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Non-domestic phosphorus release in rivers during low-flow: Mechanisms and implications for sources identification

Dupas, R., Tittel, J., Jordan, P., Musolff, A. and Rode, M. (2018) Non-domestic phosphorus release in rivers during low-flow: Mechanisms and implications for sources identification. Journal of Hydrology, 560 . 141 - 149. [Journal article]

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URL: https://www.sciencedirect.com/science/article/pii/S0022169418301896

DOI: https://doi.org/10.1016/j.jhydrol.2018.03.023

Abstract

Abstract A common assumption in phosphorus (P) load apportionment studies is that P loads in rivers consist of flow independent point source emissions (mainly from domestic and industrial origins) and flow dependent diffuse source emissions (mainly from agricultural origin). Hence, rivers dominated by point sources will exhibit highest P concentration during low-flow, when flow dilution capacity is minimal, whereas rivers dominated by diffuse sources will exhibit highest P concentration during high-flow, when land-to-river hydrological connectivity is maximal. Here, we show that Soluble Reactive P (SRP) concentrations in three forested catchments free of point sources exhibited seasonal maxima during the summer low-flow period, i.e. a pattern expected in point source dominated areas. A load apportionment model (LAM) is used to show how point sources contribution may have been overestimated in previous studies, because of a biogeochemical process mimicking a point source signal. Almost twenty-two years (March 1995-September 2016) of monthly monitoring data of SRP, dissolved iron (Fe) and nitrate-N (NO3) were used to investigate the underlying mechanisms: SRP and Fe exhibited similar seasonal patterns and opposite to that of NO3. We hypothesise that Fe oxyhydroxide reductive dissolution might be the cause of SRP release during the summer period, and that NO3 might act as a redox buffer, controlling the seasonality of SRP release. We conclude that LAMs may overestimate the contribution of P point sources, especially during the summer low-flow period, when eutrophication risk is maximal.

Item Type:Journal article
Keywords:Soluble reactive phosphorus; Iron; Redox processes; Catchment; Point source; Load apportionment
Faculties and Schools:Faculty of Life and Health Sciences > School of Geography and Environmental Sciences
Faculty of Life and Health Sciences
Research Institutes and Groups:Environmental Sciences Research Institute
Environmental Sciences Research Institute > Freshwater Sciences
ID Code:39828
Deposited By: Professor Phil Jordan
Deposited On:23 Mar 2018 17:44
Last Modified:23 Mar 2018 17:44

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