Climatic information from δ13C in plants by combining statistical and mechanistic approaches
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The approach commonly used to assess the potential for climate reconstruction is to use linear regressions to compare the isotopic signal stored in archives to instrumental climatic data sets. A new method is proposed that combines statistical and mechanistic approaches to extract climatic information from δ 13 C records in organic matter. Both a spatial and a temporal gradient of 13 C discrimination in a moss species commonly found in temperate and tropical peat bogs are compared to meteorological records. The relevance of fossil and modem analogues to elucidate palaeoenvironment records are tested. It was found that the magnitude and, in some cases, the direction of the impact of temperature, humidity and CO 2 atmospheric concentration on 13C discrimination depend on the calibration set considered. The use of a mechanistic model is shown to help greatly in specifying the joint influence of the climatic variables.Keywords:
Paleoclimatology
The study focused on the distribution of the elements of peat in the Jinbei bog of the Changbai Mountain.Samples were collected with Wardenaar peat sampler madein Netherlands.The peat bog is located in the Jinbei of Fusong countywith altitude of over 900 min Jilin province,Northeast China.The peat depth is about 1.1 m,and the area 4.925 km~(2).The peat developed between 366-1 944 a.The winter here is long and cold while summer short and humid.The annual precipitation varies between 650 mm and 900 mm and the mean temperature is 2 ℃to 5 ℃.The peat bog developed here was typically ombrotrphic,which indicated the inorganic content was mainly from rainwater.Sphagum is widely developed and the mineral where the peat began to develop is basalt mesa.Each peat profile was sectioned into 2 cm at thefield.The contentsof Ca,Mg,Na,Kand Al,Ti,Cu,Zn,Fe,Mn,Pb,Ni,Cr,Co were determined by GBC-906AASand ICP-AES respectively.The article aimed at revealing the depositional environment of the Jinbei peat bog,the changes of heavy metal elements with history and its implications for environment.The order average content in peat profile was AlFeNaKCaMgMnZnCrPbCuCoNi.Furthermore compared with the average content of trace elements with peat bogs in the Daxinganling Mountains,the elements' contents were all more than those of peat bogs in the Daxinganling Mountains except Mn and Ni.The correlation analysis between the analyzed elements indicated the differencesbetween them.Conservative elements such as Al and Ti were significantly correlated.Most of the heavy metals in peat were significantly correlated except Cu,for Cu can be easily transferred with water in acid condition.Through the enrichment analysis of the elements,the results showed that Mn,Zn,Pb,Cu,Ni,Cr and Co were significantly enriched in the top section of the peat profile.And Na and K distribution were strongly affected by their transference with water in peat.The EF value of major elements(Al、Fe、Na、K、Mg and Ca) were all less than 1,indicating relative less depositional sources of atmospheric soil dust.It was found that the distribution of major elements with depth was greatly intimate with the sediment chemistry when the peat began to develop,and Na、K were affected by bioaccumulation of plants.The increasing content of Mn,Zn,Pb Ni,Cr and Cofrom bottom to top in peat profile prove the increasing pollution of them in environment during these yearsand the increase of the metal consumption and exhaustion were the main sources,which has profound implications for environment.
Ombrotrophic
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Abstract Bog peat soils have been accumulating at Wellington Plain peatland, Victoria, Australia for the last 3300 years. Now, dried peat soils are common adjacent to bog peats. The 14 C basal age of dried peat is not different from the 14 C basal age of bog peat, which supports the theory that dried peat formed from bog peat. A novel application of 210 Pb dating links the timing of this change with the introduction of livestock to Wellington Plain in the mid‐1800s. Physical loss of material appears to have been the dominant process removing material as bog peats drained to form dried peats, as indicated by the mass balances of carbon and lead. This research has implications for the post‐fire and post‐grazing restoration of bogs in Victoria's Alpine National Park, and the contribution of peat soils to Australia's carbon emissions.
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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 Key Words: geochemistryISEB 16peat bog classification
Ombrotrophic
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We used moss increment counting to obtain well-defined samples of the topmost peat layers of two Sphagnum fuscum hummocks. The two ombrotrophic bogs, Lakkasuo in central Finland and Korvinsuo in eastern Finland, are of different ages, covering 3 and 9 ka, respectively. Using AMS dating, we traced bomb-produced 14 C through the topmost parts of the two peat profiles. A well-defined 14 C activity peak was found in both sequences dating the corresponding layer to ad 1965. A comparison between the maximum peat activities and the corresponding atmospheric values for the period of interest provides an opportunity to evaluate the amount of CO 2 emanating from the decaying peat bog, and taken up by the living sphagnum plants. Considerable variations in δ 13 C values were also observed. These variations indicate, at least partly, annual variations in the emission rate of CO 2 from decomposition of older peat in the bog, and are connected with climatic factors such as temperature and precipitation.
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Sphagnum
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ABSTRACT In the first of this pair of papers we introduced the conceptual and hydrological basis of the peatland development model—DigiBog. Here we describe the submodels which simulate (i) the production of plant litter, (ii) peat decomposition, and (iii) changes in peat hydraulic conductivity due to decomposition. To illustrate how the model works, DigiBog was applied to three example situations: Bogs 1, 2, and 3. For each, the net rainfall was held constant at 30 cm year −1 and the oxic decomposition parameter kept at 0·015 year −1 . The anoxic decomposition parameter varied from 5 × 10 −6 (Bog 1) to 5 × 10 −4 year −1 (Bog 3). Peatland development was simulated for 5000 years. For Bogs 1 and 2, plausible large peatland domes develop. Despite having a higher anoxic decomposition rate, Bog 2 grew thicker than Bog 1. This apparently counter‐intuitive result is caused by the feedback between hydraulic conductivity and degree of peat decomposition. For both Bogs 1 and 2, DigiBog also simulates transitions from wet to dry states, demarked by sudden switches from poorly decomposed to well‐decomposed peat moving upwards in the peat profile. These regime shifts result from internal peatland dynamics and not from allogenic influences, and challenge the view that peat properties are always a reflection of climate. In Bog 3, a ‘mini‐bog’ developed and persisted near the margin of the peatland; this bog can also be explained in terms of the internal feedbacks within the model. Copyright © 2011 John Wiley & Sons, Ltd.
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