillatory concentration changes over a 24-h cycle. Comparative anatomy of the vegetative organs of tracheophytes associated with the peat bog revealed the presence of an extensive lacunar system in the roots, rhizomes and leaves of several monocotyledonous species; this provides the path of minimal resistance for gas transport in waterlogged peat.

A comparison of different methods for the measurement of dissolved gas gradients in waterlogged peat cores

Depth profiles of the oxygen and methane concentrations and the redox potential in an intact peat monolith were obtained. Three methods of O 2-determination were compared; membrane inlet quadrupole mass spectrometry, an oxygen electrode and Photobacterium bioluminescence. The most sensitive at low (nmol) concentrations was the Photobacterium probe where O 2 was detectable at 5 cm depth. The mass spectrometer has the advantage at higher (μmol) concentrations of multi-species (O 2, CO 2, CH 4, Ar) simultaneous monitoring; methane was detected in the peat core at the surface, and increased continuously to reach a maximum at 16 cm. A mass spectrometry miniprobe was constructed to allow precise measurement of gas profiles at intervals of 2 mm or less.

The effect of the incubation period on the result of MPN enumerations of nitrite-oxidizing bacteria: theoretical considerations

A computer model based on Monod- and Haldane-kinetics was used to estimate the minimum incubation period required for MPN enumerations of nitrite-oxidizing bacteria. The minimum incubation period was defined as the time needed for one cell, present in the tubes inoculated with the highest dilutions, to grow into a population that oxidized all the nitrite present at the start of the incubation. Kinetic parameters used in the model were derived from literature data and applied in different combinations. The results show that the minimum incubation period may increase with decreasing initial nitrite concentrations in the incubation medium. They also show that the opposite trend, i.e. increasing minimum incubation periods with increasing nitrite concentration periods with increasing nitrite concentration, can be explained by introducing a term for substrate inhibition in the model. A MPN enumeration result obtained with samples from a waterlogged peat bog soil could only partly be explained by the model if only one set of parameters was used. This indicates that the community of nitrite-oxidizing bacteria in this soil is composed of at least two types of nitrite-oxidizing bacteria, with different kinetic parameters of nitrite oxidation and growth.

The effect of drainage on nutrient release from fen peat and its implications for water quality ?a laboratory simulation

The effect of peat moisture status on N, S, Ca, and Mg release to drainage waters was examined using a constant temperature laboratory incubation. Peat samples originating from drained and undrained sites in West Sedgemoor, Somerset Levels, SW England were compared. Three treatments: long term waterlogging, aeration, and fluctuating aeration and waterlogging were imposed on all peat samples. These treatments resulted in different rates and total amounts of N, S, Ca, and Mg release, with waterlogging resulting in highest solute release. The total amounts and rates of release of S, Ca, and Mg from peat that was undrained prior to incubation always exceeded that from drained site peat samples regardless of peat moisture status. Although the degree of waterlogging or aeration affected the rate and total amount of watersoluble N released during incubation, there was no difference between peat that was drained, and peat that was undrained, prior to incubation. Drainage of currently undrained and waterlogged peat in West Sedgemoor will result in the transfer of high concentrations of S, Ca, and Mg from the peat to the drainage ditch.

A Field Study of the Effect of Depth on Methane Production in Peatland Waters: Equipment and Preliminary Results

(1) Tubular probes of stainless steel with the outer jacket containing an open side window, and a retractable inner plunger fitted with a rubber 0-ring were built and used to sample water and gas from layers 40-60 cm, 90-1 10 cm and 125-145 cm below the surface of waterlogged peat in two peatlands, both basin swamps. Samples were collected periodically up to 2 h, each time in evacuated gas bottles, with the 0-ring on the plunger acting as a seal in the withdrawn position after time zero. The evolved gases were detected and measured by gas chromatography. (2) The amounts of methane and carbon dioxide evolved increased with depth and decreased with time. The methane, but not the carbon dioxide, evolved from deeper layers was greater in amount than could have been dissolved in all the water that the sample probe could hold. The ratio of methane: carbon dioxide evolved increased with depth to beyond the expected 2 33. (3) The results thus indicated that deep layers of the peatlands waters held occluded (trapped) and pressurized gaseous methane, or were supersaturated with dissolved methane with respect to 1 atmosphere, or both. These observations are in accord with a recent proposal on the role of methane in peatland hydrology and the carbon cycle.

A 50-Million-Year-Old Fossil Forest from Strathcona Fiord, Ellesmere Island, Arctic Canada: Evidence for a Warm Polar Climate

The remains of a fossil forest are buried within a sedimentary sequence of Eocene age (approximately 50 million years old) near Strathcona Fiord, Ellesmere Island. Large petrified tree stumps are preserved in their original growth positions in coals of the Eureka Sound Group, a sequence of sandstones, siltstones and coals deposited in a delta/floodplain environment. The dimensions of 83 stumps were recorded and their positions plotted on a plan of the exposed area of coal. The fossil stumps are roughly conical in shape, up to 1.8 m high and with roots spreading up to 5 m in diameter. They are closely spaced on the coal, some only 1 m spart. A density of 1 stump in 27 sq. m (367 stumps/Ha) was calculated for this forest. The stumps represent large forest trees that grew in freshwater, swampy conditions between large river channels. Their buttressed roots provided extra support in the waterlogged peats. The rivers periodically shifted their courses, flooding the forest and burying them under silts and sands. Wide growth rings in the fossil wood, in addition to evidence from associated sediments and vertebrate faunas, indicate favourable growing conditions in a mild, cool/warm temperate climate with high rainfall. Palaeolatitude studies suggest that the forest lay close to its present high-latitude position during the Euocene. Such a forest is therefore evidence that the Eocene polar climate was much warmer than today and that the trees were able to tolerate polar sunlight regime of continuous summer sunlight followed by months of winter darkness.Key words: fossil forest, Tertiary, Canadian Arctic, palaeoclimate, Ellesmere Island, petrified wood, Eureka Sound Group

The Speciation of Uranium and Thorium at the Broubster Natural Analogue Site, Caithness, Scotland

ABSTRACTAnomalously high concentrations of uranium, thorium and the rare earth elements (REE) are associated with peat-rich soils near Broubster, northern Scotland. The source of the anomaly has been traced to a hydrocarbon-containing mineralised zone within a uraniferous, calcareous Devonian sedimentary sequence. From there, the elements have been transported approximately 100 metres downslope and fixed within waterlogged peat deposits. The degree of concentration and fractionation accompanying actinide transport is extreme. This paper describes the results of a theoretical modelling exercise and complementary experimental study carried out to determine the chemical speciation of actinides at the Broubster site. Efforts made to identify mobilisation and retention mechanisms for uranium and thorium have led to the development of a simple model for actinide behaviour in the peat soils. The work, which forms part of an on-going programme of research into natural radionuclide migration, is primarily aimed at improving confidence in predictive models used for radiological assessment.

Sulphur distribution and metabolism in waterlogged peat

About 90% of total S in a peat profile from a valley mire was associated with organic matter, and in the anaerobic zone, most of the remaining S could be distilled as H 2S (steam-volatile H 2S). [ 35S]SO 2− 4 was rapidly incorporated into both organic and steam-volatile H 2S pools, with preferential labelling of organic matter at the surface of the peat (⩽ 10 cm depth) and of steam-volatile H 2S at greater depth (⩾ 10 cm depth). Less than 2% of the steam-volatile H 2S could be accounted for as H 2S in solution in the pore water, and evidence suggesting FeS as the source of this fraction is presented. Less than 2% of the total S in the profile was present as FeS 2 or S°, and S 2O 2− 3 and S 4O 2− 6 could not be detected. Measurements of total S content of the peat and estimates of the age of the deposit indicate a rate of S accumulation of 4.76–6.06 g S m −2yr −1. The results are discussed in the context of the mechanisms of S transformations and uptake by other mire systems.