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Lecture

Tracers and Transit Time Distributions

In course

ENV-221: Hydrology for engineers

This is an introductory course to key concepts and methods in physical and engineering hydrology. ...

Description

This lecture introduces hydrologic transport, focusing on water travel time within a catchment and solute transport. It covers various scales of the problem, examples of water pollution, and the EU WATER FRAMEWORK directive. The lecture discusses the EU directive's implementation, water quality protection, and Swiss water bodies' status. It explores methods to infer water transit times, including the long-term mean transit time concept. The lumped convolution approach and tracer breakthrough curves are also explained, along with stable isotopes of oxygen and hydrogen. The lecture concludes with the age balance in hydrologic systems and the water age balance, showcasing model results and age variability during wet and dry periods.

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Instructors (3)

Andrea Rinaldo

Paolo Benettin

I was born in Padova, Italy, in 1986. After high school, I started the Environmental Engineering program at the University of Padova (Bachelor and Master), where I followed the 'soil protection' curriculum. During my Master studies I spent a semester as Erasmus student at Wageningen University (Wageningen, the Netherlands) to follow courses in Hydrology. After graduation, I decided to bring my education further and I started a Ph.D. at the civil and environmental engineering department at the University of Padova. My Ph.D. thesis focused on hydrologic transport and travel time distributions at the catchment scale. My contribution to the subject included both new theoretical formulations and extensive numerical applications to real catchments. During my Ph.D., I also spent 7 months as visiting research fellow at Virginia Tech University (Blacksburg, USA). Since I arrived at EPFL as post-doc in 2015, I started being involved in field and experimental activities, which allowed me to learn about practical experimental problems. In 2017 I had the opportunity to by hired by the ECHO laboratory as a permanent scientist, conducting research in the field of catchment hydrology.

Sara Bonetti

Official source

Related concepts (32)

Isotope geochemistry

Isotope geochemistry is an aspect of geology based upon the study of natural variations in the relative abundances of isotopes of various elements. Variations in isotopic abundance are measured by isotope ratio mass spectrometry, and can reveal information about the ages and origins of rock, air or water bodies, or processes of mixing between them. Stable isotope geochemistry is largely concerned with isotopic variations arising from mass-dependent isotope fractionation, whereas radiogenic isotope geochemistry is concerned with the products of natural radioactivity.

Isotopic labeling

Isotopic labeling (or isotopic labelling) is a technique used to track the passage of an isotope (an atom with a detectable variation in neutron count) through a reaction, metabolic pathway, or cell. The reactant is 'labeled' by replacing specific atoms by their isotope. The reactant is then allowed to undergo the reaction. The position of the isotopes in the products is measured to determine the sequence the isotopic atom followed in the reaction or the cell's metabolic pathway.

Isotope analysis

Isotope analysis is the identification of isotopic signature, abundance of certain stable isotopes of chemical elements within organic and inorganic compounds. Isotopic analysis can be used to understand the flow of energy through a food web, to reconstruct past environmental and climatic conditions, to investigate human and animal diets, for food authentification, and a variety of other physical, geological, palaeontological and chemical processes.

Reference materials for stable isotope analysis

Isotopic reference materials are compounds (solids, liquids, gasses) with well-defined isotopic compositions and are the ultimate sources of accuracy in mass spectrometric measurements of isotope ratios. Isotopic references are used because mass spectrometers are highly fractionating. As a result, the isotopic ratio that the instrument measures can be very different from that in the sample's measurement. Moreover, the degree of instrument fractionation changes during measurement, often on a timescale shorter than the measurement's duration, and can depend on the characteristics of the sample itself.

Stable isotope ratio

The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundance of such stable isotopes can be measured experimentally (isotope analysis), yielding an isotope ratio that can be used as a research tool. Theoretically, such stable isotopes could include the radiogenic daughter products of radioactive decay, used in radiometric dating.

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