共查询到20条相似文献,搜索用时 15 毫秒
1.
The process of the transformation of fresh organic matter (OM) into more stable and recalcitrant humic substances is still not completely clear. Understanding how OM humification evolves in northern bog environments is extremely important, especially considering that they represent one of the largest terrestrial carbon pools.Structural changes of OM occurring during the humification process have been generally evaluated by indirect measurements of the degree of humification. Several approaches have been used, often providing contrasting results probably because humification is a complex process that evolves differently according to varying pedoclimatic conditions.In the present work, the authors followed the evolution of peat OM along a 165 cm bog profile (covering the mid- to late Holocene) correlating results obtained from both organic petrological and chemical investigation. Data clearly underline a significant agreement between the two perspectives, both showing either a quite immature peat material or the presence of three distinct zones along the profile. In detail, both spectroscopic (i.e., FT-IR and three dimensional fluorescence spectra, humification indexes), and Rock-Eval pyrolysis results (low residual organic carbon content and high hydrogen and oxygen index values) showed the occurrence of a central zone (from 20-30 cm to 120 cm depth) often characterized by high heterogeneity and a low degree of humification when compared to the upper ∼20 and bottom 40 cm sections. 相似文献
2.
Holocene lateral expansion, peat growth and carbon accumulation on Haukkasuo, a raised bog in southeastern Finland 总被引:1,自引:0,他引:1
Paludification intensity and peat deposition on Haukkasuo bog in southeastern Finland were studied with peat stratigraphic investigations by taking 79 samples for 14 C carbon dating and 164 volumetric samples. Peat formation of Haukkasuo, a concentric raised bog, began about 10 400 cal. BP. Lateral expansion has been largely controlled by the flat clayey floor, which has favoured rapid growth of the bog. During the first 400 years of its existence the bog covered one-fifth, and in the following 2000 years one-half, of its present extent. The long-term carbon accumulation rate averages 22.3 g C/m2 /yr in the central part of Haukkasuo and 16.7 g C/m2 /yr in its margins. The highest rates of carbon accumulation over 500-year periods were recorded in the central part of the bog in 6500–5500, 3500–2500 and 1500–0 cal. BP. The rate of vertical peat increment was higher than average in these periods, and the peat was mainly slightly humified and, when close to the surface, un compacted. The rate of carbon accumulation was lowest in 5500–3500 and 2500–2000 cal. BP, when the rate of vertical growth was lower than average and the peat was more humified than average. The formation of peat, the rate of vertical peat increment and the succession of peat types in Haukkasuo have mainly been controlled by hydrological changes caused by local factors, although climatic factors might also be important. In particular, the formation of slightly humified peat in 3300–2700 cal. BP and during the last 1300 years can be related to humid climate. 相似文献
3.
KARL‐DAG VORREN CHRISTIN ELDEGARD JENSEN EILIF NILSSEN 《Boreas: An International Journal of Quaternary Research》2012,41(1):13-30
Vorren, K.‐D., Jensen, C. E. & Nilssen, E. 2012 (January): Climate changes during the last c. 7500 years as recorded by the degree of peat humification in the Lofoten region, Norway. Boreas, Vol. 41, pp. 13–30. 10.1111/j.1502‐3885.2011.00220.x. ISSN 0300‐9483. Two peat cores from two neighbouring bogs in Lofoten, northern Norway were densely AMS dated and analysed for humification. The two cores have been influenced by human agricultural impact, especially c. 1600 cal. a BP, which may have affected the local hydrology of the bogs. From 7400 cal. a BP onwards, 19 distinct wet‐shifts are recorded in the two cores. Eight or nine of these correspond chronologically to periods of low solar activity. This correlation is most convincing during the last 2000 years. Some wet‐shifts are connected with a solar low‐activity period during the Subboreal/Subatlantic transition, which in central Europe is dated at 2750–2565 cal. a BP. For Lofoten, the corresponding Subboreal/Subatlantic transition – or the wet‐shift marking this transition – is dated at c. 2600 cal. a BP. Some wet‐shifts occur just before or just after solar low‐activity periods, but only four of the nineteen wet‐shifts are clearly not temporally connected with periods of low solar activity. Compared with the wet‐shifts in NW European (mainly British Isles) bogs, there are more frequent wet‐shifts in northern Norway. Compared with other peat cores in northern Norway, especially for the interval 6500–5000 cal. a BP, Lofoten deviates by its lack of wet‐shifts. As in England, Scotland and Ireland, there is regional variability in the temporal formation of wet‐shifts in northern Norway. 相似文献
4.
In 65 samples, we got values (unusually replicable and consistent for this type of work) of concentration, 14C/13C (AMS) age, and δ13C for: peat, dissolved organic carbon (DOC), peat fractions, and dissolved CO2 and CH4 at 50-cm intervals down to 700 cm in Ellergower Moss, a rainwater-dependent raised (domed) bog in southwest Scotland. (1) We attribute the consistency of the results to Ellergower Moss being unusually homogeneous, with unusually low hydraulic conductivity, and containing only a few gas spaces; and to the sampling methods including 18-month equilibration of in situ samplers. (2) The dissolved gas concentration depth profiles are convex and very similar to each other, though CO2 is 5-10 times more concentrated than CH4, while the profile of DOC is concave. (3) The age profile of peat is near linearly proportional to depth; that for DOC is about 500-1000 yr younger than the peat at the same depth; the dissolved gases are 500-4300 years younger than the peat. The age of the operational peat fractions humic acid and humin is similar to that of whole peat. (4) The δ13C profile for deep peat is almost constant; δ13C-CO2 is more enriched than the peat (δ13C-CO2 35‰ more); δ13C-CH4 is the same amount more depleted. Nearer the surface both dissolved gases become steadily more depleted, δ13C is about 20‰ less at the surface. (5) A simulation shows that mass flow can account for the concentration and age profiles of DOC, but for the gases diffusion and an additional source near the surface are needed as well, and diffusion accounts for over 99% of the dissolved gas movements. (6) The same processes must operate in other peatlands but the results for Ellergower should not be extrapolated uncritically to them. 相似文献
5.
天目山泥炭类脂物记录的微生物特征和植被演替 总被引:3,自引:0,他引:3
为进一步了解泥炭中微生物特征和植被的变化,对采自浙江天目山的样品进行了类脂生物标志物与有机碳同位素(δ13Corg)的测定。有机碳δ13Corg值整体偏负,显示C3植物占优势的特点。正构烷烃的分布特征表明,大多数样品来源于陆生高等植物和低等菌藻类生物,其中高碳数正构烷烃主要以C29为主峰,显示植被类型以木本植物为主,但草本植物的相对比例也发生了多次变化,且这种变化与有机质的相对贡献量密切相关。在深度100~68cm,不同来源的有机质,特别是低等菌藻类的相对贡献量都相对较少;在深度68~30cm,低等菌藻类生物的贡献逐渐变大;而表层泥炭的有机质主要来源于高等植被,菌藻类的输入较少。泥炭有机碳同位素与类脂生物标志物的综合特征表明,该区植被经历了几次明显变化,并据此可将研究区中全新世以来环境演化分为早(4100~3200aB.P.)、中(3200~700aB.P.)、晚(700aB.P.以来)三个环境演化阶段,其结论与前人的环境演化与全球气候变化研究具有较好的可比性。 相似文献
6.
7.
A proxy climate record from a raised bog in County Fermanagh, Northern Ireland, is presented. The record spans the interval between 2850 cal. yr BC and cal. yr AD 1000 and chronological control is achieved through the use of tephrochronology and 14C dating, including a wiggle‐match on one section of the record. Palaeoclimatic inferences are based on a combination of a testate amoebae‐derived water table reconstruction, peat humification and plant macrofossil analyses. This multiproxy approach enables proxy‐specific effects to be identified. Major wet shifts are registered in the proxies at ca. 1510 cal. yr BC, 750 cal. yr BC and cal. yr AD 470. Smaller magnitude shifts to wetter conditions are also recorded at ca. 380 cal. yr BC, 150 cal. yr BC, cal. yr AD 180, and cal. yr AD 690. It is hypothesised that the wet shifts are not merely local events as they appear to be linked to wider climate deteriorations in northwest Europe. Harmonic analysis of the proxies illustrates statistically significant periodicities of 580, 423–373, 307 and 265 years that may be related to wider Holocene climate cycles. This paper illustrates how the timing of climate changes registered in peat profiles records can be precisely constrained using tephrochronology to examine possible climatic responses to solar forcing. Relying on interpolated chronologies with considerable dating uncertainty must be avoided if the climatic responses to forcing mechanisms are to be fully understood. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
8.
V. A. Bobrov A. A. Bogush G. A. Leonova V. A. Krasnobaev G. N. Anoshin 《Doklady Earth Sciences》2011,439(2):1152-1156
When examining the peat deposit discovered in Vydrinaya bog, South Baikal region, the authors encountered anomalous Zn and
Cu concentrations for highmoors being up to 600–500 ppm on a dry matter basis in the Early Holocene beds (360–440 cm) formed
11 000–8500 years ago. It has been demonstrated that Zn and Cu are present inside the plant cells of peat moss in the form
of authigenic sulfide minerals of micron size. Apart from Zn and Cu, native Ag particles (5–7 um) have been encountered in
the peat of the Vydrinaya bog at a depth of 390–410 cm; these particles formed inside the organic matter of the plasma membrane
of peat moss containing Ca, Al, S, and Cu. This study suggests probable patterns of the formation of zinc sulfides, copper
sulfides, and native silver in peat moss. The results obtained indicate that biogenic mineral formation plays a significant
role in this system, which is a very important argument in the discussion on the ore genesis, in which physicochemical processes
are normally favored, while the role of living matter is quite frequently disregarded. 相似文献
9.
全球变暖背景下频发的极端气候事件, 严重影响了经济社会可持续发展。研究过去人类活动背景下的气候变化特征可为预测气候变化趋势、制定应对策略提供历史借鉴。本研究选取福建梅花山国家级自然保护区山间泥炭岩芯(长度238cm)119个沉积物进行腐殖化度分析, 结合粒度和烧失量记录, 重建近千年来福建地区高分辨率气候历史。研究结果显示, 在东亚季风区的低纬亚高山山间盆地, 泥炭沉积物腐殖化度越高, 指示气候越冷干; 腐殖化度越低, 指示气候越暖湿。梅花山泥炭腐殖化度在980~1529A.D.呈现低值(均值8.4%), 指示中世纪暖期较强的东亚季风和暖湿气候; 1529~1926A.D.呈显著高值(均值24.8%), 指示明清小冰期较弱的季风和冷干气候; 1926A.D.以来波动下降(均值22.8%), 对应了现代暖期。梅花山泥炭腐殖化度记录与区域沉积记录显示出对东亚季风的同步响应。研究结果记录了小冰期的第二次和第三次冷期, 分别为1589~1757A.D.和1842~1926A.D.。梅花山泥炭腐殖化度记录的近千年气候变化可能受太阳辐射、热带辐合带和厄尔尼诺/南方涛动等的共同驱动。
相似文献10.
M. Widera G. Jachna-Filipczuk R. Kozula S. Mazurek 《International Journal of Earth Sciences》2007,96(5):947-955
Only one quantitative method is described in the literature to estimate the consolidation coefficient of lignite seams. More
studies concentrate on the compaction of plant tissues, which explains why the obtained results are overestimated. Moreover,
most studies do commonly not determine the consolidation of the whole peat bog but usually those of some of its elements only.
We propose a new approach, which conceptually is fairly close to the Hager et al. (Fortschr Geol Rheinld Westf 29:319–352,
1981) method. Our method has been tested on an example of the first Middle-Polish Lignite Seam and the second Lusatian Lignite
Seam from some Wielkopolska lignite deposits in central Poland. The consolidation coefficients, C
c, range between 2.34 and 2.56 for the second Lusatian Lignite Seam and between 1.80 and 2.14 for the first Middle-Polish Lignite
Seam. 相似文献
11.
Rb/Sr geochronology on a folded greenstone-granitoid complex in the Agnew area, Western Australia, yields four distinct ages of igneous activity that conform with stratigraphic and intrusive relationships. They are (using , NBS 70A = 522 ppm Rb and 65.3 ppm Sr):
Ma | 87Sr/86Sr initial (IR) | |
(1) Differentiated gabbro-granophyre from a stratigraphically old (Kathleen Valley) greenstone sequence | ||
(2) Voluminous tonalite, the Lawlers Tonalite | ||
(3) A less voluminous leucogranite, and a large complex pegmatite cutting the Perseverance nickel orebody | ||
(4) Aplitic leucotonalite (very minor volumes but widespread) |