Internal loading of phosphate in rivers reduces at higher flow velocity and is reduced by iron rich sand application: an experimental study in flumes

Iron rich glauconite sand as an efficient phosphate immobilising agent in river sediments

“…Amending these Fe rich GS to sediments was successful in decreasing P peaks under natural reducing and GLU-stimulated conditions (Fig. 2), confirming what was found in a flume experiment (Van Dael et al, 2021). Under natural reducing conditions, higher Fe/Al addition and lower P/Fe ratio in the GS-treated sediment explained the lower P release and higher immobilisation efficiency (Table 2).…”

“…A mixture between the sediment and three types of GS were incubated at two GS doses, i.e., 5% and 10% (dry weight of total sediment, equivalent to 1.6 and 3.2 kg m 2 , respectively), including an unamended control. The added amount of GS was based on our previous study (Van Dael et al, 2021). All the treatments were duplicated in a full factorial design except the control that was triplicated (n = 15).…”

“…In our previous work, the immobilisation efficiency of GS as sediment amendment was tested in a dynamic flume system under hypoxic conditions. It illustrated that GS amendment reduced P release from sediment to the overlying water, with three times lower SRP concentration in GS amended treatments than in unamended treatments at a dose of 10% by weight of total sediment (Van Dael et al, 2021). The single GS treatment showed an excellent P immobilisation efficiency, while it was still unclear how the dose and the properties of GS affected its efficiency.…”

Emerging investigator series: impacts of land use on dissolved organic matter quality in agricultural watersheds: a molecular perspective

“…55 Since many of the sampled systems were shallow and close to baseflow conditions in the late summer months, the relatively high precipitation measurements for agriculturally impacted sites may have increased discharge and turbidity by remobilizing phosphorus-containing DOM substrates from sediments. 59 Enhanced surface runoff from higher precipitation levels, the highest DOC concentrations (Fig. 2), and high nutrient richness observed in the sampled agriculturally impacted watersheds can increase the degree of microbial processing in aquatic systems.…”

Seasonal variation and release of soluble reactive phosphorus in an agricultural upland headwater in central Germany

“…P releases from stream sediments tend to be more significant in slow-flowing lowland streams with considerable legacy P from point source inputs (van Dael et al, 2020b). Such experimental evidence of P release from stream sediments is still rare, but new modeling approaches may help to assess potential P losses from stream sediments to the water column (van Dael et al, 2021).…”