scholarly journals The effect of diagenesis on carbon isotope values of fossil wood

Geology ◽  
2019 ◽  
Vol 47 (10) ◽  
pp. 987-991 ◽  
Author(s):  
William E. Lukens ◽  
Peace Eze ◽  
Brian A. Schubert
Keyword(s):  
Carbon Isotope ◽  
Atmospheric Chemistry ◽  
Stable Carbon Isotopes ◽  
Fossil Wood ◽  
Cellulose Content ◽  
Deep Time ◽  
Climate Conditions ◽  
Δ13c Value ◽  
Strong Linear Correlation ◽  
Long Time

Abstract The carbon isotope (δ13C) value of modern and fossil wood is widely used as a proxy for environmental and climatic change. Many researchers who study stable carbon isotopes in modern and recently deceased trees chemically extract cellulose (δ13Ccell) rather than analyzing whole wood (δ13Cwood) due to concerns that molecular variability across tree rings could influence δ13Cwood values, and that diagenesis may preferentially degrade cellulose over lignin. However, the majority of deep-time researchers analyze δ13Cwood without correcting for possible diagenetic effects due to cellulose loss. We measured δ13Ccell, δ13Cwood, and cellulose content of 38 wood fossils that span ∼50 m.y. in age from early Eocene to late Miocene, using variability across such a large range of geologic ages and settings as a natural laboratory in diagenesis. For comparison with our measurements, we produced a literature compilation of 1210 paired δ13Ccell and δ13Cwood values made on fossil and modern trees. We report that, on average, the apparent enrichment factor (ε) between δ13Ccell and δ13Cwood (ε = δ13Ccell – δ13Cwood) is 1.4‰ ± 0.4‰ larger in deep-time samples than Holocene wood, and this can be explained by loss of cellulose during degradation, independent of atmospheric chemistry or climate conditions during growth. A strong linear correlation exists between δ13Cwood and δ13Ccell in both deep-time (r2 = 0.92) and Holocene (r2 = 0.87) samples, suggesting that either substrate can provide a reliable record of environmental conditions during growth. However, diagenetic effects must be corrected if δ13Cwood values are compared to extant trees or across long time scales, where cellulose content may vary.

Bacterial presence in polar regions associated with environment modification by chemical compounds including contaminants

2017 ◽  
Vol 25 (4) ◽  
pp. 481-491 ◽  
Author(s):  
Klaudia Kosek ◽  
Katarzyna Jankowska ◽  
Żaneta Polkowska
Keyword(s):  
Bacterial Communities ◽  
Chemical Compounds ◽  
Freshwater Ecosystems ◽  
Trophic Levels ◽  
Polar Regions ◽  
Bacterial Cells ◽  
Chemical Contamination ◽  
Climate Conditions ◽  
Biological Communities ◽  
Long Time

Microbes are omnipresent and diverse members of all biological communities. In marine and freshwater ecosystems, microorganisms form the base of the food chain supporting higher trophic levels. Even though microbes are generally thought to live in warm regions of Earth, many of them develop in cold climates. Polar regions remain relatively protected from widespread anthropogenic disturbances, which is a consequence of thier remoteness and extreme climate conditions. For a long time these regions were considered to be free from chemical contamination until scientists discovered a presence of pollutants there. Chemical contamination may induce serious disorders in the integrity of polar ecosystems influencing the growth of bacterial communities. Xenobiotics including persistent organic pollutants are transported thousands of kilometers by the air and ocean currents, and they are deposed in high-latitude regions and accumulate in all elements of the environment including bacterial communities. It is important to determine their concentration levels in bacterial cells to assess the possibility of contaminants becoming transferred to higher trophic levels; however, some species of bacteria are capable of metabolizing xenobiotics, which makes them less toxic or even removes them from the environment.

Large-scale siliciclastic input during the Paleocene-Eocene Thermal Maximum in the North Sea Basin

2021 ◽  
Author(s):  
Simin Jin ◽  
David Kemp ◽  
David Jolley ◽  
Manuel Vieira ◽  
Chunju Huang
Keyword(s):  
Carbon Isotope ◽  
North Sea ◽  
Climate Warming ◽  
Large Scale ◽  
Time Lag ◽  
Sediment Supply ◽  
Deep Time ◽  
The North ◽  
Thermal Maximum ◽  
The North Sea

<p>The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most marked climate warming event of the Cenozoic, and a potentially useful deep time analogue for understanding environmental responses to anthropogenic carbon emissions and associated warming. The response of sedimentary systems to the large-scale climate changes of the PETM are, however, still uncertain. Here, we present an extremely thick (~140 m) record of the PETM in cores from a well in the North Sea, offshore UK. In this well, a thick Paleocene-Eocene interval is developed owing to uplift of the East Shetland Platform in the late Paleocene. Carbon isotope data through this well, coupled with detailed sedimentological analysis, show that the PETM interval is contemporaneous with >200 sandstone turbidites layers. Mud deposition without turbidites dominated sedimentation below and above the PETM. These observations support previous work from other localities highlighting how climate warming during the PETM likely drove substantial changes in hydrological cycling, erosion and sediment supply. Spectral analysis of turbidite recurrence in the PETM interval suggests that the abundance of turbidites was modulated in part by ~21 kyr astronomical precession climate cycles, further emphasizing a potential climatic control on turbidite sedimentation. In detail, we note a kiloyear-scale time lag between onset of the PETM carbon isotope excursion and the appearance of turbidites in the succession, highlighting a delay between PETM carbon release and warming and the basin-wide response in sediment supply.</p>

Carbon-isotope analysis of fossil wood and dispersed organic matter from the terrestrial Wealden facies of Hautrage (Mons Basin, Belgium)

2010 ◽  
Vol 291 (1-2) ◽  
pp. 85-105 ◽  
Author(s):  
Johan Yans ◽  
Thomas Gerards ◽  
Philippe Gerrienne ◽  
Paul Spagna ◽  
Jean Dejax ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Isotope Analysis ◽  
Fossil Wood ◽  
Carbon Isotope Analysis

An annually resolved bristlecone pine carbon isotope chronology for the last millennium

2011 ◽  
Vol 76 (1) ◽  
pp. 22-29 ◽  
Author(s):  
Roderick J. Bale ◽  
Iain Robertson ◽  
Matthew W. Salzer ◽  
Neil J. Loader ◽  
Steven W. Leavitt ◽  
...  
Keyword(s):  
Carbon Isotope ◽  
Atmospheric Chemistry ◽  
El Niño ◽  
El Nino ◽  
Ring Width ◽  
White Mountains ◽  
Bristlecone Pine ◽  
Isotope Record ◽  
El Niño Events ◽  
El Nino Events

AbstractWe present the first near millennium-length, annually resolved stable isotope record from bristlecone pines (Pinus longaeva, D.K Bailey). The carbon isotope ratios from the cellulose of seven trees from the White Mountains of California, corrected for anthropogenic changes in atmospheric chemistry, are used to reconstruct growing season (June through August) precipitation back to AD 1085. Extremely negative isotope results are strongly correlated with proposed severest El Niño events over the last 500 yr, and similar values in the first half of the millennium are used to reconstruct a further 13 strong El Niño events, concentrated in the 12th Century and the mid 13th and 14th Centuries. Ring-width chronologies from adjacent sites in the White Mountains demonstrate a high degree of decadal covariance with the δ13C series, although there are several periods of notable divergence.

scholarly journals Long-memory processes in ozone and temperature variations at the region 60° S–60° N

2006 ◽  
Vol 6 (12) ◽  
pp. 4093-4100 ◽  
Author(s):  
C. Varotsos ◽  
D. Kirk-Davidoff
Keyword(s):  
Time Scales ◽  
Atmospheric Chemistry ◽  
Power Distribution ◽  
Climate Models ◽  
Global Climate Models ◽  
Fluctuation Analysis ◽  
Tropospheric Temperature ◽  
Time Intervals ◽  
Long Time ◽  
The Tropics

Abstract. Global column ozone and tropospheric temperature observations made by ground-based (1964–2004) and satellite-borne (1978–2004) instrumentation are analyzed. Ozone and temperature fluctuations in small time-intervals are found to be positively correlated to those in larger time-intervals in a power-law fashion. For temperature, the exponent of this dependence is larger in the mid-latitudes than in the tropics at long time scales, while for ozone, the exponent is larger in tropics than in the mid-latitudes. In general, greater persistence could be a result of either stronger positive feedbacks or larger inertia. Therefore, the increased slope of the power distribution of temperature in mid-latitudes at long time scales compared to the slope in the tropics could be connected to the poleward increase in climate sensitivity predicted by the global climate models. The detrended fluctuation analysis of model and observed time series provides a helpful tool for visualizing errors in the treatment of long-range correlations, whose correct modeling would greatly enhance confidence in long-term climate and atmospheric chemistry modeling.

scholarly journals Distribution and Sources of Organic Carbon in Surface Intertidal Sediments of the Rudong Coast, Jiangsu Province, China

2021 ◽  
Vol 9 (9) ◽  
pp. 992
Author(s):  
Yinan Mao ◽  
Qingyun Ma ◽  
Jiaxin Lin ◽  
Ye Chen ◽  
Qiang Shu
Keyword(s):  
Organic Carbon ◽  
Tidal Flat ◽  
Stable Carbon Isotopes ◽  
Mixing Model ◽  
Depositional Environments ◽  
Stable Carbon ◽  
Intertidal Sediments ◽  
Δ13c Value ◽  
The Mean ◽  
Tidal Flat Sediments

In this study, total organic carbon (TOC), total nitrogen (TN), and stable carbon isotopes (δ13C) were measured in surface intertidal saltmarsh and bare tidal flat sediments along the Rudong coast. The distribution and sources of organic carbon were examined under different depositional environments based on C/N ratios and a two-terminal mixing model. The results showed that the average TOC content of the vegetated saltmarsh sediments, bare tidal flat areas near vegetation (BF1), and bare tidal flat areas far from vegetation (BF2) were 4.05, 2.72, and 1.22 mg/g, respectively. The mean δ13C value within the vegetated saltmarsh area was −22.37‰, and the C/N ratio was 9.3; the corresponding values in the BF1 area were −23.27‰ and 7.95, respectively; and in the BF2 area, the corresponding values were −21.91‰ and 5.36, respectively. These C/N ratios reflect an increasing marine contribution with distance from the vegetated zone. Combined with the two-terminal mixing model, the organic carbon in the vegetated saltmarsh sediments was dominated by terrestrial sources, while the bare tidal flat sediments were more influenced by marine sources, and the bare tidal flat sediments nearer to the vegetated zone (BF1) were influenced by a combination of vegetation, marine sources, and other terrestrial factors.

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