Leaching of natural colloids from forest topsoils and their relevance for phosphorus mobility

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

“…Whereas Paruch and co-authors developed microbial source-tracking techniques based on advanced DNA methods to distinguish between different sources of microbial contamination (Paruch et al, 2015;Paruch and Paruch, 2017). Furthermore, recent work do suggest that the composition of P carrier colloids could also be a 'tracer/fingerprint' the source of P (Missong et al, 2018). Secondly, more observational data is needed, combining monitoring at the catchment outlet with in situ observation within functional zones such as riparian wetland or groundwater Gu et al, 2017) to disentangle primary mobilization from secondary delivery/remobilization.…”

“…Iron is a redox sensitive element and is commonly present in the soil-groundwater-surface water system. Mechanisms such as reduction of soil Fe-oxyhydroxides or rewetting of dried soils are known to trigger the release of P in soils, notably that of dissolved and colloidal P fractions (Turner and Haygarth, 2001;Stutter et al, 2009;Blackwell et al, 2010Blackwell et al, , 2013Obour et al, 2011;Scalenghe et al, 2012;Gu et al, 2017;Missong et al, 2018). Redox gradients also result in the precipitation or dissolution of Fe-rich particles, which have a major impact on the fate and bioavailability of P (Jiang et al, 2017).…”

“…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).…”

“…For 30 years or more, much knowledge has been gained on the basic physico-chemical processes by which P is mobilized in soils and transported to rivers, as well as on the chemical forms of the mobilized and transported P. For example, the role of wetting-drying cycles as catalysts for the production and transfer of dissolved and colloidal phosphorus is now well known (e.g., Turner et al, 2003;Butterly et al, 2011;Blackwell et al, 2013;Chen et al, 2016;Gu et al, 2018). In particular, the important role of colloids to serve as carrier of P in soils and waters has been highlighted (e.g., Henderson et al, 2012;Gottselig et al, 2014;Liu et al, 2014;Baken et al, 2016;Jiang et al, 2017;Gu et al, 2018;Missong et al, 2018). Also wellconstrained is the capacity of P to bind with manganese (Mn) and iron oxides and the influence the redox state of soils and waters has on P mobility in the environment (Scalenghe et al, 2012;Van der Grift et al, 2014;Jiang et al, 2015a,b;Smolders et al, 2017).…”

Resilience in coastal dune grasslands: pH and soil organic matter effects on P nutrition, plant strategies, and soil communities

“…However, in contrast to less mobile forms of P, colloidal P with size below 0.5 μm can travel with the water flow. Fine colloids consist for a large part of organic matter (Missong et al 2018) and can be seen as small Fe‐Al‐OM complexes, to which P is weakly sorbed. It is thus not surprising that colloidal P, as well as the total amount of colloids, was significantly higher in acidic than in calcareous dunes.…”