Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.5194/hess-27-1261-2023
Lizenz creative commons licence
Titel (primär) Seasonal variation and release of soluble reactive phosphorus in an agricultural upland headwater in central Germany
Autor Rode, M.; Tittel, J.; Reinstorf, F.; Schubert, M.; Knöller, K.; Gilfedder, B.; Merensky-Pöhlein, F.; Musolff, A.
Journal / Serie Hydrology and Earth System Sciences
Erscheinungsjahr 2023
Band/Volume 27
Heft 6
Seite von 1261
Seite bis 1277
Sprache englisch
Topic T5 Future Landscapes
Abstract Soluble reactive phosphorus concentrations (SRP) in agricultural headwaters can display pronounced seasonal variability at low flow, with the highest concentrations occurring in summer. These SRP concentrations often exceed eutrophication levels but their main sources, spatial distribution, and temporal dynamics are often unknown. The purpose of this study is therefore to differentiate between potential SRP losses and releases from soil drainage, anoxic riparian wetlands and stream sediments in an agricultural headwater. To identify the dominant SRP sources we carried out three longitudinal stream sampling campaigns on SRP fluxes. We used salt dilution tests and 222Rn to determine water fluxes in different sections of the stream, and carried out specific sampling for SRP, iron and 14C-DOC to examine possible redox-mediated mobilization from riparian wetlands and stream sediments. The results indicate that a single short section in the upper headwater reach was responsible for most SRP losses to the stream. Analysis of samples taken under summer low flow conditions revealed that the stream-water SRP concentrations, SRP-fraction for dissolved P (DP) and DOC radiocarbon ages matched those in the groundwater entering the gaining section. We argue that the seasonal variation of SRP concentrations was mainly caused by variations in the proportion of groundwater present in the streamflow, and was thus highest during summer low flow periods. Stream-sediment pore water showed evidence of reductive mobilization of SRP but the exchange fluxes were probably too small to contribute substantially to SRP stream concentrations. Examination of the combined results of this campaign and previous monitoring confirms that groundwater is also the main long-term contributor of SRP at low flow and that seepage from agricultural phosphorous is largely buffered in the soil zone. In this headwater, stream SRP loading during low flow is therefore mainly geogenic, while agricultural sources play only a minor role in SRP loading, with the dominant SRP sources being the local Paleozoic greywacke and Devonian shale. Because it is also possible for similar seasonal SRP dilution patterns to be generated by enhanced mobilization in riparian zones or wastewater inputs, precise knowledge of the different input pathways is important to the choice of effective management measures.
dauerhafte UFZ-Verlinkung
Rode, M., Tittel, J., Reinstorf, F., Schubert, M., Knöller, K., Gilfedder, B., Merensky-Pöhlein, F., Musolff, A. (2023):
Seasonal variation and release of soluble reactive phosphorus in an agricultural upland headwater in central Germany
Hydrol. Earth Syst. Sci. 27 (6), 1261 - 1277