Streams and rivers act as landscape-scale bioreactors processing large quantities of terrestrial particulate organic matter (POM). This function is linked to their flow regime, which governs residence times, shapes organic matter reactivity and controls the amount of carbon (C) exported to the atmosphere and coastal oceans. Climate change impacts flow regimes by increasing both flash floods and droughts. Here, we used a modelling approach to explore the consequences of lateral hydrological contraction, that is, the reduction of the wet portion of the streambed, for POM decomposition and transport at the river network scale. Our model integrates seasonal leaf litter input as generator of POM, transient storage of POM on wet and dry streambed portions with associated decomposition and ensuing changes in reactivity, and transport dynamics through a dendritic river network. Simulations showed that the amount of POM exported from the river network and its average reactivity increased with lateral hydrological contraction, due to the combination of (1) low processing of POM while stored on dry streambeds, and (2) large shunting during flashy events. The sensitivity analysis further supported that high lateral hydrological contraction leads to higher export of higher reactivity POM, regardless of transport coefficient values, average reactivity of fresh leaf litter and differences between POM reactivity under wet and dry conditions. Our study incorporates storage in dry streambed areas into the pulse-shunt concept (Raymond and others in Ecology 97(1):5\uffe2\uff80\uff9316, 2016. https://doi.org/10.1890/14-1684.1), providing a mechanistic framework and testable predictions about leaf litter storage, transport and decomposition in fluvial networks.The climate-related variables, river discharge, and water temperature, are the main factors controlling the quality of the bank filtrate by affecting infiltration rates, travel times, and redox conditions. The impact of temperature and discharge on manganese release from a riverbed were assessed by water quality data from a monitoring transect at a riverbank filtration site in Dresden-Tolkewitz. Column experiments with riverbed material were used to assess the Mn release for four temperature and three discharge conditions, represented by varying infiltration rates. The observed Mn release was modeled as kinetic reactions via Monod-type rate formulations in PHREEQC. The temperature had a bigger impact than the infiltration rates on the Mn release. Infiltration rates of <0.3 m3/(m2\uffc2\uffb7d) required temperatures >20 \uffc2\uffb0C to trigger the Mn release. With increasing temperatures, the infiltration rates became less important. The modeled consumption rates of dissolved oxygen are in agreement with results from other bank filtration sites and are potentially suited for the further application of the given conditions. The determined Mn reduction rate constants were appropriate to simulate Mn release from the riverbed sediments but seemed not to be suited for simulations in which Mn reduction is likely to occur within the aquifer. Sequential extractions revealed a decrease of easily reducible Mn up to 25%, which was found to reflect the natural stratification within the riverbed, rather than a depletion of the Mn reservoir.
", "keywords": ["riverbank filtration", "droughts", "PHREEQC", "0208 environmental biotechnology", "0207 environmental engineering", "column experiments", "02 engineering and technology", "6. Clean water", "climate change", "13. Climate action", "floods", "manganese", "riverbed", "organic matter degradation"]}, "links": [{"href": "http://www.mdpi.com/2073-4441/10/10/1476/pdf"}, {"href": "https://doi.org/10.3390/w10101476"}, {"rel": "related", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/Water", "name": "related record", "description": "related record", "type": "application/json"}, {"rel": "self", "type": "application/geo+json", "title": "10.3390/w10101476", "name": "item", "description": "10.3390/w10101476", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main/items/10.3390/w10101476"}, {"rel": "collection", "type": "application/json", "title": "Collection", "name": "collection", "description": "Collection", "href": "https://repository.soilwise-he.eu/cat/collections/metadata:main"}], "time": {"date": "2018-10-19T00:00:00Z"}}, {"id": "10278/5031900", "type": "Feature", "geometry": null, "properties": {"updated": "2026-07-26T16:24:43Z", "type": "Journal Article", "created": "2022-12-12", "title": "Pulse, Shunt and Storage: Hydrological Contraction Shapes Processing and Export of Particulate Organic Matter in River Networks", "description": "AbstractStreams and rivers act as landscape-scale bioreactors processing large quantities of terrestrial particulate organic matter (POM). This function is linked to their flow regime, which governs residence times, shapes organic matter reactivity and controls the amount of carbon (C) exported to the atmosphere and coastal oceans. Climate change impacts flow regimes by increasing both flash floods and droughts. Here, we used a modelling approach to explore the consequences of lateral hydrological contraction, that is, the reduction of the wet portion of the streambed, for POM decomposition and transport at the river network scale. Our model integrates seasonal leaf litter input as generator of POM, transient storage of POM on wet and dry streambed portions with associated decomposition and ensuing changes in reactivity, and transport dynamics through a dendritic river network. Simulations showed that the amount of POM exported from the river network and its average reactivity increased with lateral hydrological contraction, due to the combination of (1) low processing of POM while stored on dry streambeds, and (2) large shunting during flashy events. The sensitivity analysis further supported that high lateral hydrological contraction leads to higher export of higher reactivity POM, regardless of transport coefficient values, average reactivity of fresh leaf litter and differences between POM reactivity under wet and dry conditions. Our study incorporates storage in dry streambed areas into the pulse-shunt concept (Raymond and others in Ecology 97(1):5\uffe2\uff80\uff9316, 2016. https://doi.org/10.1890/14-1684.1), providing a mechanistic framework and testable predictions about leaf litter storage, transport and decomposition in fluvial networks.