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Sorption Behaviour and Long-term Retention of Reactive Solute in the Hyporheic Zone of Streams
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
2004 (English)In: Journal of environmental engineering, ISSN 0733-9372, Vol. 130, no 5, 573-584 p.Article in journal (Refereed) Published
Abstract [en]

This paper analyzes the transport of sorbing solutes by extending the advective storage path model developed for longitudinal transport of inert solutes in streams coupled with flow-induced uptake in the hyporheic zone. Independent observations of a conservative (3H) and a reactive (51Cr) tracer in both the stream water and the hyporheic zone were used to differentiate between hydraulic and sorption processes. The method of temporal moments was found to be inadequate for parameter determination, whereas fitting versus the entire tracer breakthrough curves with special emphasis on the tail indicates that the proposed model could be used to represent both conservative and reactive transport. Information on the tracer inventory of the conservative tracer in the hyporheic zone was found to be of vital importance to the evaluation of the hydraulic exchange. A model evaluation based on stream water data alone can yield predictions of a wash-out in the hyporheic zone that deviates markedly from the observed wash-out. This prohibits long-term predictions of the wash-out from the hyporheic zone as well as the evaluation of sorption properties. The sorption in the hyporheic zone was found to follow a two-step model, where the first step is instantaneous and the second kinetic. A model with a single-step sorption process could not reproduce the observed breakthrough curves. An evaluation of the relative importance of including sorption kinetics in solute stream transport models is elucidated by means of the analytical expressions for the temporal moments. The omission of the kinetics in the second sorption step in the hyporheic zone will result in relative errors in the moments of second order or higher. The error will increase with decreasing residence time in the hyporheic zone. Especially, long-term predictions of the wash-out from the hyporheic zone require consideration of the rate-limited sorption.

Place, publisher, year, edition, pages
2004. Vol. 130, no 5, 573-584 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-90664DOI: 10.1061/(ASCE)0733-9372(2004)130:5(573)OAI: oai:DiVA.org:uu-90664DiVA: diva2:163106
Available from: 2003-09-11 Created: 2003-09-11 Last updated: 2013-09-18Bibliographically approved
In thesis
1. Effect of Hyporheic Exchange on Conservative and Reactive Solute Transport in Streams: Model Assessments Based on Tracer Tests
Open this publication in new window or tab >>Effect of Hyporheic Exchange on Conservative and Reactive Solute Transport in Streams: Model Assessments Based on Tracer Tests
2003 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Understanding of the processes affecting solute transport in flowing water is important for the possibility to predict the evolution with time of polluted stream systems.

This thesis presents tracer experiment methodology and model developments for solute transport in streams, with special focus on retention processes and their effect on solute stream transport. Results are presented from a tracer experiment in the Säva Stream, Uppland County, Sweden, where both a conservative (3H as tritiated water) and a reactive (51Cr as trivalent chromium ion) tracer were injected simultaneously. The time and length scales of the experiment were prolonged compared to previous studies, which allowed for new critical tests of different model concepts.

It was found that the hyporheic exchange greatly affected the solute transport of both tracers. However, the retention of chromium was significantly more pronounced. About 76% of the injected chromium was lost from the stream water phase directly after the passage of the pulse 30 km downstream of the injection point. The inventory of chromium in the sediments indicated that the main part was retrieved in the hyporheic zone.

Both a diffusive and an advective hyporheic exchange model were developed and evaluated versus independent observations in the stream water and hyporheic zone. Analytical expressions for the central temporal moments of the breakthrough curve and semi-analytical solutions for the solute concentration in the Laplace domain were derived. Both models were found useful in representing the observations.

For the transport of the reactive solute, it was found essential to consider a kinetic sorption on to particulate matter in the hyporheic zone. The time needed for a wash-out of 75% of the maximum uptake in the hyporheic zone was found to be ~85 times longer for the reactive solute, compared to the conservative solute. Neglecting the sorption kinetics in the transport model yielded significant errors in the central temporal moments, which implied an incorrect description of the wash-out process from the hyporheic zone. Independent observations in the stream water and hyporheic zone as well as choice of evaluation method are essential for a correct interpretation of the processes.

A first attempt was also made to link model parameters such as the residence time in the hyporheic zone with measurable parameters of the stream. Such a relationship offers the possibility to generalize results for other streams and stream conditions. A generic study of the transport of an inert solute in the Lule River, Sweden, using this kind of relationship, indicated that the hyporheic exchange can have a large practical implication.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2003. 57 p.
Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1104-232X ; 866
Earth sciences, conservative, hyporheic exchange, model, reactive, retention, solute, sorption kinetics, stream transport, temporal moments, tracer experiment, Geovetenskap
National Category
Earth and Related Environmental Sciences
Research subject
urn:nbn:se:uu:diva-3522 (URN)91-554-5689-8 (ISBN)
Public defence
2003-10-03, Axel Hambergsalen, Geocentrum, Uppsala, 10:00
Available from: 2003-09-11 Created: 2003-09-11Bibliographically approved

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