Elemental Composition of Natural Nanoparticles and Fine Colloids in European Forest Stream Waters and Their Role as Phosphorus Carriers

Abstract

Biogeochemical cycling of elements largely occurs in dissolved state, but many elements may also be bound to natural nanoparticles (NNP, 1–100 nm) and fine colloids (100–450 nm). We examined the hypothesis that the size and composition of stream water NNP and colloids vary systematically across Europe. To test this hypothesis, 96 stream water samples were simultaneously collected in 26 forested headwater catchments along two transects across Europe. Three size fractions (~1–20 nm, >20–60 nm, and >60 nm) of NNP and fine colloids were identified with Field Flow Fractionation coupled to inductively coupled plasma mass spectrometry and an organic carbon detector. The results showed that NNP and fine colloids constituted between 2 ± 5% (Si) and 53 ± 21% (Fe; mean ± SD) of total element concentrations, indicating a substantial contribution of particles to element transport in these European streams, especially for P and Fe. The particulate contents of Fe, Al, and organic C were correlated to their total element concentrations, but those of particulate Si, Mn, P, and Ca were not. The fine colloidal fractions >60 nm were dominated by clay minerals across all sites. The resulting element patterns of NNP <60 nm changed from North to South Europe from Fe‐ to Ca‐dominated particles, along with associated changes in acidity, forest type, and dominant lithology.

Enhanced soil aggregate stability limits colloidal phosphorus loss potentials in agricultural systems

“…This was attributed to the greater contents of Fe and Al in acidic soil than in alkaline soil, and that the presence of Al and Fe oxides may have enhanced the adsorption of P and stabilization of soil aggregates [15,31,63]. Al and Fe oxides have been recognized as important carriers of P coll [64][65][66][67].…”

“…We observed that the CR value of (silt + clay)-sized particles was larger than that of aggregates of other sizes, while the CR of large macroaggregates was the lowest in most soils, indicating that the (silt + clay)sized particles contribute more to the P coll loss potential, while macroaggregates immobilized soil P coll . Colloidal P is highly bound to Fe and Al on the surface of macroaggregates [15,68], enabling the formation of a stable composite structure that can resist the shear force of pore flow [64,65]. Similarly, soil macroaggregates can increase the adsorption of P coll on the surface and reduce its mobility [26].…”

Challenges of Reducing Phosphorus Based Water Eutrophication in the Agricultural Landscapes of Northwest Europe

“…Locating and apportionment of the sources and fluxes of the dissolved vs. collodial P conveyed by rivers in landscapes remains a longstanding and fundamental challenge for catchment scientists (see McClain et al, 2003;Bol et al, 2016;Gottselig et al, 2017b;Missong et al, 2018), with major implications for land management and nutrient pollution mitigation strategies. Colloidal P is characterized as dissolved P in most routine water quality monitoring programs (Gottselig et al, 2017a), however, it is believed to have reduced bioavailability compared to the truly dissolved P (Baken et al, 2014).…”

Preferential Riverine Export of Fine Volcanogenic Particles to the Southeast Australian Margin

“…In comparison, the origin of the finest inorganic colloidal fraction transported by rivers remains far less constrained and understood. This question is of particular importance because colloidal nanoparticles have a substantial surface area, and typically serve as sinks and/or sources for trace metals, nutrients and pollutants in the natural environment (e.g., Hill and Aplin, 2001;Pokrovsky and Schott, 2002;Kulaksiz and Bau, 2013;Trostle et al, 2016;Gottselig et al, 2017).…”