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1.
Carbon dioxide emissions and the mass loss of peat incubated in situ were measured in peat soils in the Australian Alps. The carbon chemistry of incubated peats was characterized using 13C nuclear magnetic resonance (NMR). In situ decomposition decreased as a function of increasing alkyl carbon content of the initial organic matter, providing direct evidence of the oft‐cited link between substrate quality and decomposition rates. More mass loss occurred in the bog peat samples than in the dried peat samples. However, at the peat surface, the amount of CO2 emitted was not significantly different between bog peat and dried peat. Carbon inputs, and therefore the sink or source status, of these peats are yet to be quantified.  相似文献   

2.
The major bog systems in northern areas are dominated by Sphagnum species, the partially decomposed remains of which form the bulk of deep peat. By adding mono- and di-valent cations to deep peat cores (2.0-2.5 m) and measuring CH4 and CO2 concentrations in the manipulated peat cores using quadrupole mass spectrometry (QMS) we demonstrate that the lack of availability to microorganisms of essential cations is limiting decay in deep peat. The cations with the highest binding strength displaced the most cations and stimulated decay. Decay in deep peat cores was also stimulated by a C source (acetate), but not by NH4+. The addition of cations and acetate resulted in a less than additive stimulation of decay. The stimulatory effect of acetate and copper decreased in the presence of ammonium. The addition of EDTA to surface bog peat (where cations are conserved) decreased decay rates in surface peat (0.0-0.5 m) to that of the untreated deep peat (2.0-2.5 m). Deep peat was unaffected by treatment with EDTA. The effect of adding Cu2+differed with the depth from which the peat was collected. Cu2+ did not stimulate decay in surface bog peat (0.0-1.5 m) but stimulated decay in peat from 1.5-3.5 m. Below 3.5 m to the bottom of the profile (5.0 m) no positive effect was observed. By comparing deep peat with surface peat we have shown that cation limitation because of high cation exchange capacity is specific to the main mass of deep bog peat and may explain differences in decay rates between anoxic surface peat and deep peat.  相似文献   

3.
We examined the effect of cation treatments on methanogenic activity and nutrient release from exchange sites in raised bog and fen peats. Treatments consisted of cation chloride solutions (MgCl2, AlCl3 and PbCl2) applied individually. In raised bog peat Al3+ and Pb2+ increased CH4 production. A correlation was found between CH4 production and the amount of micro- and macronutrient cations released by the treatments. In calcareous fen peat, such a stimulation was also found, but there was no correlation between CH4 production and micro and macronutrient release. Direct nutrient and pH effects could not account for these observations. Thus the results support the hypothesis that the methanogenic community in the raised bog is limited by the availability of mineral nutrients and/or inactivity of exo-enzymes, both of which are bound onto exchange sites.  相似文献   

4.
Variations in sulphate (SO4 2-) concentration of porewater and net SO4 2- mobilization were related to differences in water level fluctuations during wet and dry summers in two conifer swamps located in catchments which differed in till depth and seasonality of groundwater flow. Sulphate depletion at the surface and in 20 cm porewater coincided with anoxia and occurred mainly during the summer when water levels were near the peat surface and water flow rates were low in both catchments. There was an inverse relationship between net SO4 2- mobilization and water level elevation relative to the peat surface, explaining variation in SO4 2- dynamics between the swamps during summer drought periods. Aeration of peat to 40 cm and a large net SO4 2- mobilization (10–70 mg SO4 2- m-2 d-1) occurred during a dry summer in which the water level dropped to 60 cm below the surface in the swamp receiving ephemeral groundwater inputs from shallow tills within the catchment. This resulted in high SO4 2- concentrations in the surface water and porewater (30–50 mg L-1), and elevated SO4 2- concentrations remained through the fall and winter. In contrast, within the swamp located in the catchment with greater till depth (> 1 m), continuous groundwater inputs maintained surface saturation during the dry summer, and SO4 2- mobilization and concentrations of SO4 2- in the pore water during the following fall did not increase. Susceptibility to large water table drawdown and mobilization of accumulated SO4 2- is influenced by the occurrence of ephemeral vs. continuous groundwater inputs to valley swamps during dry summer periods in the Canadian Shield landscape. This study reveals that extrapolation of results of SO4 2- cycling from one wetland to another requires knowledge of the hydrogeology of the catchment in which the wetlands are located.  相似文献   

5.
The restoration of drained peat bogs in Northwest (NW) Europe is an important task of soil protection, but needs to cope with warmer and drier summers. Our examination took place in the Pietzmoor bog (Schneverdingen, NW Germany) that had been drained for fuel peat extraction until the 1970s and rewetted since then. We determined carbon dioxide (CO2) efflux in situ and in laboratory incubations. Also, we analyzed pore water for dissolved organic carbon (DOC), total and dissolved organic N (DON), nitrate (NO3–) and ammonium (NH4+) concentration. In Schneverdingen, the summer 2003 was record-breaking hot (mean temperature June to August elevated > 3 K compared to long-term average) and dry (precipitation during the same period < 59% of long-term average). In July 2003, the water table in the Pietzmoor subsided to > 42 cm below the surface in July 2003, when in situ soil CO2 efflux was up to 23.4 g m–2 d–1 compared to 15.7 g m–2 d–1 in September. Prior to March 2003, DOC concentrations in pore water were < 180 mg l–1 and NH4+ was the dominant fraction of mineral N. In July 2003, DOC concentration rose to 249 g l–1, DON concentrations more than doubled, and NO3– became the dominant fraction of mineral N. Due to the increased future likelihood of hot and dry summers in NW Germany, peat bog restoration efforts need take care that a water table close to the surface is maintained.  相似文献   

6.
To gain insight into the effects of drying and rewetting events on anaerobic respiration in ombrotrophic peat soils, we investigated bacterial sulfate (SO4) reduction and methane (CH4) production in anaerobic incubations of intact peat microcores from 30 to 40 cm depth of Mer Bleue bog, Ontario/Canada. Concentrations of dissolved SO4, carbon dioxide (CO2), CH4, acetate, and hydrogen (H2) were recorded and net turnover rates calculated from regression. Gross rates of bacterial sulfate reduction were determined by 35SO4 tracer incubation. After incubation, the peat was dried and rewetted, with saturated peat serving as control. CO2 production was initially rapid (up to <360 nmol cm?3 d?1) and slowed towards an endpoint of 2–3 mmol l?1, which was only partly related to thresholds of Gibbs free energies of the involved processes. Acetate rapidly accumulated to levels of 600–800 μmol l?1 and remained constant thereafter. CH4 production (0–2.8 nmol cm?3 d?1) was small and delayed, even after SO4 was depleted, by about 30–40 d. Hydrogenotrophic methanogenesis was endergonic and the process thus likely followed an acetotrophic pathway. Drying and rewetting replenished the SO4 pool, enhanced SO4 reduction rates and suppressed methanogenesis. The overall contribution of net SO4 reduction and methanogenesis to the CO2 production rate was small (0.5–22%) and only enhanced in replicates subjected to drying (35–62%). The major fraction of respiration in the incubated peat cores thus followed yet unidentified pathways.  相似文献   

7.
Fog chemistry was studied for four years (April 1997–March 2001) at Mt. Rokko (altitude 931 m) in Kobe, Japan. A collection of samples was obtained at a mountainous site close to a highly industrialized area. The samples were collected by an active string-fog collector. The summer fog was dense and frequent. The geography of Mt. Rokko is linked to the seasonality of the occurrence and the thickness of the fog. Among the meteorological parameters, the relative humidity was important for the occurrence of fog. The correlation of the concentrations of the components in fog water indicated that (NH4)2SO4 and/or NH4HSO4 were involved in the process of the formation of fog drops in the atmosphere. The concentration of the components decreased with an increase in the liquid water content (LWC) of the fog, and the seasonal variation of the concentration of some components depended on the seasonal variation of the LWC. The equivalent ratio of NO3 ? to non-sea salt (nss?) SO4 2? was considerably larger than that in precipitation. Ammonium ion accounted for the largest percentage of cations, which indicates that NH4 + was an important counter cation for NO3 ? and nss-SO4 2?. A unique fog event in which the air pollutants seemed to be scavenged stoichiometrically was sometimes observed. The methodology used for collecting fog water at 60 mL intervals provided detailed information.  相似文献   

8.
Abstract

The geochemical differentiation of major elements in various peat bog profiles from Bieszczady Mountains Region (south-east of Poland) was compared to its botanical origin. Peat cores were taken from ombrotrophic, mesotrophic, and oligotrophic peatlands, which were developed in the stream valley of the River San. Twenty-four various peat samples were analysed for peat genus, degree of peat decomposition, ash content, total nitrogen, and total carbon content of hydrolytic matter as well as content of major elements: Na, K, Mg, Ca. The results show that the botanical composition of peat deposits is no reliable indication of their trophic status. The common feature of investigated Holocene peatlands is their valley localisation on the flood terrace. The specific character of local geommorpho8ogicml and hydrological condition caused that the bottom layer of all investigated bog profiles was made of wood peats (Piceaeti, Pineti, Alneti, and Saliceti peat). The geochemical investigations of stratigraphical profiles confirm that the presented peat bogs showed specific morphological separateness comparing to other raised bogs situated in mountains or lowlands  相似文献   

9.
Arylsulphatase activity was measured in blanket peat from 29 sites in northern England and Wales. Low activities (<0.5 μmolp-nitrophenol h?1 g?1 dry wt) were observed in sites close to urban and industrial areas. Sites remote from such areas had activities an order of magnitude higher.Peat transplanted into a polluted site showed a rapid loss in arylsulphatase activity which declined linearly over 12 weeks. Similar peat transplanted into a less-polluted site showed no such decline over the same period.Laboratory experiments in which peat was watered with solutions containing components of acidic deposition at realistic concentrations showed that these, with the exception of NH+4 ions, decreased enzyme activity. HSO?3 ions (or dissolved and unreacted SO2) produced the greatest decrease in enzyme activity.The results are discussed in relation to the precise cause of the low arylsulphatase activity observed in polluted blanket peat, and the possible use of this as a monitor of the ecological effects of acidic deposition.  相似文献   

10.
In soil incubation experiments we examined if there are differences in the kinetic parameters of atmospheric methane (CH4) oxidation in soils of upland forests and forested peatlands. All soils showed net uptake of atmospheric CH4. One of the upland forests included also managed (clear-cut with or without previous liming or N-fertilization) study plots. The CH4 oxidation in the forested peat soil had a higher Km (510 μl l−1) and Vmax (6.2 nmol CH4 cm−3 h−1) than the upland forest soils (Km from 5 to 18 μl l−1 and Vmax from 0.15 to 1.7 nmol CH4 cm−3 h−1). The forest managements did not affect the Km-values. At atmospheric CH4 concentration, the upland forest soils had a higher CH4 oxidation activity than the forested peat soil; at high CH4 concentrations the reverse was true. Most of the soils oxidised CH4 in the studied pH range from 3 to 7.5. The pH optimum for CH4 oxidation varied from 4 to 7.5. Some of the soils had a pH optimum for CH4 oxidation that was above their natural pH. The CH4 oxidation in the upland forest soils and in the peat soil did not differ in their sensitivities to (NH4)2SO4 or K2SO4 (used as a non-ammonium salt control). Inhibition of CH4 oxidation by (NH4)2SO4 resulted mainly from a general salt effect (osmotic stress) though NH4+ did have some additional inhibitory properties. Both salts were better inhibitors of CH4 oxidation than respiration. The differences in the CH4 oxidation kinetics in the forested peat soil and in the upland forest soils reveal that there are differences in the physiologies of the CH4 oxidisers in these soils.  相似文献   

11.
Long‐term monitoring data from eastern North America and Europe indicate a link between increased dissolved organic carbon (DOC) concentrations in surface waters over the last two decades and decreased atmospheric pollutant and marine sulphur (S) deposition. The hypothesis is that decreased acidity and ionic strength associated with declining S deposition has increased the solubility of DOC. However, the sign and magnitude of DOC trends have varied between sites, and in some cases at sites where S deposition has declined, no significant increase in DOC has been observed, creating uncertainty about the causal mechanisms driving the observed trends. In this paper, we demonstrate chemical regulation of DOC release from organic soils in batch experiments caused by changes in acidity and conductivity (measured as a proxy for ionic strength) associated with controlled SO42? additions. DOC release from the top 10 cm of the O‐horizon of organo‐mineral soils and peats decreased by 21–60% in response to additions of 0–437 µeq SO42? l?1 sulphuric acid (H2SO4) and neutral sea‐salt solutions (containing Na+, Mg2+, Cl?, SO42?) over a 20‐hour extraction period. A significant decrease in the proportion of the acid‐sensitive coloured aromatic humic acids (measured by specific ultra‐violet absorbance (SUVA) at 254 nm) was also found with increasing acidity (P < 0.05) in most, but not all, soils, confirming that DOC quality, as well as quantity, changed with SO42? additions. DOC release appeared to be more sensitive to increased acidity than to increased conductivity. By comparing the change in DOC release with bulk soil properties, we found that DOC release from the O‐horizon of organo‐mineral soils and semi‐confined peats, which contained greater exchangeable aluminium (Al) and had lower base saturation (BS), were more sensitive to SO42? additions than DOC release from blanket peats with low concentrations of exchangeable Al and greater BS. Therefore, variation in soil type and acid/base status between sites may partly explain the difference in the magnitude of DOC changes seen at different sites where declines in S deposition have been similar.  相似文献   

12.
A mixed provenance Sitka spruce plantation, planted in 1986 on a drained deep peat, has been exposed to 6 different simulated mist treatments in 4 replicated blocks since 1996. Treatments provided N and/or S at a concentration of 1.6 mol m?3, supplying ca. 50 kg S and/or N ha?1 yr?1 as N (NH4NO3), S (Na2SO4), NS Acid (NH4NO3 + H2SO4 at pH 2.5), 2NS Acid (double dose by application at twice frequency), a control treatment supplied with additional rainwater only and a 'no treatment' set of plots. Throughfall, preserved with thymol in the field, was collected using gutters with a surface area of 1 m2 in all the replicate plots, and was analysed for all major ions. Prior to treatment in 1999, S deposition in throughfall exceeded that in rain because of dry deposition of SO2 and SO4 2? to the canopy; NH4 + and NO3 ? ions were both retained in the canopy. During treatment, only 20–40% of the applied N in the high-N treatments was retained in the canopy. Acidity in the applied mist was partly neutralised by the canopy, but not primarily through exchange of base cations, leading to the conclusion that weak organic acids, in solution or in situ in the canopy, contributed to the buffering of the H+ ion deposition in the acid treatments.  相似文献   

13.
Peanut (Arachis hypogea cv. Shulamit) grown on very high calcium carbonate (CaCO3) content soils is showing iron (Fe) chlorosis symptoms. Supplying the plant with ammonium sulphate ((NH4)2SO4) in the presence of nitrapyrin (N‐Serv) for preventing nitrification reduced Fe chlorosis. Nitrate (NO‐ 3) developed in the soil with time, even with nitrapyrin present. When ammonium (NH+ 4) was even less than 20% of the total mineral N in the soil, no Fe‐stress could be observed, suggesting that the NH+ 4 uptake by the plant and the consequence of hydrogen (H+) efflux occurs from the root to the rhizosphere, resulting in a decrease of redox potential near the root, and solubilizing enough Fe near the root to overcome the chlorosis.  相似文献   

14.
Acid rain sulphate (SO42−) deposition is a known suppressant of methane (CH4) emission from wetlands. However, the hypothesised mechanism responsible for this important biogeochemical interaction, competitive exclusion of methanogens by dissimilatory SO42− reducing bacteria (SRB), lacks supporting evidence. Here, we present data from an acid rain simulation experiment in the Moidach More peat bog of NE Scotland that strengthens this hypothesis. We report a tenfold increase in estimated SO42− reduction during periods when measured CH4 emission rates were suppressed relative to controls receiving only one-tenth the SO42− of treated plots, but no treatment effect on potential methane oxidation. This tenfold increase in estimated SO42− reduction indicates the presence of a more active population of SRB in plots where CH4 emissions were reduced by over 30%.  相似文献   

15.
Abstract

Researchers frequently must store water samples >24 h after collection until chemical analyses can be accomplished. Samples are commonly stored in darkness at near‐freezing temperatures until analysis, but effects of this storage method on soil water chemistry are not well‐documented. Soil water samples were collected from eastern hemlock [Tsuga canadensis (L.) Carriere] stands and analyzed initially and over time to determine if nitrate (NC3 ‐), chloride (Cl‐), sulfate (SO4 2‐), ammonium (NH4 +), and/or total nitrogen (TN) concentrations changed when samples were stored in darkness at 2–4°C. Subsamples were analyzed <24 h after collection and reanalyzed five times in a 12 to 24 wk period following sample collection. Nitrate concentrations remained stable for at least one wk and were only slightly lower than initial concentrations after 3–16 wk of storage. Chloride and SO4 2‐ remained stable for 16 wk, while TN remained stable for 8 wk and decreased slightly after 24 wk. Most NH4 + concentrations were below the limit of quantification, but concentrations of samples with quantifiable NH4 + decreased in the first week of storage. Overall, cold storage in darkness was effective for preserving NO3 ‐, Cl‐, SO4 2‐, and TN concentrations in soil water, but NH4 + analyses should probably be performed as soon as possible after sample collection.  相似文献   

16.
For the paleoreconstruction of permafrost peat mounds and the identification of plant communities participating in the formation of peat, the contents of n-alkanes (C20–C33) have been determined, and relative changes in the stable isotope compositions of carbon and nitrogen and the C/N ratio have been analysed. Several indices (CPIalkanes, Paq, Pwax) have been calculated to assess the degree of decomposition of the peats studied and the contributions of different plant species to their formation. It has been found that shortand long-chain n-alkanes are concentrated in high-moor peat, while medium-chain alkanes are typical for transitional peat. Integrated analysis of the studied markers has shown that the botanical and material composition of peat, anaerobic conditions of bog formation, and permafrost play an important role in the preservation of organic carbon in permafrost peat mounds. Alternation of plant associations is the main reason for changes in n-alkane concentrations, C/N ratios, and δ13C values.  相似文献   

17.
In central Ontario, elevated SO4 concentrations and export have been measured in both upland and wetland-draining catchments following summer droughts, although the source of excess SO4 is unclear. The objective of this study was to determine the effects of drying and re-wetting and temperature, respectively, on the release of SO4 from the primary S pools in wetlands (Sphagnum and peat) and uplands (forest floor and mineral soil), using material collected from the PC1 catchment in Haliburton County, and from catchment S50 in the Turkey Lakes Watershed. Peat exhibited the most marked response to drying of the four materials considered, and within 24 h of re-wetting dried peat from both catchments released 3-4 times more SO4 (50-67 mg kg−1 S-SO4) than continuously moist peat (16 mg kg−1 S-SO4), although temperature had only a marginal effect on SO4 concentrations. There was no immediate response of Sphagnum to either drying or temperature, although S-SO4 concentrations in Sphagnum tended to increase over the 30-day (d) incubation. There was a small but immediate increase in S-SO4 concentrations in forest floor material (LFH) from both catchments within the first 24 h of incubation, which was greatest in treatments that were dried and/or incubated at a higher temperature. In contrast, neither temperature nor drying appeared to affect SO4 release from mineral soil collected from either site. Results of laboratory incubations suggest that increases in SO4 concentration that have been reported in wetland-draining streams immediately following summer dry periods may be quantitatively explained by drying and re-wetting of peat rather than increased mineralization in Sphagnum. Similarly, the higher SO4 concentrations that have been measured in upland streams following summer droughts may in part be due to enhanced SO4 release from the forest floor following drying and re-wetting. In contrast, while the mineral soil constitutes a large pool of total S, it does not appear to be responsive to changes in moisture or temperature in the short-term (<30 d) and therefore likely does not contribute to reported climate-related temporal variations in stream SO4.  相似文献   

18.
Enchytraeid worms (Oligochaeta) are the dominant mesofauna in wet acidic habitats. They have key roles in biogeochemical cycling, and can be used as biological indicators. Here we report the response of these worms to in situ ammonia-N (NH3-N) deposition on an ombrotrophic bog. Three years of NH3-N fumigation from an automated release system has created a gradient of NH3-N concentrations downwind of the release pipe ranging from 83 μg m−3 (near source) to 4.5 μg m−3 NH3-N (60 m from release pipe); the ambient NH3-N concentration is 0.56 μg m−3 NH3-N. Peat pH and mineral N content have increased near the ammonia release pipe. We hypothesised that enhanced N deposition at the site would have improved litter quality and thus, enchytraeid distribution would be increased along the transect compared to ambient. However, neither litter quality nor enchytraeid abundance and diversity were affected by NH3-N despite increases in peat pH and mineral N. This suggests that three years of ammonia fumigation was not enough time for plant matter exposed to ammonia to become incorporated into the peat litter layer. Enchytraeids appear not to be sensitive indicators of NH3 fumigation because there was no effect below-ground of peat chemistry on litter quality.  相似文献   

19.
Fluxes of principal anions and cations with bulk and throughfall deposition during the growing period (April–September) were investigated for three years (2001–2003) at three sites differently exposed to the second biggest Lithuanian city – Kaunas. Fluxes of all investigated anions (SO4 2?, NO3 ? and Cl?) and most cations were found to be the highest in suburban area to compare with both – Rural and urban sites. The highest seasonal variability of monthly ion fluxes and the highest differences between throughfall and bulk fluxes (net throughfall) were recorded in suburban area. The highest throughfall enrichment by sulphur was detected in spring and the beginning of summer (April, May) in urban and especially in suburban sites. For nitrogen compounds (NO3 ?, NH4 +) positive net throughfall values were characteristic for urban and suburban sites and negative for rural site almost during the entire growing period. Uptake of NH4 + ions was detected to be much higher of that for nitrates in rural area (46% vs. 22%). The most intensive enrichment of throughfall fluxes by K+ ions took place during the summer time (May, June, July), however, intensity of potassium leaching at the same amount of precipitation was the highest in suburban area.  相似文献   

20.
A field experiment was designed to evaluate the effects of differing forms of acidifying S and N compounds on the chemistry of soils and soil solutions in a low elevation coniferous forest in northern New England. Treatments consisted of O, 1500, 3000, and 6000 eq of SO4 2? or NO3 ? ha?1 for the 1987 growing season applied biweekly as H2SO4 or HNO3, or in a single application as dry] (NH4)2SO4. Acidifying treatments resulted in a significant increase in soil solution SO4 2? (1.2 to 2.6) or NO3 ? (12 to 80) in the upper B horizon. Excess strong acid anion leaching was associated with an accelerated loss of base cations, particularly MG2+ As solutions passed through the upper 25 cm of the soil profile, mean SO4 2? concentrations decreased by 5 to 50% of the initial values, indicating that much of the applied SO4 2? was immobilized in the upper portion of the pedon. Elevated concentrations of adsorbed and water-soluble SO4 2? indicate that abiotic adsorption of SO4 2? by soils is the dominant mechanism for the initial attenuation of SO4 2? concentrations in these solutions. Other soil properties showed only small or no change due to treatments over the single growing season of this study. These results indicate that H2SO4, HNO3, and (NH4)2SO4 can all effectively increase strong acid anion concentrations in the soil-soil solution system.  相似文献   

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