scholarly journals Also tropical freshwater ostracods show a seasonal life cycle

2017 ◽  
Author(s):  
Juliane Meyer ◽  
Claudia Wrozyna ◽  
Albrecht Leis ◽  
Werner Piller
Keyword(s):  
Life Cycle ◽  
Environmental Factors ◽  
Isotopic Composition ◽  
Temporal Variations ◽  
South Florida ◽  
Population Variation ◽  
Instrumental Data ◽  
Mean Values ◽  
Isotopic Signatures ◽  
Isotopic Compositions

Abstract. Isotopic signatures of ostracod shells became common proxies for the reconstruction of paleo-environmental conditions. Their isotopic composition is the result of the composition of their host water and the phenology and ecology of the target species. The sum of spatial and temporal variations from environmental factors in the species habitat defines the maximum isotopic variation of a population during the time of their shell formation. Here we present isotopic signatures (δ18O, δ13C) of living Cytheridella ilosvayi (Ostracoda) and chemical and isotopic compositions of 14 simultaneously sampled freshwater habitats in South Florida and instrumental data of the region. The chemical and isotopic compositions of the selected sites characterize the different habitats and show the influence of the source water, biological activity and the duration of exposure to the surface. Isotopic signatures of C. ilosvayi shells correlate well with the isotopic composition of their host waters. Within-sample variability of repeated isotopic measurements of ostracod shells reflect habitat dependent ranges and indicate temperature and the δ18O composition of precipitation (δ18Oprec) as regional environmental factors responsible for the population variation. Instrumental data of water temperature and δ18Oprec were used to calculate the monthly variation of a theoretical calcite in rivers of Florida showing distinct seasonal variations in values and ranges. Different configurations of the theoretical calcite were compared to the within-sample variability to identify possible calcification periods of C. ilosvayi. For a plausible calcification period the ostracod isotopic range has to correlate with mean values of the theoretical calcite with a slight positive offset (vital effect) and the extension of the theoretical calcite range. The tested model suggests a seasonal calcification period of C. ilosvayi in early spring. The surprising seasonality of a tropical ostracod life cycle is probably coupled to the hydrologic cycle of Florida. The results of this study contribute to the application of ostracod isotopes in modern calibration studies and their potential use in paleontology.

Hydrogeochemical temporal variations related to changes of seismic activity at Tenerife, Canary Islands

2021 ◽  
Author(s):  
Cecilia Amonte ◽  
María Asensio-Ramos ◽  
Gladys V. Melián ◽  
Nemesio M. Pérez ◽  
Eleazar Padrón ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Seismic Activity ◽  
Temporal Variations ◽  
Total Alkalinity ◽  
Molar Ratio ◽  
Sampling Point ◽  
Volcanic System ◽  
Mean Values ◽  
Isotopic Analyses ◽  
San Fernando

<p>The oceanic active volcanic island of Tenerife (2034 km<sup>2</sup>) is the largest of the Canarian archipelago. There are more than 1,000 galleries (horizontal drillings) in the island, which are used for groundwater exploitation and allow reaching the aquifer at different depths and elevations. During a two-year period (July 2016 to July 2018), a hydrogeochemical study was carried out in two galleries on Tenerife (Fuente del Valle and San Fernando) for volcanic monitoring purposes with weekly sampling. Physicochemical parameter of water, such us temperature (ºC), pH and electrical conductivity (E.C., µS·cm<sup>-1</sup>), were measured in-situ at each sampling point and chemical/isotopic composition of the water determined later in the laboratory.</p><p>Temperature values showed mean values of 28.1 ºC and 19.0 ºC for Fuente del Valle and San Fernando galleries, respectively. According to the average pH values, which were 6.30 for Fuente del Valle and 7.13 for San Fernando, and based on the chemical composition, both galleries are sodium-bicarbonate (Na-HCO<sub>3</sub>) type. E.C. values in both galleries presented high ranges, with mean values of 975 and 1648 µS·cm<sup>-1</sup> for Fuente del Valle and San Fernando, respectively. The total alkalinity mean value of groundwater from Fuente del Valle gallery was 11.3 mEq·L<sup>-1</sup> HCO<sub>3</sub><sup>-</sup>, while that from San Fernando was 17.3 mEq·L<sup>-1</sup> HCO<sub>3</sub><sup>-</sup>. The SO<sub>4</sub><sup>2-</sup>/Cl molar ratio was 0.59 and 3.4 for the samples from Fuente del Valle and San Fernando galleries, respectively.</p><p>The δ<sup>18</sup>O and δD isotopic analyses showed a meteoric origin of groundwaters, with mean values of -6.2‰ and -26‰ vs. VSMOW for Fuente del Valle and -6.2‰ and -21 ‰ vs. VSMOW for San Fernando. The isotopic data showed a strong interaction with endogenous gases such as CO<sub>2</sub>, H<sub>2</sub>S, H<sub>2</sub>, etc. Regarding the isotopic composition of total dissolved carbon species, expressed as δ<sup>13</sup>C<sub>TDIC</sub>, average values of -0.17‰ and 0.26‰ were obtained for Fuente del Valle and San Fernando galleries, respectively. These results show an endogenous origin CO<sub>2</sub> signature, heavier for Fuente del Valle gallery groundwater compared to that of San Fernando.</p><p>Groundwater physicochemical parameters exhibited stable values throughout the study period, while significant temporal variations were observed in the total alkalinity, SO<sub>4</sub><sup>2-</sup>/Cl<sup>-</sup> molar ratio, δ<sup>18</sup>O and δD. Changes in isotopic ratios coincided with variations observed in the alkalinity and the SO<sub>4</sub><sup>2-</sup>/Cl<sup>-</sup> molar ratio. On October 2, 2016, a seismic swarm of long-period events was recorded on Tenerife followed by a general increase of the seismic activity in and around the island. A correlation was observed between some hydrogeochemical parameters in the groundwaters of the galleries, related to observed changes of the seismic activity. This study demonstrates the suitability of monitoring the chemical and isotopic composition of groundwater from Fuente del Valle and San Fernando galleries, as they are sensitive to changes in volcanic activity on Tenerife island. The study of groundwaters associated to a volcanic system can provide information about the magmatic gas input in the aquifer, modelling how the groundwaters flow through the edifice, and offer important geochemical information that could herald a future eruption.</p>

scholarly journals Modeling calcification periods of <i>Cytheridella ilosvayi</i> from Florida based on isotopic signatures and hydrological data

2017 ◽  
Vol 14 (21) ◽  
pp. 4927-4947 ◽  
Author(s):  
Juliane Meyer ◽  
Claudia Wrozyna ◽  
Albrecht Leis ◽  
Werner E. Piller
Keyword(s):  
Biological Activities ◽  
Early Spring ◽  
South Florida ◽  
Direct Reaction ◽  
Wet Season ◽  
Mean Values ◽  
Isotopic Signatures ◽  
Applied Model ◽  
Local Fluctuations ◽  
Freshwater Habitats

Abstract. The isotopic signatures of ostracod shells are the result of the temperature and composition of their host water and the phenology and ecology of the target species. Investigations addressing the influence of site-specific environmental variations on the isotopic ranges of ostracod shells are still rare but can provide important information on habitat-dependent variations and may signify a seasonally restricted timing of calcification periods. Here we present isotopic signatures (δ18Oostr, δ13Costr) of living Cytheridella ilosvayi (Ostracoda) and physical, chemical, and isotopic (δD, δ18Owater, δ13CDIC) compositions of 14 freshwater habitats (rivers, lakes, canals, marshes, sinkholes) in South Florida from winter 2013 and summer 2014. We also present instrumental data of river temperatures and δ18O of precipitation (δ18Oprec) from this region. The physicochemical and isotopic compositions of the selected sites characterize the different habitats and show the influence of the source water, biological activity, and duration of exposure to the surface. Mean δ18Oostr and δ13Costr signatures of C. ilosvayi shells correlate well with the isotopic composition of their host waters. Within-sample variabilities in repeated isotopic measurements of single ostracod shells reflect habitat-dependent ranges. The similarly high range of ostracod δ18O in rivers and one marsh sample indicates that both temperature and δ18Oprec are responsible for their variation in the whole study area. Rivers and canals, which are predominantly influenced by the input and mixing of inorganic carbon from the catchment, show smaller δ13Costr ranges than the marsh dominated by local fluctuations in biological activities. Based on these observations, background data of water temperatures and δ18Oprec were used to calculate monthly δ18O variations in a theoretical calcite formed in rivers in Florida assuming a direct reaction on precipitation changes. The calculated values showed a high variation coupled with low mean values during the summer wet season, while during the winter dry season the variation remains small and mean values increased. Inferred configurations were used to approximate possible calcification periods of C. ilosvayi. For a plausible calcification period, mean values and ranges of δ18Oostr had to be equal to the theoretical calcite with a slight positive offset (vital effect). The applied model suggests a seasonal calcification period of C. ilosvayi in early spring that is probably coupled to the hydrologic cycle of Florida.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

Reconstructing Terrestrial Environments Using Stable Isotopes in Fossil Teeth and Paleosol Carbonates

2012 ◽  
Vol 18 ◽  
pp. 167-194 ◽  
Author(s):  
Benjamin H. Passey
Keyword(s):  
Isotopic Composition ◽  
Soil Temperature ◽  
Carbon Isotopes ◽  
Oxygen Isotopes ◽  
Precipitation Amount ◽  
Radiative Heating ◽  
Mammal Species ◽  
Isotopic Compositions ◽  
Heat Effects ◽  
Oxygen Isotopic

Carbon isotopes in Neogene-age fossil teeth and paleosol carbonates are commonly interpreted in the context of past distributions of C3 and C4 vegetation. These two plant types have very different distributions in relation to climate and ecology, and provide a robust basis for reconstructing terrestrial paleoclimates and paleoenvironments during the Neogene. Carbon isotopes in pre-Neogene fossil teeth are usually interpreted in the context of changes in the δ13C value of atmospheric CO2, and variable climate-dependent carbon-isotope discrimination in C3 plants. Carbon isotopes in pre-Neogene soil carbonates can be used to estimate past levels of atmospheric CO2. Oxygen isotopes in fossil teeth and paleosol carbonates primarily are influenced by the oxygen isotopic compositions of ancient rainfall and surface waters. The oxygen isotopic composition of rainfall is has a complex, but tractable, relationship with climate, and variably relates to temperature, elevation, precipitation amount, and other factors. Mammal species that rely on moisture in dietary plant tissues to satisfy their water requirements (rather than surface drinking water) may have oxygen isotopic compositions that track aridity. Thus, oxygen isotopes of fossil mammals can place broad constraints on paleoaridity. Carbonate clumped isotope thermometry allows for reconstruction of soil temperatures at the time of pedogenic carbonate mineralization. The method is unique because it is the only thermodynamically based isotopic paleothermometer that does not require assumptions about the isotopic composition of the fluid in which the archive mineral formed. Soil temperature reflects a complex interplay of air temperature, solar radiative heating, latent heat effects, soil thermal diffusivity, and seasonal variations of these parameters. Because plants and most animals live in and/or near the soil, soil temperature is an important aspect of terrestrial (paleo)climate.

scholarly journals Energy valuation methods for biofuels in South Florida: Introduction to life cycle assessment and emergy approaches

2013 ◽  
Author(s):  
J. Van Treese II ◽  
Edward A. Hanlon ◽  
Nana Amponsah ◽  
Jose -Luis Izursa ◽  
John C. Capece
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
South Florida ◽  
Valuation Methods

scholarly journals EFFECTS OF DIFFERENT TYPES OF CYTOPLASM ON THE KERNEL ROW NUMBER OF MAIZE INBRED LINES

AGROFOR ◽  
2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Snežana JOVANOVIĆ ◽  
Goran TODOROVIĆ ◽  
Nikola GRČIĆ ◽  
Ratibor ŠTRBANOVIĆ ◽  
Rade STANISAVLJEVIĆ ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Block Design ◽  
Inbred Lines ◽  
Mean Values ◽  
Maize Inbred Lines ◽  
Different Types ◽  
Maize Inbreds ◽  
Set Up ◽  
Kernel Row Number

The aim of the present study was to determine effects of both, different types ofcytoplasm (cms-C, cms-S and fertile) and environmental factors on the kernel rownumber of 12 maize inbreds lines. The trial with inbred lines was set up in twolocations (Zemun Polje-Selection field and Zemun Polje-Školsko dobro) in 2013and 2014. Moreover, the three-replicate trials were set up according to therandomised complete block design within each type of cytoplasm. Each plot withinthe replicate consisted of four rows. Fertile versions of inbred lines were sown intwo border rows and they were pollinators for their sterile counterparts. Statisticbiometricdata processing was based on mean values per replicate and included theanalysis of variance. According to this analysis, significant differences in thekernel row number were established among inbred lines in dependence on the typeof cytoplasm, year and the location. The average kernel row number ranged from10.3 (L9) to 15.8 (L5 and L7). The variation of the kernel row number, related to thesource of cytoplasm, was very significant. Differences (Lsd0.01) in the kernel rownumber were not determined in inbred lines L5, L8, L10 and L12 in regard to the typeof cytoplasm: cms-C, cms-S and fertile. The average kernel row numbersignificantly (P1%) varied in regard to the year of investigation. A higher averagevalue (13.75) was established in 2014 than in 2013 (13.31). The kernel row numberper year very significantly varied (Lsd0.01) in all inbreds, but the differences werenot significant in the inbreds L2, L3, L8, L9 and L12. Gained results point out toeffects of different types of cytoplasm on the kernel row number.

scholarly journals High-resolution measurements of atmospheric molecular hydrogen and its isotopic composition at the West African coast of Mauritania

2012 ◽  
Vol 9 (12) ◽  
pp. 18799-18829
Author(s):  
S. Walter ◽  
A. Kock ◽  
T. Röckmann
Keyword(s):  
High Resolution ◽  
Isotopic Composition ◽  
Molecular Hydrogen ◽  
H2 Production ◽  
West African ◽  
Mixing Ratio ◽  
The West ◽  
Isotopic Signatures ◽  
West African Coast ◽  
African Coast

Abstract. Oceans are a net source of molecular hydrogen (N2) to the atmosphere, where nitrogen (N2) fixation is assumed to be the main biological production pathway besides photochemical production from organic material. The sources can be distinguished using isotope measurements because of clearly differing isotopic signatures of the produced hydrogen. Here we present the first ship-borne measurements of atmospheric molecular H2 mixing ratio and isotopic composition at the West African coast of Mauritania (16–25° W, 17–24° N). This area is one of the biologically most active regions of the world's oceans with seasonal upwelling events and characterized by strongly differing hydrographical/biological properties and phytoplankton community structures. The aim of this study was to identify areas of H2 production and distinguish H2 sources by isotopic signatures of atmospheric H2. Besides this a diurnal cycle of atmospheric H2 was investigated. For this more than 100 air samples were taken during two cruises in February 2007 and 2008, respectively. During both cruises a transect from the Cape Verde Island towards the Mauritanian Coast was sampled. In 2007 additionally four days were sampled with a high resolution of one sample per hour. Our results clearly indicate the influence of local sources and suggest the Banc d'Arguin as a pool for precursors for photochemical H2 production, whereas N2 fixation could not be identified as a H2 source during these two cruises. With our experimental setup we could demonstrate that variability in diurnal cycles is probably influenced and biased by released precursors for photochemical H2 production and the origin of air masses. This means for further investigations that just measuring the mixing ratio of H2 is insufficient to explain the variability of a diurnal cycle and support is needed, e.g. by isotopic measurements. However, measurements of H2 mixing ratios, which are easy to conduct online during ship cruises could be a helpful tool to easily identify production areas of biological precursors such as VOC's for further investigations.

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