Print Email Facebook Twitter Forms of phosphorus in suspended particulate matter in agriculture-dominated lowland catchments: Iron as phosphorus carrier Title Forms of phosphorus in suspended particulate matter in agriculture-dominated lowland catchments: Iron as phosphorus carrier Author van der Grift, B. Osté, L. Schot, P. Kratz, A. van Popta, E. Wassen, M. Griffioen, J. Publication year 2018 Abstract The fate and environmental effects of phosphorus (P) in natural waters depend on its chemical forms. The particulate P (PP) concentration is dominant over the dissolved P concentration in agriculture-dominated headwaters in the Netherlands. Routine water quality monitoring programmes do not include the chemical fractionation of PP. To quantify the chemical forms of PP under various conditions in six agriculture-dominated lowland catchments in the Netherlands, a sequential chemical extractionmethodwas applied to suspended particulatematter (SPM) samples collected by centrifugation or filtration. Centrifuge samples had lower values for the sumof the PP fractions compared with the filtration samples due to lower contents fromPP fractions other than the Fe-P pool. With an average value of 8.8mg g−1, internationally high P contents of the SPMwere found. Ferric iron-bound P was the most important PP fraction in SPM samples (38–95%; median 74%), followed by organic P (2–38%; median 15%). Exchangeable P ranged from 0.2 to 27%, with a median of 4.4%, Ca-P ranged from 0.1 to 11% with a median of 3.9% and detrital P was present in only a small fraction (0–6%; median 1.1%). Ferric iron-bound P was the dominant PP pool throughout the entire range of watercourses (from headwater ditches to catchment outlets) and in samples taken duringwintermonths aswell as those taken during summermonths. Furthermore, the PP fraction distribution did not change markedly when flow conditions were altered from low to high discharge. The dominance of the Fe-P pool denotes the presence of Fe(III) precipitates in SPM that originate from exfiltration of anoxic Fe-bearing groundwater. These Fe(III) precipitates are a major fraction of the total SPM concentration (4 to 67% as Fe(OH)3; median 18%). Although not measured directly, our results suggest that formation of authigenic Fe(III) precipitates causes a rapid transformation of dissolved P in groundwater to PP in surface water. We advise including sequential chemical extraction of SPM monitoring programmes because the composition of particles is critical for P bioavailability, which is a key driving factor for eutrophication. Subject 2015 GeoGM - GeomodellingELSS - Earth, Life and Social SciencesGeological Survey NetherlandsGeosciences2015 EnergyPhosphate bindingSuspended particulate matterSequential chemical extractionIron hydroxidesNatural waterFiltration To reference this document use: http://resolver.tudelft.nl/uuid:dbfa48ff-ed54-473d-925d-1e138fb76256 TNO identifier 787451 Source Science of the Total Environment, 631–632, 115-129 Document type article Files To receive the publication files, please send an e-mail request to TNO Library.