Variability of the colloidal molybdate reactive phosphorous concentrations in freshwaters

Filella, Montserrat; Deville, Claire; Chanudet, Vincent; Vignati, Davide A.L.

doi:10.1016/j.watres.2006.07.010

Cited by 21 publications

(17 citation statements)

References 29 publications

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“…Additionally, the difference in analytical methods could possibly yield different conclusions. While we used ICP-MS to measure the P concentration, many researchers used the colorimetric method (e.g., molybdenum blue) to measure MRP (e.g., Bauer et al, 1996;Filella et al, 2006;Haygarth et al, 1997;Hens and Merckx, 2002). The interference of MRP in the presence of dissolved organic C, anions, and colloids and nanoparticies must be carefully evaluated in each study before drawing any conclusions (Hutchison and Hesterberg, 2004;Sinajetal., 1998).…”

Section: Discussionmentioning

confidence: 99%

“…They also found that colloidal organic macromolecules may not be carriers of dissolved P, but inorganic materials, such as the products of mineral weathering, may also play an important role. Others have also reported dissolved P as MRP in association with inorganic colloidal particles (Bauer et al, 1996;Filella et al, 2006;Hens and Merckx, 2002). Many factors seem to influence the amount of P retained by these colloids, including their chemical composition and relative size (Filella et al, 2006).…”

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Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Rick

Arai

2011

Soil Science Soc of Amer J

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Labile P is a well-recognized nonpoint sourec pollutant in agroecosystems. Predicting the fate and transport of P in watershed systems is critical in protecting water quality. In this case study, we investigated the role of soil nanoparticles in P release in South Carolina agricultural soils. Batch desorption experiments were coupled with scanning and transmission electron microscopy (EM) and x-ray absorption spectroscopy (XAS) to better assess the reactivity of soil nanoparticles. The surface soils contained a total P concentration of 260 to 940 mg kg" ', approximately 40 to 60% of which was ammonium oxalate extractable R The 30-d desorption experiments showed that P desorption was initially rapid, followed by a slow continuous release at pH 5.5 and 7. It was generally not correlated with the release of soil nanoparticles (operationally defined as 10-200 nm). Phosphorus was not readily retained on these nanoparticles at pH 4 to 7. These nanoparticles were rich in Si and S, and coated with Fe and C and trace amounts of P, Ca, Na, Mg, and Al. The EM images of nanoparticle morphology showed C-associated globular formations as well as assembled platelets and spherical nanoparticles. The colloid-and nanoparticlefaeilitated P release has often been suggested as one of the important pathways for P transport in the soil-water environment. This study presents a new aspect of nanoparticle reactivity in the soil environment, however: nanoparticles do not always contribute to P transport processes.

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Section: Discussionmentioning

confidence: 99%

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Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Rick

Arai

2011

Soil Science Soc of Amer J

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“…Nanometer‐sized particles show deviations in their chemical role in contrast to larger particles (Hochella et al, 2008). Natural fine colloids like Fe and Al oxides, clay minerals, as well as their associates with organic compounds occur in ecosystems through weathering, erosion, or mineralization processes (Filella et al, 2006) and have been recognized as ubiquitous in terrestrial ecosystems (Qafoku, 2010; Stone et al, 2010). Natural fine colloids and nanoparticles have the potential to encapsulate and bind nutrients.…”

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confidence: 99%

Distribution of Phosphorus‐Containing Fine Colloids and Nanoparticles in Stream Water of a Forest Catchment

Gottselig

Bol

Nischwitz

et al. 2014

Vadose Zone Journal

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Natural fine colloids and nanoparticles have the potential to encapsulate and bind nutrients. Their size and composition is therefore relevant to understand the transport of essential nutrients like phosphorus in an aquatic ecosystem. The aim of this study was to characterize fine colloidal and nanoparticulate bound P of distinct hydromorphological areas in stream water from a forested test site in a small headwater catchment. Asymmetric flow field flow fractionation coupled online to inductively coupled plasma mass spectrometry was applied for size‐resolved detection of P, Fe, and Al in the fractions. Online P detection was a challenge due to the low concentrations (in this study down to 0.1 μg/L) in many natural waters. Additionally, the “dissolved” organic matter (DOM) content was derived from the online UV signal. The colloidal P occurred in two size fractions (2–20 and 21–300 nm), which constituted up to 100% of the total river P discharge depending on hydromorphology. For the small size fraction, variations in P concentrations correlated with Al variations; in addition, a high Fe presence in both fractions was accompanied by high P concentrations. Moreover, DOM was detected with P in the presence of Fe and Al, suggesting that Fe and Al are carriers of P and associated with organic matter. The developed methodology enables the inputs and source regions of fine colloidal and nanoparticulate fractions within a small river of a headwater catchment to be traced and conceptually defined for the first time.

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“…and dozens of Fe‐containing minerals. Several studies have concluded that the concentration of dissolved Fe in most freshwater streams is generally less than 25 μg L −1 (Jones et al, 1974; Kennedy et al, 1974; Fox, 1988). Therefore, since the Maumee River is circumneutral and well‐oxygenated (i.e., very little Fe 2+ in solution), one can generally assume that any Fe above 25 μg L −1 in a filtered sample can be attributed to nanoparticles in the filtrate.…”

Section: Resultsmentioning

confidence: 99%

Dissolved Reactive Phosphorus Loads to Western Lake Erie: The Hidden Influence of Nanoparticles

River

Richardson

2019

J of Env Quality

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Increased dissolved reactive phosphorus (DRP) fluxes in the Maumee River in the Western Lake Erie watershed have been cited as a cause of recent hypoxia and toxic algal blooms in Western Lake Erie. Dissolved reactive P is operationally defined as the molybdate‐reactive P that passes through a 0.45‐μm filter. Unfortunately, this 0.45‐μm cutoff is not based on solute chemistry; rather, it is based on tradition dating back to the 1940s. This dissolved versus particulate operationally defined threshold may be limiting scientific understanding of the transport of reactive P in the Lake Erie watershed (and beyond). Naturally occurring nanoparticles smaller than 0.45 μm can pass through filters, inflating DRP values, as has been suggested by studies in other watersheds. Transmission electron microscopy of filtered samples from the Maumee River revealed nanoparticles of various mineralogy, which are rich in P. By analyzing public data, we estimate that approximately half of the DRP flux in the Maumee River is not truly dissolved orthophosphate; it is instead particulate P that has passed through 0.45‐μm filters. We also conducted a centrifugation experiment on previously filtered samples that likewise removed 40% of DRP and 75% of Fe. The influence of nanoparticles on DRP loads to Lake Erie has implications, including (i) helping to elucidate where reactive P originates on the landscape, (ii) designing best management practices, and (iii) improving our models of ecological response of nonpoint P loading. Core Ideas The role of nanoparticles in transporting P to Lake Erie is largely ignored. 0.45‐μm filtrate contained nanoparticles rich in P, inflating dissolved reactive P concentrations. Nanoparticles were responsible for approximately half of dissolved reactive P flux.

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Variability of the colloidal molybdate reactive phosphorous concentrations in freshwaters

Cited by 21 publications

References 29 publications

Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Role of Natural Nanoparticles in Phosphorus Transport Processes in Ultisols

Distribution of Phosphorus‐Containing Fine Colloids and Nanoparticles in Stream Water of a Forest Catchment

Dissolved Reactive Phosphorus Loads to Western Lake Erie: The Hidden Influence of Nanoparticles

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