Study on the Isotope fractionation of Zinc in Complexation with Macrocyclic Polyethers

Temperature is that property of a body which determines whether it gains or loses energy in a particular environment. In classical thermodynamics temperature is defined by the relationship between energy and entropy. Temperature can be defined only for a body that is in thermodynamic and thermal equilibrium; whilst organisms do not conform to these criteria, the errors in assuming that they do are generally small. The Celsius and Fahrenheit temperature scales are arbitrary because they require two fixed points, one to define the zero and the other to set the scale. The thermodynamic (absolute) scale of temperature has a natural zero (absolute zero) and is defined by the triple point of water. Its unit of temperature is the Kelvin. The Celsius scale is convenient for much ecological and physiological work, but where temperature is included in statistical or deterministic models, only thermodynamic temperature should be used. Past temperatures can only be reconstructed with the use of proxies, the most important of which are based on isotope fractionation.

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Unravelling the process of petroleum hydrocarbon biodegradation in different filter materials of constructed wetlands by stable isotope fractionation and labelling studies

Biodegradation ◽

10.1007/s10532-021-09942-1 ◽

2021 ◽

Author(s):

Andrea Watzinger ◽

Melanie Hager ◽

Thomas Reichenauer ◽

Gerhard Soja ◽

Paul Kinner

Keyword(s):

Stable Isotope ◽

Constructed Wetlands ◽

Hydrogen Isotope ◽

Petroleum Hydrocarbon ◽

Isotope Fractionation ◽

Isotope Effects ◽

Filter Material ◽

Hydrocarbon Biodegradation ◽

Stable Isotope Fractionation ◽

Filter Materials

AbstractMaintaining and supporting complete biodegradation during remediation of petroleum hydrocarbon contaminated groundwater in constructed wetlands is vital for the final destruction and removal of contaminants. We aimed to compare and gain insight into biodegradation and explore possible limitations in different filter materials (sand, sand amended with biochar, expanded clay). These filters were collected from constructed wetlands after two years of operation and batch experiments were conducted using two stable isotope techniques; (i) carbon isotope labelling of hexadecane and (ii) hydrogen isotope fractionation of decane. Both hydrocarbon compounds hexadecane and decane were biodegraded. The mineralization rate of hexadecane was higher in the sandy filter material (3.6 µg CO2 g−1 day−1) than in the expanded clay (1.0 µg CO2 g−1 day−1). The microbial community of the constructed wetland microcosms was dominated by Gram negative bacteria and fungi and was specific for the different filter materials while hexadecane was primarily anabolized by bacteria. Adsorption / desorption of petroleum hydrocarbons in expanded clay was observed, which might not hinder but delay biodegradation. Very few cases of hydrogen isotope fractionation were recorded in expanded clay and sand & biochar filters during decane biodegradation. In sand filters, decane was biodegraded more slowly and hydrogen isotope fractionation was visible. Still, the range of observed apparent kinetic hydrogen isotope effects (AKIEH = 1.072–1.500) and apparent decane biodegradation rates (k = − 0.017 to − 0.067 day−1) of the sand filter were low. To conclude, low biodegradation rates, small hydrogen isotope fractionation, zero order mineralization kinetics and lack of microbial biomass growth indicated that mass transfer controlled biodegradation.

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Equilibrium Cu isotope fractionation in copper minerals: a first-principles study

Chemical Geology ◽

10.1016/j.chemgeo.2021.120060 ◽

2021 ◽

Vol 564 ◽

pp. 120060

Author(s):

Shanqi Liu ◽

Yongbing Li ◽

Jie Liu ◽

Zhiming Yang ◽

Jianming Liu ◽

...

Keyword(s):

First Principles ◽

Isotope Fractionation ◽

First Principles Study ◽

Cu Isotope

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Correction to: Experimental determination of the temperature dependence of oxygen-isotope fractionation between water and chitinous head capsules of chironomid larvae

Journal of Paleolimnology ◽

10.1007/s10933-021-00196-8 ◽

2021 ◽

Author(s):

Alex Lombino ◽

Tim Atkinson ◽

Stephen J. Brooks ◽

Darren R. Gröcke ◽

Jonathan Holmes ◽

...

Keyword(s):

Temperature Dependence ◽

Experimental Determination ◽

Oxygen Isotope ◽

Isotope Fractionation ◽

Oxygen Isotope Fractionation ◽

Chironomid Larvae

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Diamond formation in an electric field under deep Earth conditions

Science Advances ◽

10.1126/sciadv.abb4644 ◽

2021 ◽

Vol 7 (4) ◽

pp. eabb4644

Author(s):

Yuri N. Palyanov ◽

Yuri M. Borzdov ◽

Alexander G. Sokol ◽

Yuliya V. Bataleva ◽

Igor N. Kupriyanov ◽

...

Keyword(s):

Electric Fields ◽

Lithospheric Mantle ◽

Isotope Fractionation ◽

Diamond Formation ◽

Mantle Minerals ◽

Electrochemical Processes ◽

Mantle Mineral ◽

Deep Earth ◽

Diamond Crystallization ◽

Global Carbon

Most natural diamonds are formed in Earth’s lithospheric mantle; however, the exact mechanisms behind their genesis remain debated. Given the occurrence of electrochemical processes in Earth’s mantle and the high electrical conductivity of mantle melts and fluids, we have developed a model whereby localized electric fields play a central role in diamond formation. Here, we experimentally demonstrate a diamond crystallization mechanism that operates under lithospheric mantle pressure-temperature conditions (6.3 and 7.5 gigapascals; 1300° to 1600°C) through the action of an electric potential applied across carbonate or carbonate-silicate melts. In this process, the carbonate-rich melt acts as both the carbon source and the crystallization medium for diamond, which forms in assemblage with mantle minerals near the cathode. Our results clearly demonstrate that electric fields should be considered a key additional factor influencing diamond crystallization, mantle mineral–forming processes, carbon isotope fractionation, and the global carbon cycle.

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