Stable isotope composition of subfossil Cerastoderma glaucum shells from the szczecin bay brackish deposits and its palaeogeographical implications (South Baltic Coast, Poland)

2012 ◽  
Vol 77 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Ryszard K. Borówka ◽  
Wacław Strobel ◽  
Stanisław Hałas
Keyword(s):  
Environmental Conditions ◽  
Isotope Composition ◽  
Thermal Conditions ◽  
Stable Isotope Composition ◽  
Radiocarbon Dates ◽  
Szczecin Lagoon ◽  
Baltic Coast ◽  
Carbon And Oxygen Isotope ◽  
The Mean ◽  
Second Period

The environmental conditions of the Szczecin Bay, which existed prior to Szczecin Lagoon, have been reconstructed on the basis of the stable carbon and oxygen isotope (18O and 13C) analysis and radiocarbon dates obtained for subfossil shells of Cerastoderma (Cardium) glaucum. The shells in the collected core were well preserved in their life positions, representing a geochemical record of past temperature variation over the middle Holocene. Three major periods with different thermal conditions have been distinguished in the interval ~ 6000–4300 cal yr BP, when the important Littorina regional transgression took place. During the first period, 6000–5250 cal yr BP, water temperature decreased by 1.4°C, and then remained constant over the second period (5250–4750 cal yr BP). In contrast, during the third period (4750–4300 cal yr BP) both δ-values were highly variable and the mean summer temperature (March–November) increased by about 3.5°C. During first two periods, δ18O and δ13C were significantly correlated, indicating stability of the environmental conditions.

scholarly journals Analysis of draught discomfort prediction models

2021 ◽  
Vol 2069 (1) ◽  
pp. 012236
Author(s):  
S M Hooshmand ◽  
S A Zolfaghari ◽  
J Toftum
Keyword(s):  
Environmental Conditions ◽  
Indoor Environment ◽  
Prediction Models ◽  
Thermal Conditions ◽  
Experimental Tests ◽  
High Accuracy ◽  
Maximum Deviation ◽  
Experimental Conditions ◽  
The Common ◽  
The Mean

Abstract One of the common local thermal discomforts that happen in an indoor environment is draught. Because of the importance of draught, many studies have been carried out to develop equations to calculate the draught rate. But because these equations are obtained from experimental tests in narrow experimental windows, their accuracy under wider environmental conditions should be analyzed. In this paper, the accuracy of equations obtained from the literature were investigated. Each equation predicted the draught rate with high accuracy and mean error of 5.3, 6.8, and 2.2% under the thermal conditions in which the equation was obtained. When applying the equations to different thermal conditions, the mean and maximum errors significantly increased and showed errors in predicting the draught rate with a maximum deviation of 63.5, 51.6, and 49.7%. These equations in some cases, even could not predict the draught rate of the reported draught discomfort percentage. Based on the results, each equation had its limitations and none of the studied equations could accurately predict the draught rate in all experimental conditions. An index that considers all relevant parameters in predicting draught discomfort can lead to a better draught rate prediction.

Chronologie Th/U des concrétions calcaires des varves du lac glaciaire de Deschaillons (Wisconsinien inférieur)

1989 ◽  
Vol 26 (5) ◽  
pp. 1041-1052 ◽  
Author(s):  
Claude Hillaire-Marcel ◽  
Christiane Causse
Keyword(s):  
Activity Ratio ◽  
Isotope Composition ◽  
Weak Acid ◽  
Mean Value ◽  
Second Phase ◽  
Low Carbon ◽  
Stable Isotope Composition ◽  
Carbon And Oxygen Isotope ◽  
Activity Ratios ◽  
Detrital Particles

Late Pleistocene Lake Deschaillons varves from the central St. Lawrence Lowlands represent a lithostratigraphic unit whose upper limit is defined by the overlying Gentilly Till, which was laid down during the last Laurentide Ice advance over the area. Calcareous concretions are imbedded in the varves. These concretions reflect two distinct phases of CaCO3 precipitation. The first phase was during the early diagenesis of the interstitial organic matter. This phase is characterized by high uranium contents (~ 8 μg∙g−1), low carbon- and oxygen-isotope composition (−22 > δ13C > −24‰, −16 > δ18O > −9‰, vs. PDB), and 14C activities lower than 3% (vs. 13.56 dpm∙g−1). The second phase of CaCO3 precipitation occurred during postglacial times, as shown by the higher 14C activity (~30%) and stable-isotope composition (δ13C > −16‰; δ18O > −9‰). No significant U uptake was observed in the corresponding concretions. Th and U activity ratios were determined. The results allow evaluation of the analytical artefacts resulting from partial leaching of the detrital particles incorporated in the concretions by the weak acid treatment used to solubilize calcite. Since the early diagenetic concretions contain a significant but variable detrital fraction, 230Th/232Th and 234U/232Th isochrons from activity ratios measured in several samples are not representative of the age of the carbonate fraction. Isochrons from activity ratios of leachate and residue from individual samples yield, however, a reproducible slope (mean value: 0.52 ± 0.01) representative of the 230Th/234U activity ratio of the pure carbonate fraction. An age of 79 800 ± 1400 years is calculated for the relevant phase of CaCO3 precipitation. It is considered, within a few hundred years, the age of the Lake Deschaillons episode, which would therefore correspond to the first Wisconsinian ice advance in southern Quebec, at the transition between isotopic stages 5a and 4 of the oceanic 18O stratigraphy.

Model-data fusion depicting the key processes and environmental drivers of photosynthates δ13C and δ18O compositions in boreal Scots Pine

2021 ◽  
Author(s):  
Kersti Leppä ◽  
Pauliina Schiestl-Aalto ◽  
Yu Tang ◽  
Elina Sahlstedt ◽  
Pasi Kolari ◽  
...  
Keyword(s):  
Data Fusion ◽  
Time Scales ◽  
Scots Pine ◽  
Environmental Conditions ◽  
Isotope Composition ◽  
Mechanistic Modeling ◽  
Environmental Drivers ◽  
Model Data ◽  
Carbon And Oxygen Isotope ◽  
Over Time

<p>Stable isotopes can diagnose the response of plants to changing climate as the performance of trees in past climatic conditions is archived in the stable carbon and oxygen isotope composition (δ<sup>13</sup>C and δ<sup>18</sup>O, respectively) of tree rings. To take advantage of these records, understanding the formation of isotopic signals in newly assimilated photosynthates is necessary. Despite a voluminous literature, there exists a gap between the model- and data-oriented studies, which if welded together would benefit this line of inquiry. A unique dataset covering two growing seasons in a boreal Scots pine stand situated in Southern Finland (61.9°N, 24.3°E) is employed and is accompanied with mechanistic modeling driven by environmental conditions. Data includes: (i) shoot gas exchange of vapor, CO<sub>2</sub> and its δ<sup>13</sup>C composition, (ii) δ<sup>13</sup>C in needle bulk sugar and sucrose alone, (iii) δ<sup>18</sup>O in water in precipitation, soil, twigs and needles, and (iv) δ<sup>18</sup>O in needle bulk sugar. Overall, observed exchange rates and isotopic composition of fluxes as well as in water and sugar pools were well reproduced using the model. We further address challenges common to the analysis of isotopic signals. Firstly, time scales and integration over them is an unavoidable challenge of data sampled at different intervals, representing either snapshots or a longer history of processes. As an example of this, we illustrate that δ<sup>18</sup>O in needle water reacts instantaneously to environmental conditions, while the δ<sup>18</sup>O signal in needle sugars is an integration over time, and thus relating the latter to instantaneous environmental conditions is less evident. Given that tree-ring studies are more and more focused on intra-annual variation in δ<sup>13</sup>C and δ<sup>18</sup>O, integration over time scales cannot be neglected. Second, using model sensitivity analysis, we showcase the relative importance of environmental drivers on the variation in δ<sup>13</sup>C and δ<sup>18</sup>O – the typical aim of empirical research and paleoclimatological reconstruction. It is commonly acknowledged that the main environmental driver of δ<sup>13</sup>C or δ<sup>18</sup>O variation can differ between sites and time periods. At the study site here, the variation in δ<sup>18</sup>O seems solely driven by relative humidity, but we can, for instance, show that this would change if the δ<sup>18</sup>O signal of source water varied considerably. We are of the opinion that illustrating such points with a model-data fusion approach is a necessary (but not sufficient) first step to bridge the gap between modeling and empirical approaches, and fostering further interpretation of isotopic signals in trees.</p>

COLONY OF THE FUNGUS Aspergillus oryzae AND SELF-AFFINE FRACTAL GEOMETRY OF GROWTH FRONTS

Fractals ◽  
1993 ◽  
Vol 01 (01) ◽  
pp. 11-19 ◽  
Author(s):  
SHU MATSUURA ◽  
SASUKE MIYAZIMA
Keyword(s):  
Aspergillus Oryzae ◽  
Environmental Conditions ◽  
Fractal Geometry ◽  
Nutrient Concentration ◽  
Incubation Temperature ◽  
Characteristic Exponent ◽  
Growth Front ◽  
Favorable Condition ◽  
The Self ◽  
The Mean

A variety of colony shapes of the fungus Aspergillus oryzae under varying environmental conditions such as the nutrient concentration, medium stiffness and incubation temperature are obtained, ranging from a homogeneous Eden-like to a ramified DLA-like pattern. The roughness σ(l, h) of the growth front of the band-shaped colony, where h is the mean front height within l of the horizontal range, satisfies the self-affine fractal relation under favorable environmental conditions. In the most favorable condition of our experiments, its characteristic exponent is found to be a little larger than that of the 2-dimensional Eden model.

scholarly journals Chemical and stable isotope composition of surface and groundwater in the surroundings of the Los Humeros Caldera, Puebla, Mexico

2019 ◽  
Vol 98 ◽  
pp. 07013
Author(s):  
Thomas Kretzschmar ◽  
Matteo Lelli ◽  
Ruth Alfaro ◽  
Juan Ignacio Sanchez ◽  
Yann Rene Ramos
Keyword(s):  
Stable Isotope ◽  
Isotope Composition ◽  
Regression Line ◽  
Sustainable Use ◽  
Geothermal Reservoir ◽  
Maximum Temperature ◽  
Stable Isotope Composition ◽  
Local Fracture ◽  
Hydrogeological Model ◽  
Fracture Systems

It is important to develop a regional hydrogeological model to identify possible recharge and discharge areas for a sustainable use of a geothermal reservoir. The Los Humeros geothermal area is situated within five surficial watersheds and coveres an area of more than 15.000 km2. A total of 208 well and spring samples were collected between June 2017 and November 2018. The stable isotope data for this region define a regression line of δDH2O = 8.032·δ18O + 12 and indicate that groundwater is recharged by regional precipitation. At least 39 groundwater wells, with a maximum temperature of 35 °C, show temperatures above the reported mean average surface temperature of 15 °C. Characteristic elements for geothermal reservoir fluids (B, Li, As) are also present in these groundwaters, indicating a possible connection between the reservoir fluid and the local groundwater through local fracture systems. Concentration of B in these hot wells is between 150 and 35000 ppb.

scholarly journals Genetic gain in the breeding program of common beans at IAC from 1989 to 2007

2010 ◽  
Vol 10 (4) ◽  
pp. 329-336 ◽  
Author(s):  
Alisson Fernando Chiorato ◽  
Sérgio Augusto Morais Carbonell ◽  
Roland Vencovsky ◽  
Nelson da Silva Fonseca Júnior ◽  
José Baldin Pinheiro
Keyword(s):  
Grain Yield ◽  
Common Bean ◽  
Genetic Gain ◽  
Grain Quality ◽  
The State ◽  
Breeding Program ◽  
Common Beans ◽  
The Common ◽  
The Mean ◽  
Second Period

The goal of the present work was to evaluate the genetic gain obtained in grain yield for the common bean genotypes from 1989 until 2007, at the Instituto Agronômico de Campinas, in the state of São Paulo. Genetic gain has been separated into two research periods; the first, from 1989 to 1996, and the second, from 1997 to 2007. In the first period, a genetic gain of 1.07 % per year was obtained, whereas for the second period, the gain was zero. However, the mean yield of the evaluated lines was approximately 1000 kg ha-1 superior to the figures obtained in the first period. The main cause for the absence of genetic gain in the second period is that the focus of the breeding program was changed to grain quality. The individualized analysis of the genotypes with carioca grains in the second period indicated the lack of genetic gain during the investigated period.

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