8 research outputs found
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
Mitochondrial physiology
As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery
Polychlorinated Biphenyls in Glaciers. 2. Model Results of Deposition and Incorporation Processes
In previous work, Alpine glaciers have been identified as a secondary source of persistent organic pollutants (POPs). However, detailed understanding of the processes organic chemicals undergo in a glacial system was missing. Here, we present results from a chemical fate model describing deposition and incorporation of polychlorinated biphenyls (PCBs) into an Alpine glacier (Fiescherhorn, Switzerland) and an Arctic glacier (Lomonosovfonna, Norway). To understand PCB fate and dynamics, we investigate the interaction of deposition, sorption to ice and particles in the atmosphere and within the glacier, revolatilization, diffusion and degradation, and discuss the effects of these processes on the fate of individual PCB congeners. The model is able to reproduce measured absolute concentrations in the two glaciers for most PCB congeners. While the model generally predicts concentration profiles peaking in the 1970s, in the measurements, this behavior can only be seen for higher-chlorinated PCB congeners on Fiescherhorn glacier. We suspect seasonal melt processes are disturbing the concentration profiles of the lower-chlorinated PCB congeners. While a lower-chlorinated PCB congener is mainly deposited by dry deposition and almost completely revolatilized after deposition, a higher-chlorinated PCB congener is predominantly transferred to the glacier surface by wet deposition and then is incorporated into the glacier ice. The incorporated amounts of PCBs are higher on the Alpine glacier than on the Arctic glacier due to the higher precipitation rate and aerosol particle concentration on the former. Future studies should include the effects of seasonal melt processes, calculate the quantities of PCBs incorporated into the entire glacier surface, and estimate the quantity of chemicals released from glaciers to determine the importance of glaciers as a secondary source of organic chemicals to remote aquatic ecosystems
Polychlorinated Biphenyls in a Temperate Alpine Glacier: 2. Model Results of Chemical Fate Processes
We present results from a chemical
fate model quantifying incorporation
of polychlorinated biphenyls (PCBs) into the Silvretta glacier, a
temperate Alpine glacier located in Switzerland. Temperate glaciers,
in contrast to cold glaciers, are glaciers where melt processes are
prevalent. Incorporation of PCBs into cold glaciers has been quantified
in previous studies. However, the fate of PCBs in temperate glaciers
has never been investigated. In the model, we include melt processes,
inducing elution of water-soluble substances and, conversely, enrichment
of particles and particle-bound chemicals. The model is validated
by comparing modeled and measured PCB concentrations in an ice core
collected in the Silvretta accumulation area. We quantify PCB incorporation
between 1900 and 2010, and discuss the fate of six PCB congeners.
PCB concentrations in the ice core peak in the period of high PCB
emissions, as well as in years with strong melt. While for lower-chlorinated
PCB congeners revolatilization is important, for higher-chlorinated
congeners, the main processes are storage in glacier ice and removal
by particle runoff. This study gives insight into PCB fate and dynamics
and reveals the effect of snow accumulation and melt processes on
the fate of semivolatile organic chemicals in a temperate Alpine glacier
A Temperate Alpine Glacier as a Reservoir of Polychlorinated Biphenyls: Model Results of Incorporation, Transport, and Release
In previous studies, the incorporation of polychlorinated biphenyls (PCBs) has been quantified in the accumulation areas of Alpine glaciers. Here, we introduce a model framework that quantifies mass fluxes of PCBs in glaciers and apply it to the Silvretta glacier (Switzerland). The models include PCB incorporation into the entire surface of the glacier, downhill transport with the flow of the glacier ice, and chemical fate in the glacial lake. The models are run for the years 1900−2100 and validated by comparing modeled and measured PCB concentrations in an ice core, a lake sediment core, and the glacial streamwater. The incorporation and release fluxes, as well as the storage of PCBs in the glacier increase until the 1980s and decrease thereafter. After a
temporary increase in the 2000s, the future PCB release and the PCB concentrations in the glacial stream are estimated to be small but persistent throughout the 21st century. This study quantifies all relevant PCB fluxes in and from a temperate Alpine glacier over two centuries, and concludes that Alpine glaciers are a small secondary source of PCBs, but that the aftermath of
environmental pollution by persistent and toxic chemicals can endure for decades
Polychlorinated Biphenyls in Glaciers. 2. Model Results of Deposition and Incorporation Processes
In
previous work, Alpine glaciers have been identified as a secondary
source of persistent organic pollutants (POPs). However, detailed
understanding of the processes organic chemicals undergo in a glacial
system was missing. Here, we present results from a chemical fate
model describing deposition and incorporation of polychlorinated biphenyls
(PCBs) into an Alpine glacier (Fiescherhorn, Switzerland) and an Arctic
glacier (Lomonosovfonna, Norway). To understand PCB fate and dynamics,
we investigate the interaction of deposition, sorption to ice and
particles in the atmosphere and within the glacier, revolatilization,
diffusion and degradation, and discuss the effects of these processes
on the fate of individual PCB congeners. The model is able to reproduce
measured absolute concentrations in the two glaciers for most PCB
congeners. While the model generally predicts concentration profiles
peaking in the 1970s, in the measurements, this behavior can only
be seen for higher-chlorinated PCB congeners on Fiescherhorn glacier.
We suspect seasonal melt processes are disturbing the concentration
profiles of the lower-chlorinated PCB congeners. While a lower-chlorinated
PCB congener is mainly deposited by dry deposition and almost completely
revolatilized after deposition, a higher-chlorinated PCB congener
is predominantly transferred to the glacier surface by wet deposition
and then is incorporated into the glacier ice. The incorporated amounts
of PCBs are higher on the Alpine glacier than on the Arctic glacier
due to the higher precipitation rate and aerosol particle concentration
on the former. Future studies should include the effects of seasonal
melt processes, calculate the quantities of PCBs incorporated into
the entire glacier surface, and estimate the quantity of chemicals
released from glaciers to determine the importance of glaciers as
a secondary source of organic chemicals to remote aquatic ecosystems