Solute Reactive Tracers for Hydrogeological Applications: A Short Review and Future Prospects

Abstract

Tracer testing is a mature technology used for characterizing aquatic flow systems. To gain more insights from tracer tests a combination of conservative (non-reactive) tracers together with at least one reactive tracer is commonly applied. The reactive tracers can provide unique information about physical, chemical, and/or biological properties of aquatic systems. Although, previous review papers provide a wide coverage on conservative tracer compounds there is no systematic review on reactive tracers yet, despite their extensive development during the past decades. This review paper summarizes the recent development in compounds and compound classes that are exploitable and/or have been used as reactive tracers, including their systematization based on the underlying process types to be investigated. Reactive tracers can generally be categorized into three groups: (1) partitioning tracers, (2) kinetic tracers, and (3) reactive tracers for partitioning. The work also highlights the potential for future research directions. The recent advances from the development of new tailor-made tracers might overcome existing limitations.

Quantifying Optically Derived Two-Dimensional Wave-Averaged Currents in the Surf Zone

“…This issue has previously been addressed with high frame rates that reduce the ratio of frames with target discontinuties to frames with consistent targets [15,16]. Introduction and decay of tracers has also been accounted for in scenarios where the user systematically introduces targets by defined input functions with decay terms (i.e., periodic inputs of a specific magnitude with a known exponential decay rate of the tracer presence [35]). However wave breaking is a chaotic, quasi-random process and the persistence of foam in the surf zone exhibits dependencies on the kind of wave breaking, water temperature, and biological/chemical content [36], necessitating more research focused on these dynamics before properly constraining such functions in the present problem.…”

Tracers and Timescales: Tools for Distilling and Simplifying Complex Fluid Mechanical Problems

“…Cao et al [12] delineate tracer types at the highest level based on the degree of interaction with the aquatic system to which they are added, with: (1) "conservative" tracers displaying virtually no interaction with materials within the system, thus behaving as inert substances under the conditions characteristic of that system and flowing passively with the fluid, and (2) "reactive" tracers defined as "compounds that undergo a chemical reaction or physicochemical interaction processes in a predictable way." Those authors explain that conservative tracers are typically used to assess physical transport processes or hydromechanical properties such as porosity, whereas reactive tracers-which are used in tandem with conservative tracers-can provide information on physicochemical properties such as sorption capacity, redox condition, or microbial activity [12]. While conservative tracer compounds have been the subject of other reviews, Cao et al [12] note that there had not previously been a systematic review of reactive tracers-a need which they fill herein, with an emphasis on subsurface and hyporheic processes.…”

“…A tracer, on the other hand, is a distinguishable dye or chemical compound that is added to a fluid system [12] and is used to learn something about the physical, biological, or chemical functioning of that system. Tracers may be natural or anthropogenic, and can be introduced either intentionally, accidentally, or without any human intervention.…”

Determinação do fator de retardamento da uranina em sedimentos quaternários do aquífero São Paulo

“…porosidade secundária ou descontinuidades estratigráficas (CAO et al, 2020;DIVINE e MCDONNELL, 2005;SILVA et al, 2009). Através de medições diretas ou indiretas de suas concentrações, a injeção de traçadores pode revelar características hidráulicas e geométricas do aquífero, como caminhos preferenciais de fluxo, dispersão hidrodinâmica, velocidade advectiva e zonas de maior ou menor condutividade hidráulica.…”